Cardiopulmonary exercise testing following acute pulmonary embolism: Systematic review and pooled analysis of global studies

Recent reports have revealed a substantial morbidity burden associated with "post-PE syndrome" (PPES). Cardiopulmonary exercise testing (CPET) has shown promise in better characterizing these patients. In this systematic review and pooled analysis, we aim to use CPET data from PE survivors to understand PPES better. A literature search was conducted in PubMed, EMBASE, and Cochrane for studies reporting CPET results in post-PE patients without known pulmonary hypertension published before August 1, 2023. Studies were independently reviewed by two authors. CPET findings were subcategorized into (1) exercise capacity (percent predicted pVO₂ and pVO₂) and (2) ventilatory efficiency (VE/VCO₂ slope and V_D/V_T). We identified 14 studies (<i>n</i> = 804), 9 prospective observational studies, 4 prospective case-control studies, and 1 randomized trial. Pooled analysis demonstrated a weighted mean percent predicted pVO₂ of 76.09 ± 20.21% (<i>n</i> = 184), with no difference between patients tested <6 months (<i>n</i> = 76, 81.69±26.06%) compared to ≥6 months post-acute PE (<i>n</i> = 88, 82.55 ± 21.47%; <i>p</i> = 0.817). No difference was seen in pVO₂ in those tested <6 months (<i>n</i> = 76, 1.67 ± 0.51 L/min) compared to ≥6 months post-acute PE occurrence (<i>n</i> = 144, 1.75 ± 0.57 L/min; <i>p</i> = 0.306). The weighted mean VE/VCO₂ slope was 32.72 ± 6.02 (<i>n</i> = 244), with a significant difference noted between those tested <6 months (<i>n</i> = 91, 36.52 ± 6.64) compared to ≥6 months post-acute PE (<i>n</i> = 191, 31.99 ± 5.7; <i>p</i> < 0.001). In conclusion, this study, which was limited by small sample sizes and few multicenter studies, found no significant difference in exercise capacity between individuals tested <6 months versus ≥6 months after acute PE. However, ventilatory efficiency was significantly improved in patients undergoing CPET ≥ 6 months compared to those <6 months from the index PE.