Association of myocardial ischemia and coronary angiographic lesions with increased left atrial dimension during exercise tolerance tests among patients without known coronary heart disease.

The association between left atrial (LA) dilation and fundamental exercise parameters has not shared equal extensive investigation as its clinical correlate, interatrial block (IAB; P waves > or =110 ms). We prospectively identified 94 consecutive patients with LA dilation on 2-dimensional transthoracic echocardiography but without atrioventricular valvular disease, hypertension, or coronary artery disease who had undergone coronary angiography after exercise tolerance tests (ETTs) for assessment of new coronary artery disease. Duke prognostic treadmill (DPT) scores were calculated and exercise capacity was expressed as METs of workload achieved. We appraised the cohort for common co-morbidities, IAB on electrocardiography at rest, and exercise-induced P-wave increments (divided into 20-ms quintiles). IAB (67% vs 34%, p = 0.002) and increased LA dimension (48 +/- 6 vs 45 +/- 5 mm, p = 0.01) were associated in patients with >70% coronary artery diameter stenoses and were equally reflected by positive ETT results (79.5% vs 20%, p <0.001), decreased METs (11.43 + [-0.60 x LA size (millimeters)], r(2) = 0.04), and lower DPT scores (35.23 + [-0.70 x LA size (millimeters)], r(2) = 0.73). Incremental P-wave change was associated with lower METs and DPT scores but with positive ETT results and significant coronary artery stenoses (p for trend <0.001). LA dimension was largest in the highest quintile (>60 ms) of P-wave change (p for trend <0.001). In conclusion, increased LA dimension is significantly associated with myocardial ischemia during ETT and is reflected by lower METs and DPT scores and a higher incidence of coronary artery diameter stenoses >70% in patients matched by age-, gender-, and LA size without preexisting coronary artery disease.