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Verapamil prevents silent myocardial perfusion abnormalities during exercise in asymptomatic patients with
J E Udelson1, R O Bonow, P T O'Gara
1Cardiology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland.
Insights
Verapamil therapy improved exercise-induced 201Tl perfusion defects in hypertrophic cardiomyopathy (HCM) patients. This suggests medical treatment can favorably modify silent myocardial ischemia in HCM.
Area of Science:
- Cardiology
- Nuclear Medicine
Background:
- Asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM) often exhibit reversible 201Tl perfusion defects during exercise, indicative of silent myocardial ischemia.
- The dynamic nature of these perfusion defects and their potential modification by medical therapy remain areas of investigation.
Purpose of the Study:
- To investigate whether oral verapamil can favorably alter exercise-induced 201Tl perfusion defects in patients with hypertrophic cardiomyopathy.
Main Methods:
- A study involving 29 patients with HCM (aged 12-55 years) who underwent exercise 201Tl emission computed tomography (ECT) under control conditions and after one week of verapamil therapy.
- Perfusion defects were assessed using a standardized scoring system on midventricular short-axis images, with improvements defined by significant changes in regional scores.
Main Results:
- Exercise treadmill time slightly increased with verapamil, though peak heart rate-blood pressure product remained unchanged.
- During control studies, 52% of patients developed perfusion defects, with 93% of these being reversible upon rest.
- Following verapamil administration, 71% of patients with reversible defects showed improvement, and 68% of initially defective regions demonstrated improvement.
Conclusions:
- Oral verapamil therapy demonstrated a favorable impact on exercise-induced 201Tl perfusion defects in patients with hypertrophic cardiomyopathy.
- These findings suggest that verapamil may favorably modify the dynamic process of silent myocardial ischemia in HCM.
Abstract:
Recent studies indicate that reversible 201Tl perfusion defects, compatible with silent myocardial ischemia, commonly develop during exercise in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM). To determine whether this represents a dynamic process that may be modified favorably by medical therapy, we studied 29 asymptomatic or minimally symptomatic patients with HCM, aged 12-55 years (mean, 28), with exercise 201Tl emission computed tomography under control conditions and again after 1 week of oral verapamil (mean dosage, 453 mg/day). Treadmill time increased slightly during verapamil (21.0 +/- 3.6 to 21.9 +/- 2.7 minutes, p less than 0.005), but peak heart rate-blood pressure product was unchanged (26.3 +/- 6.0 X 10(3) compared with 25.0 +/- 6.4 X 10(3). Two midventricular short-axis images per study were divided into five regions each, and each of these 10 regions was then analyzed on a 0-2 scale by three observers blinded with regard to the patients' therapy. Average regional scores of 1.5 or less were considered to represent perfusion defects, and a change in regional score of 0.5 or more was considered to constitute a significant change. During control studies, 15 patients (52%) developed perfusion defects with exercise (average, 3.7 regions per patient). In 14 of these patients, all perfusion defects completely reversed after 3 hours of rest; one patient had fixed defects. After administration of verapamil, exercise perfusion scores improved in 10 of the 14 patients (71%) with reversible defects; there was overall improvement in 34 of 50 (68%) regions with initially reversible perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)