Papillary Muscle Scarring May Predict Cardiac Death in Patients with Dilated Cardiomyopathy

Papillary muscle scarring (papSCAR) as detected by dark blood delayed-enhancement cardiovascular magnetic resonance (CMR) was present in 1 in 3 patients with dilated cardiomyopathy (DCM) in a recent trial and acted as an independent predictor of cardiac death.1

DCM has been associated with microvascular dysfunction via several studies highlighting impaired myocardial perfusion reserve without epicardial coronary artery disease (CAD). In patients with DCM, microvascular dysfunction may serve as a strong predictor of poor prognosis independent of LV ejection fraction (LVEF) and New York Heart Association (NYHA) functional class.1

A novel dark blood delayed-enhancement CMR technique, flow-independent dark blood delayed-enhancement (FIDDLE), has been validated against pathology for papSCAR diagnosis. After initial referencing in canine models, the technique was used in patients with first-time myocardial infarction to identify the prevalence of anterior and posterior papillary muscle infarction. The trial also proved the technique’s efficacy in detecting papSCAR, showing test sensitivity nearly double that of conventional imaging.1,2

“Using FIDDLE, the aims of the current study were to determine the prevalence of papSCAR in patients with DCM and to evaluate if papSCAR was associated with adverse outcomes,” Yodying Kaolawanich, MD, Duke Cardiovascular Magnetic Resonance Center, and colleagues wrote.1

Patients in this papSCAR trial were screened after referral for CMR at the Duke Cardiovascular Magnetic Resonance Center between 2011 and 2020. Patients with hypokinetic nondilated cardiomyopathy, an early subtype of DCM characterized by LV dysfunction despite lack of LV dilation, were included in the trial. Those with obstructive CAD, severe primary valvular disease, the diagnosis of other nonischemic disorders, or complex congenital heart disease were excluded.1

Investigators used a predefined primary endpoint of cardiac death, with secondary endpoints of a heart failure death or cardiac transplant composite and an arrhythmia composite of sudden cardiac death (SCD) or aborted SCD. Only the first event for each patient was included in the analysis in the event of composite endpoints.1

A total of 603 patients with known or suspected DCM were referred for CMR; of these, 77 were excluded, largely because of coincident CAD or the diagnosis of other nonischemic disorders. Following CMR examination, another 56 participants were removed due to normal systolic function or evidence of a non-DCM diagnosis. Ultimately, 470 patients were analyzed in the study, with a mean age of 55.3 (standard deviation [SD] 14.3) years.1

Most patients were taking angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, beta blockers, and loop diuretics. 115 patients had NYHA class 3 or 4. Mean LVEF was 31.2% (SD, 10.5%), and midwall scar was present in 109 patients, with a median extent of 2.7% of LV mass (interquartile range [IQR] 1.8%-5%).1

After screening, patients were followed up for up to 8 years; during this time, 75 deaths occurred, of which 53 were cardiac. In total, 26 of 137 patients with papSCAR (19%) reached the primary endpoint compared with 27 of 333 without papSCAR (8.1%), demonstrating a significantly higher rate of cardiac death in those with papSCAR than without (hazard ratio [HR], 2.3; 95% CI, 1.34-3.95; P = .002). The cumulative 5-year rate of cardiac death was 20.5% in patients with papSCAR and 9% in patients without papSCAR. After multivariable Cox regression analysis, investigators associated papSCAR presence with cardiac death.1

Investigators saw the heart failure composite endpoint occur in 49 patients (10.4%); of these, 35 had heart failure death and 15 had cardiac transplant. The arrhythmia composite endpoint occurred in 24 patients (5.1%), of whom 18 had SCD and 11 had aborted SCD. Patients with papSCAR had higher rates of both heart failure events (HR, 2.29; 95% CI, 1.31-4.02; P = .004) and arrhythmia events (HR, 2.48; 95% CI, 1.12-5.52; P = .03) compared to those without.1

“Overall, these findings show that papSCAR provides prognostic value across the spectrum of patients with DCM and suggest that papSAR may be an early marker of risk,” wrote Kaolawanich and colleagues.1

References

1. Kaolawanich Y, Wendell DC, Kim HW, et al. Prognostic Value of Papillary Muscle Scarring in Patients With Dilated Cardiomyopathy. JAMA Cardiol. Published online October 15, 2025. doi:10.1001/jamacardio.2025.3822

2. Wendell D, Jenista E, Kim HW, et al. Assessment of Papillary Muscle Infarction with Dark-Blood Delayed Enhancement Cardiac MRI in Canines and Humans. Radiology. 2022;305(2):329-338. doi:10.1148/radiol.220251