Comparison of Microlife BP A200 Plus and Omron M6 Blood Pressure Monitors to Detect Atrial Fibrillation in Hypertensive Patients

Introduction

Self-monitoring home blood pressure (BP) devices are currently recommended for long-term follow-up of hypertension and its management. Some of these devices are integrated with algorithms aimed at detecting atrial fibrillation (AF), which is common essential hypertension. This study was designed to compare the diagnostic accuracy of two widely diffused home BP monitoring devices in detecting AF in an unselected population of outpatients referred to a hypertension clinic because of high BP.

Methods

In 503 consecutive patients the authors simultaneously compared the accuracy of the Microlife? BP A200 Plus (Microlife) and the OMRON? M6 (OMRON) home BP devices, in detecting AF.

Results

Systolic and diastolic BP as well as heart rate (HR) values detected by the two devices were not significantly different. Pulse irregularity was detected in 124 and 112 patients with the OMRON M6 and Microlife BP A200 Plus devices, respectively. Simultaneous electrocardiogram (ECG) recording revealed that pulse irregularity was due to AF in 101 patients. Pulse irregularity detected by the OMRON M6 device corresponded to AF in 101, to supraventricular premature beats in 18, and to frequent premature ventricular beat in five patients, respectively. Pulse irregularity detected by the Microlife BP A200 Plus device corresponded to AF in 93, to supraventricular premature beats in 14, and to ventricular premature beats in five patients. The sensitivity for detecting AF was 100%, the specificity was 92%, and diagnostic accuracy 95% for the OMRON M6 and 100%, 92%, and 95 for the Microlife BP A200 Plus, respectively. AF was newly diagnosed by ECG recordings in 47 patients, and was detected in all patients by the OMRON device, and in 42 patients by the Microlife device.

Conclusion

These results indicate that OMRON M6 is more accurate than Microlife BP A200 Plus in detecting AF in patients with essential hypertension. Widespread use of these devices in hypertensive patients could be of clinical benefit for the early diagnosis and treatment of this arrhythmia and related consequences.     

Detection of acute myocardial infarction using the 12-lead ECG plus inverted leads versus the 16-lead ECG (with additional posterior and right-sided chest electrodes)

BACKGROUND: The electrocardiographic (ECG) diagnosis of acute myocardial infarction (MI) should be improved. This might be done either by regarding all 24 aspects (both positive and negative leads), or a subset hereof (e.g. 19-lead ECG), of the conventional 12-lead ECG or by using additional electrodes. The purpose of this study was to investigate the accuracy of the different ECG methods in diagnosing acute ST-elevation MI. METHODS: The study population consisted of 479 patients admitted to Lund University Hospital with acute chest pain. One conventional ECG plus leads V4R, V5R, V8 and V9 were recorded for each patient within 24 h of admittance. Biochemical markers were used as the 'gold standard' for diagnosis of MI. We measured ST-segment elevations in the 12-, 16- and 24-lead postadmission ECGs as well as in the 12-, 19- and 24-lead admission ECGs. RESULTS: The sensitivity for detecting acute MI was 28% for the postadmission 12-lead ECG, 33% for the 16-lead ECG and 37% for the 24-lead ECG. The specificities were 97%, 93% and 95%, respectively. For admission ECGs, the sensitivity was 33% for the 12-lead ECG, 45% for the 19-lead ECG and 49% for the 24-lead ECG, with specificities of 97%, 96% and 94%, respectively. CONCLUSIONS: The sensitivity for detecting acute MI was higher for the 16-, 19- and 24-lead ECGs than for the conventional 12-lead ECGs. Their specificity, however, was slightly lower. If increased sensitivity for detecting MI is desired, the 24-lead or 19-lead should be used as no additional electrodes are required.     

