Safety and efficacy of prehospital diltiazem

Prehospital Treatment of Atrial Fibrillation: Infusion Pump for Bolus and Infusion?

OBJECTIVE

The prehospital treatment for stable patients with atrial fibrillation with rapid ventricular response is rate-controlling agents such as calcium channel blockers, often diltiazem given as a bolus. At our agency we encourage the use of a bolus given via the infusion pump over two to four minutes immediately followed by a maintenance infusion, given concerns of recurrent tachycardia or hypotension secondary to rapid bolus administration. We examined if administering a bolus and infusion via an infusion pump shows better heart rate (HR) control at arrival to the emergency department (ED) compared with administration of a bolus only, while maintaining hemodynamic stability during transport. We also analyzed if a patient received a second bolus within 60 min of arrival to the ED.

METHODS

We used a retrospective propensity-matched cohort of prehospital patients with atrial fibrillation for whom diltiazem was administered, from 1/1/2018 to 12/31/2021, in our system of 10 New Jersey paramedic units. We analyzed the age, gender, and initial HR and used it to match groups. We analyzed the mode and time of administration, dosage of the bolus, and presence of hypotension prehospitally.

RESULTS

The matched groups contained 145 patients who received a prehospital diltiazem bolus only (BO) and 146 patients who received a diltiazem bolus and infusion (BI). There was no significant difference between the mean change in HR from initial paramedic arrival to ED arrival between the two groups (BO 38 vs. BI 34, p = 0.16). There was no significant difference in the need for a second bolus within the first 60 min of arrival to the ED (BO 9.7% vs. BI 11.6%, p = 0.30). Patients in the BO group were more likely to experience prehospital hypotension then in the BI group (BO 17.2% vs BI 8.2%, p = 0.01), despite receiving smaller initial bolus doses (BO 14.2 mg vs. BI 17.4 mg, p < 0.001).

CONCLUSION

Our results show no significant differences in HR control or need for repeat bolus at the ED with the use of a diltiazem infusion following a diltiazem bolus. However, even when administering larger boluses, the use of an infusion pump resulted in less hypotension.

Efficacy and Safety of Prehospital Diltiazem

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.

Prehospital Intervention Improves Outcomes for Patients Presenting in Atrial Fibrillation with Rapid Ventricular Response

OBJECTIVE

To compare outcomes of patients presenting to emergency medical services (EMS) with atrial fibrillation with rapid ventricular response (AF-RVR) who did and did not receive prehospital advanced life support (ALS) rate or rhythm control intervention(s).

METHODS

This retrospective cohort study used the 2021 ESO Data Collaborative (Austin, TX) dataset. We identified 9-1-1 scene responses for patients aged 16 to 100 years old presenting with AF and an initial heart rate ≥ 110 beats per minute (bpm). Prehospital ALS interventions for AF-RVR included medications (e.g., calcium channel blockers, beta blockers, etc.) or electrical cardioversion. Outcome measures included prehospital rate control (i.e., final prehospital heart rate < 110 bpm), emergency department (ED) discharge to home, ED and hospital length of stay, and mortality. We also evaluated prehospital adverse events-specifically bradycardia, hypotension, and cardiac arrest. We used propensity score matching to compare outcomes among treated and untreated patients with similar demographic and clinical characteristics. We determined the average treatment effect on the treated (ATET) with 95% confidence intervals (CI) and the number needed to treat (NNT).

RESULTS

After propensity score matching, prehospital outcomes were available for 4,859 treated patients matched with 4,859 similar untreated patients. Prehospital rate control was more frequent for treated than for untreated patients (41.0% vs. 18.2%, ATET +22.8%, CI: +21.1%; +24.6%, NNT = 5). Hospital outcomes were available for 1,347 treated patients matched with 1,347 similar untreated patients. Treated patients were more likely to be discharged from the ED (37.9% vs. 34.0%, ATET +3.9%, CI: +0.2%; +7.5%, NNT = 26) and less likely to die (4.3% vs. 6.7%, ATET -2.5%, CI: -4.2%; -0.8%, NNT = 40) compared to untreated patients. Hypotension occurred more often in treated patients (ATET +2.6%, CI: +1.5%; +3.7%), but resolved before ED arrival in 73% of affected patients. Otherwise, adverse event rates did not significantly differ for the two groups.

