Early electrocardiographic indices for predicting chronic doxorubicin-induced cardiotoxicity

BACKGROUND

Dealing with chemotherapy-related cardiac dysfunction (CTRCD) remains a significant problem complicated by the difficulty in early detection of cardiotoxicity. Electrocardiogram (ECG) is expected to be the most realistic methodology due to lower cost-performance and non-invasiveness. We investigated the long-term visual fluctuations in the ECG waveforms in patients with chronic doxorubicin (DOX)-induced cardiotoxicity to identify ECG indices for the early detection of cardiotoxicity.

METHODS

We conducted a retrospective case series study by reviewing the medical records of 470 consecutive patients with malignant lymphoma who were treated with DOX at our institute between January 2010 and December 2017. Of them, 23 (4.9%) patients developed left ventricular dysfunction and were diagnosed with CTRCD using echocardiography. We assessed the ECG indices on 12-lead ECG recordings before and after treatment in 15 patients; eight patients were excluded due to conduction disturbances or atrial fibrillation.

RESULTS

CTRCD was detected at a median of 475 (interquartile range, IQR: 341-1333) days after initiating chemotherapy. The evaluation of ECG indices preceding CTRCD development was performed 93 (IQR: 52-232) days before the detection of CTRCD. In the stage of CTRCD, the most significant ECG change was T-wave flattening in leads V3-V6 (12 patients, 80%). Additionally, QTa prolongation was observed in leads I and aVL (n = 10, 66%), leads II, III, and aVF (n = 9, 60%), and leads V3-V6 (n = 10, 73%). These ECG changes were not observed before the treatment but were detected mildly in the pre-CTRCD stage, which subsequently worsened in the CTRCD stage.

CONCLUSIONS

This study indicated that T-wave changes and QTa prolongation may be useful as an early indicator before the onset of CTRCD in patients with DOX-induced cardiotoxicity.

Vector synthesis high-resolution electrocardiography, atrial natriuretic peptide and N-terminal prohormone brain natriuretic peptide for estimation of cardiac load in pregnancy

AIM

We analyzed atrial natriuretic peptide (ANP), N-terminal pro-brain natriuretic natriuretic peptide (NT-proBNP) and vector synthesis high-resolution electrocardiography (ECG), to estimate cardiac load with circulatory dynamic change from pregnancy through the post-partum period.

METHODS

The subjects were singleton pregnant women (n = 19), who were divided into three stages: stage 1, 34-36 weeks of gestation; stage 2, 2-6 post-partum days; and stage 3, 1-3 months after delivery. Vector synthesis high-resolution ECG, ANP and NT-proBNP were analyzed for all subjects.

RESULTS

A pregnant woman with massive uterin liomyoma expressed largest the corrected recover time (RTc) dispersion in I + II of tow Dimensional (2D) color distribution map ANP and NT-proBNP were significantly higher in stage 2 than in stages 1 and 3.

CONCLUSIONS

ANP, NT-proBNP and vector synthesis high-resolution ECG there might be able to evaluate cardiac load of normal pregnancy.

Effect of intravenous amiodarone on QT and T peak-T end dispersions in patients with nonischemic heart failure treated with cardiac resynchronization-defibrillator therapy and electrical storm

BACKGROUND

The effect of intravenous amiodarone on spatial and transmural dispersion of ventricular repolarization in patients receiving cardiac resynchronization therapy (CRT) remains unclear.

METHODS

We studied 14 patients with nonischemic heart failure who received CRT with a defibrillator, experienced electrical storm and were treated with intravenous amiodarone. Each patient underwent 12-lead electrocardiography (ECG) and 187-channel repolarization interval-difference mapping electrocardiography (187-ch RIDM-ECG) before and during the intravenous administration of amiodarone infusion.

RESULTS

A recurrence of ventricular tachyarrhythmia was observed in 2 patients during the early period of intravenous amiodarone therapy. Intravenous amiodarone increased the corrected QT interval (from 470±52 ms to 508±55 ms, P=0.003), but it significantly decreased the QT dispersion (from 107±35 ms to 49±27 ms, P=0.001), T peak-T end (Tp-e) dispersion (from 86±17 ms to 28±28 ms, P=0.001), and maximum inter-lead difference between corrected Tp-e intervals as measured by using the 187-ch RIDM-ECG (from 83±13 ms to 50±19 ms, P=0.001).

