Cardiopulmonary exercise test in patients with refractory angina: functional and ischemic evaluation

Objectives: Refractory angina (RA) is a chronic condition clinically characterized by low effort tolerance; therefore, physical stress testing is not usually requested for these patients. Cardiopulmonary exercise testing (CPET) is con-sidered a gold standard examination for functional capacity evaluation, even in submaximal tests, and it has gained great prominence in detecting ischemia. The authors aimed to determine cardiorespiratory capacity by using the oxygen consumption efficiency slope (OUES) in patients with refractory angina. The authors also stud-ied the O-2 pulse response by CPET and the association of ischemic changes with contractile modifications by exer-cise stress echocardiography (ESE). Methods: Thirty-one patients of both sexes, aged 45 to 75 years, with symptomatic (Canadian Cardiovascular Soci-ety class II to IV) angina who underwent CPET on a treadmill and exercise stress echocardiography on a lower limb cycle ergometer were studied. ClinicalTrials.gov: NCT03218891. Results: The patients had low cardiorespiratory capacity (OUES of 1.74 +/- 0.4 L/min; 63.9 +/- 14.7% of predicted), and 77% of patients had a flattening or drop in O-2 pulse response. There was a direct association between Heart Rate (HR) at the onset of myocardial ischemia detected by ESE and HR at the onset of flattening or drop in oxygen pulse response detected by CPET (R = 0.48; p = 0.019). Conclusion: Patients with refractory angina demonstrate low cardiorespiratory capacity. CPET shows good sensi-tivity for detecting abnormal cardiovascular response in these patients with a significant relationship between flattening O-2 pulse response during CEPT and contractile alterations detected by exercise stress echocardiography.

Automated summary

The study aims to assess cardiorespiratory capacity in patients with refractory angina using oxygen consumption efficiency slope (OUES) and to investigate the association between ischemic changes and contractile modifications. The results show that patients with refractory angina have low cardiorespiratory capacity, and there is a significant relationship between flattening of O2 pulse response during CPET and contractile alterations detected by exercise stress echocardiography.