January 25th, 2011
Inappropriate ICD Shocks Linked to Increased Mortality
A large, single-center observational study has found a link between inappropriate ICD shocks and mortality. In a report published in JACC, Johannes van Rees and colleagues from the Netherlands followed 1,544 patients who received an ICD from 1996 to 2006.
Thirteen percent of patients had at least one inappropriate shock over 41 months of followup. Age below 70 and the presence of atrial fibrillation were independent predictors of inappropriate shocks. The investigators failed to find any evidence that the incidence of inappropriate shocks decreased as a result of improvements to ICDs over time.
In what the authors termed their “most important finding”, patients with at least one inappropriate shock had a 60% increase in the risk of death.The risk of death increased with subsequent additional inappropriate shocks; patients with 5 inappropriate shocks had a more than three-fold increase in risk.
“It is not acceptable that so many patients suffer from inappropriate shocks,” said Martin Schalij, senior author of the study, in an ACC press release. “ICD therapy must be improved, through both patient-tailored programming of the devices and the development of superior algorithms to allow ICDs to better determine false alarms, such as supraventricular arrhythmias.”