Author(s): Nagueh SF, Mikati I, Weilbaecher D, Reardon MJ, AlZaghrini GJ,
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Abstract BACKGROUND: Although dobutamine echocardiography (DE) is widely used to assess myocardial viability in humans, little is known about the relation between contractile reserve and myocardial structure. METHODS AND RESULTS: We evaluated 20 patients with coronary disease (64+/-13 years old, ejection fraction 28+/-7.5\%) with DE (up to 40 micrograms . kg(-1). min(-1)), rest-redistribution (201)Tl single photon emission CT, and quantitative angiography before bypass surgery. During surgery, patients underwent transmural myocardial biopsies (n=37) guided by transesophageal echocardiography to determine the extent of interstitial fibrosis and intracellular and interstitial proteins by histopathology and immunohistochemistry. Among the 37 segments biopsied, 16 recovered function as assessed 2 to 3 months later. Segments with postoperative functional recovery had more wall thickening at low-dose DE (28\% versus 3\%, P<0.001), higher thallium uptake (69\% versus 48\%, P=0.03), and less interstitial fibrosis (2\% versus 28\%, P<0.001). Quantitative angiographic parameters did not predict recovery of function. Segments with DE viability (contractile reserve and/or ischemia) had less fibrosis (2.7\% versus 28\%, P<0.001), less vimentin and fibronectin (both P<0.01), more glycogen (P=0.016), and higher thallium uptake (64\% versus 35.5\%, P<0.05) than those without viability. Viable segments by both DE and thallium had less fibrosis (1\%) than those viable by 1 of the 2 techniques (9\%) or not viable by both (28\%, P=0.005). Thickening at low-dose DE correlated well with the extent of interstitial fibrosis (r=-0.83, P<0.01). CONCLUSIONS: Contractile reserve during DE correlates inversely with the extent of interstitial fibrosis and the amount of fibronectin and vimentin and directly with rest-redistribution thallium uptake.
This article was published in Circulation
and referenced in Journal of Nuclear Medicine & Radiation Therapy