Mid-Wall Scar and Sudden Death in Dilated Cardiomyopathy

Study Questions:

What is the relationship between mid-wall late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) and risk of sudden cardiac death (SCD) and aborted SCD in patients with dilated cardiomyopathy (DCM) with left ventricular ejection fraction (LVEF) ≥40%?

Methods:

A prospective institutional registry of patients with DCM and LVEF ≥40% was analyzed. The primary endpoint was the composite of SCD and aborted SCD. Secondary endpoints included death and two broad composite endpoints. Patients with hemodynamically significant coronary stenosis, infarct pattern LGE on CMR, infiltrative diseases, and/or valvular cardiomyopathy were excluded. Patients with a prior history of ventricular tachycardia (VT), ventricular fibrillation (VF), or syncope were excluded from primary analyses. All MRIs were performed on 1.5 Tesla systems and were interpreted by two independent readers, with one third providing adjudication as needed. Amount of LGE was also quantified.

Results:

A total of 399 patients were analyzed. The median LVEF was 50% and mid-wall LGE was present in 25.3%. Median follow-up was 4.6 years. Out of the 101 patients with mid-wall LGE, 18 (17.8%) experienced SCD or aborted SCD. By comparison, only seven patients (2.3%) of those without mid-wall LGE experienced SCD or aborted SCD (adjusted hazard ratio, 9.3; 95% confidence interval, 3.9-22.2; p < 0.0001). There was no clear dose response relationship between the amount of LGE and the primary outcome. Similar results were found for SCD alone, with nine (8.9%) of those with mid-wall LGE dying suddenly compared with six (2.0%) without mid-wall LGE. Finally, although similar differences were seen for all-cause mortality, these were not statistically significant (hazard ratio, 2.0; 95% confidence interval, 1.0-4.1; p = 0.06).

Conclusions:

Mid-wall LGE in patients with DCM and LVEF ≥40% is associated with a markedly increased risk of SCD and aborted SCD.

Perspective:

This paper further augments the now increasingly well-established relationship between LGE and adverse cardiac outcomes including SCD with a careful analysis of events in a population generally not currently eligible for primary prevention implantable cardioverter-defibrillator (ICD) therapy. In the context of the recently published DANISH trial, routine use of primary prevention ICDs in DCM patients with severely reduced LVEF has been questioned. Instead, CMR-based analysis of LGE may offer an opportunity for incremental risk assessment beyond LVEF and, potentially, for better targeting of primary prevention device therapies across the LVEF spectrum. However, prospective randomized trials are required to demonstrate that the benefits of primary prevention ICDs in this population outweigh risks.


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