Effect of Cardiac Rehabilitation on Cardiorespiratory Fitness in Patients with Acute Myocardial Infarction: Role of Diabetes Mellitus and Glycated Hemoglobin Level

Purpose: Following acute myocardial infarction (AMI), patients with diabetes mellitus (DM) have a poorer prognosis than those without DM. This study aimed to investigate the benefit of cardiac rehabilitation on cardiorespiratory fitness in patients with AMI, examining whether this effect varied depending on DM and glycated hemoglobin (HbA1c) levels. Methods: Data were collected from the medical records of 324 patients diagnosed with AMI who were subsequently referred to participate in a supervised exercise-based cardiac rehabilitation program. Cardiorespiratory fitness was assessed using cardiopulmonary exercise testing before and at 3 and 6 mo after the start of cardiac rehabilitation. Linear mixed models were used to evaluate changes in cardiorespiratory fitness between patients with and without DM during the follow-up period. Results: In total, 106 patients (33%) had DM. Both patients with and without DM showed a significant improvement in cardiorespiratory fitness from baseline to the 6-mo follow-up. However, the improvement was significantly lower in patients with DM than in those without DM (1.9 ± 1.5 vs. 3.7 ± 3.2 mL/kg/min, P <.001). Among patients with DM, those with HbA1c levels < 7% showed a greater improvement in cardiorespiratory fitness than those with HbA1c ≥ 7% (2.7 ± 1.5 vs. 1.1 ± 1.8 mL/kg/min, P <.001) during the follow-up period. Conclusions: Improvements in cardiorespiratory fitness following cardiac rehabilitation were significantly lower in patients with AMI and DM. The response to cardiac rehabilitation in patients is influenced by HbA1c levels. These findings suggest potential implications for individualizing cardiac rehabilitation programming and ensuring optimal glycemic control in patients with AMI and DM.