Electrophysiologic investigation in Brugada syndrome; yield of programmed ventricular stimulation at two ventricular sites with up to three premature beats.

INTRODUCTION: Numerous reports on the inducibility of ventricular tachyarrhythmias (VT) in patients with atypical right bundle branch block and right precordial ST-elevation (Brugada syndrome) are based on multicentre studies that have used different stimulation protocols. Therefore, we prospectively investigated the inducibility of VT in these patients using a uniform protocol. METHODS: In 41 consecutive patients (29 males) showing a pattern of right bundle branch block and ST-elevation, programmed ventricular stimulation was performed in the right ventricular apex with up to three premature stimuli at sinus rhythm and at four different paced cycle lengths (500, 430, 370, and 330 ms) until refractoriness was reached or reproducible induction of a sustained (>30s) VT occurred. If a VT was not reproducibly inducible, the same protocol was repeated in the right ventricular outflow tract. RESULTS: A history of life-threatening events defined as syncope (n=17) or aborted sudden cardiac death (n=13) was present in 30 patients (73%); 11 individuals were asymptomatic. Inducibility (68%) was similar between symptomatic (n=21, 70%) and asymptomatic patients (n=7, 64%). In 16 (39%) patients, VT were reproducibly inducible. If patients were only stimulated in the right ventricular apex, inducibility rate decreased to 39%. If only two premature beats at two sites were used it was as low as 32%. The mean coupling intervals of the second and third premature stimuli inducing sustained VT were short: 189+/-21 ms vs 186+/-22 ms, respectively. Forty-four percent of all patients (i.e. 64% of the inducible patients) had inducible VT only with coupling intervals shorter than 200 ms. CONCLUSIONS: The stimulation protocol markedly influences the extent of inducibility of VT in patients with right bundle branch block and ST-segment elevation. These findings question the significance of previous multicentre studies using different stimulation protocols and should have implications for further studies.

[MRI study of left ventricular function in patients with coronary disease and myocardial dysfunction before and after coronary revascularization]. / MR-tomographische Untersuchung der linksventrikulären Funktion bei Patienten mit koronarer Herzerkrankung und myokardialer Dysfunktion vor und nach koronarchirurgischer Revaskularisation.

PURPOSE: To evaluate left ventricular (LV) myocardial function in ten patients with coronary artery disease (CAD) preoperatively and 6 months after coronary bypass grafting (CABG) by cardiac MRI. MATERIAL AND METHODS: Ten patients (mean 65.2 +/- 5.9 years) with angiographically proven CAD and an indication for elective CABG underwent prospective evaluation of global LV function and regional wall motion by Cine-MRI at rest using a multiphase FLASH-2D sequence following regions of interest (ROI)-defined diagnostics of regional myocardial wall motion by means of levocardiography. Within the ROIs a total of 613 LV myocardial segments were analyzed preceding and following surgical revascularization. Results were compared with the data of 10 healthy volunteers. RESULTS: Preoperatively, patients showed reduced stroke volume and ejection fraction compared with volunteers (p < 0.01). Enddiastolic wall thickness (EDWT) and systolic wall thickening (SWT) were significantly lower in the patients (p < 0.01). Based on preoperative levocardiography ROI-defined myocardial segments showed a significantly lower preoperative EDWT in areas with wall motion abnormalities (7.4 +/- 2.5 mm; p < 0.01) than in normal myocardium (9.2 +/- 2.1 mm). Ejection fraction (p < 0.05), endsystolic wall thickness, and SWT (p < 0.01) improved significantly after bypass surgery. On ROI-defined analysis myocardial segments with impaired preoperative wall motion (n = 243) showed a significant increase of EDWT, ESWT and SWT (p < 0.01). CONCLUSION: In patients with CAD, cardiac MRI enables the non-invasive determination of postinfarctional LV remodeling with an increased EDWT of myocardial segments with normal regional wall motion and of the improvement in global and regional myocardial function following coronary bypass surgery.

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 clear separation between hibernation and/or repetitive stunning on the one hand and myocardial scarring on the other hand is of importance. METHODS AND RESULTS: A total of 44 patients was included in this study. In 35 patients with chronic myocardial ischaemia and an indication for coronary bypass-surgery, epicardial mapping of local activation was performed. Nine patients with LV aneurysm and an indication for antitachycardia surgery were also included. For simultaneous recording of the local electrograms during sinus rhythm, a sock electrode with 102 bipolar leads was used. The regional myocardial contraction pattern was assessed from preoperative angiograms and regional myocardial metabolism (viability) from 18F-FDG PET, respectively. The results were projected on the grid of the intraoperative position of the sock electrode. This enabled regional comparison of electrogram characteristics 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-viable myocardium showed a distinct reduction of local amplitudes and prolongation 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 electrograms in regions of myocardial dysfunction may be an indicator for myocardial viability.