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LGE and Risk for Arrhythmias or Sudden Death in DCM
Study Questions:
What is the relationship between late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (MRI) and ventricular arrhythmias and sudden cardiac death in patients with dilated cardiomyopathy (DCM)?
Methods:
PubMed and Ovid were systematically searched for observational studies that evaluated the relationship between LGE and arrhythmic endpoints (sustained ventricular arrhythmia, appropriate implantable cardioverter-defibrillator [ICD] therapy, or sudden cardiac death) in patients with DCM. The identified studies were systematically reviewed and a meta-analysis was performed.
Results:
The authors identified 29 studies with 2,948 total patients. LGE was qualitatively evaluated by visual interpretation in most studies. LGE prevalence was highly variable, ranging from 21% to 70%, but was present in 44% of the overall combined population. Overall, arrhythmic endpoints occurred in 21% of patients with LGE and 4.7% of those without LGE (odds ratio, 4.3; p < 0.001). This persisted among the subgroup in studies where multivariable adjustment was performed (hazard ratio, 6.7; p < 0.001). The annual event rate was 6.9%/year among those with LGE and 1.6%/year among those without (p < 0.0001). Similar event rates were seen regardless of left ventricular ejection fraction (LVEF) ≤35% or >35%. Importantly, among patients with primary prevention ICDs, the annual event rates were 17.2%/year in those with LGE and 2.1%/year in those without (odds ratio, 7.8; p = 0.007).
Conclusions:
LGE is a powerful independent predictor of arrhythmic endpoints in patients with DCM and may be useful in determining whether patients may benefit from ICD therapy.
Perspective:
The DANISH study (Danish ICD study in Patients with Dilated Cardiomyopathy), a randomized controlled trial, recently demonstrated that implantation of ICDs in patients with DCM and LVEF <35% was not associated with reduced risk of death or cardiovascular death. There appeared to be a reduction in sudden cardiac death (hazard ratio, 0.5; p = 0.005), but this was only a secondary outcome of the trial. The current meta-analysis, demonstrates that the expected arrhythmic event rates are markedly heterogenous among patients with DCM and may be 4- to 8-fold more common among those with LGE than those without. Consequently, the authors raise the question as to whether the results of the DANISH study might be different if LGE had been required among the inclusion criteria. More controversially, the authors raise the question as to whether ICD therapy also potentially could be helpful among those DCM patients with LVEF >35% and LGE, given similar risk stratification by LGE in this population. Both of these intriguing hypotheses merit further study. Other important questions also deserve investigation such as: What is the appropriate interval for re-evaluating with MRI those patients with DCM who do not initially have LGE?
Keywords: Arrhythmias, Cardiac, Cardiomyopathy, Dilated, Death, Sudden, Cardiac, Defibrillators, Implantable, Diagnostic Imaging, Gadolinium, Heart Failure, Magnetic Resonance Imaging, Primary Prevention, Risk, Stroke Volume
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