Maximal functional capacity in subjects with isolated left bundle branch block: a pilot study

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Sociedad Española de Cardiología. Background Left bundle branch block (LBBB) has been commonly associated with adverse cardiovascular (CV) events, but the effect of an isolated LBBB on maximal functional capacity is not well characterized. Purpose To evaluate maximal functional capacity in adults with isolated LBBB and compare it to healthy population-derived predicted values (adjusted for sex, age, weight, and height). Methods This descriptive pilot study included subjects with isolated LBBB derived from outpatient clinics of two academic hospitals. All subjects underwent maximal cardiopulmonary exercise testing (CPET) and a Global Physical Activity Questionnaire (GPAQ). The primary endpoint was to evaluate maximal functional capacity according to population-derived predicted values of peak oxygen consumption (peakVO2): pp-peakVO2. The secondary endpoint was to evaluate adverse CV events (CV deaths or hospitalizations) at follow-up. Results A total of 27 (18 women and 9 men) participants were included. The median (interquartile range) age of the sample and time to screening from the first LBBB diagnosis were 62 (51-71) and 3.4 (1.1-8.4) years, respectively. The results of the GPAQ score showed that 19 patients were highly active, and 8 were moderately active. The median of peakVO2 and pp-peakVO2 were 19.3 (15-22.5) mL/kg/min and 88 (79.3-104.4) %, respectively. There were no adverse CV events at a median follow-up after CPET of 3.1 (2.7-3.4) years. Conclusion In this pilot study, adults with isolated LBBB showed reduced maximal functional capacity, despite the absence of cardiac disease and a baseline moderate to highly active lifestyle.