Clinical Safety and Parameters of Maximum Oxygen Uptake (VO₂Max) Testing in Pakistani Patients With Heart Failure

To determine the parameters of maximum oxygen uptake (VO2max) in a Pakistani systolic heart failure cohort and its safety in a clinical setting.

Descriptive study.

Armed Forces Institute of Cardiology, National Institute of Heart Diseases, Rawalpindi, from June 2011 to January 2013.

Maximum oxygen uptake test was performed in patients with severe heart failure, who could perform the VO2max treadmill test. Age, Body Mass Index (BMI) ejection fraction, VO2max and respiratory exchange ratios and their correlations were determined.

Out of 135 patients, 77% (n=104) were males, with a mean age of 45.9 ±15.7 years. Weight of patients ranged from 30 kg to 107 kg (mean 63.29 ±13.6 kg); mean BMI was 23.16 ±4.56 kg/m2. All patients presented with either NYHA class of III (50.3%; n=68) or IV (49.7%; n=67); mean ejection fraction was 22.54 ±5.7% (10 - 35%, IQ:20 - 25). The VO2 max of the patients ranged from 3 to 32 ml/kg/minute (mean 12.85 ±4.49 ml/kg/minute). Respiratory exchange ratio was over 1 for all patients (1.12 - 1.96, mean = 1.36 ±0.187). There was a negative correlation with age (r = -0.204; p = 0.028) whereas a positive correlation was found with exercise time (r = 0.684; p = 0.000), hemoglobin (r = 0.190; p = 0.047) and ejection fraction (r = 0.187 ; p = 0.044).

Cardiopulmonary exercise testing in a high-risk heart failure cohort is safe and provides information beyond the routine clinical evaluation of heart failure patients.