Submaximal heart and pulmonary evaluation: a novel noninvasive test to identify pulmonary hypertension in patients with systemic sclerosis

Diagnostic utility of sub-maximum cardiopulmonary exercise testing in the ambulatory setting for heart failure with preserved ejection fraction

Pulmonary hypertension is commonly associated with heart failure with preserved ejection fraction. In heart failure with preserved ejection fraction, the elevated left-sided filling pressures result in isolated post-capillary pulmonary hypertension or combined pre- and post-capillary pulmonary hypertension. Although right heart catheterization is the gold standard for diagnosis, it is an invasive test with associated risks. The ability of sub-maximum cardiopulmonary exercise test as an adjunct diagnostic tool in pulmonary hypertension-associated heart failure with preserved ejection fraction is not known. Forty-six patients with heart failure with preserved ejection fraction and pulmonary hypertension (27 patients with combined pre- and post-capillary pulmonary hypertension and 19 patients with isolated post-capillary pulmonary hypertension) underwent sub-maximum cardiopulmonary exercise test followed by right heart catheterization. The study also included 18 age- and gender-matched control subjects. Several sub-maximum gas exchange parameters were examined to determine the ability of sub-maximum cardiopulmonary exercise test to distinguish between isolated post-capillary pulmonary hypertension and combined pre- and post-capillary pulmonary hypertension. Conventional echocardiogram measures did not distinguish between isolated post-capillary pulmonary hypertension and combined pre- and post-capillary pulmonary hypertension. Compared to isolated post-capillary pulmonary hypertension, combined pre- and post-capillary pulmonary hypertension had greater ventilatory equivalent for carbon dioxide (VE/VCO₂) slope, reduced delta end-tidal CO₂ change during exercise, reduced oxygen uptake efficiency slope, and reduced gas exchange determined pulmonary vascular capacitance. The latter was significantly associated with right heart catheterization determined pulmonary artery compliance (r = 0.5; p = 0.0004). On univariate analysis, sub-maximum VE/VCO₂, delta end-tidal carbon dioxide, and gas exchange determined pulmonary vascular capacitance emerged as independent predictors of the extrapolated maximum oxygen uptake (%predicted) (β-coefficient values of –7.32, 95% CI: –13.3 – (–1.32), p = 0.01; 8.01, 95% CI: 1.96–14.05, p = 0.01; 8.78, 95% CI: 2.26–15.29, p = 0.01, respectively). Sub-maximum gas exchange parameters obtained during cardiopulmonary exercise test in an ambulatory setting allows for discrimination between isolated post-capillary pulmonary hypertension and combined pre- and post-capillary pulmonary hypertension. Additionally, sub-maximum cardiopulmonary exercise test derived VE/VCO₂, delta end-tidal carbon dioxide, and gas exchange determined pulmonary vascular capacitance influences aerobic capacity in heart failure with preserved ejection fraction.

Comparison of change in end tidal carbon dioxide after three minutes of step exercise between systemic sclerosis patients with and without pulmonary hypertension

OBJECTIVES

Pulmonary hypertension (PH) is an important cause of morbidity and mortality in patients with SSc. The submaximal heart and pulmonary evaluation (step test) is a non-invasive, submaximal stress test that could be used to identify SSc patients with PH. Our aims were to determine whether change in end tidal carbon dioxide ([Formula: see text]) from rest to end-exercise, and the minute ventilation to carbon dioxide production ratio ([Formula: see text]), both as measured by the step test, differ between SSc patients with and without PH. We also examined differences in validated self-report questionnaires and potential PH biomarkers between SSc patients with and without PH.

METHODS

We performed a cross-sectional study of 27 patients with limited or dcSSc who underwent a right heart catheterization within 24 months prior to study entry. The study visit consisted of questionnaire completion; history; physical examination; step test performance; and phlebotomy. [Formula: see text], [Formula: see text], self-report data and biomarkers were compared between patients with and without PH.

RESULTS

SSc patients with PH had a statistically significantly lower median (interquartile range) [Formula: see text] than SSc patients without PH [-2.1 (-5.1 to 0.7) vs 1.2 (-0.7 to 5.4) mmHg, P = 0.035], and a statistically significantly higher median (interquartile range) [Formula: see text] [53.4 (39-64.1) vs 36.4 (31.9-41.1), P = 0.035]. There were no statistically significant differences in self-report data or biomarkers between groups.

CONCLUSION

[Formula: see text] and [Formula: see text] as measured by the step test are statistically significantly different between SSc patients with and without PH. [Formula: see text] and [Formula: see text] may be useful screening tools for PH in the SSc population.