Adenosine response and failure to convert paroxysmal supraventricular tachycardia in the emergency department.

BACKGROUND AND IMPORTANCE: Although adenosine is the recommended first-line therapy for patients with paroxysmal supraventricular tachycardia (SVT), it may fail to restore normal sinus rhythm. The factors associated with this failure remain unclear.

OBJECTIVE: To assess the response rate to adenosine and identify the factors causing adenosine failure in the management of paroxysmal SVT.

DESIGN, SETTING, AND PARTICIPANTS: This retrospective study was conducted on adult patients diagnosed with paroxysmal SVT and treated with adenosine in the emergency departments of two large tertiary hospitals between June 2015 and June 2021.

OUTCOME MEASURE AND ANALYSIS: The primary outcome of the study was the patient response to adenosine, defined as the restoration of sinus rhythm documented in the patients' files. Backward-stepwise multivariate logistic regression was used to examine the predictors of adenosine failure based on the overall response to adenosine therapy.

MAIN RESULTS: A total of 404 patients, with a mean age of 49 (SD 15) years and a BMI of 32 (SD 8) kg/m2, and treated with adenosine for paroxysmal SVT, were included. Sixty-nine percent of patients were women. The overall response rate to any adenosine dose was 86% (n = 347). The baseline heart rate did not significantly differ between adenosine responders and non-responders (179.6 ± 23.1 vs. 183.2 ± 23.4). An association was observed between the history of paroxysmal SVT and successful response to adenosine (odds ratio = 2.08; 95% confidence interval 1.05-4.11).

CONCLUSION: The findings of this retrospective study suggested that the use of adenosine restored normal sinus rhythm in 86% of patients with paroxysmal SVT. Furthermore, a history of paroxysmal SVT and older age were associated with an increased chance of adenosine success.