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T vector and loop characteristics in coronary artery disease and during acute ischemia
Aigars Rubulis1, Jens Jensen, Gunilla Lundahl
1Department of Cardiology, Karolinska Institutet, Karolinska Hospital, Stockholm, Sweden.
Insights
T loop morphology effectively distinguishes coronary artery disease (CAD) patients from healthy individuals. Ventricular repolarization is significantly impacted by ischemia, particularly in hypertensive patients, highlighting vulnerability during percutaneous coronary intervention (PCI).
Area of Science:
- Cardiology
- Electrophysiology
- Medical Imaging
Background:
- Acute or permanent ventricular repolarization heterogeneity increases sudden cardiac death risk.
- Ischemia is a significant risk factor for ventricular repolarization abnormalities.
Purpose of the Study:
- To characterize ventricular repolarization using T vector and T loop morphology in coronary artery disease (CAD) patients.
- To assess the response of repolarization parameters to short-term ischemia induced by coronary occlusion during percutaneous coronary intervention (PCI).
Main Methods:
- Vectorcardiography was used to measure T vector (Televation, Tazimuth, QRS-T angle) and T loop (Tarea, Tavplan, Teigenv) parameters in 56 CAD patients and 10 healthy controls.
- ST vector magnitude (ST-VM) and its change (STC-VM) served as reference measures.
- Measurements were taken at rest and during ischemia induced by coronary occlusion in CAD patients undergoing PCI.
Main Results:
- At rest, T loop morphology (Tarea, Teigenv) differed significantly between CAD patients and controls, while T vector angles did not.
- Ischemia induced significant changes in T loop parameters in the overall CAD group.
- The left anterior descending (LAD) subgroup showed changes in T vector angles during ischemia.
- Hypertensive patients exhibited a more pronounced ischemic response in T loop morphology (Tarea).
Conclusions:
- T loop morphology is a more effective discriminator of CAD than T vector angles.
- Coronary occlusion during PCI significantly impacts ventricular repolarization, especially in the LAD territory.
- Hypertensive patients with CAD are particularly vulnerable to ischemic changes in ventricular repolarization.
Objective:
Three-dimensional characterization of the ventricular repolarization by the T vector and T vector loop morphology in coronary artery disease (CAD), and their response to short-term (no flow) ischemia induced by coronary occlusion during a percutaneous intervention (PCI).
Background:
The risk for sudden cardiac death is increased in conditions of acute or permanently heterogeneous ventricular repolarization, for which ischemia is a risk factor.
Methods:
Fifty-six CAD patients without visible collateral circulation were studied during an elective single-vessel PCI, and 10 healthy controls twice at rest. T vector parameters (Televation, Tazimuth, and QRS-T angle), and T loop parameters (Tarea, Tavplan, and Teigenv) were measured by vectorcardiography. ST vector magnitude (ST-VM) and its change (STC-VM) were used for reference.
Results:
At rest, T vector loop morphology (Tarea, Teigenv) was significantly different in CAD patients and controls, while T vector angles did not separate the groups. Ischemia induced significant changes in T loop parameters in the entire CAD group, whereas in the LAD subgroup significant changes were seen also in T vector angle. The T loop morphology was significantly different at baseline and a more pronounced response to ischemia (Tarea) was seen in patients with, than in those without, a history of hypertension.
Conclusion:
T loop morphology, rather than the T vector angle, separated CAD patients from healthy controls. Coronary occlusion had significant impact on ventricular repolarization, as assessed by T vector and morphology analysis, and most prominently in the LAD group. Hypertensive patients appeared especially vulnerable to ischemia.
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