Agreement between actual and synthesized right-sided and posterior electrocardiographic leads in identifying ischemia

ObjectiveA 12-lead electrocardiogram (ECG) is the standard of care for chest pain patients. However, 12-lead ECGs have difficulty detecting ischemia of the right ventricle or posterior wall of the heart. New technology exists to mathematically synthesize these leads from a 12-lead ECG; however, this technology has not been evaluated in the emergency department (ED). We assessed the level of agreement between synthesized 18-lead ECGs and actual 18-lead ECGs in identifying ST elevations, ST depressions, and T wave inversions in ED patients.MethodsActual 12- and 18-lead ECGs were acquired and synthesized 18-lead ECGs were produced based on waveforms from 12-lead ECGs. A blinded cardiologist interpreted the actual and synthesized 18-lead ECGs to identify the presence of abnormalities. Using actual 18-lead ECGs as the reference, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and kappa of synthesized 18-lead ECGs in identifying abnormalities were determined.ResultsData from 295 patients were analyzed. There was 100% agreement between synthesized 18-lead ECGs and actual 18-lead ECGs in identifying ST elevations and ST depressions (sensitivity, specificity, PPV, and NPV of 100%, and kappa of 1.00). Synthesized 18-lead ECGs had 95% sensitivity, 80% specificity, 97% PPV, and 70% NPV in identifying T wave inversions, when compared with actual 18-lead ECGs (kappa: 0.70).ConclusionSynthesized 18-lead ECGs demonstrated 100% agreement with actual 18-lead ECGs in the identification of ST elevations and ST depressions and good agreement in the identification of T wave inversions in a sample of patients ED patients with complaints suspicious of cardiac origin.     

Panoramic ECG display versus conventional ECG: ischaemia detection by critical care nurses

Aim: To compare accuracy and certainty of diagnosis of cardiac ischaemia using the Panoramic ECG display tool plus conventional 12-lead electrocardiogram (ECG) versus 12-lead ECG alone by UK critical care nurses who were members of the British Association of Critical Care Nurses (BACCN). Background: Critically ill patients are prone to myocardial ischaemia. Symptoms may be masked by sedation or analgesia, and ECG changes may be the only sign. Critical care nurses have an essential role in detecting ECG changes promptly. Despite this, critical care nurses may lack expertise in interpreting ECGs and myocardial ischaemia often goes undetected by critical care staff. Method: British Association of Critical Care Nurses (BACCN) members were invited to complete an online survey to evaluate the analysis of two sets of eight ECGs displayed alone and with the new display device. Results: Data from 82 participants showed diagnostic accuracy improved from 67·1% reading ECG traces alone, to 96·0% reading ECG plus Panoramic ECG display tool (P < 0·01, significance level α = 0·05). Participants' diagnostic certainty score rose from 41·7% reading ECG alone to 66·8% reading ECG plus Panoramic ECG display tool (P < 0·01, α = 0·05). Conclusion: The Panoramic ECG display tool improves both accuracy and certainty of detecting ST segment changes among critical care nurses, when compared to conventional 12-lead ECG alone. This benefit was greatest with early ischaemic changes. Critical care nurses who are least confident in reading conventional ECGs benefit the most from the new display. Relevance to clinical practice: Critical care nurses have an essential role in the monitoring of critically ill patients. However, nurses do not always have the expertise to detect subtle ischaemic ECG changes promptly. Introduction of the Panoramic ECG display tool into clinical practice could lead to patients receiving treatment for myocardial ischaemia sooner with the potential for reduction in morbidity and mortality.     

