Calcium Administration to Prevent Hypotension Caused by Diltiazem Administration in the Treatment of Atrial Fibrillation With Rapid Ventricular Response

Diltiazem, a calcium channel blocker is the standard of care for treatment of stable patients with atrial fibrillation and rapid ventricular response. Many emergency physicians opine that calcium, the "antidote" for calcium channel blockers, when given prior to diltiazem administration, mitigates the common adverse effect of hypotension.

In order to obtain evidence related to this belief, we will study the effects of placebo (normal saline 50ml) versus calcium gluconate (2 grams in normal saline 50ml). Hemodynamically stable patients in afib with rvr will be identified on their arrival to the emergency department. Those who consent to the study will be enrolled and the pharmacy will be contacted to provide a blinded study sample to the patient's bedside. After initial vital signs are recorded the study sample will be infused via pump over a 10 minute period. Vitals will be recorded on its completion and a diltiazem bolus (0.25mg/kg, max 20mg) will be administered. Vitals will be recorded at 3, 5, 10, 20 and 30 minutes post start of diltiazem bolus.

The primary outcome of hypotension will be calculated using rates (frequencies). The rate of hypotension will be compared between the two groups using Chi square analysis. The groups will be compared for similarity using means(sd) and frequencies(percentages). Any variables that differ by group will be controlled for with a multiple logistic regression analysis.

A 35% rate of hypotension is estimated for the placebo group and a hypothesized 22% in the treatment group (a relative 37% decrease). This will require a minimum total sample size of 378 (184/ group) . We may terminate the study earlier if we achieve power.