A 12-lead ECG-method for quantifying ischemia-induced QRS prolongation to estimate the severity of the acute myocardial event

Pseudo precordial ST-segment depression

We present a case with acute coronary syndrome and very unusual QRS widening in the acute phase. The case highlights that non-specific intraventricular conduction delay should be considered as a high risk ECG pattern predicting poor prognosis.

The ratio of QRS/RV6-V1: a new electrocardiographic predictor of short- and long-term adverse clinical outcomes in patients with acute myocardial infarction combined with new-onset right bundle branch block

Background

A few studies have focused on electrocardiography (ECG) parameters correlating with clinical prognosis in patients with acute myocardial infarction (AMI) combined with new-onset right bundle branch block (RBBB).

Objective

To assess the prognostic value of a new ECG parameter, namely, the ratio of QRS duration/RV₆-V₁ interval (QRS/RV₆-V₁), in patients with AMI combined with new-onset RBBB.

Materials and methods

A total of 272 AMI patients combined with new-onset RBBB who received primary percutaneous coronary intervention (P-PCI) were retrospectively enrolled in the study. First, the patients were divided into survival group and non-survival group. Demographic, angiographic, and ECG characteristics were compared between the two groups. Receiver operating characteristic (ROC) curve was used to screen the best ECG parameter for predicting 1-year mortality. Second, the ratio of QRS/RV₆-V₁, a continuous variable, was converted to the high ratio group and low ratio group according to the optimal cutoff value point determined by the X-tile software. We compared the patient's demographic, angiographic, and ECG characteristics, in-hospital major adverse cardiovascular events (MACE), and 1-year mortality between the two groups. Multivariate logistic and Cox regressions were used to evaluate whether the ratio of QRS/RV₆-V₁ was an independent prognostic factor of in-hospital MACE and 1-year mortality.

Results

The ROC curve showed that the ratio of QRS/RV₆-V₁ had a higher value for predicting in-hospital MACE and 1-year mortality than the QRS duration, RV₆-V₁ interval, and RV₁ interval. The patients in the high ratio group had significantly higher CK-MB peak and Killip class, lower ejection fraction (EF%), higher ratio of the left anterior (LAD) descending artery as infarct-related artery (IRA), and longer total ischemia time (TIT) than those in the low ratio group. The QRS duration was wider in the high ratio group than that in the low ratio group, whereas RV₆-V₁ was narrower in the high ratio group compared with that in the low ratio group. The in-hospital MACE rate (93.3% vs. 31.0%, p < 0.001) and 1-year mortality rate (86.7% vs. 13.2%, p < 0.001) in the high ratio group were higher than those in the low ratio group. The higher ratio of QRS/RV₆-V₁ was an independent predictor of in-hospital MACE (odds ratio, 8.55; 95% CI, 1.40-52.37; p = 0.02) after adjusting other confounders. Cox regression showed that the higher ratio of QRS/RV₆-V₁ predicted higher 1-year mortality of the patients with AMI combined with new-onset RBBB [hazard ratios (HR), 12.4; 95% CI, 7.26-21.22); p < 0.001] than the lower ratio of QRS/RV₆-V₁, and the HR still stayed at 2.21 even after a multivariable adjustment (HR, 2.21; 95% CI, 1.05-4.64); p = 0.037).

Conclusion

According to the results of our study, the high ratio of QRS/RV₆-V₁ (>3.0) was a valuable predictor of short- and long-term adverse clinical outcomes in AMI patients combined with new-onset RBBB. The implications of the high ratio of QRS/RV₆-V₁ were severe ischemia and pseudo synchronization between bi-ventricle.

Post hoc assessment of relationship between coronary stenosis, ECG and ventricular function in patients with heart disease

Cardiovascular diseases including cardiac arrhythmias lead to fatal events in patients with coronary artery disease, however clinical associations from echocardiography, electrocardiography (ECG) and biomarkers remain unknown. We sought to identify the factors that may be related to elevated QRS intervals in patients with risk for coronary artery disease. In this study, we performed analysis of clinical data from 503 patients and divided into two groups, i.e., patients with either <50% coronary artery stenosis or >50% coronary artery stenosis. We further examined patients with elevated ECG parameters such as QRS>100ms and QTc>440ms. Patients with >50% coronary artery stenosis exhibited significant increases in age, triglycerides, and troponin levels. Further, ECG parameters demonstrated increased QRS and QTc durations, while echocardiographic parameters highlighted a decreased in ejection fraction (EF) and fractional shortening (FS). Patients with QTc>440ms exhibited increased Brain natriuretic peptide and Creatinine levels with a decrease in eGFR clearance rates. Patients with QRS>100ms had greater left ventricular (LV) mass, LV internal diameter in systole and diastole. Multimodal logistic regression showed significant relation between QTc, age and creatinine. These findings suggest that patients with significant coronary stenosis may have lower EF and FS with prolonged QRS intervals demonstrating greater risk for arrhythmic events.

