Prevalence of pulmonary hypertension in mitral regurgitation and its influence on outcomes

OBJECTIVE: Pulmonary hypertension (PHT) commonly coexists with significant mitral regurgitation (MR), but its prevalence and prognostic importance have not been well characterised. In a large cohort of adults with moderate or greater MR, we aimed to describe the prevalence and severity of PHT and assess its influence on outcomes. METHODS: In this retrospective study, we analysed the National Echocardiography Database of Australia (data from 2000 to 2019). Adults with an estimated right ventricular systolic pressure (eRVSP), left ventricular ejection fraction >50% and with moderate or greater MR were included (n=9683). These subjects were then categorised according to their eRVSP. The relationship between PHT severity and mortality outcomes was evaluated (median follow-up of 3.2 years, IQR 1.3–6.2 years). RESULTS: Subjects were aged 76±12 years, and 62.6% (6038) were women. Overall, 959 (9.9%) had no PHT, and 2952 (30.5%), 3167 (32.7%), 1588 (16.4%) and 1017 (10.5%) patients had borderline, mild, moderate and severe PHT, respectively. A ‘typical left heart disease’ phenotype was identified with worsening PHT, showing rising E:e′, right and left atrial sizes increasing progressively, from no PHT to severe PHT (p<0.0001, for all). With increasing PHT severity, 1- and 5-year actuarial mortality increased from 8.5% and 33.0% to 39.7% and 79.8%, respectively (p<0.0001). Similarly, adjusted survival analysis showed the risk of long-term mortality progressively increased with higher eRVSP levels (adjusted HR 1.20–2.86, borderline to severe PHT, p<0.0001 for all). A mortality inflection was apparent at an eRVSP level >34.00 mm Hg (HR 1.27, CI 1.00–1.36). CONCLUSIONS: In this large study, we report on the importance of PHT in patients with MR. Mortality increases as PHT becomes more severe from an eRVSP of 34 mm Hg onwards.