Overshoot phenomenon of oxygen uptake during recovery from maximal exercise in patients with previous myocardial infarction

The overshoot in oxygen uptake ((V) over dotO(2) overshoot) during recovery from maximal exercise is thought to reflect an overshoot in cardiac output. We investigated whether this phenomenon is related to cardiopulmonary function during exercise in cardiac patients. A total of 201 consecutive patients with previous myocardial infarction underwent cardiopulmonary exercise testing (CPX). An apparent (V) over dotO(2) overshoot during the recovery from CPX (6.5 +/- 8.1% increase relative to the peak (V) over dotO(2)) was observed in ten patients. A comparison of patients with the (V) over dotO(2) overshoot to those without the (V) over dotO(2) overshoot revealed that the former had a significantly lower left ventricular ejection fraction (40.1 +/- 19.1 vs. 55. 2 +/- 14.9%, respectively, p = 0.002) and larger left ventricular diastolic and systolic dimensions. Patients with the (V) over dotO(2) overshoot also had a significantly lower peak (V) over dotO(2) (13.1 +/- 6.1 vs. 18.1 +/- 4.5 ml/min/kg, p < 0.001), lower Delta(V) over dotO(2)/Delta WR (work rate) (6.6 +/- 3.8 vs. 9.5 +/- 1.7 mL/min/W, p < 0.0001), and a higher (V) over dotE (minute ventilation)/(V) over dotO(2) (carbon dioxide output) slope (45.0 +/- 18.6 vs. 32.6 +/- 6.6, p < 0.0001) than those without the overshoot. A (V) over dotO(2) overshoot during recovery from maximal exercise was found in 5% of patients with previous myocardial infarction. This condition, which suggests a transient mismatch between cardiac contractility and afterload reduction, was found to be related to impaired cardiopulmonary function during exercise.