What question did this study set out to answer?

To determine whether late gadolinium enhancement on cardiac magnetic resonance predicts appropriate implantable cardioverter-defibrillator therapies or all-cause mortality in patients with nonischemic cardiomyopathy.

January 9, 2025Heart RhythmOpen Access

Late-gadolinium enhancement predicts appropriate device therapies in nonischemic recipients of primary prevention implantable cardioverter-defibrillators

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Why the study?

Better risk stratification is needed to evaluate patients with nonischemic cardiomyopathy for prophylactic ICDs, and CMR imaging may be useful in this regard.

Does significant late gadolinium enhancement on CMR predict appropriate ICD therapies in patients with nonischemic cardiomyopathy receiving primary prevention ICDs?

Key Points

To determine whether late gadolinium enhancement on cardiac magnetic resonance predicts appropriate implantable cardioverter-defibrillator therapies or all-cause mortality in patients with nonischemic cardiomyopathy.
Retrospective cohort study of 344 patients with nonischemic cardiomyopathy undergoing primary prevention implantable cardioverter-defibrillator placement at Cleveland Clinic between 2003 and 2021 with prior cardiac magnetic resonance within 12 months.
Myocardial late gadolinium enhancement was quantified by pixel intensity (≥5 standard deviations above reference) and categorized as none/minimal (<2%) versus significant (≥2%) over a median follow-up of 61 months.
Significant late gadolinium enhancement was present in 219 patients (64%) and predicted the primary outcome of appropriate device therapies (24% vs. 8%; subhazard ratio [HR] 2.99, 95% CI 1.48–6.02, P = .002).
Significant late gadolinium enhancement did not predict the secondary composite endpoint of all-cause mortality, transplant, or left-ventricular assist device implantation (26% vs. 17%; HR 1.34, 95% CI 0.78–2.29, P = .287).

Structured PICO

Does significant late gadolinium enhancement on CMR predict appropriate ICD therapies in patients with nonischemic cardiomyopathy receiving primary prevention ICDs?

Population

344 patients with nonischemic cardiomyopathy (NICM) who underwent primary prevention implantable cardioverter-defibrillator (ICD) implantation at Cleveland Clinic between 2003 and 2021 with cardiac magnetic resonance (CMR) imaging within 12 months before implant.

Intervention

Significant late gadolinium enhancement (LGE) on CMR (≥2% myocardium)

Comparator

None or minimal LGE on CMR (<2% myocardium)

Outcome

Appropriate ICD therapieshard clinical

In patients with nonischemic cardiomyopathy, significant LGE (≥2%) on CMR is a strong predictor of appropriate primary prevention ICD therapies, suggesting its potential utility in risk stratification for sudden cardiac arrest.

Implication

CMR LGE may refine ICD risk stratification in NICM; leaves open whether it should guide implantation decisions.

Abstract

BACKGROUND: Better risk stratification is needed to evaluate patients with nonischemic cardiomyopathy (NICM) for prophylactic implantable cardioverter-defibrillators (ICDs). Growing evidence suggests that cardiac magnetic resonance (CMR) imaging may be useful in this regard. OBJECTIVE: We aimed to determine if late gadolinium enhancement (LGE) seen on CMR (dichotomized as none or minimal <2% vs significant ≥2%) predicts appropriate ICD therapies (primary endpoint) or all-cause mortality/transplant/left-ventricular assist device (LVAD) implantation (secondary endpoint) in patients with NICM. METHODS: We identified 344 patients with NICM who underwent primary prevention ICD implantation at Cleveland Clinic between 2003 and 2021 with CMR within 12 months before implant. LGE was calculated as percentage myocardium with pixel intensity ≥5 standard deviations higher than that of reference myocardium. Endpoints were adjudicated retrospectively by chart review. RESULTS: A total of 125 of 344 patients (36%) had none or minimal LGE, and 219 (64%) had significant LGE. Over a median follow-up of 61 months, 53 patients (24%) with significant LGE vs 10 (8%) with none or minimal LGE met the primary endpoint, and 56 patients (26%) vs 21 (17%) met the secondary endpoint, respectively. Significant LGE predicted the primary outcome in multivariable competing-risks regression (hazard ratio [HR] 2.99, 95% confidence interval [CI] 1.48-6.02, P = .002), but did not predict the secondary outcome in multivariable Cox regression (HR 1.34, 95% CI 0.78-2.29, P = .287). CONCLUSION: In patients with NICM and primary prevention ICDs, LGE ≥2% is predictive of appropriate device therapies but not all-cause mortality/LVAD/transplant. LGE may be a relatively specific predictor of sudden cardiac arrest risk and therefore could potentially be used during evaluation for prophylactic ICD implantation.