Dopamine agonists and valvular heart disease in patients with Parkinson's disease: evidence and mystery

Journal of Neurology - High doses of the ergot dopamine agonists, pergolide and cabergoline, frequently cause valvular regurgitation and, somewhat less frequently, valvular heart disease (VHD) in...     

Dopamine agonists and Parkinson's disease

The therapeutic use of dopamine agonists for Parkinson's disease, clinical guidelines for their introduction into antiparkinson regimens, and their range of adverse effects are reviewed. The role played by the dopaminomimetic ergots in elucidating dopamine receptor function, and laboratory methods that identify dopamine agonists, are also examined.     

Dopamine agonists in Parkinson's disease

Dopamine agonists are established as effective drugs for the symptomatic treatment of Parkinson's disease (PD) throughout its course. As monotherapy, they produce effective control of motor symptoms and combine this with a low risk for motor complications. As an adjunct to levodopa, they improve motor control and limit the need for levodopa in those patients in whom this may be considered relevant. The non-ergot dopamine agonists in particular have a good safety profile, although as with other agonists, sedation, and cognitive and behavioral problems may be limiting in some patients. Pramipexole has shown benefit in improving depressive symptoms in PD. Ropinirole and pramipexole have both demonstrated a reduction in the rate of loss of nigrostriatal innervation as determined by imaging in PD patients, when compared with levodopa. Thus, dopamine agonists contribute to several dimensions of the management of PD and have become an integral part of the disease treatment algorithm.     

Dopamine agonists and neuroprotection in Parkinson's disease

Dopamine agonists are effective in reversing the motor symptoms of Parkinson's disease (PD). They have also shown that they can delay or prevent the onset of motor complications associated with levodopa use. Recent attention has focused on the possible role for dopamine agonists in neuroprotection. Numerous studies have demonstrated that a variety of dopamine agonists can protect dopaminergic neuronal function in several toxin model systems. Pramipexole in particular has shown efficacy in reducing toxicity to MPTP, MPP, rotenone and 6-hydroxydopamine. Recent studies in early PD using imaging parameters as a surrogate marker of dopaminergic neuronal integrity have shown that pramipexole and ropinirole can apparently retard the rate of cell loss. These observations are of considerable interest, but additional studies are required to confirm a neuroprotective function for these dopamine agonists.     

Dopamine agonists in the treatment of Parkinson's disease

Dopamine agonists are highly effective as adjunctive therapy to levodopa in advanced Parkinson's disease and have rapidly gained popularity as a monotherapy in the early stages of Parkinson's disease for patients less than 65-70 years old. In the latter case, dopamine agonists are about as effective as levodopa but patients demonstrate a lower tendency to develop motor complications. However, dopamine agonists lose efficacy over time and the number of patients remaining on agonist monotherapy decreases to less than 50% after 3 years of treatment. Thus, after a few years of treatment the majority of patients who started on dopamine agonists will be administered levodopa, in a combined dopaminergic therapy, in order to achieve a better control of motor symptoms.     

Two cases of patients with Parkinson's disease developing valvular heart disease while taking cabergoline

We experienced 2 patients of valvular heart disease in Parkinson's patients taking cabergoline. Patient 1 was a 79-year-old woman who began taking 4 mg cabergoline daily after being diagnosed with Parkinson's disease (PD) in June 2003. She presented with dyspnea in November 2005. The patient had cardiomegaly, pulmonary congestion, and pleural effusion, and an echocardiogram showed valvular heart disease in the form of aortic regurgitation (AR) (grade I), tricuspid regurgitation (TR) (grade I), and mitral regurgitation (MR) (grade III). Cabergoline was thought to have caused these phenomena, so it was replaced with pramipexole, and after administration of diuretics and angiotensin-converting enzyme inhibitors (ACEIs) the patient's symptoms gradually disappeared. MR, AR and TR also disappeared 3 months later. Patient 2 was a 74-year-old woman who presented with sluggish movement in April 2001 and subsequently developed Parkinson's. While being administered 700 mg levodopa (Menesit) and 4 mg cabergoline, the patient presented with shortness of breath in April 2005. An echocardiogram showed valvular heart disease in the form of MR (grade I) and TR (grade I). Heart function improved with the administration of diuretics. However, heart function again worsened in November 2005, and the patient presented with edema of the lungs and lower limbs. An echocardiogram in January 2006 showed worsening MR (grade III) and TR (grade II), and the patient also had pulmonary hypertension. ACEIs were administered along with diuretics and cabergoline was replaced with pramipexole, but the patient also developed malignant syndrome and disseminated intravascular coagulation (DIC) and later died. Patient 2 is the first case in Japan of death due to heart failure caused by the side effects of cabergoline. Caution is usually needed when treating a Parkinson's patient for valvular heart disease due to a dopamine agonist, and periodic checks for heart murmurs and echocardiography are crucial. When signs of heart failure develop during treatment with an ergot preparation of dopamine agonist, it is essential to immediately either stop the administration of the ergot preparation or change to a non-ergot preparation of dopamine agonist.     

