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

Abstract

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.

Acknowledgments

The study team was assembled as part of the Spring 2022 University of California, Los Angeles, Prehospital Care Research Forum (PCRF) research workshop hosted at ESO Inc. in Austin, Texas. We specifically acknowledge David Page (DP), Scott Bourn (SB), Remle P. Crowe (RPC), Antonio Fernandez (AF), David Wampler (DW), and Brent Myers (BM) for their contributions to the success of the forum. We thank ESO and RPC for the availability and preparation of the dataset used for analysis. The content derived from this dataset remains the property of ESO Inc. ESO is not responsible for any claims arising from works based on the original data, text, tables or figures. We acknowledge RPC, SB, and AF for providing feedback on the initial study design and the manuscript.

Authors’ Contributions

RSL, CO, ERW, SRD, LBF and LHB conceived the research question and designed the study. The literature review was conducted by all authors and finalized by CO and LHB. LHB conducted data analysis. All authors reviewed the results and participated in their interpretation. Manuscript sections were drafted by all authors; the combined manuscript was edited by SRD and LHB. The final manuscript was reviewed and approved by all authors.

Data Availability Statement

The ESO Data Collaborative data are available upon request to and review by ESO.

Disclosure Statement

Mr. Dowker reports grant-funding from the National Institutes of Health (grant R01-HL137964) and the American Heart Association (grant 19SFRN34760762) as well as concurrent employment with the Green Oak Charter Township Fire Department, Michigan.

Additional information

Funding

The workshop where this study originated was supported by grant funding from the GMR Foundation for Research and Education, but GMR had no role in the design, execution, or reporting of this study.