Differences in pulmonary function and exercise capacity in patients with idiopathic dilated cardiomyopathy and idiopathic pulmonary arterial hypertension

Peak circulatory power is a strong prognostic factor in patients with idiopathic pulmonary arterial hypertension

BACKGROUND

Studies have shown that peak circulatory power (peak CircP; peak oxygen uptake × peak systolic blood pressure) is a variable predictor of prognosis in patients with left heart failure. It remains unknown whether peak CircP also predicts outcome in patients with idiopathic pulmonary arterial hypertension (IPAH).

METHODS

Patients with newly diagnosed IPAH who underwent symptom-limited cardiopulmonary exercise testing (CPET) from 1 January 2011 to 1 January 2014 in Fuwai Hospital were prospectively enrolled and followed for up to 66 months for cardiac events (mortality and lung transplantation).

RESULTS

One hundred forty patients with IPAH (104 female, mean age: 33 ± 11 years) were studied. During follow-up (mean: 42 ± 14 months), 24 patients died and 1 patient underwent lung transplantation. In the univariate analysis, peak oxygen uptake(VO₂), oxygen uptake at anaerobic threshold, ventilation (VE)/carbon dioxide output (VCO₂) slope, end-tidal partial pressure of carbon dioxide at anaerobic threshold, peak systolic blood pressure (SBP), the change of SBP, the change of heart rate, peak work rate, peak CircP, pulmonary vascular resistance, cardiac index and World Health Organization functional class were predictive of cardiac events (all P < .05).In the multivariate analysis, Peak CircP in the fourth model had the highest significance compared with peak VO₂ and VE/VCO₂ slope in the second and third model (chi-square = 5.26, P < .02, HR: 0.99, 95% CI: 0.99 to 1.00).

CONCLUSIONS

Peak CircP, better than peak VO₂ and VE/VCO₂slope, was a strong predictor of cardiac events among exercise parameters in patients with IPAH.

Oxygen Uptake Efficiency Slope Predicts Poor Outcome in Patients With Idiopathic Pulmonary Arterial Hypertension

BACKGROUND

Few published studies have evaluated the power of the oxygen uptake efficiency slope (OUES) to predict outcomes in patients with idiopathic pulmonary arterial hypertension (IPAH), who typically die of right-sided heart failure. Our study sought to evaluate the power of OUES to predict clinical worsening and mortality in patients with IPAH.

METHODS AND RESULTS

Patients with newly diagnosed IPAH who underwent symptom-limited cardiopulmonary exercise testing from November 11, 2010, to June 25, 2015, in our hospital were prospectively enrolled and followed for up to 66 months. Clinical worsening and mortality were recorded. A total of 210 patients with IPAH (159 women; mean age, 32±10 years) were studied with a median follow-up of 41 months. Thirty-one patients died, 1 patient underwent lung transplantation, and 85 patients presented with clinical worsening. The univariate analysis revealed that OUES, OUESI (OUESI=OUES/body surface area), peak oxygen uptake (V˙O2), peak V˙O2/kg, ventilation (V˙E)/carbon dioxide output (V˙CO2) slope, peak systolic blood pressure, heart rate recovery, pulmonary vascular resistance, cardiac index, N-terminal prohormone brain natriuretic peptide, and World Health Organization functional class were all predictive of clinical worsening and mortality (all P<0.05). Multivariate analysis demonstrated that OUESI and cardiac index were independently predictive of clinical worsening, and OUESI and N-terminal prohormone brain natriuretic peptide were independently predictive of mortality. Patients with OUESI ≤0.52 m-2 had a worse 5-year survival rate than patients with OUESI >0.52 m-2 (41.9% versus 89.8%, P<0.0001).

CONCLUSIONS

The OUES, a submaximal parameter obtained from cardiopulmonary exercise testing, provides prognostic information for predicting clinical worsening and mortality in patients with IPAH.