CONCLUSIONS

In this propensity score matched study of patients presenting to EMS with AF-RVR, prehospital ALS interventions were associated with more frequent prehospital rate control, more frequent discharge to home from the ED, and lower mortality.

Safety and Efficacy of Prehospital Diltiazem for Atrial Fibrillation with Rapid Ventricular Response

INTRODUCTION

Atrial fibrillation (AFIB) with rapid ventricular response (RVR) is a common tachydysrhythmia encountered by Emergency Medical Services (EMS). Current guidelines suggest rate control in stable, symptomatic patients.

PROBLEM

Little is known about the safety or efficacy of rate-controlling medications given by prehospital providers. This study assessed a protocol for prehospital administration of diltiazem in the setting of AFIB with RVR for provider protocol compliance, patient clinical improvement, and associated adverse events.

METHODS

This was a retrospective, cohort study of patients who were administered diltiazem by providers in the Orange County EMS System (Florida USA) over a two-year period. The protocol directed a 0.25mg/kg dose of diltiazem (maximum of 20mg) for stable, symptomatic patients in AFIB with RVR at a rate of &gt;150 beats per minute (bpm) with a narrow complex. Data collected included patient characteristics, vital signs, electrocardiogram (ECG) rhythm before and after diltiazem, and need for rescue or additional medications. Adverse events were defined as systolic blood pressure &lt;90mmHg or administration of intravenous fluid after diltiazem administration. Clinical improvement was defined as a heart rate decreased by 20% or less than 100bmp. Original prehospital ECG rhythm interpretations were compared to physician interpretations performed retrospectively.

RESULTS

Over the study period, 197 patients received diltiazem, with 131 adhering to the protocol. The initial rhythm was AFIB with RVR in 93% of the patients (five percent atrial flutter, two percent supraventricular tachycardia, and one percent sinus tachycardia). The agreement between prehospital and physician rhythm interpretation was 92%, with a Kappa value of 0.454 (P &lt;.001). Overall, there were 22 (11%) adverse events, and 112 (57%) patients showed clinical improvement. When diltiazem was given outside of the existing protocol, the patients had higher rates of adverse events (18% versus eight percent; P = .033). Patients who received diltiazem in adherence with protocols were more likely to show clinical improvement (63% versus 46%; P = .031).

CONCLUSION

This study suggests that prehospital diltiazem administration for AFIB with RVR is safe and effective when strict protocols are followed.Rodriguez A, Hunter CL, Premuroso C, Silvestri S, Stone A, Miller S, Zuver C, Papa L. Safety and efficacy of prehospital diltiazem for atrial fibrillation with rapid ventricular response. Prehosp Disaster Med. 2019;34(3):297-302.

Frequency of "on-label" use of intravenous diltiazem for rate control in patients with acute-onset atrial fibrillation or atrial flutter

Purpose

The study was designed to characterize "on-label" use of i.v. diltiazem in patients with acute atrial fibrillation or flutter (AFF).

Methods

An IRB-approved, single-center, retrospective, observational design was used. Eligible patients had acute AFF with heart rate >120 bpm and received i.v. diltiazem from June 1, 2012, to June 30, 2014. The primary outcome was frequency of on-label use of i.v. diltiazem, defined as use of at least one FDA-approved weight-based bolus dose followed by an infusion, if appropriate, in the absence of contraindications.

Results

A total of 300 patients were screened; 97 patients were included for analysis. I.V. diltiazem was used on-label in only 14 patients (14%). Of the 96 patients who received an initial diltiazem bolus injection, the median dose was significantly higher in patients for whom the diltiazem dose was on-label, as follows: 17.5 mg (interquartile range [IQR]), 10-20 mg vs. 10.0 mg (IQR, 10-20 mg), p < 0.02). Twenty-nine patients (35%) in the off-label group had a therapeutic response to diltiazem alone compared with 8 patients (57%) in the on-label group (p = 0.11). More patients treated with off-label diltiazem bolus injection required additional rate control medications (41% vs. 7%, p < 0.04).

Conclusion

In most patients, i.v. diltiazem was not used in accordance with FDA labeling. For most, i.v. diltiazem doses were lower than recommended and many of these patients required additional rate control medications to achieve a therapeutic response.