ELECTROMECHANICAL CHARACTERIZATION OF CHRONIC MYOCARDIAL-INFARCTION IN THE CANINE CORONARY-OCCLUSION MODEL

Background-Defining the presence, extent, and nature of the dysfunctio nal myocardial tissue remains a cornerstone in diagnostic cardiology. A nonfluoroscopic, catheter-based mapping technique that can spatially associate endocardial mechanical and electrical data was used to quan tify electromechanical changes in the canine chronic infarction model. Methods and Results-We mapped the left ventricular (LV) electromechan ical regional properties in 11 dogs with chronic infarction (4 weeks a fter LAD ligation) and 6 controls. By sampling the location of a speci al catheter throughout the cardiac cycle at multiple endocardial sites and simultaneously recording local electrograms from the catheter tip , the dynamic 3-dimensional electromechanical map of the LV was recons tructed. Average endocardial local shortening (LS, measured at end sys tole and normalized to end diastole) and intracardiac bipolar electrog ram amplitude were quantified at 13 LV regions. Endocardial LS was sig nificantly lower at the infarcted area (1.2+/-0.9% [mean+/-SEM], P<0.0 1) compared with the noninfarcted regions (7.2+/-1.1% to 13.5+/-1.5%) and with the same area in controls (15.5+/-1.2%, P<0.01). Average bipo lar amplitude was also significantly lower at the infarcted zone (2.3/-0.2 mV, P<0.01) compared with the same region in controls (10.3+/-1. 3 mV) and with the noninfarcted regions (4.0+/-0.7 to 10.2+/-1.5 mV, P <0.01) in the infarcted group. In addition, the electrical maps could accurately delineate both the location and extent of the infarct, as d emonstrated by the high correlation with pathology (Pearson's correlat ion coefficient=0.90) and by the precise identification of the infarct border. Conclusions-Chronic myocardial infarcted tissue can be charac terized and quantified by abnormal regional mechanical and electrical functions. The unique ability to assess the regional ventricular elect romechanical properties in various myocardial disease states may becom e a powerful tool in both clinical and research cardiology.