Recording locations in multichannel magnetocardiography and body surface potential mapping sensitive for regional exercise-induced myocardial ischemia

Introduction This study aimed to identify the optimal locations in multicha nnel magnetocardiography (MCG) and body surface potential mapping (BSPM) to detect exercise-induced myocardial ischemia. Methods We studied 17 healthy controls and 24 coronary artery disease (CAD) patients with stenosis in on e of the main coronary artery branches: left anterior descending (LAD) in 1 1 patients, right (RCA) in 7 patients, and left circumflex (LCX) in 6 patie nts. MCG and BSPM signals were recorded during a supine bicycle stress test . The capability of a recording location to separate the groups was quantif ied by subtracting the mean signal amplitude of the normal group from that of the patient group during the ST segment and at the T-wave apex, and divi ding the resulting amplitude difference by the corresponding standard devia tion within all subjects. Results In MCG the optimal location for ST depres sion was at the right inferior grid for the RCA, at the mid-inferior grid f or the LCX, and in the middle of these locations for the LAD subgroup (mean ST amplitudes: CAD -80 +/- 360fT, controls 610 +/- 660fT; p < 0.001). In B SPM it was on the left upper anterior thorax for the LAD, left lower anteri or thorax for the RCA, and on the lower back for the LCX subgroup (mean ST amplitudes: CAD -39 +/- 61 muV and controls 38 +/- 38 muV; p < 0.001). In M CG the optimal site for T-wave amplitude decrease was the same as the one f or the ST depression. In BSPM it was on the middle front for the LAD, on th e back for the LCX and on the left abdominal area for the RCA group. In acc ordance with electromagnetic theory, the largest ST segment and T-wave ampl itude changes took place in MCG in locations orthogonal to those in BSPM. C onclusion This study identified magnetocardiographic and BSPM recording loc ations which are sensitive for detecting transient myocardial ischemia by e valuation of the ST segment as well as the T-wave. These locations strongly depend on ischemic regions and are outside the conventional 12-lead ECG re cording sites.