Hogwood AC; Division of Cardiology, Charlottesville, Virginia
Smarz K; Golino M; Tysarowski M; et al

Current Problems in Cardiology. 51(10):103382, 2026 Oct.

BACKGROUND: Modern treatment of ST-elevation myocardial infarction
(STEMI), emphasizing prompt reperfusion, has improved clinical outcomes by
preserving cardiac function. Despite this, cardiorespiratory fitness
remains impaired. The purpose of this study was to assess determinants of
cardiorespiratory fitness in patients with reperfused STEMI and preserved
cardiac function.

METHODS: We prospectively collected data from two patient cohorts with
reperfused STEMI who underwent cardiopulmonary exercise testing on either
a semi-supine cycle ergometer (Cohort 1) or treadmill (Cohort 2). Peak
oxygen consumption (VO2) was measured as mL.kg-1.min-1 and as
percent-predicted. Cardiac reserve was measured with Doppler
echocardiography using heart rate (HR), stroke volume (SV), and cardiac
output (CO) before and at peak exercise. Arterial-venous oxygen difference
(a-v O2diff) was calculated using the Fick equation.

RESULTS: We included ninety-five patients (58 [51-65] years, 34% female)
tested 41 [37-45] days after STEMI (Cohort 1: n = 39; Cohort 2: n = 56).
Resting LVEF was 55 [50-59] %, with 2 (2%) having <40%. E’ velocity was
8.8 [7.3-10.5] and E/e’ was 7.6 [6.5-9.2]. Peak VO2 was 20.0 [16.3-22.9]
mL.kg-1.min-1, and 74 (78%) and 24 (25%) patients had reduced peak VO2 at
<80% and <60% of predicted, respectively. A significant positive
correlation was observed between peak VO2 and peak CO (R = 0.42, p =
0.0001), SV (R = 0.24, p = 0.02), HR (R = 0.36, p = 0.006), and a-v O2diff
(R = 0.49, p < 0.0001). Peak HR and SV were each independent predictors of
peak VO2 using multivariate analyses (all p < 0.01).

CONCLUSION: Cardiorespiratory fitness remains impaired after successfully
reperfused recent STEMI, despite rather preserved resting cardiac
function. Cardiac and peripheral reserve partially explain the
impairments, and preserving these may improve fitness after STEMI.