Comparison of dopa decarboxylase inhibitor (carbidopa) combined with levodopa and levodopa alone on the cardiovascular system of patients with parkinson's disease.

The effects of carbidopa combined with levodopa (carbidopa/levodopa) and levodopa alone on the cardiovascular system of patients with Parkinson's disease were evaluated. Thirty-eight patients who had been on stable doses of levodopa underwent a complete cardiac examination, including measurement of recumbent and erect blood pressure and 24 hour ambulatory electrocardiographic monitoring. Patients were classified with respect to the presence or absence of clinically significant heart disease and ventricular arrhythmias. Nineteen of the 38 patients (50 percent) had heart disease, and 12 (32 percent) had significant ventricular arrhythmias. Eleven of the 12 with arrhythmias had underlying heart disease. The incidence of arrhythmias did not correlate with the dose of levodopa. The patients were subsequently randomly assigned to treatment groups receiving either carbidopa/levodopa or levodopa alone. There was no significant difference in the severity of ventricular arrhythmias or in the incidence of orthostatic hypotension in the group assigned to carbidopa/levodopa compared with the group receiving levodopa.