We present an electrocardiogram with triphasic QRS morphology variation and discuss the mechanism and clinical implications for this finding.We present an electrocardiogram with triphasic QRS morphology variation and discuss the mechanism and clinical implications for this finding.
A sexagenarian man presented to the emergency department with one episode of syncope. The electrocardiogram (ECG) revealed an alternating bundle branch block with alternating PR interval. Cardiac biomarkers were negative...A sexagenarian man presented to the emergency department with one episode of syncope. The electrocardiogram (ECG) revealed an alternating bundle branch block with alternating PR interval. Cardiac biomarkers were negative, and the echocardiogram revealed a structurally normal heart. What is the mechanism?
The QT interval is a key indicator in assessing arrhythmia risk, evaluating drug safety, and supporting clinical diagnosis in cardiology. The QT interval is significantly influenced by heart rate so it must be accurately...The QT interval is a key indicator in assessing arrhythmia risk, evaluating drug safety, and supporting clinical diagnosis in cardiology. The QT interval is significantly influenced by heart rate so it must be accurately corrected to ensure reliable clinical interpretation. Conventional correction formulas, such as Bazett's formula, are widely utilized but often criticized for inaccuracies, either under- or overcorrecting QT intervals in different physiological conditions. The recently developed AccuQT method, utilizing transfer entropy for QT correction, has demonstrated superior consistency in healthy populations and improved accuracy in diagnosing long QT syndrome (LQTS) compared to conventional approaches. In this study, we evaluate the AccuQT method using 24-h Holter recordings from patients with various genetic heart diseases, including hypertrophic cardiomyopathy (HCM) and LQTS, compared to the healthy controls. Additionally, we analyzed heart rate variability with the recently developed scaled-dependent detrended fluctuation analysis (DFA). The mean QTc using the AccuQT method in the patient group was significantly longer (476 ms) than in the healthy population (410 ms), as expected. The Bazett's formula resulted in significantly longer mean QTc in the healthy population (460 ms) and in patient group (490 ms). The DFA scaling exponent was lower at short scales for patient group compared to healthy controls. It also detected a difference between HCM patients with clinical disease and asymptomatic gene carriers with no signs of the disease. In conclusion, the AccuQT method provides reliable QT interval correction in patients with genetic cardiac diseases, demonstrating superior precision compared to Bazett's formula. AccuQT effectively captures time-dependent QT interval changes, enhancing diagnostic accuracy. Additionally, scale-dependent DFA analysis shows promise in differentiating patients with clinical hypertrophic cardiomyopathy from asymptomatic gene carriers, suggesting potential utility in earlier identification of at-risk individuals.
BACKGROUND: Ischemia with non-obstructive coronary arteries (INOCA) represents a diagnostic and therapeutic challenge, often related to coronary microvascular dysfunction (CMD). Identifying non-invasive electrocardiograp...BACKGROUND: Ischemia with non-obstructive coronary arteries (INOCA) represents a diagnostic and therapeutic challenge, often related to coronary microvascular dysfunction (CMD). Identifying non-invasive electrocardiographic markers that predict ischemia in this population remains a clinical priority. P-wave peak time (PWPT), reflecting atrial conduction delay, has been linked to ischemic pathophysiology. METHODS: This retrospective, observational study included 444 patients who underwent coronary angiography with normal epicardial arteries followed by SPECT myocardial perfusion imaging (MPI) due to persistent anginal symptoms. Patients were classified into three groups based on the percentage of reversible left ventricular ischemia: <5 %, 5-10 %, and > 10 %. P-wave indices-including PWPT in leads DII and V1-were measured digitally by two independent observers. Multivariate logistic regression identified independent predictors of >10 % ischemia. ROC analysis assessed the discriminative power of PWPT. RESULTS: PWPT-DII and PWPT-V1 were significantly prolonged in patients with >10 % ischemia (63 ± 8 ms and 58 ± 9 ms, respectively) compared to patients with <5 % ischemia (55 ± 7 ms and 50 ± 8 ms; both p < 0.001). PWPT-DII yielded an AUC of 0.82 (95 % CI 0.77-0.86), outperforming PWPT-V1 (AUC 0.76). In multivariate models, PWPT-DII (OR 1.15, 95 % CI 1.08-1.23), PWPT-V1 (OR 1.10, 95 % CI 1.03-1.17), age, diabetes mellitus, and E/e' ratio emerged as independent predictors of significant ischemia. CONCLUSIONS: Prolonged PWPT, particularly in lead DII, was observed to be independently associated with myocardial ischemia in INOCA. Incorporating PWPT into standard ECG interpretation may aid in risk stratification and early identification of CMD in patients with normal coronary angiograms but ongoing ischemic symptoms.
