Ability of Holter electrocardiographic recording and atrial stimulation to detect sinus nodal dysfunction in symptomatic and asymptomatic patients with sinus bradycardia

Holter electrocardiographic recording and functional testing (determination of corrected sinus recovery time and estimated sinoatrial conduction time) were performed in 51 patients with sinus bradycardia. Thirty-seven patients were symptomatic; eight were known to have the sick sinus syndrome before study. Electrocardiographic abnormalities diagnostic of the sick sinus syndrome were found with Holter recording in 20 patients. When abnormal functional testing was defined with currently used criteria (corrected sinus recovery time greater than 525 msec or sinoatrial conduction time greater than 120 msec, or both), 12 of the 20 patients with an abnormal Holter electrocardiogram had abnormal and 8 had normal functional testing (sensitivity rate 60 percent); 23 of the 31 patients with normal Holter recordings had normal and 8 had abnormal functional testing (specificity rate 74 percent). These criteria for abnormal functional testing gave an apparent false positive rate of 40 percent and a false negative rate of 26 percent, using Holter electrocardiographic abnormalities as the criteria for sick sinus syndrome. When abnormal functional testing was defined as corrected sinus recovery time greater than 600 msec or sinoatrial conduction time greater than 130 msec, or both, the sensitivity rate remained at 60 percent but the specificity rate increased to 94 percent and the false positive rate decreased to 14 percent. Functional testing and the Holter electrocardiogram in combination are more useful than either alone in revealing sinus nodal dysfunction in asymptomatic and symptomatic patients with sinus bradycardia. When corrected sinus recovery time greater than 525 msec or sinoatrial conduction time greater than 120 msec, or both, is used to define functional testing as normal, the combination of a normal Holter electrocardiogram and normal functional testing is strong evidence against significant sinus nodal dysfunction.