Conventional and atypical antipsychotics and the risk of hospitalization for ventricular arrhythmias or cardiac arrest

Background: Conventional antipsychotic drugs have been implicated as a cause of ventricular arrhythmias and cardiac arrest, but no definitive information is available regarding atypical antipsychotics. We compared the effect of conventional and atypical antipsychotics on the risk of hospitalization for ventricular arrhythrmas and cardiac arrest. Methods: We conducted a case-control study on residents of nursing homes in 6 US states by using data from the Minimum Data Set linked to Medicare inpatient claims. Cases were residents hospitalized for ventricular arrhythmias or cardiac arrest between July 4, 1998, and December 30, 1999. For each case, we identified up to 5 controls residing in the same facility during the same period. The sample consisted of 649 cases and 2962 controls. Results: Use of conventional antipsychotics was associated with a nearly 2-fold increase in risk of hospitalization for ventricular arrhythmias or cardiac arrest (adjusted odds ratio, 1.86; 9.5% confidence interval, 1.27-2.74). There was no increased risk associated with the use of atypical antipsychotics (odds ratio, 0.87; 95% confidence interval, 0.58-1.32). The risk of hospitalization for ventricular arrhythmias or cardiac arrest was highest among conventional users with cardiac disease (odds ratio, 3.27; 95% confidence interval, 1.95-5.47). However, cardiac disease and conventional antipsychotics did not show a synergistic effect (synergy index, 1.19). Conclusions: Conventional but not atypical antipsychotics are associated with an increased risk of hospitalization for ventricular arrhythmias and cardiac arrest. The prescription of conventional antipsychotics in patients with cardiac disease should be carefully weighed.