Evaluating the Role of Erythrocyte-Related Markers in Predicting Adenosine Response in Supraventricular Tachycardia

Supraventricular tachycardia (SVT) accounts for ~50 000 emergency department (ED) visits annually. Adenosine is a commonly used pharmacologic intervention, but predictors of success remain unclear. Erythrocytes rapidly clear adenosine from circulation and whether hematologic variables influence cardioversion outcomes is unknown.

To evaluate whether hematocrit, hemoglobin or red blood cell (RBC) count, are associated with adenosine efficacy in treating SVT.

This multicenter retrospective cohort study included adult ED patients treated with adenosine for SVT between January 2021 to August 2024. Logistic regression evaluated the association between hematologic variables and adenosine conversion, adjusting for weight-based dose and total calcium.

Of the 303 encounters representing 256 unique patients, 61% converted after the first adenosine dose and 70% converted overall. Hematologic variables were not associated with first-dose cardioversion. For total conversion, higher hematocrit (per 10%-unit increase) was significantly associated with reduced odds (OR 0.60; 95% CI 0.36-0.99; P = 0.045) of cardioversion, but only in calcium adjusted model. Among patients requiring multiple doses, higher hematocrit (per 10%-unit; OR 0.23; 95% CI 0.09-0.58; P = 0.002), hemoglobin (per 1 g/dL; OR 0.67; 95% CI 0.53-0.85; P < 0.001), and RBC count (per 1 million/µL; OR 0.44; 95% CI 0.21-0.93; P = 0.031) were associated with reduced odds of subsequent cardioversion in calcium adjusted models.

Hematologic variables were not associated with initial adenosine cardioversion, but in patients requiring additional doses, higher erythrocyte markers were associated with reduced conversion, once accounting for total calcium. This may be due to increased erythrocyte mediated drug clearance. These findings warrant further research to inform clinical relevance.