Franke et al.’s meta-analysis drew conclusions from 19 studies and showed rates of inappropriate therapy to be 17.9%(9). Other studies show rates of inappropriate therapy varied widely, from anywhere between 2.9% to as high as 30%(7,14,8–10). The lowest of these was from a retrospective cohort analysis of 105 patients where 3 subjects (2.9%) received inappropriate shocks (having previously received appropriate therapy). All 3 were implanted for secondary prevention, and were all triggered by atrial fibrillation(10). Kron et al.’s study demonstrated one of the highest rates of inappropriate therapy in 24.3% of their patients, again most commonly caused by supraventricular arrhythmias – a theme reflected across multiple of the abovementioned papers(14). Mohsen et al was another study in the literature which showed that, although 36.7% patients received appropriate therapy, 63.3% received no appropriate therapy, and 30% of individuals received inappropriate therapy(11).

Although a well-recognised drawback of ICD implantation, there are few studies that have thoroughly investigated inappropriate therapy. The most expansive study in the collection described above has a relatively short follow-up period and, as previously highlighted, the small sample size limits and underpowers the ability for statistical analysis. We were unable to find significant data that identifies patients who are at higher risk of inappropriate therapy based on their demographics.