# Prognostic Implications of Cardiac Magnetic Resonance Imaging Characteristics in Primary Mitral Regurgitation

## TL;DR

This study shows that a specific cardiac MRI measurement, left atrial emptying fraction, predicts worse outcomes after surgery for a heart valve condition called primary mitral regurgitation.

## Contribution

The study identifies reduced CMR-left atrial emptying fraction as a novel independent predictor of adverse postoperative outcomes in primary mitral regurgitation patients.

## Key findings

- Reduced CMR-left atrial emptying fraction (LAEF) was independently associated with higher risk of adverse outcomes after mitral valve surgery.
- Patients with CMR-LAEF <30% had significantly higher 5-year event rates and increased risk of adverse outcomes.
- CMR-LAEF threshold of 30% provided added prognostic value confirmed by multiple performance metrics.

## Abstract

Knowledge remains limited regarding the relationship between cardiac magnetic resonance (CMR) preoperative characteristics and postoperative clinical outcomes in primary mitral regurgitation (MR).

The authors assessed the prognostic value of CMR preoperative characteristics in patients with primary MR due to prolapse or flail undergoing mitral valve surgery.

We retrospectively studied 284 patients (median age 61 years, 24% women) with chronic significant primary MR, who underwent CMR and echocardiography (echo) prior to mitral valve repair surgery. The endpoint was a composite of all-cause mortality, hospitalization for heart failure, stroke, or life-threatening ventricular arrhythmia.

Over a median follow-up of 7.3 years (Q1-Q3: 3.4-10.5), adverse events occurred in 36 (13%) patients. CMR-left atrial emptying fraction (LAEF) (HR: 1.84 [95% CI: 1.32-2.56]; P < 0.001), CMR-right ventricular ejection fraction (HR: 1.36 [95% CI: 1.00-1.84]; P = 0.047), and CMR-indexed aortic forward stroke volume (HR: 1.40 [95% CI: 0.99-2]; P = 0.059) were each associated with a higher risk of adverse outcomes (HR for decrease in 1 SD). After adjusting for clinical and imaging risk factors, reduced CMR-LAEF remained independently associated with adverse prognosis (adjusted HR: 1.78 [95% CI: 1.27-2.48]; P < 0.001). Patients with CMR-LAEF <30% had higher 5-year event rates (28% vs 4%; P < 0.001) and were at a substantially higher risk of adverse outcomes (adjusted HR: 3.78 [95% CI: 1.83-7.80]; P < 0.001), with added prognostic value confirmed by multiple performance model metrics.

In patients with primary MR, among CMR and echo preoperative characteristics, reduced CMR-LAEF, with a threshold value of 30%, is markedly associated with an increased risk of postoperative adverse outcomes.