Noninvasive characterization of stunned, hibernating, remodeled and nonviable myocardium in ischemic cardiomyopathy

OBJECTIVES We evaluated a novel protocol of dual-isotope, gated single-phot on emission computed tomographic (SPECT) imaging combined with low and high dose dobutamine as a single test for the characterization of various types of altered myocardial dysfunction. BACKGROUND Myocardial perfusion tomography and echocardiography have been u sed separately for the assessment of myocardial viability. However, it is p ossible to assess perfusion, function and contractile reserve using gated S PECT imaging. METHODS We studied 54 patients with ischemic cardiomyopathy using rest and 4 h redistribution thallium-201 imaging and dobutamine technetium-99m sesta mibi SPECT imaging. The sestamibi images were acquired 1 h after infusion o f the maxima tolerated dose of dobutamine and again during infusion of dobu tamine at a low dose to estimate contractile reserve. Myocardial segments w ere defined as hibernating, stunned, remodeled or scarred. RESULTS Severe regional dysfunction was present in 584 (54%) of 1,080 segme nts. Based on the combination of function and perfusion characteristics in these 584 segments, 24% (n = 140) were labeled as hibernating; 23% (n = 136 ) as stunned; 30% (n = 177) as remodeled; and 22% (n = 131) as scarred. Con tractile reserve, represented by improvement in wall motion/thickening by l ow dose dobutamine, was observed in 83% of stunned, 59% of hibernating, 35% of remodeled and 13% of scarred myocardial segments (p < 0.05). CONCLUSION It is possible with this new imaging technique to characterize d ysfunctional myocardium as stunned, hibernating remodeled and nonviable. Th ese subtypes often coexist in the same patient. (C) 2000 by the American Co llege of Cardiology.