Effects of pacing-induced and balloon coronary occlusion ischemi on left atrial function in patients with coronary artery disease

OBJECTIVES The aim of this study was to compare left atrial (LA) function in 16 patients with distal left anterior descending (LAD) and in 16 patients with proximal left circumflex (LCx) coronary artery stenosis at rest and immediately after pacing-induced tachycardi (LAD-pacing [P] and LCx-P) or coronary occlusion (LAD-CO and LCx-CO). BACKGROUND During left ventricular (LV) ischemia, compensatory augmentation of L contraction enhances LV filling and performance. The left atrium is supplied predominantly by branches arising from the LCx. Therefore, we hypothesized that one mechanism for the loss of atrial contraction may be ischemic L dysfunction. METHODS Left ventricular and L pressure–are relations were derived from simultaneous double-tip micromanometer pressure recordings and automatic boundary detection echocardiograms. RESULTS Immediately after pacing or after coronary occlusion, LV end-diastolic pressure, LV relaxation, L mean pressure and LV stiffness significantly increased in all patients. However, the are of the loop of the L pressure–are relation, representing the L pump function, significantly decreased in groups LCx-P and LCx-CO (from 14 ± 3 to 9 ± 2, and from 16 ± 4 to 9 ± 2 mm Hg·cm2, respectively, p < 0.05), whereas it increased in groups LAD-P and LAD-CO (from 12 ± 3 to 54 ± 10, and from 16 ± 3 to 49 ± 8 mm Hg·cm2, respectively, p < 0.001). CONCLUSIONS In patients with LAD stenosis, LV supply or demand ischemi is associated with enhanced L pump function. However, in patients with proximal LCx stenosis who develop the same type and degree of ischemia, L branches might have been affected, rendering the L ischemic and unable to increase its booster pump function.