Cycle length of nonsustanied ventricular tachycardias among ICD patients: implications on subsequent appropriate therapies.

BACKGROUND: ICD patients with episodes of nonsustained ventricular tachycardias (NSVT) are at risk of appropriate therapies. However, the relationship between the cycle length (CL) of such NSVTs and the subsequent incidence of appropriate interventions is unknown. METHODS: 416 ICD patients with LVEF < 45% were studied. ICD programming was standardized. NSVT was defined as any VT of 5 or more beats at ≥ 150 bpm occurred in the first 6 months after implantation that terminated spontaneously and was not preceded by any appropriate therapy. The mean follow-up was 41 ± 27 months. RESULTS: We analyzed 2201 NSVTs (mean CL = 323 ms) that occurred in 250 patients; 111 of such episodes were fast (CL ≤ 300 ms). Secondary prevention (HR = 1.7; p < 0.001), number of NSVT episodes (HR = 1.05; 95% CI 1.04-1.07; p < 0.001) and beta-blocker treatment (HR = 0.7; p = 0.04) were independent predictors of appropriate interventions; however, the mean CL of NSVTs was not (p = 0.6). There was a correlation between the mean CL of NSVTs and the CL of the first monomorphic VT: r = 0.88; p < 0.001. This correlation was especially robust in individuals with > 5 NSVTs (r = 0.97; p < 0.001), with an agreement between both values greater than 95%. Patients with any fast NSVT experienced a higher incidence of VF episodes (26%) compared to those without NVSTs (3%) or with only slow NSVTs (7%); p < 0.001. CONCLUSIONS: Unlike the burden, the CL of NSVTs is not a predictor of subsequent appropriate interventions. However, there is a close relationship between the CL of NSVTs and that of arrhythmias that will later lead to appropriate therapies.

Timing of Ablation and Prognosis of Patients With Electrical Storm and Scar-Related Left Ventricular Dysfunction.

Although radiofrequency catheter ablation (RFCA) is indicated in electrical storm (ES) refractory to antiarrhythmic drugs, its most appropriate timing has not been determined. Our objective is to analyse the impact of the timing of RFCA on 30-day mortality in patients with ES and previous scar-related systolic dysfunction. In this multi-centre study, we analysed 104 patients (age: 72 ± 10, left ventricular ejection fraction: 30 ± 6%) attended consecutively due to an ES caused by monomorphic ventricular tachycardia. Sixty-four subjects were treated with RFCA (mean time from admission = 83 ± 67 hours) and 40 were not. Upon admission 25 (24%) individuals had severe heart failure. Mortality rate at 30 days was 24 (23%) patients. RFCA was associated with a reduction of 30-day mortality (hazard ratio = 0.2; p = 0.008). After showing a positive correlation between the time of the RFCA (hours) and survival at 30 days (C-statistic = 0.77; p <0.001), we found that only subjects ablated >48 hours after admission had lower mortality at 30 days than those treated conservatively: 38% (no RFCA) versus 30% (RFCA ≤48 hours) versus 7% (RFCA >48 hours) (adjusted hazard ratio for RFCA >48 hours vs others = 0.2; p = 0.007). Among the patients ablated, those who were non-inducible had lower 30-day mortality: 8% versus 29% (p = 0.03). Extracorporeal membrane oxygenation was associated with a higher rate of non-inducibility in RFCA >48 hours (100% vs 76%; p = 0.03), but not in RFCA ≤48 hours (60% vs 60%; p = 1). In conclusion, among high-risk patients with ES, RFCA performed >48 hours after admission is associated with a reduction in 30-day mortality. In such subjects, the probability of successful RFCA increases when performed under extracorporeal membrane oxygenation support.