Sex differences in implantable cardiac defibrillator therapy according to arrhythmia detection times

Objective In implantable cardiac defibrillators (ICDs), long-detection times safely reduce unnecessary and inappropriate therapies. We aimed to evaluate ICD treatment of ventricular arrhythmias in women, compared with men, also taking into account ICD detection. Methods The Advance III trial randomised patients implanted with an ICD for primary or secondary prevention in two arms-long and nominal ventricular arrhythmias detection times before therapy delivering (number of intervals needed to detect (NID) 30/40 and 18/24, respectively). The main endpoint of this post hoc analysis was the incidence of ICD therapies evaluated through Kaplan-Meier method and univariate Cox regression models. Results Overall, 1902 patients (304 women, 65 +/- 11 years) were randomised. Women showed a lower risk of ICD therapy (HR 0.63, 95% CI 0.43 to 0.93, p=0.022); this difference was observed only in the long-detection arm (HR 0.37, p=0.013) and not in the short detection arm (HR 0.82, p=0.414). No significant sex differences were observed concerning inappropriate therapies and mortality rate. Long-detection settings significantly reduced overall ICD therapies and appropriate ICD therapies, both in women (overall HR 0.31, p=0.007; appropriate HR 0.33, p=0.033) and in men (overall HR 0.69, p=0.006; appropriate HR 0.73, p=0.048). Conclusions In patients with ICDs, the strategy of setting a long-detection time to treat ventricular arrhythmias (NID 30/40) reduces overall delivered therapies, both in women and men, when compared with nominal setting (NID 18/24). The reduction was significantly higher in women. Overall, women were less likely to experience ICD therapies than men; this result was only observed in the long-detection arm.