Interatrial block during exercise tolerance tests as an additional parameter for the diagnosis of ischemic heart disease

Introduction: Interatrial block (IAB; P-wave duration, >= 120 milliseconds) is associated with increases of left atrial pressure. We studied the use of TAB during exercise tolerance test (ETT) in diagnosis of ischemic heart disease. Method: Exercise tolerance tests were performed in 149 patients (mean age, 50 years; male, 60.4%). P-wave duration was measured at rest, at each stage of exercise using the Bruce protocol, and in recovery. As clinically indicated, 71 patients subsequently underwent nuclear stress test and/or catheterization. The evidence of ischemia (EOI) was considered present according to the more definite test, that is, catheterization over nuclear stress test over ETT. Results: Among patients who did not have TAB at rest (n = 115), 63 patients (54.7%) developed TAB during the ETT. The incidence of TAB during the ETT was higher in patients with EOI than patients without EOI (88.9% vs 51.9%, P = .03). When IAB during the ETT and positive ETT were used together to detect EOI, they were more accurate (86.1% vs 81.7%) than the ETT alone. Among patients with TAB at rest (n = 34), patients with EOI had a higher incidence of P-wave duration increase of more than 20 milliseconds during the recovery period than patients without EOI (100% vs 21.8%, P = .015). When using P-wave duration increase of more than 20 milliseconds during the recovery period in conjunction with positive ETT, the sensitivity in detecting EOI was higher than using the ETT alone (100% vs 0%), but the specificity was worsened (68.8% vs 84.4%). Conclusion: New TAB and worsening of TAB during ETT appeared in patients with ischemic heart disease and may be used as additional parameters for the ETT interpretation. (c) 2005 Elsevier Inc. All rights reserved.