We aimed to determine the frequency and predictors of exercise limitation after pulmonary embolism (PE), and to assess its association with health-related quality of life (HRQOL) and dyspnea.
100 patients with acute PE were recruited at five Canadian hospitals from 2010-2013. Cardiopulmonary exercise testing (CPET) was performed at 1 and 12 months. Quality of life, dyspnea, six-minute walk distance (6MWD), residual clot burden (perfusion (Q) scan; CT pulmonary angiography (CTPA)), cardiac function (echocardiogram) and pulmonary function tests (PFT) were measured during follow-up. The prespecified primary outcome was percent-predicted peak oxygen uptake (VO2 peak) <80% on 1-year CPET.
At 1-year, 40/86 (46.5%) of patients had percent-predicted VO2 peak <80% on CPET, which was associated with significantly worse generic HRQOL, PE-specific HRQOL and dyspnea scores, and significantly reduced 6MWD at 1-year. Predictors of the primary outcome included male sex (relative risk (RR)= 3.2 [95% CI 1.3-8.1]), age (RR 0.98 [0.96-0.99] per 1-year age increase), body mass index (BMI) (RR 1.1 [1.01-1.2] per 1 kg/m2 BMI increase), and smoking history (RR 1.8 [1.1-2.9]), as well as percent-predicted VO2 peak <80% on 1-month CPET (RR 3.8 [1.9-7.2]) and 6MWD at 1-month (RR 0.82 [0.7-0.9] per 30m increased walking distance). Baseline or residual clot burden were not associated with the primary outcome. Mean PFT and echocardiogram (pulmonary artery pressure, right and left ventricular systolic function) results at 1 year were similarly within normal limits in exercise limited and non-exercise limited patients.
Almost half of PE patients have exercise limitation at 1 year which adversely influences HRQOL, dyspnea and walking distance. CPET or 6MWD testing at 1-month may help to identify patients with a higher risk of exercise limitation at 1-year after PE. Based on our results, we believe that deconditioning that occurs after acute PE could underlie this exercise limitation, but cannot exclude that this may have been present pre-PE.