INTRODUCTION: Left ventricular hypertrophy (LVH) is associated with complex structural changes in the myocardium, which may alter the electrocardiogram (ECG). The ECG is the initial test for patients with suspected heart...INTRODUCTION: Left ventricular hypertrophy (LVH) is associated with complex structural changes in the myocardium, which may alter the electrocardiogram (ECG). The ECG is the initial test for patients with suspected heart disease. Electrocardiographic criteria for LVH diagnosis have a low sensitivity compared to the echocardiogram (ECHO). The advent of tele-ECG and the availability of automatic analysis systems have made the large-scale use of electrocardiography possible. However, there are only a few studies on the prevalence and prognosis of LVH automatically detected in the ECG. OBJECTIVE: To evaluate the association between the Glasgow program score for LVH in the ECG and overall mortality in an electronic cohort of primary care patients in Brazil. METHODS: Patients from the CODE (Clinical Outcomes in Digital Electrocardiology) cohort, older than 18 years, who underwent digital ECG recording from 2010 to 2017, were included. The University of Glasgow Automated ECG Interpretation program was used to analyze the ECGs. ECG LVH was classified into definite LVH if the LVH-Glasgow score was≥6.3, probable LVH if the score was between 5.0 and 6.3, possible LVH if the score was between 4.0 and 5.0, and no LVH if the score was <4.0. To assess the relationship between the LVH-Glasgow score and mortality, Cox regression adjusted for age, sex, and comorbidities was used. RESULTS: The CODE database included 1,558,415 patients, with 1,389,331 patients over 18 years old. Technically unsatisfactory ECGs that could compromise the analysis were excluded. The Glasgow program automatically excludes the diagnosis of LVH if LBBB, WPW, or pacemaker rhythm have been detected before the tests for LVH are undertaken. The prevalence of an abnormal LVH-Glasgow score (≥4.0) was 18.5 %. At a median follow-up of 3.47 years, the general population's all-cause mortality rate was 2.68 %. After multivariate adjustment, the presence of definite LVH had a higher risk of overall mortality (95 % CI; HR 1.64 (1.59-1.69)); probable LVH (95 % CI; HR 1.18 (1. 14-1.23)) and possible LVH (95 % CI; HR 1.09 (1.05-1.13)) were also associated with increasing risk of death. CONCLUSIONS: The LVH-Glasgow score can be a prognostic tool in ECG analysis. In this population, a higher score was associated with a higher risk of overall mortality.
BACKGROUND: Interatrial block (IAB) is an electrocardiographic manifestation of atrial conduction delay and structural remodeling. While it has been linked to atrial fibrillation (AF) and thromboembolic events, its poten...BACKGROUND: Interatrial block (IAB) is an electrocardiographic manifestation of atrial conduction delay and structural remodeling. While it has been linked to atrial fibrillation (AF) and thromboembolic events, its potential role in predicting left atrial appendage (LAA) thrombus formation remains underexplored. This study aimed to investigate the association between IAB and the presence of LAA thrombus in patients with nonvalvular AF (NVAF) or atrial flutter referred for rhythm control procedures. METHODS: In this retrospective observational study, 750 patients with NVAF who underwent transesophageal echocardiography (TEE) prior to catheter ablation or cardioversion were evaluated. P-wave parameters were measured from digitally amplified 12‑lead ECGs, and IAB was defined according to current consensus criteria. Patients were stratified by the presence of LAA thrombus, and multivariate logistic regression was used to identify independent predictors. RESULTS: LAA thrombus was detected in 10.8 % of patients. Those with thrombus were older and had higher thromboembolic risk scores, more frequent history of stroke, and lower left ventricular ejection fraction (LVEF). Interatrial block was observed in 85.2 % and advanced IAB in 44.4 % of patients with thrombus. In multivariate analysis, IAB (OR: 2.698; p = 0.008), larger LA diameter, lower LVEF, and greater P-wave dispersion were independently associated with thrombus presence. CONCLUSION: IAB is independently associated with LAA thrombus in NVAF patients and may serve as a noninvasive marker to identify individuals at higher thromboembolic risk, potentially guiding the need for TEE before rhythm control.
