BACKGROUND: Coronary no-reflow phenomenon (NRP) is a complex condition that can be observed frequently after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS) and is associated with significant adverse cardiac events and a poor prognosis. In this study, we aimed to evaluate the relationship between the frontal QRS-T angle, which has been associated with myocardial repolarization and adverse cardiac outcomes in previous researches, and NRP. METHODS: Our retrospective, single center study included 1207 patients hospitalized in our clinic with ACS between 2020 and 2025. The primary endpoint in this research was the occurrence of NRP, and patients were divided into two categories according to this condition. 46 patients with NRP were identified. A control group of patients who did not occur NRP, matched 1:2 in terms of age and gender, was identified (n = 92). Electrocardiograms of the patients were evaluated before PCI and frontal QRS-T angles were recorded. Clinical features, frontal QRS-T angle, and laboratory parameters were statistically evaluated to differentiate between the two categories. RESULTS: The frontal QRS-T angle was significantly greater in the patient group with NRP than in the control group (105.8 ± 51.9 vs. 54.5 ± 37.7, P < 0.001). As a result, frontal QRS-T angle was independently associated with NRP in ACS patients (P < 0.001) and predicted NRP with a cut-off value of 73.0, 71.7% sensitivity and 70.3% specificity in ROC-Curve analysis (AUC: 0.802, 95% CI: 0.731–0.873, P < 0.001). CONCLUSION: In our research, we observed that the frontal QRS-T angle was an independent predictor of NRP in the ACS patient group. We believe this may be particularly important in the treatment of NRP, early detection of high-risk patients, and improvement of prognosis through appropriate measures. CLINICAL TRIAL REGISTRATION: Not applicable.

A septuagenarian man underwent dual chamber pacemaker (DDDR - Boston Scientific Massachusetts, U.S.) insertion for a complete heart block. Intra-procedural lead parameters were within normal limits. Frequent multisite origin premature ventricular complexes were noted even on pre-procedural electrocardiogram (ECG). On the follow-up ECG one pacing spike on the QRS of the first beat was followed by two pacing spikes on the T wave with a total of three pacing spikes on the whole QRST of the first complex. What is the mechanism?

Aim To compare electrocardiographic parameters and characteristics of myocardial contractility by echocardiography data in patients with chronic heart failure (CHF) with low left ventricular ejection fraction (LV EF) and atrial fibrillation (AF).Material and methods The study included 66 patients with CHF and LV EF ≤40%. Electrocardiography was used to assess the QRS complex duration, QRS fragmentation, frontal QRS-T angle (fQRS-Ta), and 3D vectorcardiographic parameters, including the planarity of QRS loop, and the spatial QRS-T angle (sQRS-Ta). Echocardiography assessed LV EF, global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE).Results Statistically significant correlations between electrocardiographic parameters and LV EF were not found. The presence of QRS fragmentation was associated with impaired GLS, higher GWW values, and lower GWE. A number of weak but significant correlations was observed: GLS worsened with increasing QRS duration, fQRS-Ta, and sQRS-Ta and decreasing QRS planarity index; GWW increased with increasing QRS duration; GWI, GCW, and GWE decreased as the QRS planarity index decreased. GWI decreased with increasing sQRS-Ta; GCW decreased with increasing fQRS-Ta and sQRS-Ta; GWE decreased with increasing QRS duration, fQRS-Ta and sQRS-Ta.Conclusion Correlations were found between indicators of myocardial electrical remodeling and parameters of myocardial contractility, strain, and performance in CHF patients with low LV EF and AF. Further study of these parameters may be promising for assessing the severity of changes in myocardial structure and function in patients with various cardiovascular pathologies.

With the increased prevalence of atrial fibrillation (AF) - a rhythm disturbance in heart's top chambers - there is growing interest in accurate non-invasive diagnosis of atrial activity to improve its therapy. A key component in non-invasive analysis of atrial activity is a successful removal of the ventricular QRST complexes from electrocardiograms (ECGs). In this study, we have developed a new approach for an objective and physiologically-based evaluation of QRST cancellation methods based on comparisons with the power spectra of the AF. Three commonly used QRST cancellation methods were evaluated; namely, average beat subtraction, singular value cancellation, and principal component analysis. These methods were evaluated in time and frequency domains using a set of synthesized ECGs preserving the atrial-specific temporal and spectral properties. It was observed that the ABS method provided the best estimation when QRST morphological variability is low, while PCA produces an overall best estimate when a large QRST morphological variability is present.