Aims: 

We investigated the relative contribution of systolic and diastolic function of the left ventricle and ventriculo-arterial coupling in 24 dogs after recovery from an acute myocardial infarction.

Methods: 

Cardiac function was assessed using echocardiography and left heart catheterization with a conductance catheter at baseline and 11 weeks after ligation of the circumflex coronary artery and clinical recovery.

Results: 

There were increases in left ventricular end-diastolic pressure (mean+/­SE 14 ± 3 mmHg at baseline vs. 23 ± 4 in heart failure) and regional systolic function (wall motion score index 1 vs. 1.8 ± 0.1), a decrease in left ventricular ejection fraction (70 ± 1 vs. 57 + 1%) while cardiac output (2.8 ± 0.3 vs. 2.7 ± 0.2 L/min) was unchanged. Cardiac contractility was depressed (end systolic elastance (Ees) 6.1 ± 0.2 vs. 2.1 ± 0.2 mmHg/ml, preload recruitable stroke work slope 128 ± 13 vs. 72 ± 5 mmHg/ ml, dP/dtmax 3677 ± 821 vs. 2570 ± 407 mmHg/sec). There were increases in time constant of relaxation (Tau 27 ± 5 vs. 38 ± 2 ms) and end diastolic volume (41 ± 5 vs. 65 ± 3 ml), while capacitance, measured with volume at pressure 15 and 20 mmHg, was unchanged. The ventriculo-arterial coupling was markedly decreased (Ees/arterial elastance 1.4 ± 0.2 vs. 0.6 ± 0.1).

Conclusion: 

Recovery after acute myocardial infarction was characterized by systolic dysfunction, delayed relaxation and ventricular dilation with a severe ventriculo-arterial uncoupling and without clinical signs of overt heart failure.