ORAL VERAPAMIL EFFECTS ON GLOBAL AND REGIONAL LEFT VENTRICULAR DIASTOLIC FILLING IN HYPERTROPHIC CARDIOMYOPATHY

Abstract

To assess the effects of oral verapamil therapy on global and regional left ventricular (LV) diastolic filling of hypertrophic cardiomyopathy (HCM), we studied 9 patients with HCM by radionuclide ventriculography and M-mode echocardiography before and after 2 weeks of oral verapamil therapy (240 mg/day). LV regional function was assessed by subdividing the LV region of interest into 4 regions from which global, septal, apical and lateral time-activity curves and their first-derivative curves were derived. Diastolic asynchrony during early diastole was measured as the sum of the absolute values (total Δt) of the time differences ( Δt) from peak filling rate in the global left ventricle to that in each of the 3 regions. Verapamil did not alter LV systolic function globally and regionally. Global LV peak filling rate improved after verapamil therapy from 1.92±0.59 to 2.35±0.63 end-diastolic counts/s (p<0.02) without altering regional peak filling rates significantly. Global and regional times to peak filling rate showed a shortening or no change despite a tendency to increase in the diastolic time after verapamil therapy. The total Δt decreased from 93±61 to 41±23 ms after verapamil (p<0.05), indicating more synchronous LV diastolic filling after verapamil. There was a negative correlation between the global peak filling rate and the total Δt (r= -0.54, p<0.05, n=18), suggesting that the global peak filling rate may improve after verapamil therapy in association with the decrease in the asynchronous LV diastolic filling. Thus, verapamil was effective in improving impaired LV filling in HCM, which might be related to reduction in regional LV diastolic asynchronous filling.