Association of Duke prognostic treadmill scores with change in P-wave duration during exercise tolerance tests in patients with interatrial block and coronary heart disease.

Interatrial block (IAB), as denoted by P waves > or =110 ms in duration, is believed to be associated with underlying ischemia, particularly with that of its principal interatrial conduction pathway, the Bachmann bundle. In this study, the association between Duke prognostic treadmill (DPT) scores and change in P-wave duration in IAB was investigated in patients who underwent cardiopulmonary exercise tolerance tests (CPETTs). Twenty-seven patients with IAB and 42 control patients without IAB on electrocardiography at rest who had evidence of myocardial ischemia on coronary angiography after CPETTs were identified consecutively. P-wave measurements were obtained independently at the beginning of every CPETT stage and also when P-wave changes occurred. Increments in P-wave durations were measured to the nearest 20 ms. DPT scores were calculated for the 2 groups. There was no significant difference between the groups in mean values for DPT scores and for exercise capacity. However, change in P-wave duration in patients with IAB was significantly associated with mean DPT score. As the change in P-wave duration increased, the DPT score was significantly less (p = 0.003). DPT scores were more significant with P-wave changes of >20 ms compared with P-wave changes of < or =20 ms (p = 0.00001). In conclusion, in patients with coronary heart disease and IAB at rest, increases in P-wave durations during CPETTs are inversely associated with DPT scores.