Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) proved to be a powerful predictor of ventricular tachyarrhythmic events in patients with cardiomyopathy, regardless of ischemic or nonischemic etiology.
Marcello Disertori, MD, of S. Chiara Hospital in Trento, Italy, and colleagues sought to assess the role of LGE in ventricular tachyarrhythmic event risk stratification in both ischemic and nonischemic cardiomyopathy with ventricular dysfunction.
Given the important role ventricular fibrosis plays in ventricular arrhythmias, its assessment by LGE CMR has been suggested as a possible marker for sudden death risk stratification.
Researchers analyzed 19 studies that included 2850 patients with 423 arrhythmic events. The primary or secondary outcomes were related to ventricular events, such as cardiac sudden death, aborted sudden death, sustained ventricular tachycardia, ventricular fibrillation, and appropriate implantable cardioverter defibrillator (ICD) therapy with the inclusion of antitachycardia pacing. They also included studies that used a composite end point, as long as arrhythmic events could be analyzed separately.
The 423 arrhythmic events, defined as a composite of cardiac sudden death, aborted sudden death, ventricular tachycardia/ventricular fibrillation, and ICD therapy, occurred at a prevalence of 14.8% with an annualized event rate of 5.3%
The composite arrhythmic end point was reached in 23.9% of patients with positive LGE vs 4.9% of patients with negative LGE (annualized event rate: 1.7%; P<.0001), and LGE correlated with arrhythmic events in different patient groups. Pooled odds ratios (OR) in the overall population were 5.62 (95% confidence interval [CI]: 4.20-7.51) and there were no significant differences between patients with ischemic cardiomyopathy and patients with nonischemic cardiomyopathy.
Dr Disertori and colleagues also examined a subgroup of 11 studies, encompassing 1178 patients with mean ejection fractions ≤30% in which the pooled OR increased to 9.56 (95% CI: 5.63-16.23) with a negative likelihood ratio of 0.13 (95% CI: 0.06-0.30). In this same subgroup with mean ejection fraction ≤30%, the arrhythmic end point was reached in 25.8% of patients with positive LGE (annualized event rate 10.3%) vs 3.1% of patients with negative LGE (annualized event rate: 1.2%: P<.0001).
Some of the limitations of this meta-analysis included the differing arrhythmic end points, the inconsistent LGE-CMR techniques and cut-offs, and the fact that a majority of the studies included were performed in “single, tertiary cardiologic centers.”
Nonetheless, according to the researchers, “The prognostic power of LGE is particularly strong in patients with severely depressed EF [ejection fraction]. LGE testing may thus improve the appropriateness of ICD implantation in patients with severely depressed EF by identifying a lower-risk group unlikely to benefit from ICD.”
“However, to be put into practice, LGE-CMR protocols need to be standardized with respect to execution modalities and the setting of diagnostic thresholds,” they concluded.
Disertori M, Rigoni M, Pace N, et al. Myocardial fibrosis assessment by late gadolinium enhancement is a powerful predictor of ventricular tachyarrhythmias in patients with ventricular dysfunction of ischemic and nonischemic etiology: a meta-analysis. JACC Cardiovasc Imag. 2016. doi:10.1016/j.jcmg.2016.01.033.