Signal characteristics of multichannel epicardial electrograms in chronic ischaemic and scarred myocardium: electromechanical mismatch indicates viability in regions of myocardial dysfunction

Background To predict the outcome after myocardial revascularisation, a cle ar separation between hibernation and/or repetitive stunning on the one han d and myocardial scarring on the other hand is of importance. Methods and r esults A total of 44 patients was included in this study. In 35 patients wi th chronic myocardial ischaemia and an indication for coronary bypass-surge ry, epicardial mapping of local activation was performed. Nine patients wit h LV aneurysm and an indication for antitachycardia surgery were also inclu ded. For simultaneous recording of the local electrograms during sinus rhyt hm, a sock electrode with 102 bipolar leads was used. The regional myocardi al contraction pattern was assessed from preoperative angiograms and region al myocardial metabolism (viability) from F-18-FDG PET, respectively. The r esults were projected on the grid of the intraoperative position of the soc k electrode. This enabled regional comparison of electrogram characteristic s to local contraction patterns and viability. For the characterisation of local electrograms, peak-to-peak amplitude and duration of activation were calculated using custom-made automated computer -algorithms. Dysfunctional but viable areas showed normal or almost normal electrographic signal characteristics. In contrast, dysfunctional and non-v iable myocardium showed a distinct reduction of local amplitudes and prolon gation of signal duration. These changes were even more intense in areas of LV aneurysms. Conclusions In patients with chronic ischaemic myocardium, a mismatch between mechanical function and local electrogram characteristics was observed in areas with preserved metabolism. Thus, normal epicardial e lectrograms in regions of myocardial dysfunction may be an indicator for my ocardial viability.