Increased variance of P wave duration on the electrocardiogram distinguishes patients with idiopathic paroxysmal atrial fibrillation

We hypothesized that the variance of P wave duration (P variance) in the 12-lead ECG could reflect the spatial dispersion of P wave duration due to inhomogeneous and delayed propagation of sinus impulses in the atria, and moreover could present better reproducibility than maximum P wave duration and P wave dispersion that have already been used for the prediction of idiopathic paroxysmal AF. We also tested a semiautomated PC-based method to improve the accuracy and reproducibility of P wave measurements. A 12-lead ECG was obtained from 60 patients with idiopathic paroxysmal AF and from 50 healthy controls. All ECGs were analyzed manually using magnifying lens and calipers, while 20 randomly selected ones were scanned and analyzed on screen using common commercial software. P maximum, P dispersion, and P variance were all significantly higher in patients with paroxysmal AF than in controls. A P maximum value of 110 ms, a P dispersion value of 40 ms, and a P variance value of 120 ms2 separated patients from controls with a sensitivity of 88%, 83%, and 80%, respectively and a specificity of 75%, 85%, and 74%, respectively. The reproducibility of P variance was higher compared to P dispersion and P maximum. Finally, the PC-based method significantly increased accuracy and reproducibility of P wave measurements. Thus, the variance of P wave duration could be a useful ECG marker for the prediction of paroxysmal idiopathic AF and the use of PC-based methods may enhance the accurate measuring of P wave duration on the ECG.     

Incremental Changes in QRS Duration Predict Mortality in Patients with Atrial Fibrillation

Background: The purpose of this study was to evaluate serial changes in QRS duration in the 12-lead electrocardiogram (ECG) and their prognostic value in patients with atrial fibrillation (AF).
Methods: Retrospective evaluation of the 12-lead ECG was performed in 822 patients with AF. Inclusion criteria included AF in two sequential ECGs and an echocardiogram obtained within 7 days of the second ECG. The mean age of the 228 patients enrolled in the study was 71.2 ± 12.9 and 45.6% were females. Nearly half of the patients had hypertension (49.5%) and a history of heart failure (44.7%). The patients were followed for 21 ± 19 months, and the end point was all-cause mortality.
Results : Cox proportional hazards analysis demonstrated that the independent predictors of mortality in AF patients were age, renal insufficiency, a history of stroke, heart rate, incremental QRS prolongation (P = 0.0418), and the absence of warfarin use. Patients with QRS prolongation >15 ms had a worse prognosis than those with QRS prolongation ≤15 ms (P = 0.0019).
Conclusions: A progressive increase in QRS duration predicted a poor prognosis in patients with AF in our study. A prospective study is needed to substantiate the prognostic value of QRS prolongation in AF patients.     

Physician attitudes about prehospital 12-lead ECGs in chest pain patients

INTRODUCTION: The prehospital 12-lead electrocardiogram (ECG) has become a standard of care. For the prehospital 12-lead ECG to be useful clinically, however, cardiologists and emergency physicians (EP) must view the test as useful. This study measured physician attitudes about the prehospital 12-lead ECG. HYPOTHESIS: This study tested the hypothesis that physicians had "no opinion" regarding the prehospital 12-lead ECG. METHODS: An anonymous survey was conducted to measure EP and cardiologist attitudes toward prehospital 12-lead ECGs. Hypothesis tests against "no opinion" (VAS = 50 mm) were made with 95% confidence intervals (CIs), and intergroup comparisons were made with the Student's t-test. RESULTS: Seventy-one of 87 (81.6%) surveys were returned. Twenty-five (67.6%) cardiologists responded and 45 (90%) EPs responded. Both groups of physicians viewed prehospital 12-lead ECGs as beneficial (mean = 69 mm; 95% CI = 65-74 mm). All physicians perceived that ECGs positively influence preparation of staff (mean = 63 mm; 95% CI = 60-72 mm) and that ECGs transmitted to hospitals would be beneficial (mean = 66 mm; 95% CI = 60-72 mm). Cardiologists had more favorable opinions than did EPs. The ability of paramedics to interpret ECGs was not seen as important (mean = 50 mm; 95% CI = 43-56 mm). The justifiable increase in field time was perceived to be 3.2 minutes (95% CI = 2.7-3.8 minutes), with 23 (32.8%) preferring that it be done on scene, 46 (65.7%) during transport, and one (1.4%) not at all. CONCLUSIONS: Prehospital 12-lead ECGs generally are perceived as worthwhile by cardiologists and EPs. Cardiologists have a higher opinion of the value and utility of field ECGs. Since the reduction in mortality from the 12-lead ECG is small, it is likely that positive physician attitudes are attributable to other factors.     

