Prognostic impact of atrio-ventricular conduction abnormalities in non-ischemic cardiomyopathy.

BACKGROUND

Late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) improves prediction of ventricular arrhythmias (VA) in non-ischemic cardiomyopathy (NICM), but risk stratification within LGE+ cases remains challenging. Atrioventricular block (AVB) has been proposed as a predictor of VA, but contemporary data are scarce.

OBJECTIVE

To assess the prognostic value of AVB in a contemporary cohort of patients with NICM studied with CMR.

METHODS

Retrospective cohort study including 616 patients with NICM, with assessment of AVB at electrocardiogram (ECG) and LGE at CMR. The primary arrhythmic end point included any appropriate implantable cardioverter defibrillator therapy, sustained monomorphic ventricular tachycardia, resuscitated cardiac arrest, and sudden death. The secondary heart failure (HF) end point included HF hospitalization, heart transplant, left ventricular assist device implant, and death due to end-stage HF.

RESULTS

AVB was observed in 9% of patients and was associated with more severe cardiac dysfunction (left ventricular ejection fraction [LVEF] 29% vs 37%, P < .001) and higher prevalence of LGE (63% vs 46%, P = .02). AVB independently predicted the combined arrhythmic end point in addition to LGE and LVEF (hazard ratio [HR], 2.7; P = .007), and was particularly impactful when present alongside LGE; among LGE+ patients, AVB significantly increased the risk of the primary end point (adjusted HR 3.4, P < .001). In contrast, AV block was not a significant predictor of the HF end point at multivariate analysis (P = .11).

CONCLUSION

AVB is a strong and independent predictor of VA and sudden death in NICM, in addition to LGE and LVEF. In addition, AVB has a significant impact on the risk stratification of LGE+ cases, identifying a small sub-group of patients with extremely high arrhythmic risk.