Determinants and Mechanisms of Postoperative Effort Intolerance in Suspected Lung Cancer　― An Exercise-Stress Echocardiography Study ―

Background: Decreased exercise tolerance after pulmonary resection for lung cancer is strongly associated with a poor prognosis, but its determinants remain underexplored. We investigated the mechanisms of postoperative effort intolerance in lung cancer using combined exercise-stress echocardiography and cardiopulmonary exercise testing (ESE-CPET). Methods and Results: We prospectively analyzed 38 patients with suspected non-small cell lung cancer who underwent pulmonary resection. Preoperative and 6-month postoperative evaluations included resting echocardiography, ESE-CPET, and pulmonary function tests. Pulmonary vascular function was assessed using the mean pulmonary artery pressure/cardiac output (MPAP/CO) slope (n=38). Postoperative peak oxygen consumption (V̇O 2 ) significantly decreased (19.4 vs. 17.3 mL/min/kg, P<0.001). Multiple regression analysis identified left atrial reservoir strain (B 0.797 [95% confidence interval: 0.138–1.456], P=0.019) and number of resected segments (−5.448 [−10.99 to −0.047], P=0.048) as independent predictors of postoperative change in peak V̇O 2 . Subgroup analysis showed greater changes in systolic pulmonary artery pressure during exercise (∆SPAP) and steeper postoperative MPAP/CO slopes in patients with ≥3 resected segments vs. <3 (P<0.001 and P=0.052 for time-group interaction). A preoperative MPAP/CO slope >2.0 predicted larger increases in peak SPAP following ≥3-segment resection (P=0.006), signifying increased pulmonary vascular stress. Conclusions: ESE-CPET demonstrated that extensive pulmonary resection adversely affects postoperative exercise tolerance and pulmonary vascular function, leading to greater ∆SPAP and steeper MPAP/CO slopes.