ABSTRACT

BACKGROUND - Ventricular fibrillation (VF) storm after myocardial infarction (MI) is a life-threatening condition that necessitates multiple defibrillations. Catheter ablation is a potentially effective treatment strategy for VF storm refractory to optimal medical treatment. However, its impact on patient survival has not been verified in a large population.

METHODS - We conducted a multicenter, retrospective observational study involving consecutive patients who underwent catheter ablation of post-MI refractory VF storm without preceding monomorphic ventricular tachycardia. The target of ablation was the Purkinje-related ventricular extrasystoles triggering VF. The primary outcome was in-hospital and long-term mortalities. Univariate logistic regression and Cox proportional-hazards analysis were used to evaluate clinical characteristics associated with in-hospital and long-term mortalities, respectively.

RESULTS - One-hundred ten patients were enrolled (65±11years; 92 men; left ventricular ejection fraction [LVEF] 31±10%). VF storm occurred at acute phase of MI (4.5±2.5 days after the MI onset during index hospitalization for MI) in 43 (39%) patients, subacute (>1 week) in 48 (44%), and remote (>6 months) in 19 (17%). The focal triggers were found to originate from the scar border zone in 88 (80%) patients. During in-hospital stay after ablation, VF storm subsided in 92 (84%) patients. Overall, 30 (27%) in-hospital deaths occurred. The duration from the VF occurrence to the ablation procedure was associated with in-hospital mortality (odds ratio for each one-day increase: 1.11; 95% confidence interval [CI]: 1.03-1.20; p=0.008). During follow-up after discharge from hospital, only one patient developed recurrent VF storm. However, 29 (36%) patients died with a median survival time of 2.2 years (interquartile range: 1.2-5.5 years). Long-term mortality was associated with LVEF<30% (hazard ratio [HR]: 2.54; 95%CI: 1.21-5.32; p=0.014), New York Heart Association class ≥III (HR: 2.68; 95%CI: 1.16-6.19; p=0.021), a history of atrial fibrillation (HR: 3.89; 95%CI: 1.42-10.67; p=0.008), and chronic kidney disease (HR: 2.74; 95%CI: 1.15-6.49; p=0.023).

CONCLUSIONS - In patients with MI presenting with focally-triggered VF storm, catheter ablation of culprit triggers is life-saving and appears to be associated with short- and long-term freedom from recurrent VF storm. Mortality over long-term follow-up is associated with the severity of underlying cardiovascular disease and comorbidities in this specific patient population.