Left Atrial Function as a Reliable Predictor of Exercise Capacity in Patients With Recent Myocardial Infarction

Abstract

To examine the relation between left atrial (LA) function and exercise performance. Retrospective study at a referral cardiopulmonary exercise laboratory in a university hospital. Forty-one patients with recent myocardial infarction. M-mode echocardiography and cardiopulmonary exercise testing combined with radionuclide ventriculography. Hemodynamic measurements were obtained at rest and peak exercise. LA fractional shortening at rest was used as an index of global LA function. LA fractional shortening had fair correlations with peak oxygen consumption (r=0.67, p<0.01) and exercise duration (r=0.71, p<0.01). Although there were no significant relations between LA fractional shortening and hemodynamic measurements at rest, LA fractional shortening was positively related to peak cardiac output (r=0.61, p<0.01) and peak stroke volume (r=0.57, p<0.01), and negatively related to peak pulmonary arterial wedge pressure (r=-0.44, p<0.05). In addition, LA fractional shortening correlated significantly with an increase in left ventricular (LV) end-diastolic volume from rest to peak exercise (r=0.48, p<0.02), but did not correlate with the changes in ejection fraction and end-systolic volume during exercise. An increase in LV end-diastolic volume during exercise was significantly related to peak oxygen consumption (r=0.46, p<0.02), peak cardiac output (r=0.60, p<0.01), and peak stroke volume (r=0.53, p<0.01), whereas the changes in ejection fraction and end-systolic volume during exercise were not related to these indexes. Exercise capacity and LV performance during exercise were mainly dependent on LV diastolic filling rather than systolic contraction during exercise. LA fractional shortening at rest reflected LV diastolic filling during exercise and, therefore, predicted cardiac output and stroke volume responses to exercise and exercise capacity in patients with recent myocardial infarction.