Electrocardiographic changes during prolonged coronary artery occlusion in man: comparison of standard and high-frequency recordings

Detection of acute myocardial ischaemia using electrocardiographic methods is generally based on assessment of the ST segments in the standard 12-lead electrocardiogram (ECG). Several studies have also shown changes in high-frequency QRS components during acute ischaemia. The purpose of the present study was to determine the changes in high-frequency QRS components during prolonged percutaneous transluminal coronary angioplasty (PTCA) and to compare these changes with ST-segment deviations in the standard 12-lead ECG. The study population consisted of 19 patients receiving prolonged PTCA. Standard and high-resolution signal-averaged ECGs were recorded before and during balloon inflation. The high-resolution recordings were performed using bipolar X, Y and Z leads. The QRS complexes in the high-resolution signal-averaged ECGs were analysed within a bandwidth of 150–250 Hz. During inflation, significant reductions in high-frequency QRS components were observed (12–72%). Changes in the high-frequency QRS components were seen in four of the patients without ST-segment deviation in the standard ECG. The correlation between the ST-segment deviation and the reduction in high-frequency QRS components was weak (r = 0·27). Acute coronary artery occlusion produces changes in high-frequency QRS components, even in the absence of ST-segment deviation in the standard ECG. Further studies need to be carried out to evaluate whether analysis of high-frequency QRS components could provide a method for detecting myocardial ischaemia and give additional information to that available in the ST segment in the standard ECG.     

Blood pressure monitoring with home monitors versus mercury sphygmomanometer

OBJECTIVE: To determine the accuracy of three automatic monitors (arm, wrist, finger) for blood pressure measurement manufactured by Omron compared with a standard mercury sphygmomanometer. PRIMRY END POINT: Difference in the mean blood pressure readings from each monitor; the secondary end point was difference in pulse readings. DESIGN: A single-visit, crossover trial tested each device twice on the left arm of each participant; the average of the two readings was recorded. The pulse readings from each monitor were also recorded. ANOVA was used to compare mean blood pressure readings and pulse readings from each device. RESULTS: A total of 55 persons (mean age 53 y; 36 women) met inclusion criteria and completed the study. The mean systolic and diastolic readings obtained from the electronic arm unit were comparable to the mercury readings (124.4/78.02 vs. 129.45/77.87 mm Hg, respectively; p > 0.05 for both readings). The mean results obtained from the wrist and finger monitors differed significantly from those of the mercury readings (145.44/89.58 and 113.94/69.07 mm Hg, respectively; p < 0.05 for both monitors compared with control). No difference was measured in the mean pulse readings between the comparisons (p = 0.72). The absolute difference in systolic and diastolic blood pressure readings from control varied the least wih the arm monitor. CONCLUSIONS: Compared with the mercury sphygmomanometer, the arm monitor was the most accurate in measuring blood pressure. The wrist and finger monitors resulted in statistically significant mean systolic and diastolic differences compared with the mercury sphygmomanometer.     

