The use of adenosine and adenosine triphosphate testing in the diagnosis, risk stratification and management of patients with syncope: Current evidence and future perspectives

- Syncope is a significant source of cardiovascular-related morbidity.
- Adenosine is potentially useful for non-invasive investigation of syncope causes.
- We analyze the biochemical properties and pathophysiologic mechanisms of adenosine.
- We also present the current level of evidence for its use in clinical practice.
- We assess the value of adenosine for risk-stratification of patients with syncope.

Syncope is a significant source of cardiovascular-related morbidity yet the etiology is frequently obscure and the identification of patients at highest risk is challenging. Adenosine (AD) and adenosine triphosphate (ATP) administrations have been suggested as potentially useful non-invasive tools in the diagnostic workup of patients with neurally-mediated or bradycardia-related syncope. It has been postulated that both compounds by modulating the autonomic innervation in the heart and exerting negative chronotropic and dromotropic effects in the conduction system, may unmask the mechanism of syncope. However, the clinical implications derived from the efficacy of both tests in the investigation of syncope remain unclear mainly due to inconclusive and occasionally contradictory results of published studies. This review article summarizes recent and past information in the use of ATP and AD in the investigation of syncope with emphasis on clinical trials. We present the current level of evidence for the use of these agents in clinical practice, identify areas where further research is warranted and highlight the future perspectives of these agents as complements to an accurate risk-stratification of patients with syncope.