Persistent second-degree atrioventricular block following adenosine infusion for nuclear stress testing.

The agents used for nuclear stress testing (NST) including adenosine, dobutamine, and dipyridamole, are generally well tolerated and the incidence of serious complications associated with their use in NST is relatively low. Adenosine possesses a potent inhibitory effect on the atrioventricular (AV) node and may induce a transient conduction defect which could result in first-, second-, or third-degree heart block in some patients. The use of the potent AV nodal blocker adenosine for nuclear stress testing in patients with evidence of underlying conduction system disease may result in serious complications. We present the case of a 79-year-old man who had sustained second-degree AV block requiring permanent pacemaker implantation following adenosine infusion for nuclear stress testing. We also review the literature regarding the association between adenosine NST and AV block.