The accuracy of pulse oximetry in the emergency department

The objective of this retrospective study was to identify factors affecting the accuracy of pulse oximetry in the ED. Over a 3-year period, 664 consecutive emergency department (ED) patients had simultaneous arterial blood gas (ABG) and pulse oximeter readings taken. Pulse oximeter saturations (SpO2) were compared with ABG CO-oximeter saturations (SaO2) for accuracy. Multiple variables including age, sex, hemoglobin, bicarbonate, pH, and carboxyhemoglobin (COHb) were analyzed to see if they affected SpO2 accuracy. ROC curves were used to determine the best pulse oximeter threshold for detecting hypoxia. Using multivariate analysis, COHb was the only statistically significant factor affecting the accuracy of pulse oximetry. In patients with COHb <2%, SpO2 overestimated SaO2 by more than 4% in 8.4% of cases. In patients with COHb > or = 2%, SpO2 overestimated SaO2 by more than 4% in 35% of cases. The best pulse oximetry threshold for detecting hypoxia is 92%. At this threshold, if COHb is <2%, pulse oximetry has a sensitivity of 0.92 and specificity of 0.90. If COHb is > or =2%, sensitivity is 0.74 and specificity is 0.84. For patients likely to have a COHb < 2, pulse oximetry is an effective screening tool for detecting hypoxia. However, more caution must be exercised when using pulse oximetry in patients likely to have a COHb > or = 2%.     

Cellular technology improves transmission success of pre-hospital electrocardiograms

Study objectiveIn rural settings, long distances and transport times pose a challenge for achieving early reperfusion goals in patients with ST-elevation myocardial infarction (STEMI). This study investigated the association between the method of pre-hospital 12-lead ECG transmission (radio transmission vs. cellular phone transmission) and the success of transmission and legibility of 12-lead ECGs in a rural setting.MethodsObservational study of pre-hospital 12-lead ECG transmission to the emergency department (ED) in a predominantly rural area. Success of transmission and the legibility of the 12-lead ECG were analyzed to identify barriers to 12-lead ECG transmission and reasons for failed transmission.ResultsEmergency medical services performed ECGs on 1140 patients, 917 of which they attempted to transmit, including 43 cases requiring emergent catheterization. Twelve-lead ECG transmission was successful in 236 (70%) of 337 radio attempts and 441 (76%) of 580 cellular attempts (difference 6.0%, 95% CI 1.1-12.1). Legibility increased from 164 (49%) of 337 radio attempts to 389 (67%) of 580 cellular attempts (difference 18.4%, 95% CI 11.8–24.9).ConclusionThe success of transmission and legibility of 12-lead ECGs was significantly higher with cellular technology by emergency medical service agencies in comparison to radio transmission. In rural settings with lengthy transport times, utilization of cellular technology for transmission of pre-hospital 12-lead ECGs may improve door-to-balloon times for STEMI patients.     

Signal quality indices and data fusion for determining clinical acceptability of electrocardiograms

A completely automated algorithm to detect poor-quality electrocardiograms (ECGs) is described. The algorithm is based on both novel and previously published signal quality metrics, originally designed for intensive care monitoring. The algorithms have been adapted for use on short (5-10?s) single- and multi-lead ECGs. The metrics quantify spectral energy distribution, higher order moments and inter-channel and inter-algorithm agreement. Seven metrics were calculated for each channel (84?features in all) and presented to either a multi-layer perceptron artificial neural network or a support vector machine (SVM) for training on a multiple-annotator labelled and adjudicated training dataset. A single-lead version of the algorithm was also developed in a similar manner. Data were drawn from the PhysioNet Challenge 2011 dataset where binary labels were available, on 1500 12-lead ECGs indicating whether the entire recording was acceptable or unacceptable for clinical interpretation. We re-annotated all the leads in both the training set (1000 labelled ECGs) and test dataset (500 12-lead ECGs where labels were not publicly available) using two independent annotators, and a third for adjudication of differences. We found that low-quality data accounted for only 16% of the ECG leads. To balance the classes (between high and low quality), we created extra noisy data samples by adding noise from PhysioNet's noise stress test database to some of the clean 12-lead ECGs. No data were shared between training and test sets. A classification accuracy of 98% on the training data and 97% on the test data were achieved. Upon inspection, incorrectly classified data were found to be borderline cases which could be classified either way. If these cases were more consistently labelled, we expect our approach to achieve an accuracy closer to 100%.     

The use of a portable three-lead ECG monitor to detect atrial fibrillation in general practice

Objective: To evaluate how well an inexpensive portable three-lead ECG monitor PEM identified patients with atrial fibrillation (AF) compared to a normal 12-lead ECG.

