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[Transient myocardial ischemia in patients after myocardial infarction and late cell potentials]
W Banasiak1, A Fuglewicz, P Ponikowski
1Kliniki Chorób Wewnetrznych, Wojskowego Szpitala Klinicznego, Wrocławiu.
Insights
Transient ischemia during exercise increases ventricular late potentials (LP) in coronary artery disease (CAD) patients post-myocardial infarction (MI). However, it does not affect the substrate for LP in those without prior MI.
Area of Science:
- Cardiology
- Electrophysiology
- Diagnostic Imaging
Background:
- The link between myocardial ischemia and ventricular late potentials (LP) in coronary artery disease (CAD) is debated.
- Late potentials (LP) are potential indicators of arrhythmogenic substrates.
Purpose of the Study:
- To investigate the impact of transient, exercise-induced ischemia on the presence of LP in CAD patients.
- To differentiate the effect of ischemia on LP based on myocardial infarction (MI) history.
Main Methods:
- Signal-averaged electrocardiography (SAECG) was used to assess LP.
- Patients with CAD were divided into groups with and without prior MI.
- SAECG recordings were taken at baseline and during exercise-induced ischemia.
- Key SAECG parameters analyzed included QRS duration, RMS voltage, and LPD.
Main Results:
- Transient ischemia significantly increased the presence of LP in CAD patients with a history of MI.
- Ischemia did not alter the arrhythmogenic substrate for LP in patients without a history of MI.
- Specific SAECG criteria defined the presence of ventricular late potentials.
Conclusions:
- Exercise-induced ischemia plays a role in the manifestation of LP in CAD patients, particularly those with prior MI.
- The arrhythmogenic substrate for LP is influenced by prior MI in the context of transient ischemia.
Abstract:
The role of myocardial ischaemia in the development of late potentials (LP) on the signal-averaged ECG (SAECG) in patients with coronary artery disease (CAD) remains controversial. The aim of the study was to assess the influence of transient, scintigraphically-proven (Tc-99mMI-BI), exercise-induced ischaemia on the presence of LP in 51 pts with angiographically documented CAD. Patients were divided into 2 groups: 26 pts (mean age 53 +/- 7.7) without the history of myocardial infarction (MI) (Group I) and 25 pts (mean age 56.8 +/- 6.4) after MI (Group II). SAECG recording were performed at baseline (A) and during exercise-induced ischaemia (B). The following time-domain parameters of SAECG were analyzed: the root mean square voltage of the last 40 and 50 ms of filtered QRS (RMS40, 50), total time duration of filtered QRS (t0QRS) and time duration potentials < 40 microV (LPD). The ventricular late potentials (LP) were defined as the presence of at least two of the following criteria: tQRS > 114 ms, RMS 40 < 20 mV and LPD > 38 ms. We conclude that transient exercise-induced ischaemia increased the presence of LP in pts with CAD after MI but did not alter the arrhythmogenic substrate for LP in those without the history of MI.