Dopamine agonists, receptor selectivity and dyskinesia induction in Parkinson's disease

Levodopa and the dopamine agonists are effective symptomatic treatments for Parkinson's disease, and all patients receive at least one of these agents during their illness. Long-term use of levodopa is commonly associated with motor complications such as dyskinesia, and both the dosing frequency and total daily dose of levodopa determine the rate of onset and severity. Dopamine agonists have gained popularity as first-line monotherapy in Parkinson's disease, as they effectively reverse motor deficits and reduce the risk of motor complications. Long-acting dopamine agonists providing continuous, rather than pulsatile, dopaminergic stimulation appear able to avoid dyskinesia induction. Current treatments act predominantly on D2 receptors, but drugs acting on both the D1 and D2 receptor families may produce an additive motor response, although this remains to be proven in patients with Parkinson's disease. Most currently used dopamine agonists are selective for D2-like receptors, with only pergolide and apomorphine potentially interacting with D1 receptor populations.     

High risk factors for valvular heart disease from dopamine agonists in patients with Parkinson’s disease

An association between ergot-derived dopamine agonists and asymptomatic valvular heart disease in Parkinson’s disease has been established. For safe use of these agonists, it is important to specify those at high risk for valvular heart disease among patients with Parkinson’s disease. We performed a nested case-control study of 223 patients with Parkinson’s disease. In results of multivariable logistic analyses, use of pergolide, use of cabergoline, age, male sex, and hypertension were independent significant risk factors for left-sided valvular regurgitation. In patients receiving cabergoline or pergolide, elderly (≥70 years) hypertensive patients had a markedly high risk for valvular regurgitation (odds ratio 94.5) as compared to non-elderly (<70 years) patients without hypertension. The risk of valvular regurgitation caused by pergolide or cabergoline was found to be highly enhanced by comorbid hypertension or aging, suggesting that special attention should be paid when prescribing cabergoline or pergolide for those patients. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Heart valvular disease in patients with Parkinson's disease treated with high-dose pergolide

The authors report the clinical, echocardiographic, and pathologic findings in two patients treated with more than 5 mg of pergolide daily who developed symptomatic severe heart failure due to restrictive valvular disease. They also describe the echocardiographic data of another eight patients taking similar doses of pergolide presenting no clinical signs of heart failure. The findings suggest a possible role of high doses of pergolide in inducing restrictive valvular disease.     

Meta-analysis of heart valve abnormalities in Parkinson's disease patients treated with dopamine agonists.

Valvular heart disease in patients being treated with ergot-derivative dopamine agonists (Ergot-DA) for Parkinson's disease has been reported to occur as a consequence of serotonine receptor stimulation. Goal of this analysis was to estimate the incidence of those changes from recently published studies and to determine its clinical relevance. Medline searches were performed to identify cross-sectional, echocardiographic studies comparing patients treated with dopamine agonists or controls, in terms of valvular changes. Observational studies of valve changes in Parkinsonian patients were used to estimate the incidence of severe valvulopathy. The results from 7 cross-sectional studies including 477 patients treated with Ergot-DA, 127 patients with non-Ergot-DA, and 364 control patients were analyzed. Moderate-to-severe valvular changes were detected in 26% of patients treated with Ergot-DA, 10% of patients treated with non-Ergot DA, and 10% of control patients. Severe valvulopathy was less than 1% both in cross-sectional and observational studies. The high rate of moderate valvular changes in patients treated with Ergot-DA suggests that close surveillance of the patients is required. Severe valvulopathy was less than 1% in the studies analyzed.     

