[Acute and chronic effects of verapamil on indices of systolic and diastolic function of the left ventricle in patients with hypertrophic cardiomyopathy].

The aim of this study has been the analysis of acute and chronic effects of Verapamil on resting left ventricular (LV) systolic and diastolic function indices derived from ECG gated radionuclide Angiocardiography (GRA) in patients (pts) affected by Hypertrophic Cardiomyopathy (HCM). 18 pts with HCM were imaged in basal conditions (twice in two different days) and after i.v. infusion of Verapamil 0.1 mg/kg (1st acute test); than chronic oral treatment of Verapamil (240 mg/die) was started. Three months later 14 pts were studied again, during oral chronic therapy and after a second administration of Verapamil i.v. 0.1 mg/kg (2nd acute test). After acute infusion we observed a significant increase of the peak filling rate (PFR) (from 3.3 +/- 0.9 to 3.51 +/- 0.71 EDV/sec, P less than 0.01) and a shortening of the time to PFR (from 188.1 +/- 24.9 to 165 +/- 30 msec, P less than 0.005). No significant variations of the contribution of atrial systole to the ventricular filling (AS) (from 17.03 +/- 5.96 to 18.15 +/- 6.91%), of the heart rate (from 70 +/- 12 to 69 +/- 12 bat/min), and of systolic function indices, ejection fraction (EF) (from 74.4 +/- 9.7 to 74.30 +/- 10.02), peak ejection rate (ER) (from 4.17 +/- 0.92 to 4.10 +/- 0.9), ejection time (ET) (from 307.4 +/- 46.4 to 322.22 +/- 48.6) were noticed. After chronic oral therapy we observed a significant shortening of the time to PFR (from 197.5 +/- 16.7 to 182.8 +/- 13.7 msec, P 0.01), while the remaining indices of diastolic function we analyzed (PFR from 3.2 +/- 0.6 to 3.3 +/- 0.8 EDV/sec; AS from 17.1 +/- 4.9 to 17.1 +/- 6.6%), the systolic function indices (EF from 74.4 +/- 10.5 to 75.4 +/- 9.4%; ER from 4.2 +/- 0.8 to 4.2 +/- 0.6 EDV/sec; ET from 309.6 +/- 48.5 to 308.9 +/- 40.5 msec) and the heart rate (from 67.7 +/- 8 to 66 +/- 8) were not modified. If a 30 msec time to PFR variation was considered significative (confidence limit of 95% between absolute changes measured on two basal studies) the 1st acute test was predictive of chronic efficacy in 10/14 (71%) pts. Four of five pts in which a shortening of TTPFR was observed during the 2nd acute test, showed the same effect with a higher chronic dose of Verapamil (360 mg/die). Our results suggest that Verapamil after acute or chronic treatment improves diastolic filling of LV, without worsening systolic indices.(ABSTRACT TRUNCATED AT 400 WORDS)