In response to: Grossman D, Rosenthal H, DeVivo A. “No More H’s and T’s: An Action-Based Paradigm for Managing Cardiac Arrest.” ACEP Now. August 2026.

Cardiac arrest resuscitation algorithms have evolved from a safety framework into a cognitive cage. Algorithm-centric care, most prominently the American Heart Association sequences, improved consistency and survival, yet gains have plateaued, and outcomes vary among patients receiving guideline-concordant care.^1,2

Clinicians increasingly encounter arrests in which the same algorithm produces different responses in patients who look identical by rhythm or arrest location. This reflects not technique or protocol deviation but the limits of treating cardiac arrest as one uniform disease.

Cardiac arrest is a heterogeneous syndrome, with time-dependent shifts in what limits resuscitation.^3,4,5 Dr. Grossman and colleagues alluded to this in “No More H’s and T’s;” we would extend their action-based framework with a phenotype-based, physiology-driven model.

Electrical, circulatory, and metabolic failures are common examples, and naming the dominant one turns those action-based steps into a diagnostic framework.

Such a model draws on skills every emergency clinician already has, each suited to a different predominant portion of the arrest cycle: separating pseudo-pulseless electrical activity from true asystole on bedside ultrasound, recognizing the limits of adrenergic support in refractory ventricular fibrillation, or reading a point-of-care blood gas to guide metabolic correction. Each answer points to the next intervention, from invasive monitoring to early extracorporeal cardiopulmonary resuscitation. Because the dominant phenotype can shift during a single resuscitation, the approach rewards continual reassessment and integration of real-time data.

Emergency medicine bridges the prehospital setting and the ICU, making the emergency department a natural proving ground for precision resuscitation. We thank Dr. Grossman and colleagues for advancing this conversation.

References

1. Ong MEH, Perkins GD, and Cariou A. Out-of-hospital cardiac arrest: Prehospital management. The Lancet. 2018;391(10124):980–988. https://doi.org/10.1016/S0140-6736(18)30316-7
2. Andersen LW, Holmberg MJ, Berg KM, Donnino MW, and Granfeldt A. In-hospital cardiac arrest: A review. JAMA. 2019;321(12):1200–1210. https://doi.org/10.1001/jama.2019.1696
3. Gilmore CM, Rea TD, Becker LJ, and Eisenberg MS. Three-phase model of cardiac arrest: Time-dependent benefit of bystander cardiopulmonary resuscitation. Am J Cardiol. 2006; 98(4):497–499. https://doi.org/10.1016/j.amjcard.2006.02.055
4. Vilke GM, Chan TC, Dunford JV, Metz M, Ochs G, Smith A, et al. The three-phase model of cardiac arrest as applied to ventricular fibrillation in a large, urban emergency medical services system. Resuscitation. 2005; 64(3):341–346. https://doi.org/10.1016/j.resuscitation.2004.09.011
5. Patil KD, Halperin HR, and Becker LB. Cardiac arrest: Resuscitation and reperfusion. Circ Res. (2015)116(12):2041–2049. https://doi.org/10.1161/CIRCRESAHA.116.304495