Diaphragmatic weakness in patients attending a cardiovascular rehabilitation program

Background: Diaphragmatic thickness measured by ultrasound at rest is a structural marker that may be altered in patients with cardiovascular disease; however, its behavior in cardiac rehabilitation settings remains poorly understood. Objective: To determine the prevalence of reduced diaphragmatic thickness in patients undergoing cardiac rehabilitation. Material and method: Cross-sectional observational study including 198 patients in phase II cardiac rehabilitation. Anthropometric measurements, body composition, and diaphragmatic ultrasound at rest were performed. Spearman correlation was used for continuous variables, and Mann-Whitney U test for group comparisons. Results: Mean age was 61.26 ± 13.68 years. Mean diaphragmatic thickness was 1.65 ± 0.40 mm. Reduced diaphragmatic thickness (< 1.8 mm) was observed in 68.6% of patients. No significant differences were found by sex (U: 4,954.0; p = 0.2127) or age (ρ: 0.026; p = 0.728). A weak positive correlation was observed with BMI (ρ: 0.148; p = 0.037), while abdominal circumference showed a non-significant trend (ρ: 0.132; p = 0.065). Conclusion: A high prevalence of reduced diaphragmatic thickness was identified in patients undergoing cardiac rehabilitation, with limited associations to anthropometric variables. Further studies incorporating functional assessment and multivariate analysis are required.