Clinical valuation of ST changes in a group of patients with ventricular arrhythmias: The inSighT Study
Jerzy Krzysztof Wranicz1, Michał Kałowski1, Dirk Bastian2
1Department of Electrocardiology, Medical University of Lodz, Lodz, Poland.
Insights
Ischemic changes, indicated by ST deviations on implantable cardioverter-defibrillator (ICD) intracardiac electrocardiograms (EGM), preceded malignant ventricular arrhythmias (VT/VF) in 34% of patients. These ST changes suggest potential ischemic events before VT/VF episodes.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Malignant ventricular arrhythmias (VT/VF) pose a significant risk in patients with coronary artery disease (CAD).
- Implantable cardioverter-defibrillators (ICDs) offer therapeutic intervention for VT/VF and possess advanced monitoring capabilities.
Purpose of the Study:
- To determine the prevalence of ischemic changes, detected via ST deviations in ICD intracardiac electrocardiograms (EGM), preceding VT/VF episodes.
- To investigate the association between ST deviations and the occurrence of malignant ventricular arrhythmias.
Main Methods:
- The inSighT study enrolled 481 patients with CAD or high risk of CAD, implanted with ICDs featuring ST monitoring.
- Intracardiac EGM ST levels preceding VT/VF events were compared to baseline levels using statistical analysis.
- Evaluated events underwent visual inspection and exclusion of non-ischemic causes, inappropriate therapy, or prior VT/VF.
Main Results:
- Significant ST-segment changes, unrelated to non-ischemic causes, were observed in 71 out of 165 (34%) VT/VF episodes.
- These ST changes occurred in 56 patients, representing 34% of all patients experiencing VT/VF.
- No demographic or clinical factors were associated with an increased likelihood of pre-VT/VF ST-segment changes.
Conclusions:
- Characteristic ST-segment changes, likely indicative of ischemic events, were identified in 34% of VT/VF episodes.
- This finding highlights the potential role of ischemia as a trigger for malignant ventricular arrhythmias in susceptible patients.
Background:
The inSighT study was designed to determine the prevalence of ischemic changes as recorded by implantable cardioverter-defibrillator (ICD) ST deviations in intracardiac electrocardiograms (EGM) over the 24 h preceding malignant ventricular arrhythmias (VT/VF).
Methods:
The study enrolled patients with known coronary artery disease (CAD) or high risk of future development of CAD implanted with an ICD equipped with an ST monitoring feature (Ellipse™/Fortify Assura™, St. Jude Medical). Device session records were collected at each in-clinic follow-up. EGM ST levels of the beats over the 15 minutes prior to VT/VF events were compared using a t test with those from a baseline period of 23-24 h prior to the VT/VF event. All events with p < .05 were visually inspected to confirm they were evaluable; additional criteria for exclusion from further analysis included inappropriate therapy, aberrant conduction, and occurrence of VT/VF within 24h prior to the current event.
Results:
The study enrolled 481 ICD patients (64 ± 11 years, 83% male) in 14 countries and followed them for 15±5 months. A total of 165 confirmed VT/VF episodes were observed, of which 71 events (in 56 patients, 34% of all patients with VT/VF) were preceded by significant (p < .05) ST-segment changes unrelated to known non-ischemic causes. None of the analyzed demographic and clinical factors proved to be associated with greater odds of presenting with ST-segment changes prior to VT/VF episode.
Conclusion:
In this exploratory study, characteristic ST-segment changes, likely representative of ischemic events, were observed in 34% of all patients with VT/VF episodes.
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