Symptomatic bradycardia complicating the use of intravenous dipyridamole for thallium-201 myocardial perfusion imaging.

Intravenous dipyridamole was given for routine thallium-201 myocardial perfusion imaging. The patient developed chest discomfort followed by cardiovascular collapse with sinus arrest and a nodal escape rhythm at 28 beats per minute. He was rapidly resuscitated without adverse sequelae. A reversible posteroinferior perfusion defect and proximal right coronary artery occlusion were found. Symptomatic bradycardia after dipyridamole may be mediated by ischaemia.