Title
Exploratory Analysis: Comparative safety and efficacy of a novel combined IV and PO diltiazem protocol
for acute rate control.
Investigators
Brad Hall, PharmD, MS (Medical Student – Morsani College of Medicine University of South Florida),
Fred Blind, MD (Emergency Medicine Attending Physician – Lakeland Regional Health), Kayla Wilson,
PharmD, (Pharmacist – Lakeland Regional Health)
Background
Atrial fibrillation accounts for approximately 1% of all emergency department (ED) visits, with
approximately 65% of these patients requiring admission. Symptomatic relief and acute rate control
using calcium channel blockers or beta blockers are routinely used in this population. If left untreated,
patients can develop serious conditions such as heart failure, angina, myocardial infarction,
respiratory failure, or ventricular ectopy.
In the emergency department, the traditional protocol includes diltiazem injection given as a bolus of
0.25 mg/kg (max 25 mg). If heart rate remains uncontrolled after 15 minutes, a second bolus of 0.35
mg/kg (max 35 mg) may be given. If after another 15 minutes the heart rate still remains uncontrolled,
a continuous infusion of 5-15 mg/hour will be initiated. The oral protocol includes diltiazem injection
given as a bolus, but at a lower dose with more frequent administrations allowed, with 10 mg every 15
minutes as needed for heart rate greater than 100, up to four doses total. Additionally, diltiazem 60 mg
immediate-release oral tablets are administered every 6 hours.
Hypothesis
Our hypothesis is that there will be no significant difference in acute rate control at 3 hours between a
traditional intravenous bolus and infusion protocol and an intravenous bolus and oral regimen.
Methods
This is a single center, retrospective, cohort evaluation of patients in the emergency department
receiving diltiazem for acute rate control. Patients admitted and discharged January 1, 2015 and May
30, 2019 will be screened for inclusion in this study. Two groups are being compared, one which receives
a traditional IV bolus and IV infusion treatment and a novel IV bolus and PO regimen. Inclusion Criteria
are at least 18 years of age and received at least one dose of intravenous diltiazem in the emergency
department. Exclusion Criteria are incomplete data, aortic dissection, pre-medication heart rate less
than 100 bpm, or patient received other rate control medication(s) during current visit
Our primary outcome is the incidence of treatment failure, as defined as defined as HR of > 110
beats/min at 3 ± 1 hour, a switch in therapy from PO immediate-release diltiazem to IV continuous
infusion diltiazem, the requirement of an additional IV diltiazem bolus within four hours from the start
of PO or IV continuous infusion, or addition/switch of therapy to another rate control or antiarrhythmic
agent within three hours. Secondary outcomes include time to heart rate control and total intravenous
diltiazem dose administered. Safety outcomes include incidence of bradycardia as defined as a heart
rate less the 60 bpm and incidence of hypotension, systolic blood pressure less than 90 mmHG within 4
hours. Up to 400 patients may be included in each group, with a goal of including all patients receiving
PO diltiazem during the study period.
Results
IRB approval and reliance agreement obtained. Data collection is on-going.
Conclusions
Data collection is on-going and expected to be completed by October 2020.