Prediabetes influences cardiac rehabilitation in coronary artery disease patients.

Background: An abnormal glucose tolerance (AGT) in coronary artery disease (CAD) patients could negatively influence recovery after an acute event but the question, relevant in the field of cardiac rehabilitation (CR), is still controversial.
Design: Prospective study, aiming to establish the prevalence of AGT and its possible influence on functional recovery in CAD patients without a previous diagnosis of diabetes mellitus (DM).
Methods: An oral glucose tolerance test was performed on 230 CAD patients without known DM, submitted to a 2-week period of intensive exercise-based CR after a recent acute myocardial infarction or coronary artery bypass graft. Functional capacity was assessed by a cardiopulmonary exercise test (CPET) and by 6-minute walking tests (6MWT) performed both on admission and at discharge.
Results: The prevalence of AGT in our population was 53%. Exercise capacity was lower in AGT patients (maximum workload achieved at CPET 79.3 ± 29.9 vs. 91.8 ± 36.9 W, p = 0.01; peak-VO(2) 17.8 ± 4.7 vs. 19.8 ± 5.6 ml/kg/min, p = 0.01). In the subgroup of AGT patients characterized by an inferior walking capacity at baseline, the increment in the distance walked was less than in the controls (Δ6MWT: 81.9 ± 60.1 vs. 109.1 ± 72.1, p = 0.04). An independent, negative, association was observed between AGT and Δ6MWT in patients with lower baseline test, and between maximum workload and peak-VO(2) in the whole population.
Conclusions: A high prevalence of AGT was observed in a population of CAD patients without known DM after an acute coronary event. AGT is associated to a lower functional recovery, and to a reduced exercise capacity at the end of CR.