Utility of High-Resolution Magnetocardiography to Predict Later Cardiac Events in Nonischemic Cardiomyopathy Patients With Normal QRS Duration

Abstract

found as a normal variant. 4,5 Late potential in the early or middle portion of the QRS complex may be buried in the QRS and undetectable.Multichannel magnetocardiography (MCG) has been reported to have superior spatial and temporal resolution power, and allow detailed evaluation of the propagation of LV activation. 7, 8 In the present study, we hypothesized that MCG would detect left intraventricular disorganized conduction (LiDC) caused by localized LV conduction block, and thus be able to predict future cardiac events. Methods Study Population and Data AcquisitionThis study was approved by the Institutional Review Board of the National Cerebral and Cardiovascular Center, with a waiver of individual consent (M23-050, M24-050-2). We retrospectively reviewed the medical records of patients I n nonischemic dilated cardiomyopathy (NIDCM) patients, fibrosis and cellular degeneration in the left ventricular (LV) myocardium result in localized conduction block. 1 As the LV conduction delay becomes pronounced, QRS duration increases and prolonged QRS is known to be associated with poor prognosis. 2 However, even in NIDCM patients with apparently normal QRS duration, a cardiac event rate of 33% in approximately 1.5 years has been reported. 3 The prognosis of these particular patients is indeed not favorable. Therefore, novel indicators capable of predicting cardiac events sensitively even in NIDCM patients with normal QRS duration are required.Various methods that reflect left intraventricular conduction abnormality in NIDCM have been proposed. Although the usefulness of fragmented QRS (fQRS) observed on 12-lead ECG 4,5 and late potential detected on signalaveraged ECG (SAECG) 6 have been reported, their uses are limited. fQRS is defined qualitatively and can also be Utility of High-Resolution Magnetocardiography to Predict Later Cardiac Events in Nonischemic Cardiomyopathy Patients With Normal QRS DurationShoji Kawakami, MD; Hiroshi Takaki, MD, PhD; Shuji Hashimoto; Yoshitaka Kimura, MD; Takahiro Nakashima, MD; Takeshi Aiba, MD, PhD; Kengo F. Kusano, MD, PhD; Shiro Kamakura, MD, PhD; Satoshi Yasuda, MD, PhD; Masaru Sugimachi, MD, PhD Background: Nonischemic dilated cardiomyopathy (NIDCM) patients, even those with a narrow QRS, are at increased risk for major adverse cardiac events (MACE). We hypothesized that 64-channel magnetocardiography (MCG) would be useful to detect prognostic left intraventricular disorganized conduction (LiDC) by overcoming the limitations of fragmented QRS (fQRS, qualitative definitions, low specificity) and late potential (abnormality undetectable in earlier QRS).

Isolated Late Activation Detected by Magnetocardiography Predicts Future Lethal Ventricular Arrhythmic Events in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy

“…9- 11 We recently demonstrated that MCG detects left intraventricular disorganized conduction in patients with nonischemic dilated cardiomyopathy and a narrow QRS, which predicted major adverse cardiac events. 12 In this study, we hypothesized that MCG mapping could noninvasively visualize a scar-related isolated late activated potential (ILA), and that the presence of ILA could stratify the risk of future arrhythmic events in ARVC patients. and V2 or beyond in the absence of CRBBB, and TWI in leads V1-4 in the presence of CRBBB were considered abnormal.…”

Unshielded magnetocardiography: Repeatability and reproducibility of automatically estimated ventricular repolarization parameters in 204 healthy subjects

“…VR analysis is considered one of the most useful applications of MCG, mainly to recognize ischemic, inflammatory, or degenerative abnormalities (Tavarozzi, Comani, Del Gratta, Di Luzio et al., ). However, although some attempts to assess the reproducibility and comparability of MCG parameters gathered with different instrumentations have been reported (Burghoff, Nenonen, Trahms, & Katila, ; Nalbach et al., ; Pesola et al., ; Smith et al., ; Takala et al., ), a standardization adequate for clinical application is still missing, especially taking into account the potential source of error due to different S/Nr and/or sequential data acquisition (Bang et al., ; Hänninen et al., ; Kawakami et al., ; Mäkijärvi et al., ; Shin et al., ) as occurs with most instrumentations for unshielded MCG (Fenici, Brisinda, & Meloni, ; Leder et al., ) due to their limited number of sensors.…”

“…Compared to the electrocardiogram (ECG), MCG provides additional information, being CMF less affected by tissue conductivities, and is more sensitive to tangential currents, and capable to detect vortex currents too (Brockmeier et al., ; Fenici Brisinda, & Meloni ). Although mainly confined in research laboratories, MCG is increasingly used to study cardiac arrhythmias (Fenici, Brisinda, Venuti, & Sorbo, ; Fenici, Brisinda, & Meloni, ; Kwong, Leithäuser, Park, & Yu, ; Mäkijärvi et al., ) and ventricular repolarization (VR) abnormalities (VRa) due to different cardiopathy (Kawakami et al., ), especially ischemic heart disease (IHD) (Agarwal, Saini, Alyousef, & Umscheid, ; Brisinda, Bottelli, Napolitano, Priori, & Fenici, ; Fenici, Brisinda, Meloni, Sternickel, & Fenici, ; Hailer, Chaikovsky, Auth‐Eisernitz, Schäfer, & Van Leeuwen, ; Kandori et al., ; Kwon et al., ; Leithäuser, Park, Hill, Lam, & Jung, ; Li et al., ; Lim et al., ; Ogata et al., ; Park & Hill, ; Park, Leithäuser, Hill, & Jung, ; Park et al., ; Shin et al., ; Steinisch et al., ; Tolstrup et al., ; Wu et al., ).…”

MAGNETO cardiography parameters to predict future Sudden Cardiac Death (MAGNETO-SCD) or ventricular events from implantable cardioverter defibrillators: study protocol, design and rationale

“…A trial of 49 patients with dilated cardiomyopathy presenting with or without VA underwent MCG recording; prolongation of the end part of the MCG T-wave was associated with the VA group. 14 Kawakami et al 15 prospectively studied VA risk in 51 patients with non-ischaemic cardiomyopathy for a mean follow-up of 2.9 years. They found that left intraventricular disorganised conduction (described as a deviation from the typical global clockwise left ventricle depolarisation) on MCG was predictive of major adverse cardiac events.…”