Dopamine agonists in the treatment of early Parkinson's disease: a meta-analysis

Our objective was to perform a meta-analysis of randomized controlled trials of dopamine agonists (DA) as monotherapy as well as adjunctive therapy for the early treatment of Parkinson's disease (PD). A systematic literature search was conducted through April 2007. Both efficacy and safety endpoints were evaluated. DA monotherapy showed superior efficacy but more frequent adverse events compared to placebo. In addition, DA demonstrated inferior efficacy to levodopa, but was associated with fewer motor complications. However, DAs were associated with a greater incidence of nuisance side effects, such as hallucinations, somnolence and dizziness. The use of DA is an effective treatment option for the treatment of early PD and appears especially useful among PD patients with wearing-off phenomenon or dyskinesias on levodopa; however it may result in more adverse events and higher withdrawal rates.     

Valvular heart disease in Parkinson's disease treated with ergot derivative dopamine agonists.

Valvular heart disease, associated with ergot derivative dopamine agonists, has been reported in patients with Parkinson's disease (PD). There are few comparative studies on the frequency, severity, and dose dependency of valvular disease associated with ergot derivatives. We analyzed these factors in 58 PD patients who were taking ergot derivatives (22 were taking bromocriptine and 36 were taking pergolide) and compared them with 20 age-matched controls based on the two-dimensional echocardiographic findings. Aortic, mitral, and tricuspid valvular thicknesses, as well as tenting areas and tenting distance of the mitral valve were measured. We also assessed the correlation between the cumulative or daily doses of ergot derivatives and each valvular parameter. There was no significant increase in the frequency of valvulopathy in the PD patients taking bromocriptine or pergolide. We identified a positive correlation between the daily dose of pergolide and the tenting area of the mitral valve (r = 0.385; P = 0.020). However, other valvular parameters were not found to correlate with the age, disease duration, treatment duration, or dosage of medication. Our study failed to uncover definitive harmful effects of ergot derivative dopamine agonists on cardiac valves; this is considering the relatively lower daily doses than other reported cases. To establish a dosage dependency with valvulopathy, a more detailed study with higher doses of ergot derivatives for longer duration of treatment may be needed.     

Valvular heart disease in Parkinson's disease patients treated with dopamine agonists: a reader-blinded monocenter echocardiography study.

Fibrotic valvular heart disease (VHD) has been reported in association with ergot dopamine agonists (DAs), but the current database is insufficient regarding clinical relevance and comparison to data on non-ergot DAs. We evaluated the effects of four DAs (pergolide, cabergoline, ropinirole, pramipexole) on morphology and function of heart valves in patients with Parkinson's disease (PD) to determine the frequency and clinical relevance of DA-induced VHD. A total of 85 patients treated with ergot or non-ergot DAs and 38 age-matched controls were evaluated by transthoracic echocardiography. Valvular pathology was assessed by established criteria of valvular regurgitation and a VHD scoring system. Both grading systems revealed increased frequency of VHD in ergot DA patients compared to both non-ergot DA patients and controls with 22% of ergot DA patients having moderate VHD versus 3% of non-ergot DA patients and none of controls (P = 0.001). We did not find correlations of echocardiographic findings with duration/cumulative dose of treatment, age, or vascular risk factors. Our data suggest that ergot DAs are associated with higher prevalence of VHD compared to non-ergot DAs and controls. Standard echocardiography seems sufficient to detect VHD in PD patients treated with DAs.     

Dopamine agonists in the treatment of non-motor symptoms of Parkinson's disease: depression

Background:  Psychiatric symptoms such as depression are common non-motor comorbidities of Parkinson's disease (PD). Depressive symptoms in patients with PD are a major complication that impairs quality of life independent of motor symptoms. The relationship between PD and comorbid depression is not completely understood.
Methods and Results:  Evidence suggests that both PD and depression may be mediated by degeneration of the dopaminergic system. Recent and ongoing research is exploring the potential role of dopamine agonists in the treatment of depressive symptoms in patients with PD.
Conclusion:  Experimental studies suggest a primary relationship and the importance of dopaminergic mechanisms in PD and depression. Patients with PD and depression might benefit from a global approach. Thus, treatment with dopamine agonists promises to reduce motor complications as well as depressive symptoms, avoiding multiple drug interactions as well as possible antidepressant medication side effects.     

Dopamine receptors in Parkinson's disease

1. Parkinson's disease is associated with profound decreases in striatal dopamine concentrations. 2. There are significant increases in the densities of striatal D1 and D2 receptors as part of the compensatory mechanism. 3. Levodopa therapy induces a down-regulation of both D1 and D2 receptors to normal densities. 4. Positron emission tomography detects striatal changes in early Parkinson's disease or toxin-induced parkinsonism.