Effects of Isolated LBBB on Maximal Functional Capacity

Maximal functional capacity will be evaluated using incremental and symptom-limited cardiopulmonary exercise testing (CPET) on a bicycle ergometer, beginning with a workload of 10 W and increasing gradually in a ramp protocol at 10-W increments every 1 minute. We will define maximal functional capacity as when the patient stops pedalling because of symptoms, and the respiratory exchange ratio (RER) is ≥1.1. During exercise, patients were monitored with 12-lead electrocardiogram and blood pressure measurements every 2 minutes. Gas exchange data and cardiopulmonary variables were averages of values taken every 10 seconds. Peak oxygen consumption (PeakVO2) will be defined as the highest value of oxygen consumption during the last 20 seconds of exercise.

Doppler echocardiogram examinations were performed under resting conditions using 2-dimensional echocardiography. Left ventricular end-diastolic volume and left ventricular ejection fraction will be measured according to the European Society of Echocardiography