Cardiopulmonary exercise testing in patients with pulmonary hypertension: clinical recommendations based on a review of the evidence

ABSTRACT

Pulmonary hypertension (PH) remains an ominous diagnosis despite advances in pharmacological and surgical therapy. Early and effective diagnosis is important for clinicians making treatment determinations and patients wishing to understand the prognostic implications of their illness. Cardiopulmonary exercise testing (CPX) has the power to reveal the underlying pathophysiological consequences of the disease process. Research, especially over the last 10-15 years, has demonstrated the utility of this tool. Several CPX variables have been shown to be consistently altered in patients with PH and more so as severity of disease increases. However, to further enhance clinical application, additional research is needed to better define optimal CPX measures and associated cutoff values. This paper gives class-based recommendations with associated levels of evidence for the use of CPX in the PH patient population.

KEYWORDS:

• pulmonary hypertension
• cardiopulmonary exercise testing
• oxygen consumption
• ventilatory efficiency
• minute ventilation/carbon dioxide production slope
• partial pressure of end tidal carbon dioxide
• evidenced-based recommendations

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Key issues

• PH is a rapidly progressive disease with a 1-yr mortality rate of 15% despite advances in medical therapy.

• CPX testing has been used in the clinical assessment of patients with cardiovascular and pulmonary disease for decades. It can uncover abnormalities in the oxygen consumption (VO₂) cascade, such as ventilatory inefficiency and reduced aerobic capacity commonly seen in patients with PH.

• The CPX variables that are consistently demonstrated as valuable in patients with PH are VO₂ (reduced), the VE/VCO₂ slope or ratio (increased) and the P_ETCO₂ (reduced).

• While US and European guidelines advocate for CPX as a part of the diagnostic evaluation of patients with PH, a formal class recommendation with an associated level of evidence designation has not been given.

• A Class IIa recommendation, level of evidence B, for the incorporation of CPX in the diagnostic evaluation of PH is suggested. A Class IIb recommendation, level of evidence B, for CPX for clinical prognostication is suggested. Class IIb, level of evidence C, is suggested for the use of CPX in determining therapeutic efficacy of PH interventions.

• Hopefully, this systematic approach to the characterization of the current knowledge of CPX in the context of PH will encourage the clinical use of this tool where appropriate and prompt additional research to address remaining questions.