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Clinical importance of late potential in patients with angina pectoris
T Akiya1, S Horinaka, M Arakawa
1Department of Medicine, Dokkyo University School of Medicine, Tochigi.
Insights
Late potentials, indicators of heart electrical instability, are more common in patients with exertional angina pectoris (AP) and vasospastic angina (VSA), especially with severe coronary stenosis. This highlights the need for careful management in these patients.
Area of Science:
- Cardiology
- Electrophysiology
- Diagnostic Medicine
Background:
- Angina pectoris, particularly vasospastic angina (VSA), is linked to potentially lethal ventricular tachycardia.
- Late potentials (LPs) are subtle electrocardiographic signals that may indicate arrhythmogenic substrates.
- Understanding the prevalence and significance of LPs in different angina presentations is crucial for risk stratification.
Purpose of the Study:
- To assess the clinical importance and incidence of late potentials in patients experiencing angina-like chest pain.
- To differentiate LP prevalence across exertional angina pectoris (AP), chest pain syndrome (CPS), and vasospastic angina (VSA) groups.
- To investigate the relationship between the severity of coronary stenosis and the presence of LPs.
Main Methods:
- 171 patients with angina-like pain were categorized into AP (n=82), CPS (n=39), and VSA (n=50) groups based on coronary angiography and acetylcholine challenge tests.
- Late potentials were identified using specific criteria: filtered QRS duration >130 ms and/or root-mean-square voltage in the last 40 ms <15 microV.
- LP incidence was compared between groups and correlated with the degree of coronary artery stenosis.
Main Results:
- Late potentials were significantly more frequent in the AP (23.2%) and VSA (38.0%) groups compared to the CPS group (7.7%).
- Within the VSA group, patients with >90% coronary vasospasm showed a markedly higher LP incidence (84.2%) than those with <90% vasospasm (15.8%).
- In the AP group, LPs were predominantly found in patients with severe (>90%) coronary stenosis (89.5%).
Conclusions:
- Late potentials are strongly associated with severe organic coronary stenosis, observed in both exertional angina pectoris and vasospastic angina.
- The findings suggest that inhomogeneous electrical excitation, possibly due to frequent angina attacks and significant occlusion, underlies LP generation.
- Patients with VSA or AP exhibiting late potentials require stringent clinical management due to their potential association with serious cardiac events.
Abstract:
Angina pectoris, especially vasospastic angina, is associated with lethal ventricular tachycardia. The clinical importance of late potential in angina pectoris was assessed in 171 patients with angina-like pain. Patients were categorized into three groups based on coronary angiography. Patients in the exertional angina pectoris (AP) group exhibited at least 75% organic stenosis of a major coronary artery after intracoronary injection of a nitrate drug (82 patients). Patients in the chest pain syndrome (CPS) group had no significant organic stenosis of the coronary artery and the acetylcholine-loading test produced negative results (39 patients). Patients in the vasospastic angina (VSA) group had a positive acetylcholine-loading test (50 patients). When the filtered QRS duration was prolonged to above 130 msec and/or the root-mean-square voltage in the last 40 msec was below 15 microV in VCM-3000, the late potential was judged to be positive. The incidence of late potential was higher in the AP group (23.2%) and the VSA group (38.0%) than in the CPS group (7.7%) (p < 0.05, p < 0.01). Comparison of late potential incidence between patients with coronary vasospasm below 90% (group 1) and patients with above 90% (group 2) induced by the acetyl-choline-loading test in the VSA group showed more late potential in group 2 than in group 1 (84.2% vs 15.8%). Late potential was present in 19 (23.2%) patients in the AP group, but only 2 (10.5%) had under 90% degrees of coronary stenosis and the other 17 (89.5%) had greater than 90% degrees of stenosis. Thus, late potential was mainly observed in patients with severe organic stenosis. These results suggest that the origin of late potential is associated with inhomogeneous electrical excitation induced by frequent angina attack and the duration of total or near total occlusion. Strict clinical management is required for patients with VSA or AP associated with late potential.