Female Sex and Myocardial Fibrosis Predict Arrhythmic Risk in Mitral Valve Prolapse: Study
USA: Researchers have found in a recent study that patients with mitral valve prolapse (MVP) undergoing cardiovascular magnetic resonance imaging, female sex, and myocardial fibrosis were independently associated with life-threatening arrhythmic events. The risk was substantially higher when both factors were present, highlighting their potential value for arrhythmic risk stratification in MVP.
The study, published in Circulation: Cardiovascular Imaging, was led by Amr Darwish of the Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Texas, and colleagues. Although MVP is generally considered a benign condition, a subset of patients can develop serious ventricular arrhythmias and sudden cardiac death. Identifying those at increased risk remains challenging.
The researchers prospectively followed 550 consecutive patients with MVP who underwent cardiovascular magnetic resonance (CMR) at a tertiary academic center between May 2008 and December 2021. Patients with conditions such as coronary artery disease, cardiomyopathy, infiltrative disease, or previous cardiac surgery were excluded.
The median patient age was 62 years, and women accounted for 50% of the cohort. Late gadolinium enhancement (LGE), a CMR marker of myocardial fibrosis, was detected in 210 patients (38%). Participants were followed for a median of 4.4 years, representing approximately 2,700 patient-years of follow-up.
The primary outcome included sudden cardiac death, aborted sudden cardiac arrest, and sustained or inducible ventricular tachycardia or ventricular fibrillation requiring implantable cardioverter-defibrillator placement or ventricular ablation at an MVP-related scar site.
Key findings included:
- Forty-eight patients (8.7%) experienced a life-threatening arrhythmic event during follow-up.
- Female sex was independently associated with a higher risk of arrhythmic events, with a hazard ratio of 3.33.
- Presence of myocardial fibrosis detected by LGE was also independently associated with increased risk, with a hazard ratio of 3.17.
- Patients who were both female and had LGE-positive myocardial fibrosis represented the highest-risk group.
- Five-year event-free survival was 76.5% among women with LGE compared with 98.5% among men without LGE.
- The associations remained significant after accounting for other clinical characteristics, including mitral regurgitation severity, mitral annular disjunction, bileaflet prolapse and symptoms.
The findings indicate that sex and myocardial tissue characteristics may add important information beyond conventional MVP and mitral regurgitation assessment. CMR detection of myocardial fibrosis could help identify patients needing closer arrhythmic monitoring, particularly women presenting with symptoms such as palpitations or syncope.
However, the researchers noted several limitations. The single-center design may have introduced referral and selection bias. The study assessed replacement fibrosis using LGE but did not evaluate diffuse fibrosis through T1 mapping or extracellular volume measurements. Papillary muscle fibrosis, another potential arrhythmic substrate, was also not comprehensively examined.
Overall, the findings suggest that female sex combined with myocardial fibrosis may identify a higher-risk MVP phenotype. Larger, multicenter studies are needed to confirm these associations and determine their role in future risk stratification and management.
Reference:
https://doi.org/10.1161/CIRCIMAGING.126.020017
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