Cardiopulmonary exercise test in patients with subacute pulmonary emboli

OBJECTIVE: Patients presenting with suspected pulmonary embolism (PE) may present a challenge, particularly if diagnostic testing is not immediately available or clinically not indicated (iodine allergy, pregnancy, renal dysfunction). These patients have abnormal regional gas exchange that can be recognized by a cardiopulmonary exercise test (CPET), which may become helpful in their evaluation. METHODS: A retrospective analysis was performed of outpatients evaluated for subacute exertional dyspnea of 2 to 12 weeks duration with a test for PE and CPET. A total of 108 patients met inclusion criteria. Thirty patients (27.8%) had confirmed PE. RESULTS: The patients with PE had increased nadir ventilatory equivalent ratio for carbon dioxide (VE/VCO2), decreased peak oxygen uptake/predicted, and decreased end exercise saturation (P < .005 for all). All patients but 1 had normal breathing reserve (>15%). A normal nadir VE/VCO2 excluded PE with 100% sensitivity. By using a "flow chart strategy," the exercise test had 92.8% sensitivity and 92.1% specificity for PE. Eight patients with PE died during follow-up (3.8 +/- 4.6 years), 6 of PE-related causes. Peak VO2/kg was the best predictor of all-cause mortality and nadir VE/VCO2 for PE-related mortality. There were no serious complications from any of the exercise tests. CONCLUSION: PE may be excluded by a normal nadir VE/VCO2 in patients presenting with subacute dyspnea. A combination of decreased peak VO2/kg, increased nadir VE/VCO2, normal breathing reserve, and exercise-induced desaturation may be sensitive and specific for PE. CPET may assist in identifying subacute PE in patients with contraindications to use of computed tomography angiography or ventilation perfusion scans. Cite this article: Topilsky, Y., Hayes, C. L., Khanna, A. D., & Allison, T. G. (2012, MARCH/APRIL). Cardiopulmonary exercise test in patients with subacute pulmonary emboli. Heart & Lung, 41(2), 125-136. doi:10.1016/j.hrting.2011.06.009.