Prompt improvement of left ventricular function and preservation of topography with combined reperfusion and intravenous nitroglycerin in acute myocardial infarction

Reperfusion alone during acute myocardial infarction (AMI) preserves left ventricular (LV) topography but causes 'stunning', with delayed or no recovery of function. To determine whether adjunctive intravenous nitroglycerin (NTG) accelerates functional recovery, we prospectively measured function and topography by repeated two-dimensional echocardiography between 1 day and 6 months in 5 groups of patients (n = 73) with a first AMI: placebo (group 1), NTG alone (group 2), NTG combined with successful reperfusion after 4 h (group 3) or failed reperfusion (group 4), and successful reperfusion alone (group 5). Asynergy decreased promptly (p < 0.001) and ejection fraction improved (p < 0.001) between day 1 and 6 months in groups 2 and 3 compared to baseline and groups 1, 4 and 5. Infarct expansion and thinning found in group 1 were prevented in groups 2, 3, 4 and 5. Diastolic volume increased in the anterior subgroup 1 but not 2, 3, 4 and 5. This is the first demonstration that reperfusion combined with adjunctive NTG produces earlier, greater and persistent recovery of LV function in addition to attenuation of remodeling in patients after AMI.

Effect of left ventricular unloading with captopril on remodelling and function during healing of anterior transmural myocardial infarction in the dog

OBJECTIVE

To determine whether left ventricular (LV) unloading with captopril between two days and six weeks during healing after transmural anterior acute myocardial infarction might prevent further LV remodelling and preserve function in the canine model.

DESIGN

Serial LV topographic and functional parameters (two-dimensional echocardiograms) and hemodynamics over six weeks and scar topography (planimetry) and collagen (hydroxyproline) at six weeks were measured in 34 chronically instrumented dogs; 24 with anterior transmural acute myocardial infarction (coronary artery ligation and collateral obliteration) that had been randomized at two days post infarction to therapy with oral 50 mg bid placebo (n = 12) or captopril (n = 12) for six weeks, and 10 with sham infarction.

MAIN RESULTS

At six weeks, captopril and placebo groups had similar scar mass (7.7 versus 8.1% LV), infarct hydroxyproline and transmurality but the captopril group showed significantly less (P less than or equal to 0.05) infarct expansion and thinning, cavity dilation, epicardial and endocardial bulge. Between two days and six weeks, captopril decreased mean left atrial and arterial pressures compared to placebo or sham. Echocardiograms at two days showed similar LV asynergy, ejection fraction, infarct expansion and thinning with placebo and captopril. In contrast, echocardiograms between two days and six weeks showed that: further expansion and thinning occurred with placebo but not captopril; LV volumes increased with placebo but decreased with captopril; total LV asynergy was unchanged with placebo but decreased with captopril; and LV ejection fraction was unchanged with placebo but increased with captopril. At six weeks, LV ejection fraction was 10% higher (45 versus 35%, P less than 0.001) and LV aneurysm was less frequent (33 versus 100%, P less than 0.005) with captopril compared to placebo.

CONCLUSIONS

Chronic LV unloading with captopril therapy during healing after canine transmural anterior acute myocardial infarction limits further remodelling, decreases aneurysm formation and improves function.

Effect of long-term captopril therapy on left ventricular remodeling and function during healing of canine myocardial infarction

To determine whether the long-term reduction of preload and afterload by captopril during healing after acute anterior myocardial infarction might attenuate left ventricular remodeling and improve function, 30 chronically instrumented dogs with infarction produced by left anterior descending coronary artery ligation were randomized 2 days later to oral therapy with placebo (n = 15) or captopril, 50 mg twice daily (n = 15), for 6 weeks. Serial hemodynamic as well as topographic and functional variables (two-dimensional echocardiography) were measured over 6 weeks. Scar topography (planimetry), occluded bed size (coronary arteriography) and collagen (hydroxyproline) content were measured at 6 weeks. Between 2 days and 6 weeks, captopril decreased (p less than 0.001) mean arterial pressure and mean left atrial pressure more than did placebo, but it did not influence heart rate. Infarct scar mass, transmurality and collagen content at 6 weeks were similar in the two groups but scars showed less (p less than 0.001) thinning and expansion with captopril than with placebo. Echocardiograms showed similar infarct expansion and thinning in the two groups at 2 days but less aneurysm with captopril at 6 weeks. Between 2 days and 6 weeks, expansion index (infarct-/noninfarct-containing segment length) decreased (p less than 0.001) with captopril but increased (p less than 0.001) with placebo. Also, thinning ratio (infarct/normal wall thickness) decreased (p less than 0.001) with placebo but did not change (p = NS) with captopril. By 6 weeks, left ventricular asynergy and volumes showed a greater decrease (p less than 0.01) and global ejection fraction a greater increase (p less than 0.05) with captopril.(ABSTRACT TRUNCATED AT 250 WORDS)