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Abnormal QRS-T angles in 5796 women and men aged 50-64: an electrocardiographic analysis providing mechanistic
Lennart Bergfeldt1, Rut Hellsing2, David Molnar3
1Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden; Region Västra Götaland, Department of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
Insights
Abnormal QRS-T angles, linked to sudden cardiac death, were studied using vectorcardiography. Findings offer insights into cardiac electrical disturbances and potential implications for left ventricular hypertrophy management.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Imaging
Background:
- Abnormal QRS-T angles are significant predictors of cardiovascular mortality, including sudden cardiac death.
- These abnormalities are more prevalent in diabetic patients (∼20%) compared to the general population (∼5-6%).
- The underlying mechanisms, involving electrical activation and/or recovery disturbances, remain largely unknown.
Purpose of the Study:
- To investigate the mechanistic background of abnormal QRS-T angles.
- To explore electrical activation and recovery patterns associated with these angles.
- To provide insights for future prognostic and interventional studies in cardiology.
Main Methods:
- Utilized Frank vectorcardiography (VCG) and 12-lead ECG in 311 participants from the Swedish CArdio-Pulmonary bio-Imaging Study (SCAPIS).
- Defined abnormal QRS-T angles using established cut-off values (>124° peak, >119° mean) based on percentile data.
- Analyzed electrical activation and recovery patterns in relation to QRS-T angle deviations.
Main Results:
- Deviations in QRS and QRSarea-vectors were more frequent (90%) than T- and Tarea-vector deviations (65%).
- Standard ECG identified underlying pathophysiology in 20% of cases, with left bundle branch block (LBBB) and left ventricular hypertrophy criteria being most common (9-10% each).
- Significant variability in vector directions was observed in the subgroup with LBBB.
Conclusions:
- The study provides mechanistic insights into abnormal QRS-T angles, valuable for future cardiovascular research.
- Findings suggest potential implications for left bundle branch area pacing strategies.
- Results may inform approaches to managing left ventricular hypertrophy.
Introduction:
Abnormal QRS-T angles are prognostic markers for cardiovascular deaths including sudden cardiac death. They occur in ∼5-6% of population-based cohorts but in ∼20% of patients with diabetes. The mechanistic background, electrical activation and/or recovery disturbances, is not known and the topic of this study.
Methods:
Applying Frank vectorcardiography (VCG) and simultaneously recorded scalar 12‑lead ECG, electrical activation and recovery of abnormal QRS-T angles were studied in 311 participants (5.4%) from a population-based cohort of 5796 women and men in the main Swedish CArdio-Pulmonary bio-Imaging Study (SCAPIS) in Gothenburg. Cut-off values for the peak and mean QRS-T angles were > 124° and > 119°, based on the >95th percentile among all 1080 participants in the pilot SCAPIS and reference values for normal directions (Q1-Q3) from 319 apparently healthy (30%) of them.
Results:
Of 311 cases 17% had known cardiac disease. Deviations of QRS and QRSarea-vectors from reference limits (90%) were significantly more common than deviations of T- and Tarea-vectors (65%). Standard ECG signs suggested pathophysiology in 20%; left bundle branch block (LBBB) and voltage criteria for left ventricular hypertrophy being most frequent (9-10%) each. Sub-group analysis of the 30 with LBBB showed very large variability in vector directions.
Conclusions:
Our observations provide mechanistic insights about abnormal QRS-T angles of potential value for future prognostic and interventional studies. The results also have potential implications for LBB area pacing and the approach to left ventricular hypertrophy.
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