Design: Cross-sectional method comparison study.

Setting: From April 2014 to February 2015, we included patients coming to the general practice clinic “Lægerne Sløjfen”, Aalborg, Denmark for a routine ECG. Patients with severe dementia, mental illness or poor ECG readings were excluded. After oral and written informed consent an ECG and PEM recordings were obtained simultaneously. The PEM recordings were analyzed by two general practitioners (GPs) in training and ECG recordings were evaluated by a senior GP and a cardiologist. Both the PEM and the ECG recordings were analysed blinded.

Subjects: Ninety-three patients were included and four were excluded due to poor ECG readings.

Main outcome measures: The sensitivity and specificity of PEM compared to a standard 12-lead ECG.

Results: Eighty-nine of the 93 (95.7%) patients had ECGs of a satisfactory technical quality and were included in the study. The sensitivity of diagnosing AF by PEM recordings was 86.7% and the specificity was 98.7% when compared to a 12-lead ECG. According to the cardiologist, the misclassification of three PEM recordings were due to interpretation errors and not related to the PEM recording per se.

Conclusions: The inexpensive portable PEM device recording diagnosed AF with a high sensitivity and specificity.

• KEY POINTS

• Simple ECG monitors could be useful to identify atrial fibrillation and thereby lead to a better prevention of stroke.

• The PEM device was easy to use and 95.7% of the recordings were technically acceptable for detecting atrial fibrillation.

• The PEM device has a high sensitivity and specificity in detecting atrial fibrillation compared to a standard 12-lead ECG.

• Further studies should evaluate the clinical usefulness of the PEM device, e.g. to detect intermittent atrial fibrillation.

     

Sinus and paced P wave duration and dispersion as predictors of atrial fibrillation after pacemaker implantation in patients with isolated sick sinus syndrome

The aim of this study was to prospectively evaluate the sinus and the paced P wave duration and dispersion as predictors of AF after pacemaker implantation in patients with isolated sick sinus syndrome (SSS). The study included 109 (69 women, mean age 72 +/- 11 years) patients with SSS, 59 with bradycardia-tachycardia syndrome (BTS). A 12-lead ECG was recorded before pacemaker implantation and during high right atrial and septal right atrial pacing at 70 and 100 beats/min. The ECGs were scanned into a computer and analyzed on screen. The patients were treated with AAIR (n = 52) or DDDR pacing. The P wave duration was measured in each lead and mean P wave duration and P wave dispersion were calculated for each ECG. AF during follow-up was defined as: AF in an ECG at or between follow-up visits; an atrial high rate episode with a rate of > or =220 beats/min for > or =5 minutes, atrial sensing with a rate of > or =170 beats/min in > or =5% of total counted beats, mode-switching in >/=5% of total time recorded, or a mode switching episode of > or =5 minutes recorded by the pacemaker telemetry. The ECG parameters were correlated to AF during follow-up. Mean follow-up was 1.5 +/- 0.9 years. None of the ECG parameters differed between patients with AF and patients without AF during follow-up, nor was there any difference between groups after correction for BTS and age. BTS was the strongest predictor of AF during follow-up (P < 0.001). P wave duration and dispersion measured before and during pacemaker implantation were not predictive of AF after pacemaker implantation in patients with isolated SSS.     

