Reduction of myocardial ischemia by gallopamil: a dual-isotope study with thallium-201 and iodine-123 phenylpentadecanoic acid.

Abstract

The present study was performed for characterizing the effect of chronic oral treatment with the calcium antagonist gallopamil on regional myocardial perfusion and free fatty acid utilization in poststenotic human myocardium. Twenty-two patients with angiographically documented coronary artery disease and stable angina pectoris underwent consecutive dual-isotope studies following simultaneous injection of 80 MBq thallium-201 and 200 MBq iodine-123 phenylpentadecanoic acid (IPPA) during a symptom-limited stress test. Radionuclide studies were performed after 1 week of placebo treatment (baseline), 4 weeks after oral treatment with 50 mg of gallopamil t.i.d. and again after 1 week of double-blind treatment with gallopamil or placebo. As compared to baseline, initial (poststress) uptake of both tracers in poststenotic myocardial segments was significantly improved after 4 weeks of treatment with gallopamil [thallium-201, +9.0%; p < 0.001; 95% confidence interval (CI), 4.3-13.6%; IPPA, +11.8%; p = 0.003; 95% CI, 4.2-19.3%]. Poststenotic IPPA-clearance was likewise significantly increased (+28.2%; p < 0.001; 95% CI, 12.4-44.0%) indicating a considerably enhanced myocardial fatty acid oxidation after treatment. In the final double-blind phase, myocardial uptake of both tracers as well as IPPA clearance remained enhanced in the subgroup of patients receiving gallopamil and returned to baseline values in patients receiving placebo. Thus, in poststenotic myocardium, chronic treatment with gallopamil provokes an improvement of both regional myocardial perfusion (as demonstrated by an increased tracer uptake in poststress scintigrams) and regional myocardial fatty acid utilization (as demonstrated by an increased uptake and clearance of IPPA).