BACKGROUND: Hypertensive crisis (HC) is recognized as a contributing factor in the development of cardiac arrhythmias. This study aims to assess Tp-e interval, Tp-e/QT (TQR), and Tp-e/QTc (TQcR) ratios in patients experi...BACKGROUND: Hypertensive crisis (HC) is recognized as a contributing factor in the development of cardiac arrhythmias. This study aims to assess Tp-e interval, Tp-e/QT (TQR), and Tp-e/QTc (TQcR) ratios in patients experiencing hypertensive urgency and emergency, in order to evaluate the potential risk of ventricular arrhythmias. METHODS: A prospective study was conducted involving HC patients admitted to a tertiary hospital's emergency department between June 1, 2022, and June 30, 2024. Patients were categorized into three groups: hypertensive emergency, hypertensive urgency, and control group. Data collected included demographic characteristics, vital signs, laboratory results, and electrocardiography (ECG) parameters such as Tp-e interval, TQR, and TQcR. RESULTS: Among the 235 eligible patients, 57 % were female and 43 % male. The hypertensive urgency group included 130 patients, the emergency group 45, and the control group 60. Statistically significant differences in Tp-e, TQR, and TQcR values were observed across all groups (p < 0.001). These metrics demonstrated moderate positive correlations with both systolic and diastolic blood pressures. CONCLUSION: Increased Tp-e, TQR, and TQcR values identified in HC patients suggest a heightened risk for ventricular arrhythmias. These findings support the routine evaluation of these ECG.
We report an elderly woman who presented with cardiac arrest due to complete heart block. She developed progressive T-wave inversions in leads V3-V6 due to pacinginduced cardiac memory, accompanied by marked QTc prolonga...We report an elderly woman who presented with cardiac arrest due to complete heart block. She developed progressive T-wave inversions in leads V3-V6 due to pacinginduced cardiac memory, accompanied by marked QTc prolongation. These repolarization abnormalities occurred despite normal electrolytes and non-obstructive coronary angiography and culminated in polymorphic ventricular tachycardia. This case highlights cardiac memory as an underrecognized proarrhythmic substrate in bradyarrhythmia and the importance of serial ECG monitoring to detect evolving repolarization changes and mitigate arrhythmic risk.
Anterior ST-segment elevation is conventionally attributed to acute occlusion of the left anterior descending (LAD) artery. However, isolated right ventricular myocardial infarction (RVMI), though exceedingly rare, may p...Anterior ST-segment elevation is conventionally attributed to acute occlusion of the left anterior descending (LAD) artery. However, isolated right ventricular myocardial infarction (RVMI), though exceedingly rare, may present with a similar electrocardiographic pattern, thereby posing a diagnostic challenge. We describe a 44-year-old male patient who presented with acute retrosternal chest pain and exhibited dome-like ST-segment elevation in leads V1-V4, without reciprocal ST-segment depression in the inferior leads. Despite initial suspicion of anterior ST-elevation myocardial infarction (STEMI) due to presumed LAD involvement, emergent coronary angiography revealed a complete proximal occlusion of the right coronary artery (RCA), which gave rise to a well-developed posterior descending artery (PDA) following recanalization, alongside a small PDA from the left circumflex artery, consistent with a balanced-dominant coronary circulation. A diagnosis of isolated RVMI was subsequently confirmed. This case emphasizes the need to consider RVMI in the differential diagnosis of anterior ST-segment elevation, particularly in patients with balanced-dominant anatomy, where dual-PDA supply may obscure classic inferior infarct patterns and lead to diagnostic confusion.
