Predictors of Mortality in Verapamil Overdose: Usefulness of Serum Verapamil Concentrations

Abstract

Verapamil poisoning may result in life-threatening cardiovascular morbidities and fatalities. To date, prognosticators of mortality have been poorly investigated and the use of serum verapamil concentration for prognosis remains unclear. We aimed to evaluate the ability of usual clinical and laboratory parameters including serum verapamil concentrations measured on admission to predict outcome (survival versus death) in verapamil poisoning. We reviewed the medical records of all intentional and symptomatic verapamil poisonings admitted over 8 years to two medical intensive care units. Clinical and laboratory parameters were measured in 65 patients, and final outcomes of survival or death recorded. A multivariable analysis was conducted to evaluate the prognostic values of recorded parameters. Life-threatening complications of verapamil poisonings included shock (62%), atrioventricular blocks (24%), sinoatrial blocks (20%), acute respiratory distress syndrome (19%) and cardiac arrest (11%) resulting in death (8%). Verapamil concentration measured on intensive care unit admission was the only independent factor associated with mortality (p = 0.01). The optimal verapamil cut-off point was 5.0 μM (100% sensitivity, 91% specificity), which conferred a 2.76-times increase in odds of fatality. In conclusion, cardiovascular monitoring and assessment of organ failure are vital in symptomatic verapamil poisonings. The serum verapamil concentration has excellent prognostic ability for predicting fatality in verapamil overdose.