Atrial secondary mitral regurgitation: prevalence, characteristics, management, and long-term outcomes.

Background: The prevalence, clinical characteristics, management and long-term outcomes of patients with atrial secondary mitral regurgitation (ASMR) are not well described.

Methods: We performed a retrospective, observational study of consecutive patients with grade III/IV MR determined by transthoracic echocardiography. The aetiology of MR was grouped as being either primary (due to degenerative mitral valve disease), ventricular SMR (VSMR: due to left ventricular dilatation/dysfunction), ASMR (due to LA dilatation), or other.

Results: A total of 388 individuals were identified who had grade III/IV MR; of whom 37 (9.5%) had ASMR, 113 (29.1%) had VSMR, 193 had primary MR (49.7%), and 45 (11.6%) were classified as having other causes. Compared to MR of other subtypes, patients with ASMR were on average older (median age 82 [74-87] years, p < 0.001), were more likely to be female (67.6%, p = 0.004) and usually had atrial fibrillation (83.8%, p = 0.001). All-cause mortality was highest in patients with ASMR (p < 0.001), but similar to that in patients with VSMR once adjusted for age and sex (hazard ratio [HR] 0.81, 95% confidence interval [CI] 0.52-1.25). Hospitalisation for worsening heart failure was more commonly observed in those with ASMR or VSMR (p < 0.001) although was similar between these groups when age and sex were accounted for (HR 0.74, 95% CI 0.34-1.58). For patients with ASMR, the only variables associated with outcomes were age and co-morbidities.

Conclusions: ASMR is a prevalent and distinct disease process associated with a poor prognosis, with much of this related to older age and co-morbidities.