The spiked helmet sign is an electrocardiographic (ECG) abnormality characterized by a dome-and-spike pattern where upright QRS complexes are preceded by upslope and followed by downslope of the ECG baseline. Numerous st...The spiked helmet sign is an electrocardiographic (ECG) abnormality characterized by a dome-and-spike pattern where upright QRS complexes are preceded by upslope and followed by downslope of the ECG baseline. Numerous studies have demonstrated that the spiked helmet sign is a marker of critical, usually noncardiac illness and a high risk of death. In this report we describe an ECG abnormality we termed volcanic mountain sign that appears to be a variant of the spiked helmet sign. In the volcanic mountain sign, a negative QRS complex mimicking the central vent of a volcano starts from the top of a mountain-shaped dome or from the bottom of a crater-like depression. The volcanic mountain sign too is seen in patients with acute, severe and occasionally lethal noncardiac illnesses. Resolution of the acute clinical condition is associated with prompt resolution of the volcanic mountain sign.
INTRODUCTION: Age-related shifts in pediatric ECG morphology are well described, yet the classic maturation milestones have never been tested head-to-head in a case-control design that yields diagnostic-accuracy metrics...INTRODUCTION: Age-related shifts in pediatric ECG morphology are well described, yet the classic maturation milestones have never been tested head-to-head in a case-control design that yields diagnostic-accuracy metrics for congenital heart disease (CHD). METHODS: In this retrospective diagnostic-accuracy study we reviewed 1637 12‑lead ECGs recorded in 2023 at a Brazilian tertiary cardiac center and its tele-ECG network. CHD was confirmed in 349 children; 1288 children with structurally normal hearts served as controls. An ECG was classified negative when R > S in V6 and an inferior axis were present and ≤ 35 months: no rsR' > 120 ms, pure-R, qR or pure-q in V1; 36-95 months: above criteria plus either R < S in V1 or R ≥ S but <6 mm; ≥ 96 months: above criteria plus S > R in V1. Any other pattern was deemed positive. Sensitivity, specificity and likelihood ratios (LR+, LR-) were calculated for three prespecified age strata. RESULTS: Infants (1-35 months): sensitivity 67.5 % (95 % CI 60.4-74.5), specificity 88.8 % (86.0-91.7), LR+ 6.05, LR- 0.37. Transition pattern (36-95 months): sensitivity 66.7 % (57.4-76.0), specificity 87.0 % (83.7-90.2), LR+ 5.11, LR- 0.38. Adult-like pattern (≥ 96 months): sensitivity 71.6 % (61.8-81.4), specificity 90.5 % (87.6-93.4), LR+ 7.52, LR- 0.31. CONCLUSIONS: A rapid age-tiered analysis delivers moderate rule-in (LR+ ≈ 5-8) and rule-out power (LR- ≈ 0.3-0.4). The tool is not a stand-alone diagnostic test. Full waveform interpretation remains essential once a tracing is flagged. CLINICAL TRIAL REGISTRATION: None.
In rare cases of acute coronary syndrome, atypical, single lead ST elevation with or without associated ST depression and negative T waves in many leads may underlie multivessel coronary disease. We report the case of el...In rare cases of acute coronary syndrome, atypical, single lead ST elevation with or without associated ST depression and negative T waves in many leads may underlie multivessel coronary disease. We report the case of elderly man admitted for. syncope followed by epigastric pain, increased hs-TnI peak values and more pronounced ST-segment elevation in V3 than other leads. Coronary angiography showed multi-vessel coronary artery disease and the patient underwent coronary angioplasty.
