Comparison of endocardial electromechanical mapping with radionuclide perfusion imaging to assess myocardial viability and severity of myocardial ischemia in angina pectoris

The assessment of left ventricular electromechanical activity using a novel , nonfluoroscopic 3-dimensional mapping system demonstrates considerable di fferences in electrical and mechanical activities within regions of myocard ial infarction or ischemia. We sought to determine whether these changes co rrelate with indexes of myocardial perfusion, viability, or ischemia. A 12- segment comparative analysis was performed in 61 patients (45 men, 61 +/- 1 2 years old) with class III to IV angina, having reversible and/or fixed my ocardial perfusion defects on single-photon emission computed tomographic p erfusion imaging. A dual-isotope protocol was used, consisting of rest and 4-hour redistribution thallium images followed by adenosine technetium-99m sestamibi imaging. Average rest endocardial unipolar voltage (UpV) and loca l shortening (LS) mapping values were compared with visually derived perfus ion scores. There was gradual and proportional reduction in regional UpV an d LS in relation to thallium-201 uptake score at rest (p = 0.0001 and p = 0 .0002, respectively) and redistribution studies (p = 0.0001 and p = 0.003, respectively). UpV greater than or equal to7.4 mV and LS greater than or eq ual to5.0% had a sensitivity of 78% and 65%, respectively, with a specifici ty of 68% and 67% for detecting viable myocardium. UpV values of 12.3 and 5 .4 mV had 90% specificity and sensitivity, respectively, to predict viable tissue. UpV, but not LS, values differentiated between normal segments and those with adenosine-induced severe perfusion defects (11.8 +/- 5.3 vs 8.8 +/- 4.1 mV, p = 0.005). Catheter-based left ventricular assessment of elect romechanical activity correlates with the degree of single-photon emission computed tomographic perfusion abnormality and con identify myocardial viab ility with a greater accuracy than myocardial ischemia. (C) 2001 by Excerpt a Medica, Inc.