Significance of abnormal blood pressure response during exercise-induced myocardial dysfunction after recent acute myocardial infarction

Abstract

The relation between exercise left ventricular ejection fraction and blood pressure (BP) responses after an acute myocardial infarction (AMI) was investigated. Twenty-eight to 37 days after an uncomplicated AMI, 224 consecutive patients underwent exercise radionuclide angiography in the 40 ° semisupine position. In 180 patients (group A, 80%), BP increased more than 5 mm Hg every stage; in 44 patients, BP responses were abnormal; in 33 (group B, 15%), BP did not increase during 2 stages; in 11 (group C, 5%), it decreased more than 5 mm Hg after an initial increase. Ejection fraction did not differ significantly among the 3 groups at rest (51 ± 13 in group A, 50 ± 18 in group B, 47 ± 13 in group C [difference not significant]) or at peak exercise (51 ± 16% in group A, 46 ± 19% in group B, and 43 ± 16% in group C, [difference not significant]). Exercise-induced left ventricular failure or hemodynamic decompensation occurred in 22 patients. In these patients, ejection fraction at rest was 44 ± 19% and decreased to 35 ± 16% (p < 0.05) with exercise. Only 9 of these patients (41 %) had abnormal BP responses, with the other 13 (59%) showing a normal BP response. The 35 patients with abnormal BP responses in the absence of hemodynamic decompensation were asymptomatic, terminating exercise because of fatigue. The ejection fraction at rest and during exercise in these patients was similar to that in patients with normal BP responses. Thus, after a recent AMI, abnormal BP responses during exercise associated with clinical evidence of hemodynamic decompensation are related to myocardial dysfunction. However, in the absence of symptoms, such abnormal BP responses are not related to severity of left ventricular dysfunction, and in some patients may be ascribed to exertional reduction in systemic resistance.