Phase angle is associated with functional capacity after early post-myocardial infarction cardiac rehabilitation – CaRe-ME study

Background Phase angle (PhA) derived from bioelectrical impedance analysis is a non-invasive marker of nutritional status at the cellular level, reflecting cellular membrane integrity and body cell mass quality. Associations between PhA and functional performance have been reported in chronic conditions and later phases of cardiac rehabilitation (CR); however, evidence in early post-myocardial infarction (MI) CR is limited. Purpose To evaluate, if PhA is associated with functional capacity after post-MI CR. Methods This prospective study enrolled patients referred to early post-MI CR. Functional capacity was assessed using peak oxygen uptake (VO2) and handgrip strength. PhA was measured using bioelectrical impedance analysis. Additional nutritional parameters included body mass index, skeletal muscle index and Nutritional Risk Score 2002. Results Preliminary data was available in 45 patients (mean age 59.4 ± 10.4 years; 68.9% men). Median VO2 was 18.29 [17.25–19.32] and mean PhA was 5.65 ± 0.85 degrees. PhA correlated positively with VO2 (R=0.40; p=0.01). Among other parameters only age was strongly inversely associated with VO2 (R=−0.69; p<0.001), while sex, hand grip strength, body mass index, skeletal muscle index and Nutritional Risk Score 2002 did not show significant associations. In an age-adjusted regression model, PhA remained independently associated with VO2 (β=0.606 per 1 degree increase in PhA; 95% CI 0.013–1.200; p=0.046), while age remained an independent negative correlate of VO2 (p<0.001). Grip strength differed only by sex (women 26.55 [20.84–30.57] vs men 47.37 [38.73–59.37] kg, p< 0.001). Conclusions PhA was positively associated with VO2 and remained significant after age adjustment. These findings suggest that PhA, as a marker of cellular-level nutritional status, may capture clinically relevant aspects of functional capacity in early CR after MI.