Left main coronary artery compression by dilated pulmonary artery in pulmonary arterial hypertension: a systematic review and meta-analysis

Objective: Pulmonary arterial hypertension (PAH) can lead to left main coronary artery compression (LMCo), but data on the impact, screening and treatment are limited. A meta-analysis of LMCo cases could fill the knowledge gaps in this topic.

Methods: Electronic databases were searched for all LMCo/PAH studies, abstracts and case reports including pulmonary artery (PA) size. Restricted maximum likelihood meta-analysis was used to evaluate LMCo-associated factors. Specificity, sensitivity and accuracy of PA size thresholds for diagnosis of LMCo were calculated. Treatment options and outcomes were summarized.

Results: A total of five case-control cohorts and 64 case reports/series (196 LMCo and 438 controls) were included. LMCo cases had higher PA diameter (Hedge's g 1.46 [1.09; 1.82]), PA/aorta ratio (Hedge's g 1.1 [0.64; 1.55]) and probability of CHD (log odds-ratio 1.22 [0.54; 1.9]) compared to non-LMCo, but not PA pressure or vascular resistance. A 40 mm cut-off for the PA diameter had balanced sensitivity (80.5%), specificity (79%) and accuracy (79.7%) for LMCo diagnosis, while a value of 44 mm had higher accuracy (81.7%), higher specificity (91.5%) but lower sensitivity (71.9%). Pooled mortality after non-conservative treatment (n = 150, predominantly stenting) was 2.7% at up to 22 months of mean follow-up, with 83% survivors having no angina at follow-up.

Conclusion: PA diameter, PA/aorta ratio and CHD are associated with LMCo, while hemodynamic parameters are not. Data from this study support that a PA diameter cut-off between 40 and 44 mm can offer optimal accuracy for LMCo screening. Preferred treatment was coronary stenting, associated with low mid-term mortality and symptom relief. Diagnosis and management of left main coronary artery compression (LMCo) in patients with pulmonary arterial hypertension (PAH).