Evaluation of the risk of atrial fibrillation using disperse analysis of P in ECG

The aim of the study was to find new ECG markers of atrial fibrillation (AF) risk. The clinico-functional status of 371 patients was studied using standard 12-lead ECG. According to 24-hour monitoring, 190 (51.2%) patients had AF, while 181 (48.8%) patients did not. The groups were age- and gender-comparable. The study demonstrated low significance of P elongation in standard lead II in the two groups (15.3% and 18.8% of cases, respectively) and Macrus index (18.9% and 17. 7%, respectively). At the same time, the minimum P length in all 12 leads was significantly lower in patients with AF (an average of 63.28 and 70.05 msec, respectively, p < 0. 05). The most significant differences were observed in the values of normalized P length (an average of 15.68 and 29.50 msec, respectively, p < 0.05) and P dispersion (an average of 51.28 and 42.39 msec, p < 0.05). The study found certain peculiarities of the dynamics of these parameters in correlation with a growth of AF frequency, as well as the importance of their correlation with the presence of heart failure and stable stenocardia. The authors presume that new markers of AF risk should be evaluated through disperse analysis of standard ECG registered in 12 standard leads.     

Statistical Methodology: VI. Mathematical Modeling of the Electrocardiogram Using Factor Analysis

Abstract. The ECG is a 12-lead-vector system and is known to contain redundant information. Factor analysis (PA) is a statistical technique that improves measured data and eliminates redundancy by identifying a minimum number of factors accounting for variance in the data set. Objective: To identify the minimum number of lead-vectors required to predict the 12-lead ECG.
Methods: A total of 104 ECGs were obtained from 24 normal men, 22 normal women, and 28 men and 30 women with variable pathologies. Each ECG lead was simultaneously acquired and digitized, resulting in a voltage-time data array stored for mathematical analysis. Each array was factor-analyzed to identify the minimum number of lead-vectors spanning the ECG data space. The 12-lead ECG was then predicted from this minimum lead-vector set. ANOVA was used to test for statistical significance between normal and pathologic data groups.
Results: FA revealed that 3 lead-vectors accounted for 99.12%± 0.92% (95% CI ± 0.18%) of the variance contained in the 12-lead ECG voltage-time data for all 104 cases. There were no statistically significant differences between men and women (99.25%± 0.66% vs 98.98 ± 1.11%; p = 0.139). Statistically significant differences were noted between normal and acute myocardial infarction ECGs (99.5%± 0.27% vs 98.66 ± 1.25%; p = 0.00003). The measured and predicted leads were almost identical. A 3-dimensional spatial ECG derived from the 3-lead-vector set resulted in variable curved surfaces that differed by pathology.
Conclusions: The 12-lead ECG can be derived from only 3 measured leads and graphed as a 3-D spatial ECG. This type of data processing may lead to instantaneous acquisition and may enhance the diagnostic capability of the ECG from routine bedside telemetry equipment.     

Matrix of regularity for improving the quality of ECGs

The 12-lead electrocardiography (ECG) is the gold standard for diagnosis of abnormalities of the heart. However, the ECG is susceptible to artifacts, which may lead to wrong diagnosis and thus mistreatment. It is a clinical challenge of great significance differentiating ECG artifacts from patterns of diseases. We propose a computational framework, called the matrix of regularity, to evaluate the quality of ECGs. The matrix of regularity is a novel mechanism to fuse results from multiple tests of signal quality. Moreover, this method can produce a continuous grade, which can more accurately represent the quality of an ECG. When tested on a dataset from the Computing in Cardiology/PhysioNet Challenge 2011, the algorithm achieves up to 95% accuracy. The area under the receiver operating characteristic curve is 0.97. The developed framework and computer program have the potential to improve the quality of ECGs collected using conventional and portable devices.     

The V-Quick patch versus the standard 12-lead ECG system: time is the essence

Introduction

The V-Quick patch template system is compared with the standard 12-lead electrocardiogram (ECG) acquisition technique in this paper. The objectives of the study were: (a) to study and compare the time taken to produce the printed 12-lead ECG and (b) to look at the level of agreement when the ECGs were compared by two blinded, independent assessors.

Methods

One hundred and fifty each of male and female volunteers signed an informed consent form to participate in the clinical study. Nurses were put through a 4-h training session to familiarise themselves with the V-Quick patch system. The timings were measured with a stopwatch with the specific start and end points defined. The final ECG printouts were then compared by two blinded, independent assessors for several set criteria.

