Non-invasive recording of the arrhythmogenic substrate within the QRS-complex using magnetocardiography JACC February 1996 ABSTRACTS- Poster 373A Insufficiently reflect the complete verddcular mass electrically activated. The a~Jptication of electrical presordial mapping is time consuming, and may not detect the Information content as recorded by magnetocardicgrap~. Magne- tocardingraphio precordial mapping (MCG) with synchroneous recording of 49 channels using SQUID sensors ~ performed in a magnatfcatiy shielded room (background noise < 5 fTIv'Hz) in normal parsons (norm), in post- myocardial infarction patients (post-MI pts) and in patients prone to sus- tained veofdcular tacbycardia (VT-pts). Visual or automatic definition of the T-wave's end in single channels was unreliable with or without filtering due to the high sensitivity of the recording. Thus, the dispersion was dotermined by analysing the synchronlclty of the end of T-wave: the ampl~rdas of all tracings were normatized, summed up and filtered. The Ql"-disporsion was quantltied in this sum crave as the negative slope of the end of the T-weve, indicating a non-homoganslty of cardiac repelarizatfon. Resu~: Group. N Downslope of MCG.T.wave map Norm 25 -2.8:~ 1.3 Post-MI-pts 30 -1.7:1:0.0 VT-pts 12 -1.2:E0.9 slgnllk:anoe: norm vs post-Ml: p = 0.002, norm vs V'l'-pts: p - 0.004, post-MI ~ VT-pts: p ,, 0.05 Thus, the inhomngenezty in repolarization in the 49-channel presordial magnatsoardiograpbic mapping is indicated by a slow downslopo of the end of the combined T-w~ve in VT-patients. This dewnsfope is intermediate in post-MJ-patlents without anl"=ythmias and steep in normals. ~ A n a l y s i s o f P h a s e a n d E n v e l o p e o f High Frequency Components In the M a g n e t o c a r d i o g r a m t o I d e n t i f y H i g h R i s k Patients Michael Oeff, Alfred Unkl, Peter Endt, Lutz Trahms I Cardiopulmon. Dept., Klinikum Benjamin Franklin, Fmie Unfversft~t Berlfn; I Physikalisch-Technische Bundasanstalt Berlin, FR Germany Low amplitude fragmented catdias signals am usutiay not detectable within the QRS complex due to inadequate filtering; variable signals are eliminated by the signal averaging technique. To investigate if low amplitude cardiac signals within the QRS complex different from background noise character- ize patients (pts) w~th high risk of malignant tachyarrhythmias, single-beat high resolution rnegnofocardicgraphic recordings (MCG) of 16 normal per- sons (NORM) and 12 patients mit ventricular tachyan'nythmlas (VTVF) were investigated. Multichannsi MCG was recorded in a highly shielded room with a baskgmund noise of < 5 tT/~'R"z. Complex binomial bandpass filtering (70-100 Hz) was applied to preserve fragmented activity dudng ventdcular activation (i.e. within the QRS). Unpredictable (Pv) and periodic changes (Pc) of the low amplitude fragmented signals within QRS were calculated by analysis of phase and envelope of these signals (representing combined time and frequency analysis) and graphically displayed. Results: Presentation of Pv and Pc of cardiac low amplitude signals in consecutive alngle-beat analysis. Identification of periodic, however variable micropotentials within and efter the QRS complex, differentiating NORM from VTVF (N: normal pemons, +: VTVF persons). O,I; 0 . 