Reasons for Termination of Treadmill and Cycle Ergometer Exercise Tests in Patients After Myocardial Infarction: The Role of Clinical Profile and Exercise Capacity.

Background: Exercise testing is routinely performed before initiation of phase II cardiac rehabilitation to assess exercise capacity and determine safe training intensity. However, exercise tests may be terminated before reaching the target heart rate due to various cardiovascular and non-cardiovascular factors. The aim of this study was to analyze the reasons for terminating exercise tests performed on a treadmill and a cycle ergometer, with particular emphasis on the impact of the patient's clinical profile and exercise capacity. Methods: A retrospective analysis was conducted on 336 patients after myocardial infarction (74 women and 262 men) referred to inpatient phase II cardiac rehabilitation between 2019 and 2022. Patients were divided into two matched groups according to the type of exercise test performed: treadmill and cycle ergometer. Reasons for test termination, exercise performance parameters, and demographic and clinical characteristics were analyzed. Results: The most common reasons for exercise test termination were fatigue (55.1%) and achievement of the target heart rate (37.2%), with no significant differences between testing modalities. Lower limb pain was significantly more frequent during cycle ergometer testing compared with treadmill testing (16.1% vs. 7.1%; p = 0.011). Patients tested on the treadmill achieved significantly higher exercise capacity (7.19 vs. 5.28 METs (metabolic equivalents); p < 0.001), higher peak heart rate, and higher rate-pressure product. Multiple regression analysis showed that the association between exercise modality and lower limb pain was not independent after adjustment for clinical and demographic variables, indicating that the observed differences were largely explained by patient clinical characteristics. Conclusions: The most common reasons for exercise test termination were patient fatigue and attainment of the target heart rate, confirming the safety of submaximal exercise testing in post-myocardial infarction patients. Lower limb pain was more frequently observed during cycle ergometer testing in unadjusted analysis; however, this association was not independent of clinical variables, indicating that it is primarily related to the patient's clinical profile rather than the exercise modality. Exercise testing should therefore be individualized according to clinical status, functional capacity, and rehabilitation goals.