Results

The V-Quick patch system was proved to be significantly faster than the standard 12-lead system in the acquisition of the ECG in both male and female volunteers. The time taken in male volunteers was also noted to be significantly faster than in female volunteers.

Conclusion

The two assessors shared a 100% agreement level when comparing the ECGs acquired by both techniques in the same individual (intra-assessor agreement) and when each ECG was read by the two assessors separately (inter-assessor agreement).     

QT dispersion from body surface ECG does not reflect the spatial dispersion of ventricular repolarization in sheep

The correlation between the QT dispersion on body surface ECG and the dispersion in ventricular repolarization from the cardiac surface was studied in six sheep anesthetized with pentobarbital. The standard 12-lead body surface ECG and multiple ventricular epicardial ECGs were simultaneously recorded. The activation-recovery interval (ARI) was measured from the unipolar epicardial ECGs. The pooled QT dispersion from the six animals was significantly smaller than the pooled ARI dispersion (22.7 +/- 2.6 vs 33.0 +/- 6.9 ms, P < 0.01). There was no correlation between the QT and ARI dispersion. The unipolar epicardial ECGs were then converted into bipolar ECGs and epicardial QT intervals were subsequently acquired from these ECGs. The average value of epicardial QT dispersion from the six animals was similar to that of body surface ECG, but was less than the ARI dispersion (27.5 +/- 6.8 vs 33.0 +/- 6.9, P < 0.01). A good correlation between the epicardial QT dispersion and ARI dispersion was identified (r = 0.84, P < 0.05). In addition, a prolongation in ventricular repolarization, induced by an increase in coronary flow, elicited a pooled ARI dispersion of 62.3 +/- 6.2 ms (n = 6), which was larger than the simultaneously recorded body surface QT dispersion (28.3 +/- 9.8 ms, n = 6, P < 0.01). No correlation between the ARI and QT dispersion was found in the presence of the prolonged ventricular repolarization. In conclusion, QT dispersion from a 12-lead body surface ECG seems to underestimate the spatial dispersion of ventricular repolarization acquired from sheep epicardium.     

Detection of STEMI Using Prehospital Serial 12-Lead Electrocardiograms

Objective: Repeated or serial 12-lead electrocardiograms (ECGs) in the prehospital setting may improve management of patients with subtle ST-segment elevation (STE) or with a ST-segment elevation myocardial infarction (STEMI) that evolves over time. However, there is a minimal amount of scientific evidence available to support the clinical utility of this method. Our objective was to evaluate the use of serial 12-lead ECGs to detect STEMI in patients during transport in a Canadian emergency medical services (EMS) jurisdiction. Methods: We performed a retrospective study of suspected STEMI patients transported by EMS in the Chaudière-Appalaches region (Québec, Canada) between August 2006 and December 2013. Patients were monitored by a serial 12-lead ECG system where an averaged ECG was transmitted every 2 minutes. Following review by an emergency physician, ECGs were grouped as having either a persistent STE or a dynamic STE that evolved over time. Results: A total of 754 suspected STEMI patients were transported by EMS during the study period. Of these, 728 patients met eligibility criteria and were included in the analysis. A persistent STE was observed in 84.3% (614/728) of patients, while the remaining 15.7% (114/728) had a dynamic STE. Among those with dynamic STE, 11.1% (81/728) had 1 ST-segment change (41 no-STEMI to STEMI; 40 STEMI to no-STEMI) and 4.5% (33/728) had ≥ 2 ST-segment changes (17 no-STEMI to STEMI; 16 STEMI to no-STEMI). Overall, in 8.0% (58/728) of the cohort, STEMI was identified on a subsequent ECG following an initial no-STEMI ECG. Conclusions: Through recognition of transient ST-segment changes during transport via the prehospital serial 12-lead ECG system, STEMI was identified in 8% of suspected STEMI patients who had an initial no-STEMI ECG.