Bimodal distribution of QRS complex duration in patients with dilated cardiomyopathy undergoing an ICD implant procedure

Background/Introduction

In patients with heart failure with reduced ejection fraction (HFrEF), QRS duration is of the uttermost importance. Substantial proportion of patients with HFrEF and sufficiently prolonged QRS complex, especially those with left bundle branch block (LBBB), may significantly benefit from cardiac resynchronization therapy.

Purpose

The aim of the study was to analyse the distribution of the QRS durations in patients with HFrEF undergoing ICD implant procedure to better understand the phenomenon of QRS prolongation.

Methods

All patients undergoing the implant procedure in our centre between January 2017 and December 2021 for HFrEF caused by coronary artery disease (CAD) or dilated cardiomyopathy (DCM) were analysed for the inclusion into the study. The exclusion criteria were (1) coincidence of CAD with DCM, (2) upgrade from any other cardiac rhythm management device, (3) unavailability of the ECG recording or ECG recording with insufficient quality before the implant procedure, (4) more than one ventricular premature beat in the recording. The study used automatically measured QRS duration by Mortara EKG machines (299 recordings with ELI350, 98 with ELI380, and 10 with ELI250). Statistical analysis was performed in R software [1] with the function locmodes for the visualisation of probability density and excess mass test [2] for assessing statistical significance, both from the multimode package.

Results

The study included 407 patients. In 113 patients with DCM and 177 patients with CAD, the implantation was based on primary prevention (PP) indications, and 24 and 93 patients with DCM and CAD were implanted for secondary prevention (SP) indications. The distribution of QRS durations in the CAD-PP, as well as CAD-SP was unimodal (p=ns). In the DCM-PP group, the distribution was bimodal (p=0.012), in the DCM-SP group, the trend was non-significantly bimodal (p=0.076). Both DCM groups taken together had clearly bimodal distribution (p=0.002 – probability density curve according to locmodes function in the figure). The values between 139 and 142 ms were not present in this group. Below this border zone, two other patients fulfilled the criteria of LBBB, both with the duration close to the border zone (137 and 138 ms). Above this zone, 8 patients had right bundle branch block, the rest had LBBB.

Conclusions

Bimodal distribution of QRS duration values in patients with DCM supports the idea of sudden change of left bundle conduction rather than slow progression of local changes. In CAD, scars and other local impairments in conduction may hide these changes and no clear border zone can be set. With the well-known differences in the measurements of main ECGmachine manufacturers, criteria for bundle branch block in DCM could be set with high accuracy.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Charles University Research Program “Cooperatio – Cardiovascular Science” and the Ministry of Health of the Czech Republic Conceptual Development of Research Organization

Use of multiple biomarkers for evaluation of anthracycline-induced cardiotoxicity in patients with acute myeloid leukemia

AIM

To assess cardiac toxicity of anthracycline treatment with six biomarkers of cardiac injury: myoglobin, creatine kinase MB (CK-MB mass), cardiac troponin T (cTnT), cardiac troponin I (cTnI), heart-type fatty acid binding protein (H-FABP), glycogen phosphorylase BB (GPBB).

METHODS

We evaluated anthracycline-induced cardiotoxicity in 12 acute myeloid leukemia patients (mean age 51.3-/+10.7 years, 7 females). All biomarkers were measured at the baseline, after first chemotherapy (CT) with anthracyclines, after last CT with anthracyclines (total cumulative dose 479.8-/+106.2 mg/m2) and 6 months thereafter. Values above the reference range were considered elevated.

RESULTS

GPBB increased above the cut-off (7.30 microg/L) in 2 (16.7%) patients after first CT, in 3 (25.0%) patients after last CT and remained elevated in 2 (16.7%) patients within 6 months after CT. CTnI became elevated (above 0.40 microg/L) in 1 (8.3%) patient after first and last CT and within 6 months after CT. CTnT remained negative (below 0.01 microg/L) during CT in all patients. Six months after CT, delayed cTnT positivity was found in 1 (8.3%) patient. All patients with cTnI or cTnT positivity had elevated GPBB. Other biomarkers (myoglobin, CK-MB mass, H-FABP) remained within the reference range in all patients.

CONCLUSION

Our preliminary results suggest that GPBB could be a new promising marker for detection of anthracycline-related cardiotoxicity and probably superior to cardiac troponins. The predictive value for development of cardiomyopathy in the future is not clear and will be evaluated during a prospective follow-up.

Multimarker approach to evaluation of cardiac toxicity during preparative regimen and hematopoietic cell transplantation

Cardiac toxicity of preparative regimen (PR) containing high-dose Cyclophosphamide (120 mg/kg) followed by hematopoietic cell transplantation (HCT) was evaluated with 6 biomarkers of cardiac injury: N-terminal pro brain natriuretic peptide (NT-proBNP), creatine kinase MB (CK-MB mass), cardiac troponins (cTnT, cTnI), heart-type fatty acid binding protein (H-FABP), glycogen phosphorylase BB (GPBB). Twenty-three patients (mean age 44.5+/-10.6 years, 15 males) with acute leukemia were studied. All biomarkers were measured the day before PR, the day after PR, the day after HCT and 14 days after HCT. We found NT-proBNP elevations above 500 ng/L in 6 (26.1 %) patients after PR, in 9 (39.1 %) after HCT and in 7 (30.4 %) 14 days after HCT. GPBB became elevated (above 7.30 microg/L) in 5 (21.7 %) patients after PR, remained elevated in 5 (21.7 %) after HCT and in 2 (8.7 %) 14 days after HCT. A significant correlation between elevation in NT-proBNP and GPBB was found. Other markers remained within the reference range early after PR and HCT. Our findings show that administration of PR and HCT for acute leukemia is associated with acute neurohumoral activation of cardiac dysfunction (significant rise in NT-proBNP) and may lead to GPBB elevation. These changes could indicate acute cardiac toxicity due to treatment and require further follow-up. The predictive value for development of cardiomyopathy in the future is unclear. Further studies will be needed to define the potential role of new biomarkers in this context.