Relation between exercise capacity and left ventricular systolic versus diastolic function during exercise in patients after myocardial infarction

Background It is known that left ventricular systolic function at rest does not correlate well with exercise capacity of patients with heart failure. However, the contribution of left ventricular diastolic dysfunction, especially during exercise, to exercise capacity of cardiac patients remains to be determined. Objective To determine the impact of left ventricular systolic and diastolic function during exercise on exercise capacity of patients with left ventricular dysfunction after myocardial infarction. Methods A symptom-limited exercise test was performed with measurements for hemodynamics and uptake of oxygen (V-O2) of 26 men who had previously suffered myocardial infarction. These patients were divided into two groups according to their peak V-O2 (group 1 with peak V-O2 greater than or equal to 16 ml/kg per min, n =13; and group 2 with peak V-O2 <16 ml/kg per min, n = 13). Pulmonary arterial pressure, left ventricular and systemic arterial pressure, and cardiac output were measured at rest and during exercise. Results At rest, there was no difference between the two groups in terms of hemodynamic parameters except for minimal dP/dt, minimal left ventricular pressure (LVP) and time constant for decay of left ventricular pressure (<tau>). During peak exercise, cardiac output, left ventricular end-diastolic pressure (EDP), minimal dP/dt, minimal LVP, and tau for the two groups were significantly different. Furthermore, peak V-O2 was significantly correlated with tau, minimal LVP, minimal dP/dt, EDP, and maximal dP/dt during peak exercise for the whole group of patients, Conclusion Left ventricular diastolic function during exercise, i.e. diastolic reserve, may be an important determinant of exercise capacity of patients with left ventricular dysfunction after myocardial infarction. Coron Artery Dis 12:217-225 (C) 2001 Lippincott Williams & Wilkins.