Objective: To assess the value of cardiopulmonary exercise test in the evaluation of cardiac function in patients with chronic left heart failure caused by dilated cardiomyopathy.
Methods: Fifty-three inpatients aged 18 year and over with chronic left heart failure caused by dilated cardiomyopathy at Fuwai Hospital from October 2010 to October 2011 were selected and divided into 2 groups according to the New York Heart Association (NYHA) heart function classification. One group had 20 cases for class II and another 33 cases for class III-IV. All of them received cardiopulmonary exercise tests. Synchronous measurement and record of gas exchange indices were taken during every breath, and so were heart rate, blood pressure, electrocardiogram and blood oxygen saturation. At the same time, other routine tests were also performed. After exercise test, anaerobic threshold and peak oxygen consumption indices were calculated and statistically analyzed. They also received subsequent follow-ups of 1 day, 1 week, 1 month, 6 months and 1 year, including activities, clinical manifestations and cardiac adverse events.
Results: At baseline, the differences in gender, age, body mass index, concurrent diseases, left ventricular end-diastolic diameter, left ventricular ejection fraction and serum creatinine had no statistical significance (P > 0.05). Compared with cardiac function class II group, the class III-IV group had higher left atrial diameter, level of amino terminal pro-B-type natriuretic peptide (NT-proBNP), incidence of atrial fibrillation ((51.4 ± 7.5) vs (43.6 ± 7.7) mm, (2 607 ± 1 782) vs (1 312 ± 901) µg/L, 42.4% (14/33) vs 5.0% (1/20)) and lower glomerular filtration rate, peak oxygen consumption, levels of anaerobic threshold ((72 ± 20) vs (97 ± 23) ml/min, (13.7 ± 2.6) vs (20.5 ± 3.6) ml·min(-1)·kg(-1), (10.7 ± 1.5) vs (13.3 ± 2.1) ml·min(-1)·kg(-1)) (all P < 0.01). And NT-proBNP and cardiac function classification showed a positive correlation (OR = 1.002, P = 0.003) while peak oxygen consumption, anaerobic threshold and cardiac function classification were negatively correlated (OR = 0.736, 0.608; P = 0.011, 0.001).
Conclusions: Cardiopulmonary exercise test objectively reflects the cardiopulmonary reserve of heart failure patients with dilated cardiomyopathy. And the parameters of anaerobic threshold and peak oxygen consumption may reflect the patient's motor ability quantitatively and accurately.