CLINICAL DECISION-ANALYSIS MODELING - SHORT-TERM CONTROL OF VENTRICULAR RESPONSE RATE IN ATRIAL-FIBRILLATION OR ATRIAL-FLUTTER DIGOXIN VERSUS DILTIAZEM

Objective. To develop a clinical decision model to compare the outcome of therapy with digoxin versus diltiazem for short-term control of ve ntricular response rate (VRR) in patients with atrial fibrillation or atrial flutter. Design. Review of data from two studies that examined the percentages of response and frequency of adverse reactions in pati ents treated with intravenous digoxin or diltiazem to control VRR in a trial fibrillation or flutter. We constructed a clinical decision mode l and performed sensitivity analysis to determine if the model's predi ctions could be altered. Setting. Large teaching, university hospitals . Participants. Adults age 18 years or older treated with intravenous digoxin or intravenous diltiazem for atrial fibrillation or flutter (V RR greater-than-or-equal-to 120 beats/min). Patients with severe heart failure New York Heart Association class III or IV, a surgical proced ure prior to the exacerbation, or an acute myocardial infarction were excluded. Measurements and Main Results. We measured VRR control after 1 and 24 hours of therapy (VRR < 100 beats/min or decrease of greater -than-or-equal-to 20%) and assessed the likelihood that a patient woul d suffer an adverse drug reaction. Initial assumptions were that the p robability digoxin would achieve VRR control was 0.10 (95% confidence interval 0.04-0.20) at 1 hour and 0.70 (95% CI 0.56-0.80) at 24 hours; the probability that diltiazem would achieve VRR control was 0.94 (95 % CI 0.82-0.99) at 1 hour and 0.83 (95% CI 0.68-0.94) at 24 hours; and the probability of no serious adverse drug reaction would be 0.90 (95 % CI 0.80-0.96) for digoxin and 0.96 (95% CI 0.86-0.98) for diltiazem. Results. Diltiazem was superior to digoxin with respect to the compos ite end point score at 1 hour (91.20 vs 17.29) and 24 hours (81.65 vs 66.43). Digoxin was superior to diltiazem at 24 hours only if the VRR was assumed to be at the highest 95% CI limit for digoxin and simultan eously at the lowest 95% CI for diltiazem (74.62 vs 68.63). Conclusion s. Clinical decision analysis suggests that intravenous diltiazem is s uperior to intravenous digoxin in controlling VRR in patients with atr ial fibrillation or flutter.