5 0.4 I .3 P " 0 , : 0.1 O,O 4- 4- 4--I- • .I. 4. t~4. % , ~ + , =.o ,.a ~o o.o zo.o u.o P c ~ Single-beat analysis of high resolution magnetocardicgram using binomial filtering and 2-dimensional spoctrofemperal analysis identified variable irreg- ular mlcropetantisls even with the QRS to identify patients with malignant tachyanythmlas. Non-l.nvasive Recording of the Arrhythmogenic ~ubslrats Within the O R S , Complex Using M a g n e t o c a r d i o g r a p h y Michael gall, Lutz Trahms f, Peter Endt, Heinz-Pater Schultheiss. Cardiopulmon. Dept., Klinikum Benjamin Franklin, Freie Universit~t Berlin: 1 Physikalisch-Technisohe Bundesenstaft Berlin, FR Germany Electrical instability of the ventdcutar myocardium is characterized by frag- mented etectrograms during its aclJvation. Signal averaged ECG (SAECG) only detects "late potentials" longer than the QRS-complex. To investigate the clinical significance of pathologic activation within the total QRS com- plex, high-resolution magnetoeardiographic mapping was poffonned in 26 nomnal persons (NORM), 32 post-MI patieofs (33 ± 7 days after MI) wilhout symptomatic arrhythmias (aMl-pts), and in 24 pts with venfficular tachycardia (Vl"-pts). The magnetocardtOgTam (MCG) was recorded in a shielded room (multi-sensor SQUID-system, 37 channels, noise < 5 f l " l V ~ ) and analyzed using binomial non-recursive filtering providing a ,near phase response of the MCG. A scorn (FI) characterized the extent of the intraventrlcular frag- mentation. MCG results were compared to signal average ECG findings (SAECG). Results'. Group R (~r, it~ve SAECG NORM 2O ± 6 0/27 aMId31s 28 ~ 11 3/32 VT-pts 50+17 11/22 NORM vs aMh p = 0.002, NORM vs VTVF: p = 0,0001, aMIvs VTVF: p = 0.0001 Outing 1 -year-foflow-up of the post-MI pts, 2 pis having higher score values (34, 40, resp.) suffered from anbythmic events. Thus, high-resolution magnetocardiographic mapping with QRS analysis using new filtering techniques allowed idantifK:atJon of patients prone to malignant tachyarrhythmias and may reveal a prognostic relevance. Clinical S i g n f f i c a n c e o f V e n l d c u i e r L a t e P o t e n l i e l s i n I d i o p a t h i c Dilated C a r d i o m y o p a t h y - - A P r o s p e c t i v e S t u d y i n 120 Patlents Wolfram Grimm, Volker Menz, J0rgan Hoffmann, Ursula Knop, Jens Winzenburg, Bernhard Maisch. Phillips-University Marburg, Gen'nany Signal-avemgod ECG (SAECG) was performed in 120 patients with idio- pathic dil&'ed card~omyupatby (DCM, 50 -4- 12 years, EF 31 4- 11%). DCM was defined as cardiomegaly with left venMcular EF _< 50% in the absence of any comnery alenosis > 50% by angicgrapby, and no hiato~j of byperten- sign or valvular disease. All 120 study patients with DCM were prospectively followed beginning from the time of SAECG analysis until May 1995. Major arrhy~mic events during follow-up were defined as sustained VT or VF, or sudden cardiac death, i.e. death within 1 hour after the onset of symptoms or unwitnessed death. In patients without bundle branch block (n = 82), time domain analysis of the SAECG (Corezonles PREDICTOR) was used to detect late potentials. Late potentials were considered to be present if 1) QRS-duration was > 114 ms, and2) RMS 40 was < 20 p.V and/or LAS 40 was > 38ms a t 4 0 Hz filtering. In patients with bundle branch block (QRS > 110 ms; n = 38), speofrotemporal analysis of the SAB?J3 was performed automatically with the use of software (FFT-Plus, ART). Late potentials were considered to be present if a nsrmality factor of < 30% was derived from analysis of the x, y or z lead. Results: SAECG revealed ventdcular late potentials in 22 of 120 patients wit~ OCM (18%). Oudng 11:1:6 months follow-up, 14 of 120 study patients with DCM (12%) had a major arrhythmlc event as defined above. Major an'bythmic events did occur in 3 of 22 patie~s with late potentials (14%) and in 11 of 98 patian',s wiffmat late potentials (11%). Sensilk, ify, specifity, positive and negative predictive accuracy of late potentials for the occurrence of major arrhythmic events were 21%, 82%, 14% and 89% r e s p e ~ . Cono/usion: In this selected patient popula, on with idiopathic dilated car- diomyopethy, ventdcutar late potentials detected by SAECG have a low sensitivity and a low positive ~ accuracy for the ocourrence of major arrhythmic events during follow-up.