In primary MR patients, LV fibrosis is more prevalent in MVP than non-MVP, suggesting a unique pathophysiology beyond volume overload in MVP. LV fibrosis in primary MR may represent a risk marker of arrhythmic events.

Background: Non-ischemic cardiomyopathy (NICM) is a leading cause of reduced left ventricular ejection fraction (LVEF) and is associated with high mortality risk from progressive heart failure and arrhythmias. Myocardial scar on cardiovascular magnetic resonance imaging (CMR) is increasingly recognized as risk marker for adverse outcomes, however LV dysfunction remains the basis for determining a patient's eligibility for primary prophylaxis implantable cardioverter-defibrillator (ICD). We wanted to investigate the relationship of LVEF and scar to long term mortality and mode of death in a large cohort of patients with NICM. Methods: This study is a prospective, longitudinal outcomes registry of 1020 consecutive patients with NICM who underwent clinical CMR for the assessment of LVEF and scar at three centers. Results: During a median follow-up of 5.2 (IQR 3.8, 6.6) years 277 (27%) patients died. On survival analysis LVEF≤35% and scar were strongly associated with all-cause (log-rank test p=0.002 and p<0.001, respectively) and cardiac death (p=0.001 and p<0.001, respectively). While scar was strongly related to sudden cardiac death (SCD) (p=0.001), there was no significant association between LVEF≤35% and SCD-risk (p=0.57). On multivariable analysis including established clinical factors, LVEF and scar are independent risk-markers of all-cause and cardiac death. The addition of LVEF provided incremental prognostic value albeit insignificant discrimination improvement by C-statistic for all-cause and cardiac death, however no incremental prognostic value for SCD. Conversely, scar extent demonstrated significant incremental prognostic value and discrimination improvement for all three endpoints. On net reclassification analysis, the addition of LVEF resulted in no significant improvement for all-cause death 11.0% (95% CI -6.2-25.9%), cardiac death 9.8% (95% CI -5.7-29.3%), and SCD 7.5% (95% CI -41.2-42.9%). Conversely, the addition of scar extent resulted in significant reclassification improvement of 25.5% (95% CI 11.7-41.0%) for all-cause death, 27.0% (95% CI 11.6-45.2%) for cardiac death, and 40.6% (95% CI 10.5-71.8%) for SCD. Conclusions: Myocardial scar and LVEF are both risk markers for all-cause and cardiac death in patients with NICM. However, while myocardial scar has strong and incremental prognostic value for SCD risk stratification, LVEF has no incremental prognostic value over clinical parameters. Scar assessment should be incorporated into patient selection criteria for primary prevention ICD placement.

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BackgroundRoutine cine cardiovascular magnetic resonance (CMR) allows for the measurement of left atrial (LA) volumes. Normal reference values for LA volumes have been published based on a group of European individuals without known cardiovascular disease (CVD) but not on one of similar United States (US) based volunteers. Furthermore, the association between grades of LA dilatation by CMR and outcomes has not been established. We aimed to assess the relationship between grades of LA dilatation measured on CMR based on US volunteers without known CVD and all-cause mortality in a large, multicenter cohort of patients referred for a clinically indicated CMR scan.MethodWe identified 85 healthy US subjects to determine normal reference LA volumes using the biplane area-length method and indexed for body surface area (LAVi). Clinical CMR reports of patients with LA volume measures (n = 11,613) were obtained. Data analysis was performed on a cloud-based system for consecutive CMR exams performed at three geographically distinct US medical centers from August 2008 through August 2017. We identified 10,890 eligible cases. We categorized patients into 4 groups based on LAVi partitions derived from US normal reference values: Normal (21–52 ml/m2), Mild (52–62 ml/m2), Moderate (63–73 ml/m2) and Severe (> 73 ml/m2). Mortality data were ascertained for the patient group using electronic health records and social security death index. Cox proportional hazard risk models were used to derive hazard ratios for measuring association of LA enlargement and all-cause mortality.ResultsThe distribution of LAVi from healthy subjects without known CVD was 36.3 ± 7.8 mL/m2. In clinical patients, enlarged LA was associated with older age, atrial fibrillation, hypertension, heart failure, inpatient status and biventricular dilatation. The median follow-up duration was 48.9 (IQR 32.1–71.2) months. On univariate analyses, mild [Hazard Ratio (HR) 1.35 (95% Confidence Interval [CI] 1.11 to 1.65], moderate [HR 1.51 (95% CI 1.22 to 1.88)] and severe LA enlargement [HR 2.14 (95% CI 1.81 to 2.53)] were significant predictors of death. After adjustment for significant covariates, moderate [HR 1.45 (95% CI 1.1 to 1.89)] and severe LA enlargement [HR 1.64 (95% CI 1.29 to 2.08)] remained independent predictors of death.ConclusionLAVi determined on routine cine-CMR is independently associated with all-cause mortality in patients undergoing a clinically indicated CMR.