Accuracy of Echocardiography to Evaluate Pulmonary Vascular and RV Function During Exercise

Abstract

Objectives: The authors have compared exercise echocardiography and exercise cardiac magnetic resonance imaging with simultaneous invasive pressure registration (ExCMRip) for the assessment of pulmonary vascular and right ventricular (RV) function.

Background: Exercise echocardiography may enable early diagnosis of pulmonary vascular disease, but its accuracy is untested.

Methods: Exercise imaging was performed in 61 subjects (19 athletes, 9 healthy nonathletes, 8 healthy BMPR2 [bone morphogenetic protein receptor type II] mutation carriers, 5 patients with new or worsening dyspnea after acute pulmonary embolism, and 20 patients with chronic thromboembolic pulmonary hypertension). Echocardiographic variables included mean pulmonary artery pressure (mPAP) and systolic pulmonary artery pressure (sPAP), cardiac output (CO), RV fractional area change, tricuspid annular systolic excursion, and RV end-systolic pressure-area ratio as a surrogate measure of RV contractile reserve. ExCMRip provided measurements of CO, RV ejection fraction, mPAP, sPAP, and RV end-systolic pressure-volume ratio at rest and during exercise. Abnormal pulmonary vascular reserve was defined as mPAP/CO slope >3 mm Hg/l/min by ExCMRip.

Results: Echocardiographic determination of mPAP/CO was possible in 53 of 61 subjects (87%). mPAP/CO by echocardiography was higher than that obtained by ExCMRip (+0.9 mm Hg/l/min; 95% limits of agreement, -3.6 to 5.4), but enabled accurate identification of patients with abnormal pulmonary vascular reserve (area under the receiver-operating characteristic curve, 0.88 [95% confidence interval (CI): 0.77 to 1.00; p < 0.0001]). Simplified relationships between sPAP and exercise intensity had similar accuracy in identifying subjects with pulmonary vascular disease (area under the receiver-operating characteristic curve, 0.95 [95% CI: 0.88 to 1.01]; p < 0.0001). RV fractional area change by echocardiography correlated strongly with RV ejection fraction by ExCMRip, whereas a moderate correlation was found between tricuspid annular systolic excursion and RV ejection fraction. A moderate correlation was found between ratios of peak exercise to resting RV end-systolic pressure-area ratio and RV end-systolic pressure-volume ratio (r = 0.64; p < 0.0001).

Conclusions: Echocardiographic estimates of RV and pulmonary vascular function are feasible during exercise and identify pathology with reasonable accuracy. They represent valid screening tools for the identification of pulmonary vascular disease in routine clinical practice.

Keywords: cardiac magnetic resonance imaging; echocardiography; exercise; pulmonary artery pressure; pulmonary hypertension; right ventricular function.