[Relationship between exercise tolerance and early heart function impairment in patients with acute ST-elevation myocardial infarction and normal left ventricular ejection fraction].

Objective: To explore the relationship between early heart function impairment and exercise tolerance in patients with acute ST-elevation myocardial infarction (STEMI) and normal left ventricular ejection fraction (LVEF).

Methods: A total of 229 patients with a LVEF of ≥ 50% were retrospectively reviewed. There were 199 males and 30 females with a mean age of 56.2 ± 11.1 years. They underwent cardiopulmonary exercise testing (CPET) early after STEMI in a single exercise laboratory. Demographic data, presence of concomitant diseases, characteristics of STEMI, echocardiography and CPET findings were evaluated.

Results: Their mean LVEF was 60.2% ± 6.9% and the values of Vo(2 peak) and Vo(2AT) were (21.8 ± 5.7) ml×kg(-1)×min(-1) and (19.4 ± 4.8) ml×kg(-1)×min(-1) respectively. Peak oxygen uptake (Vo(2 peak)) showed a positive correlation with LVEF (r = 0.17, P = 0.012), E/A (r = 0.15, P = 0.033) and peak myocardial systolic velocity (Sm) (r = 0.30, P < 0.001). On the contrary, it varied inversely with peak A wave velocity (A) (r = -0.20, P = 0.005), E/Em (r = -0.16, P = 0.022) and left atrial pressure (LAP) (r = -0.16, P = 0.021). And there was a similar correlation between oxygen uptake at anaerobic threshold (Vo(2AT)) and LAP (r = -0.17, P = 0.031). After adjustments of subject demographic features and cardiovascular risk factors, Vo(2 peak) was still associated with LVEF (β = 0.149, s = 0.051, sβ = 0.178, 95%CI 0.048 - 0.250, P = 0.004) and Sm (β = 0.606, s = 0.167, sβ = 0.245, 95%CI 0.277 - 0.936, P < 0.001). So did the relationship between Vo(2AT) and LAP (β = -0.271, s = 0.117, sβ = -0.172, 95%CI -0.501 - -0.040, P = 0.022).

Conclusion: The exercise tolerance may be affected by early heart function impairment in STEMI patients. CPET is a sensitive detection tool of decreased heart function.