The most widely utilized indexes of sinus node dysfunction are the sinus node recovery time (SNRT) and the corrected sinus node recovery time (CSNRT), which generally require catheterization. Adenosine has negative chronotropic effect on the sinoatrial node. Non-invasive and reliable sinus node function test with intravenous adenosine was investigated.

The clinical value of rapid intravenous injection of adenosine for assessing sinus node dysfunction was examined in 14 patients with sick sinus syndrome (SSS) and 31 controls. After prophylactic insertion of a temporary pacemaker in the right ventricle, overdrive suppression test was conducted using the standard technique and CSNRT was measured to evaluate the sinus node function. Then, the CSNRT after administration of an intravenous bolus of adenosine (6 mg and 12 mg) was measured. Post-adenosine corrected sinus node recovery time (ADO: SNRT) was calculated by subtracting the basal sinus cycle length from the longest sinus cycle length. When ADO: SNRT over 550 msec was assumed as an indicator of sinus node dysfunction, intravenous injection of 6 mg of adenosine had a sensitivity of 85% and specificity of 100%, and 12 mg of adenosine had a sensitivity of 100% and specificity of 90% for detection of sick sinus syndrome. There were significant differences in ADO: SNRT between patient and control group (6 mg 1501±1081 msec vs 64±109 msec; 12 mg 4005±2055 msec vs 216±315 msec, respectively).

ADO: SNRT was a highly sensitive and specific index for diagnosing sick sinus syndrome, and should be considered as an alternative to invasive testing in patients with suspected sick sinus syndrome.