Ischemic QRS prolongation as a predictor of ventricular fibrillation in a canine model

OBJECTIVES

An acute coronary occlusion and its possible subsequent complications is one of the most common causes of death. One such complication is ventricular fibrillation (VF) due to myocardial ischemia. The severity of ischemia is related to the amount of coronary arterial collateral flow. In dog studies collateral flow has also been shown to be associated with QRS prolongation. The aim of this study was to investigate whether ischemic QRS prolongation (IQP) is associated with impending VF in an experimental acute ischemia dog model.

METHODS

Degree of IQP and occurrence of VF were measured in dogs (n = 21) during coronary occlusion for 15 min and also during subsequent reperfusion (experiments conducted in 1984).

RESULTS

There was a significant difference in absolute IQP between dogs which developed VF during reperfusion (47 ± 29 ms, mean ± SD) and those which did not (12 ± 10 ms; p = .001).

CONCLUSIONS

IQP during acute coronary occlusion is associated with reperfusion VF in an experimental dog model and might therefore be a potential predictor of malignant arrhythmias in patients with acute coronary syndrome.

Ischemic QRS prolongation as a biomarker of myocardial injury in STEMI patients

BACKGROUND

Patients with acute coronary occlusion (ACO) may not only have ischemia-related ST-segment changes but also changes in the QRS complex. It has recently been shown in dogs that a greater ischemic QRS prolongation (IQP) during ACO is related to lower collateral flow. This suggests that greater IQP could indicate more severe ischemia and thereby more rapid infarct development. Therefore, the purpose was to evaluate the relationship between IQP and measures of myocardial injury in patients presenting with acute ST-elevation myocardial infarction (STEMI).

METHODS

Seventy-seven patients with first-time STEMI were retrospectively included from the recently published SOCCER trial. All patients underwent a cardiac magnetic resonance (CMR) examination 2-6 days after the acute event. Infarct size (IS), myocardium at risk (MaR), and myocardial salvage index (MSI) were assessed and related to IQP. IQP measures assessed were; computer-generated QRS duration, QRS duration at maximum ST deviation, absolute IQP and relative IQP, all derived from a pre-PCI, 12-lead ECG.

RESULTS

Median absolute IQP was 10 ms (range 0-115 ms). There were no statistically significant correlations between measures of IQP and any of the CMR measures of myocardial injury (absolute IQP vs IS, r = 0.03, p = 0.80; MaR, r = -0.01, p = 0.89; MSI, r = -0.05, p = 0.68).

CONCLUSIONS

Unlike previous experimental studies, the IQP was limited in patients presenting at the emergency room with first-time STEMI and no correlation was found between IQP and CMR variables of myocardial injury in these patients. Therefore, IQP does not seem to be a suitable biomarker for triaging patients in this clinical context.

Association between QRS duration on prehospital ECG and mortality in patients with suspected STEMI

BACKGROUND

QRS duration has previously shown association with mortality in patients with acute myocardial infarction treated with thrombolytics, less is known in patients with suspected ST segment elevation myocardial infarction (STEMI) when assessing QRS duration on prehospital ECG. Thus, the objective was to investigate the prognostic effect of QRS duration on prehospital ECG and presence of classic left and right bundle branch block (LBBB/RBBB) for all-cause mortality in patients with suspected STEMI.

METHOD

In total 2105 consecutive patients (mean age 64±13years, 72% men) with suspected STEMI were prospectively included. QRS duration was registered from automated QRS measurement on prehospital ECG and patients were divided according to quartiles of QRS duration (<89ms, 89-98ms, 99-111ms and >111ms). Primary endpoint was all-cause 30-day mortality. Predictors of all-cause mortality were assessed using Cox proportional hazards analysis.

RESULTS

Among all patients median QRS duration was 98ms (IQR 88-112ms). RBBB-morphology was seen in 126 patients (6.0%) and LBBB in 88 patients (4.2%), 80% were treated with percutaneous coronary intervention and the final diagnosis was STEMI in 1777 patients (84%). Thirty-day mortality was 7.6% in patients with suspected STEMI. In multivariable analysis, QRS duration>111ms (hazard ratio (HR) 3.08; 95% confidence interval (CI): 1.71-5.57, p=0.0002), LBBB - morphology (HR 3.0; 95% CI: 1.38-6.53, p=0.006) and RBBB (HR 3.68; 95% CI: 1.95-6.95, p<0.0001) were associated with 30 day all-cause mortality.

CONCLUSION

In patients with suspected STEMI, QRS prolongation, LBBB, and RBBB on prehospital ECG are associated with increased risk of death.