Efficacy and Safety of Prehospital Diltiazem

Abstract

Objective

This study assesses the likelihood of clinical improvement and adverse events from EMS-administered diltiazem. Current prehospital protocols direct paramedics to administer diltiazem, a calcium channel blocker, to decrease the heart rate (HR) of symptomatic, hemodynamically stable patients with rapid atrial fibrillation. However, diltiazem can also cause systemic hypotension and bradycardia, which can precipitate end-organ injury. 

Methods

To assess whether the rate control benefit of prehospital diltiazem outweighs the risk of adverse events, we conducted a retrospective chart review of all adult patients who received diltiazem from Maryland Advanced Life Support EMS clinicians between January 1, 2019, and March 31, 2022. Collected data included patient demographics, vital signs, diltiazem dose, transport times, administered medications, and procedures. The main outcomes were clinical improvement (HR <100 beats per minute or ≥20% decrease from the maximum HR) and adverse events (bradycardia or hypotension). Multivariable logistic regression was used for statistical analysis.

Results

During the study period, 2396 patients received prehospital diltiazem and 94% of these patients (n = 2254) were included in the study. Overall, 1414 (63.8%) patients improved clinically, 604 (27.3%) patients achieved rate control as defined by a HR of <100 beats per minute, and 78 patients (3.5%) experienced an adverse event. Patients over the age of 50 were less likely to clinically improve with diltiazem administration. Adverse events were more likely in patients with systolic blood pressures (SBP) less than 140 mmHg, patients with maximum HR of less than 120 beats per minute, and patients who received nitroglycerin.

Conclusions

Prehospital diltiazem is effective and safe for most patients. Adverse events are more likely in patients with baseline SBP less than 140 mmHg, HR less than 120 beats per minute, and concurrent nitroglycerin administration. Future opportunities for research include examining the relationship between adverse events and underlying etiology as well as investigating downstream outcomes.

Author Contributions

EP, AM, and ML designed the study. TC queried the data and AM and ML oversaw data quality checks. AM, ML, and RT provided statistical advice on study design and EP analyzed the data. EP drafted the manuscript and all authors contributed substantially to its revision. AM takes responsibility for the paper as a whole.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Data Availability Statement

The participants of this study did not give written consent for their data to be shared publicly; therefore, supporting data is not available.