Latent defects of atrioventricular conduction in right coronary artery disease

The purpose of this study was to investigate the occurrence of latent defects in AV conduction in patients with right coronary artery disease. Twenty-two patients with greater than 50 per cent obstruction of the right coronary artery and a predominant right coronary artery system or pattern were studied with His bundle electrograms and determinations were made of the functional refractory period of the AV node and the point at which AV Wenckebach developed during rapid atrial pacing with a fixed cycle length. The patients were studied prior to or at least six months after the onset of clinical or electrocardiographic evidence of acute infarction. Similar measurements were made in eighteen control subjects with less than 50 per cent occlusion of the right coronary artery. The results showed significant prolongation of the functional refractory period (467 ± 63 msec. for patients with right coronary disease versus 408 ± 43 msec. in the control group; P <0.01) and earlier development of atrioventricular Wenckebach during rapid atrial pacing (143 ± 22 BPM in the coronary obstruction group versus 172 ± 19 BPM in the control group; P<0.01) in patients with significant disease of the right coronary artery when compared to the control group. Although all patients were found to have resting intervals on the His bundle electrogram within normal limits, the group with right coronary obstruction had slightly longer values for the resting P-H interval (122 ± 19 msec. versus 101 ± 31 msec. in the control group; P<0.05). This study establishes that latent defects in atrioventricular conduction exist in patients with significant disease of the right coronary artery in the absence of acute infarction.