Pub Date: Wednesday, Sept. 5, 2012
Author: Marco Guazzi, MD, PhD, FACC and Ross Arena, PhD, PT, FAHA
Citation: Guazzi M, Adams V, Conraads V, Halle M, Mezzani A, Vanhees L, Arena R, Fletcher GF, Forman DE, Kitzman DW, Lavie CJ, Myers J. Clinical recommendations for cardiopulmonary exercise testing data assessment in specific patient populations. Circulation. 2012: published online before print September 5, 2012, 10.1161/CIR.0b013e31826fb946.
Cardiopulmonary exercise testing (CPX) merges traditional exercise testing procedures (ECG, blood pressure, perceived exertion, etc.) with ventilatory expired gas analysis (i.e. oxygen consumption, carbon dioxide production and minute ventilation). The combination of these variables affords the ability to assess an individual’s response to physical exertion in a highly refined manner. Thus, CPX is highly valuable when unexplained exertional limitations are present as this assessment technique can help to isolate physiologic abnormalities in the cardiovascular, pulmonary and/or skeletal muscle systems. Moreover, a number of CPX variables have proven to be highly prognostic in a number of patient populations. Currently, CPX is a clinical standard of care in patients with unexplained exertional dyspnea as well as those diagnosed with heart failure. Moreover, emerging evidence strongly suggests CPX has clinical utility in patients with suspected/confirmed pulmonary arterial hypertension or secondary pulmonary hypertension, pulmonary disease, hypertrophic cardiomyopathy, suspected myocardial ischemia, and suspected mitochondrial myopathy. Thus, it is likely the clinical application of CPX will expand in the coming years.
While original research demonstrating the value of CPX is robust and numerous review papers as well as scientific statements have been written on the topic, actual clinical utilization of this exercise assessment remains suboptimal. A potential reason for lower utilization of CPX in clinically warranted situations is an inability for clinicians to easily identify and interpret the most relevant data. In truth, most software packages operating CPX systems generate reports and graphs that are oftentimes difficult for the clinician decipher. Moreover, a number of variables included in these reports do not provide essential, evidence based, clinical information for a given test indication. Appropriate clinical utilization of CPX may increase if a simplified approach to key data identification and interpretation was available.
The new clinical CPX statement, which was a joint effort from the European Society of Cardiology and American Heart Association, published in both the European Heart Journal and Circulation (September epub ahead of print), provides a streamlined approach to key data identification and interpretation. The body of original research in CPX is reviewed and used to justify which variables should be assessed for a given test indication. While certain variables overlap and are universal to all test indications, others are unique to the reason for CPX. From this review of evidence, simplified, color-coded, one page reporting sheets are provided for the following test indications: 1) heart failure, 2) suspected or confirmed hypertrophic cardiomyopathy, 3) unexplained exertional dyspnea, 4) suspected or confirmed pulmonary arterial hypertension/secondary pulmonary hypertension, 5) chronic obstructive lung disease or interstitial lung disease, 6) suspected myocardial ischemia, and 7) suspected mitochondrial myopathy. Based on the color-coded value for each pertinent CPX value obtained, an evidence-based prognostic and/or diagnostic interpretation is provided. We view this approach as a major step forward in simplifying CPX interpretation with high clinical applicability.
In closing, based on the body of research in this area, CPX clearly provides highly valuable clinical information in a number of patient populations. As co-chairs of the writing group that developed this joint statement, it is our hope that clinicians whose patients would benefit from CPX find this document to be highly valuable to their practice.
-- The opinions expressed in this commentary are not necessarily those of the editors or of the American Heart Association --