BACKGROUND: The QT interval on an ECG is influenced by heart rate, requiring correction formulae for adjusted QT (QTc) values. In daily clinical practice, Bazett's formula is the most commonly used; however, the FDA gene...BACKGROUND: The QT interval on an ECG is influenced by heart rate, requiring correction formulae for adjusted QT (QTc) values. In daily clinical practice, Bazett's formula is the most commonly used; however, the FDA generally recommends Fridericia's formula for drug development, aside from exceptional circumstances. Other commonly used formulae include Framingham and Hodges. This study compared the accuracy of these four frequently used formulae in correcting the QT interval for heart rate. METHODS: We retrospectively assessed ECGs from 22,063 medically assessed healthy individuals who participated in phase 1 trials between 1997 and 2023. Pearson correlation coefficient (r) between QTc and heart rate (HR) and the linear regression slope (b) were calculated for each formula and the influence of age, sex body mass index and heart rate. RESULTS: The study analyzed 16,170 males and 5893 females (mean age: 34.9 ± 15.3 years) to assess QTc-heart rate (HR) correlations. The Fridericia formula showed the strongest reliability, with the lowest correlation (r = 0.018) and a nearly horizontal regression slope (b = 0.04). The Hodges (r = -0.182, b = -0.39) and Framingham (r = 0.200, b = 0.43) formulae followed. The Bazett formula performed worst (r = 0.483, b = 1.12). Fridericia remained the most accurate across subgroups except in low BMI groups and differed significantly from other formulae in both sexes (P < 0.05). CONCLUSIONS: In apparently healthy individuals, Fridericia formula is the most reliable method for correcting the QT interval for heart rate and we recommend its use in studies involving healthy subjects.
BACKGROUND: While single‑lead ECGs offer accessibility, their performance and reliability for QTc assessment remains uncertain. Current State-of-the-art AI systems, though promising, often lack transparency, raising conc...BACKGROUND: While single‑lead ECGs offer accessibility, their performance and reliability for QTc assessment remains uncertain. Current State-of-the-art AI systems, though promising, often lack transparency, raising concerns about clinical trustworthiness. METHODS: We developed an uncertainty-aware AI model to measure RR/QT intervals from single‑lead ECGs. Training used retrospective datasets (∼400,000 ECGs) from clinical 12‑lead systems, with testing on 2050 manually annotated AliveCor KardiaMobile single‑lead (lead-I) ECGs. QTc Fridericia values were calculated using a first-order approximation and delta method for uncertainty propagation. Performance was evaluated using (1) Bland-Altman analysis and uncertainty calibration (ENCE), (2) Classification performance for QTc prolongation at 450/470/500 ms thresholds using probabilistic outputs and area under the receiver operator curve (AUROC) and (3) QT nomograms for risk visualization. RESULTS: The model demonstrated strong QTc estimation performance with integrated uncertainty quantification. After excluding 11 % of ECGs flagged as unreliable through uncertainty analysis, the remaining 89 % showed excellent agreement with 12‑lead reference values (mean bias: -0.7 ms, limits of agreement: -42 to +41 ms). The excluded high-uncertainty cases exhibited substantially larger errors (mean bias: 15.3 ms, limits of agreement: -104 to +134 ms). Uncertainty estimates were well-calibrated (ENCE: 14.6 %), enabling effective identification of unreliable predictions for expert review while maintaining clinical-grade accuracy in retained cases. Classification achieved excellent AUROCs in low-uncertainty cases: 0.87 [95 % CI: 0.85-0.89](≥450 ms), 0.90 [95 % CI: 0.86-0.93](≥470 ms), 0.96 [95 % CI: 0.92-1.00](≥500 ms). CONCLUSIONS: By integrating uncertainty quantification, this AI model enables trustworthy QTc monitoring using single‑lead ECGs, dynamically flagging unreliable measurements. This approach enhances clinical safety and expands access to cardiac risk assessment in remote settings. The methodology sets a precedent for developing transparent, reliable AI tools in healthcare, prioritizing trust over traditional explainability.
Left bundle branch area pacing (LBBAP) is now a common implantation strategy for both pacing and resynchronization based device therapies. While LBBAP has been (somewhat paradoxically) demonstrated to be effective in cas...Left bundle branch area pacing (LBBAP) is now a common implantation strategy for both pacing and resynchronization based device therapies. While LBBAP has been (somewhat paradoxically) demonstrated to be effective in cases of preexisting left bundle branch (LBB) block, and criteria for LBB capture have been established; minimal focus has been towards the intrinsic refractory rate of the LBB. Herein, we demonstrate a case of LBBAP rate exceeding the refractory period of the LBB, resulting in alternating LBBAP capture and non-selective septal pacing. Implicit understanding of this physiology has important sequel for accurate assessment of lead placement during implantation.