CONCLUSIONS

Intravenous amiodarone suppressed the electrical storm and decreased the QT and Tp-e dispersions in patients treated by using CRT with a defibrillator.

Detection of peripartum myocardial burden by vector-projected 187 channel electrocardiography and serum NT-proBNP

There is no reliable method of screening for pregnant women at high risk of developing severe myocardial disorders. In this study, we used vector-projected 187 channel electrocardiography (DREAM-ECG) and serum biochemical markers to evaluate peripartum myocardial burden in pregnant women. Forty-one pregnant women were examined at 36-37 weeks gestation (GW36), 7 days postpartum (PPD7), and 1 month postpartum (PPM1). Ten non-pregnant control women were assessed at a single time point. Heart rate, sympathetic index, and repolarization index (RTc dispersion) were quantified using the DREAM-ECG system, and serum levels of NT-proBNP, cardiac troponin T, estrogen, and progesterone were determined. Heart rate and the sympathetic index decreased from GW36 to PPM1 (P = 0.0031). The repolarization index decreased over time and was greater than in non-pregnant controls (31 ± 13 ms). Estrogen and progesterone at PPD7 and PPM1 were significantly lower than those at GW36 (P < 0.0001, P < 0.001). NT-proBNP at PPD7 was greater than at GW36 (median 29 pg/mL at GW36, 86 pg/mL at PPD7), and decreased at PPM1 in comparison to PPD7 (median 18.5 pg/mL). Troponin T was in the normal range during the whole period (< 0.003 ng/mL). In conclusion, these results indicate that the peripartum myocardial burden in pregnant women does not return to normal nonpregnant levels by PPM1. We propose that both repolarization indexes such as RTc dispersion by DREAM-ECG and serum biochemical markers may identify pregnant women at high risk of developing severe myocardial damage in the peripartum period.

Body surface two-dimensional spectral map of atrial fibrillation using vector-projected 187 channel electrocardiography

Atrial cycle length during atrial fibrillation and flutter waves may be correlated with atrial refractoriness and organization. The nature of the frequency by spectral analysis may reflect a profile of atrial cycle length. In this study, we developed a novel body surface 2-dimensional spectral map during fibrillation using vector-projected 187 channel ECG (187ch VP-ECG).The study consisted of 28 patients (24 with atrial fibrillation (AFIB) and 4 atrial flutter (AFL) with valvular heart disease). We performed spectral analysis by maximum entropy modeling (MEM) in 4 second nonaveraged 187ch electrical current waves by 187ch VP-ECG. Body surface spectral features were displayed according to the frequency and power magnitude components. We verified the accuracy of the spectral features by a 64ch magnetocardiography (MCG). The average dominant frequency in AFL by 187ch VP-ECG was lower than those in AFIB (4.6 ± 0.9 Hz in AFL, 7.2 ± 0.9 Hz in AFIB, P < 0.01). Comparison of average dominant frequency between 187ch VP-ECG and 64 ch MCG demonstrated good agreement (y = 0.86x+0.84, r(2) = 0.89, P < 0.0001). Body surface 2-dimensional spectral features demonstrated homogenous spectrum patterns in AFL, and in-homogenous spectrum patterns in AFIB.In conclusion, novel body surface spectral mapping using 187ch VP-ECG may represent a 2-dimensional spectral feature that may be related to atrial refractoriness and organization.

