Comparison of Weight-Based Dose vs. Standard Dose Diltiazem in Patients With Atrial Fibrillation Presenting to the Emergency Department

Adam L. Ross, PHARMD; David M. O'Sullivan, PHD; Michael J. Drescher, MD, FACEP; Michelle A. Krawczynski, PHARMD, BCPS

Disclosures

J Emerg Med. 2016;51(4):440-446. 

In This Article

Abstract and Introduction

Abstract

Background: Despite evidence-based recommended weight-based (WB) dosing of diltiazem for the initial treatment of atrial fibrillation (AF) with rapid ventricular response (RVR), many providers utilize lower initial doses of diltiazem.

Objective: We sought to determine whether a low, standard dose of diltiazem is noninferior to WB diltiazem as an initial bolus dose in the treatment of AF with RVR.

Methods: This retrospective review included patients who presented to the emergency department (ED) of an urban, academic tertiary medical center experiencing AF with RVR from November 2010 to August 2014. Adult patients were categorized by the dose of diltiazem received; 10 mg standard dose or 0.2–0.3 mg/kg WB dose. The primary outcome of successful treatment was defined as a composite of the following parameters 15 min after the initial bolus dose: heart rate (HR) < 100 beats/min, reduction of HR ≥ 20%, or a conversion to normal sinus rhythm.

Results: Four hundred and fifty-six patients who received diltiazem were included for study evaluation (standard dose: n = 255 patients, WB: n = 201 patients). Baseline characteristics, medical history, and medication use before ED presentation were similar between the groups. Significant differences at baseline between the groups included weight and HR at presentation. The primary outcome of successful treatment was attained in 60.8% of the standard dose patients and 68.7% of the WB patients (p = 0.082).

Conclusions: In patients presenting to the ED, we found that standard dose diltiazem was noninferior to WB dosing in the initial treatment of AF with RVR.

Introduction

Atrial fibrillation (AF) is a common cardiac dysrhythmia that requires many patients to seek emergency treatment each year.[1] Currently, the American Heart Association estimates the prevalence of AF in the United States to be 3–6 million and is expected to double by 2050.[2] Approximately 60%–70% of patients with AF present to the emergency department (ED) with rapid ventricular response (RVR).[3] AF with RVR occurs when the heart rate (HR) increases in response to inappropriate ventricular rate control, such as β-adrenergic stimulation or the absence of vagal stimulation.[4,5] AF with RVR can lead to significant morbidity and mortality if not treated promptly.[4] Complications of untreated AF with RVR can include hemodynamic instability, tachycardia-induced cardiomyopathy, arterial thromboembolism, cerebrovascular accidents, and death.[4,6,7]

The 2014 American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guideline for the acute management of patients with rapid AF suggest using an intravenous (IV) β-receptor antagonist (BB) or a non-dihydropyridine calcium channel antagonist (CCB) to slow RVR in the absence of hemodynamic instability or pre-excitation syndromes.[4] One of the most common medications used clinically to slow RVR is diltiazem.[8] There are data showing that CCB may be more effective at treating RVR than BB.[9–11] The AHA/ACC/HRS guidelines recommend an initial diltiazem bolus dose that is weight-based (WB) (0.25 mg/kg) given over 2 min, followed by a continuous-rate infusion of diltiazem at 5–15 mg/h.[4] Furthermore, they advise an additional, higher WB bolus of diltiazem (0.35 mg/kg) after 15 min if the patient does not demonstrate an adequate response to the initial bolus.[4,12,13]

Importance

Despite the long-standing WB guideline recommended dosing, recent research has investigated whether this dosing strategy is necessary for reduction of a rapid ventricular rate.[14] A non-WB or lower WB strategy has been utilized by providers at our institution and others.[14] This strategy carries the thought of "start low, and go slow" in lieu of a single, larger WB dose, despite the well-studied safety of WB diltiazem dosing.[3,9–13,15–18] A previously published retrospective study proposed that low-dose diltiazem (<0.2 mg/kg) might be as effective as guideline recommended WB diltiazem in treating RVR, and result in less hypotension.[14]

Goal of This Investigation

We hypothesize that diltiazem may not require WB dosing to emergently and adequately treat patients presenting to the ED in AF with RVR. The aim of this study was to determine whether a low, standard dose of diltiazem is noninferior to WB diltiazem as an initial IV bolus dose in the treatment of AF with RVR.

processing....