Acute effect of captopril administration on baroreflex sensitivity in patients with acute myocardial infarction.

Depressed baroreflex sensitivity (BRS) after acute myocardial infarction (AMI) is considered an indication of decreased vagal and/or increased sympathetic tone. To determine the effect of angiotensin converting enzyme inhibitors (ACEI) on BRS after AMI we studied 27 patients with a first Q wave AMI, no signs of heart failure and no history of arterial hypertension or diabetes mellitus. An additional group of 10 patients with the same clinical characteristics served as controls. On the 5th day after the onset of AMI, three consecutive boluses of phenylephrine were given intravenously and baseline BRS was taken as the mean slope of the linear regression lines of RR intervals over systolic blood pressure. QT interval was also measured and corrected according to Bazett's formula (QTc). Consequently, a single oral dose of captopril 50 mg or placebo was given to treatment or control group patients, respectively; BRS and QTc were reassessed 1 h later. One hour after captopril administration BRS increased from 5.95 +/- 2.80 to 9.14 +/- 3.46 ms.mmHg-1 (P < 0.0001); QTc increased from 414 +/- 46 to 425 +/- 46 ms (P < 0.0001), systolic blood pressure decreased from 125 +/- 19 to 115 +/- 15 mmHg (P = 0.0002), while heart rate did not change significantly. Baseline BRS was correlated only with age (r = -0.74, P < 0.0001). In the control group, 1 h after placebo, no difference was observed in any variable compared to baseline. Captopril appears to improve BRS immediately in the early phase of AMI.

Relation between changes in blood flow of the contralateral coronary artery and the angiographic extent and function of recruitable collateral vessels arising from this artery during balloon coronary occlusion.

OBJECTIVES: The purpose of this study was to investigate changes in the magnitude of blood flow through the contralateral coronary artery in relation to the development of recruitable collateral vessels arising from this artery to supply a balloon-occluded coronary vessel. BACKGROUND: Recruitable collateral vessels have been shown to emerge suddenly to supply an occluded coronary artery, but their physiologic effect cannot always be predicted angiographically. METHODS: Twenty-four patients were studied during four successive balloon dilations for single left anterior descending coronary artery stenosis. Before and during each balloon occlusion, blood flow in the proximal right coronary artery was measured by intracoronary Doppler flow velocimetry and quantitative coronary angiography. Estimates of chest pain and ST segment elevation were also obtained. RESULTS: Fourteen patients developed angiographically visible recruitable collateral vessels (high grade in 6 [group III], low grade in 8 [group II]), whereas 10 patients (group I) did not. During the four successive balloon occlusions, the right coronary artery flow showed transient reproducible increases in group III (first occlusion 66.4 +/- 36.8%, fourth occlusion 64 +/- 23.9%, all p = 0.036), progressive increases in group II (from first occlusion 17.9 +/- 26.6% [p = 0.08] to fourth occlusion 60.4 +/- 35.9% [p = 0.014]) and no significant changes in group I. Between the first and the fourth occlusion, the severity of chest pain and the magnitude of ST segment elevation declined significantly in group II but did not change in groups I and III. CONCLUSIONS: During balloon coronary artery occlusion, the transient appearance of recruitable collateral vessels is associated with a transient increase in blood flow through the collateral donor artery. This increase in coronary flow appears to reflect collateral function better than the angiographic assessment, especially in patients with poor collateral vessel recruitment.

The effects of early captopril treatment on left ventricular volumes and function in patients with and without depressed global ejection fraction after acute myocardial infarction.

To determine the effects of captopril on left ventricular volumes and function in patients with and without depressed ventricular function following acute myocardial infarction (AMI) we studied 78 patients with a first Q wave AMI and no clinical evidence of heart failure. All patients underwent radionuclide ventriculography (RVG) on the 4th day after admission and were then randomly assigned to receive conventional treatment alone (36 patients, control group) or with the addition of oral captopril, 25 mg three times daily (42 patients, captopril group). RVG was repeated one month after the baseline examination. After one month the left ventricular ejection fraction (LVEF) significantly increased in the captopril group (from 43.2 +/- 1.3 to 50.9 +/- 1.6%, P < 0.001) and remained relatively unchanged in the control group (from 47 +/- 1.3 to 49.2 +/- 1.7%, P = ns). In the captopril group the subgroup of patients with a baseline LVEF < 45% demonstrated a significant decrease in end-systolic volume index (ESVI) (from 53.3 +/- 3.2 to 42.4 +/- 2.8 ml. m-2, P < 0.002) and a highly significant improvement in LVEF (from 36.3 +/- 1.3 to 49.6 +/- 1.8%, P < 0.00005). In the control group, LVEF also increased in those in whom it was < 45% (from 38 +/- 1.4 to 42 +/- 2.4%, P < 0.01), but the increase was less than that in the captopril group (P < 0.01), mainly due to an increase in end-diastolic volume index (EDVI) (from 78.2 +/- 4.6 to 84.6 +/- 12.3 ml.m-2, P = ns).(ABSTRACT TRUNCATED AT 250 WORDS)