Comorbid Chronic Lung Disease on Heart Failure

Patients performed an upright graded bicycle exercise using a personalized protocol or performed a motorized treadmill exercise using a modified Bruce protocol. Peak VO2 and peak respiratory exchange ratio (RER) were defined as the highest 30-second average value obtained during exercise. The anaerobic threshold (AT) was determined by V-slope method. The VE(minute ventilation)/VCO2 (carbon dioxide production) at AT was calculated as the average VE/VCO2 for 1 minute during AT and immediately after AT. If AT could not be determined, the lowest VE/VCO2 was determined by averaging the three lowest consecutive 0.5-minute data points.