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Anatomical M-mode: A novel technique for the quantitative evaluation of regional wall motion analysis during
Abstract:
Recognition of abnormal wall motion during dobutamine echocardiography requires an expert observer. Anatomical M-mode echocardiography may offer a novel quantitative approach to interpretation, amenable to less expert readers. We studied the application of this new modality to 124 patients (80 with known coronary anatomy and 44 patients at low probability of coronary disease) who underwent dobutamine echocardiography, using a standard protocol. Wall motion was interpreted by an experienced reader, using digitally stored 2-dimensional echocardiographic images at rest and peak stress. Percentage of systolic thickening was measured offline using anatomical M-mode echocardiography in the basal and mid segments at rest and peak dose, and compared with wall motion scores and coronary angiography. Of 729 segments, wall motion was identified as normal in 449, ischemic or viable in 171 and showed resting WM abnormalities only in 109 segments. After exclusion of the apex, anatomical M-mode measurements were feasible in 729 of 960 possible basal- and mid-zone segments (76%). Measurement of systolic thickening at peak dose was reproducible within (r2 = 0.83) and between observers (r2 = 0.93). Systolic thickening was significantly greater in segments with normal wall motion (37 +/- 2%) compared with ischemic or viable segments (30 +/- 2%, p < 0.001), and scar segments (23 +/- 3%, p < 0.001). There was an increment of thickening from rest to stress in normal and viable segments, no change in scar, and a decrement in ischemic segments. Significant coronary artery disease (defined by stenoses >70% diameter) was present in 59 patients. Systolic thickening showed significant variation between segments interpreted by wall motion scoring and angiography as true and false positive and true and false negative (p < 0.05). Measurement of systolic thickening using anatomical M-mode echocardiography offers an objective method to quantify systolic thickening at dobutamine echocardiography but has limited clinical feasibility.