Novel algorithm for identifying T-wave current density alternans using synthesized 187-channel vector-projected body surface mapping

The noninvasive evaluation of ventricular T-wave alternans (TWA) in patients with lethal ventricular arrhythmias is an important issue. In this study, we propose a novel algorithm to identify T-wave current density alternans (TWCA) using synthesized 187-channel vector-projected body surface mapping (187-ch SAVP-ECG). We recorded 10 min of 187-ch SAVP-ECG using a Mason-Likar lead system in the supine position. A recovery time (RT) dispersion map was obtained by averaging the 187-ch SAVP-ECG. The TWCA value was determined from the relative changes in the averaged current density in the T-wave zone (Tpeak ± 50 ms) for two T-wave types. We registered 20 ECG recordings from normal controls and 11 ECG recordings from nine subjects with long QT syndrome (LQT). We divided LQT syndrome subjects into two groups: group 1 provided 9 ECG recordings without visually apparent TWAs, and group 2 provided 2 ECG recordings with visually apparent TWAs. The QTc interval values in the LQT groups were higher than those in the control (515 ± 60 ms in LQT G-1, 600 ± 27 ms in LQT G-2 vs. 415 ± 19 ms in control, P < 0.001). The RTendc dispersion values among the LQT subjects were higher than those of the control subjects (48 ± 19 ms in LQT G-1, 65 ± 30 ms in LQT G-2 vs. 24 ± 10 ms in control, P < 0.01). The mean TWCA value was significantly higher in the LQT G-2 group with visually apparent TWCAs (0.5 ± 0.2% in control, 2.1 ± 1.2% in LQT G-1, and 32.3 ± 6.9% in LQT G-2). Interestingly, the two-dimensional distribution of TWCA in LQT was inhomogeneous and correlated with the distribution of increased RT dispersion. We conclude that a novel algorithm using 187-ch SAVP-ECG might provide new insights into body surface TWCA.

Development and significance of a fetal electrocardiogram recorded by signal-averaged high-amplification electrocardiography

Although ultrasonic diagnostic imaging and fetal heart monitors have undergone great technological improvements, the development and use of fetal electrocardiograms to evaluate fetal arrhythmias and autonomic nervous activity have not been fully established. We verified the clinical significance of the novel signal-averaged vector-projected high amplification ECG (SAVP-ECG) method in fetuses from 48 gravidas at 32-41 weeks of gestation and in 34 neonates. SAVP-ECGs from fetuses and newborns were recorded using a modified XYZ-leads system. Once noise and maternal QRS waves were removed, the P, QRS, and T wave intervals were measured from the signal-averaged fetal ECGs. We also compared fetal and neonatal heart rates (HRs), coefficients of variation of heart rate variability (CV) as a parasympathetic nervous activity, and the ratio of low to high frequency (LF/HF ratio) as a sympathetic nervous activity. The rate of detection of a fetal ECG by SAVP-ECG was 72.9%, and the fetal and neonatal QRS and QTc intervals were not significantly different. The neonatal CVs and LF/HF ratios were significantly increased compared with those in the fetus. In conclusion, we have developed a fetal ECG recording method using the SAVP-ECG system, which we used to evaluate autonomic nervous system development.

Detection of non-ST-elevation myocardial infarction using magnetocardiogram: new information from spatiotemporal electrical activation map

BACKGROUND AND AIM

Non-ST-segment elevation myocardial infarction (NSTEMI) cannot be easily detected in the emergency room. We evaluate a method to detect NSTEMI using 64-channel magnetocardiography (MCG).

METHODS

MCG recordings were made in 20 NSTEMI patients (aged 59.7+/-12.4 years), 15 young (aged 26.8+/-3.4 years), and 13 age-matched control subjects (aged 57.3+/-3.6). We evaluated three approaches to analysis, including 1) determination when individual subjects' MCG results fell outside normal ranges for ten MCG parameters, 2) the magnetic field map at the T-wave peak (T-MFM), and 3) a pair of spatiotemporal activation graphs (STAGs) showing two projections of electrical excitation during repolarization.

RESULTS

Significant differences were found between normal controls and patients for all MCG parameters. None of the healthy controls had more than four MCG abnormal parameters, whereas 19 NSTEMI patients (95%) were abnormal in more than four parameters. STAGs and T-MFM also showed clear differences between healthy controls and NSTEMI patients.

CONCLUSIONS

These results suggest that the MCG is sensitive to changes in the cardiac electrical pathway after myocardial infarction as described by these graphs and parameters, and therefore MCG may be a useful tool to detect severe ischemic patients.