A systematic review for sudden cardiac death in hypertrophic cardiomyopathy patients with myocardial fibrosis: a CMR LGE study

Summary

To our knowledge this represent the first attempt at a formal meta-analysis to demonstrate that SCD is predicted by LGE, not just VT/VF.

Background

Hypertrophic cardiomyopathy (HCM) is a genetic disease that affects the cardiac sarcomere, resulting in myocardial hypertrophy and disarray. Affected patients have a predisposition for malignant ventricular tachyarrhythmias and, consequently, sudden cardiac death (SCD). In single center studies, late gadolinium enhancement (LGE) defined fibrosis has been linked to the substrate for VT/VF. However, despite innumerable investigations, SCD has not been definitely attributable to LGE. Explanations for this are believed to be related to insufficient statistical power.

Methods

We performed an electronic search of MEDLINE, PubMED and CMR abstracts for original data published or presented between Jan 01 - Mar 11. Key search terms: HCM, LV fibrosis, SCD and LGE. Studies were screened for eligibility based on inclusion criteria: referral for CMR exam with LGE for HCM; and follow-up for incidence of VT/VF and SCD. Relevant studies were summarized and the following data were abstracted: socio-demographic information; study design; incidence of reported VT/VF; SCD. Categorical variables were evaluated between pt groups via Chi-square test.

Results

A total of 64 studies were initially identified. Of these, 4 (6.3%) were identified and included (n=1,063 pts, range 202 to 424). Three prospective and 1 retrospective studies were included. LGE was detected in 59.6% of pts. Mean follow-up was 43±14mo. Age 22-90 yrs (63% male). As expected, the presence of myocardial fibrosis was associated with VT/VF (χ2=6.5, p<0.05; OR 9.0 (95% CI 1.2 to 68.7). Moreover, myocardial fibrosis strongly predicted SCD (χ2=6.6, p<0.05; OR 3.3 (95% CI 1.2 to 9.7).

Conclusions

Despite single center CMR studies, LGE has consistently predicted VT/VF while prediction of SCD has remained paradoxically unlinked. Although the lack of studies meeting our criteria limited our ability to perform a comprehensive meta-analysis, we have been able to demonstrate for the first time that LGE-defined fibrosis is a predictor of SCD in patients with HCM. This observation now demands a multi-center RCT for confirmation but supports the consideration of a primary indication of AICD implantation in HCM with LGE.

Funding

Internal.