Late Potentials from Signal-Averaged Electrocardiogram May Provide Long-Term Additional Risk Stratification in Patients with Previous Myocardial Infarction and Preserved Ejection Fraction

The identification of patients at risk for cardiac death or life-threatening arrhythmias (CD/LTA) in patients with a previous history of myocardial infarction (MI) without reduced systolic function still remains an important goal. Signal-averaged electrocardiogram (SAECG) provides useful prognostic information in MI patients. Methods: SAECG and left ventriculography were performed in patients who had suffered MI at least 6 months prior. The study population included 103 patients (89 men, mean age 63±9 years) who had no heart failure symptoms and a left ventricular ejection fraction (LVEF) of at least 50%. The filtered QRS duration (f-QRS) and root mean square voltage of the terminal 40 ms of the QRS complex (RMS40) were obtained by SAECG. Late potentials (LP) were considered to be present if f-QRS >130 ms or if RMS40 >15 µV. Results: LP were present in 38% (39 patients). During the follow-up period (110±40 months), 8 patients had CD (n=7) and/or LTA (n=3). CD/LTA was significantly associated with LVEF (p=0.0444) and the presence of LP (p=0.0083). The presence of LP (p=0.0381, hazard ratio 9.424, 95%CI 1.131 to 78.532) was independently associated with CD/LTA. Patients with LP had a higher risk of CD/LTA (log rank p=0.0036). Conclusion: LP may be used as a long-term predictor of CD/LTA in patients with a previous history of MI and preserved ejection function.