Increased T wave complexity can indicate subclinical myocardial ischemia in asymptomatic adults

• Published in: Journal of electrocardiology 2011-11, Vol.44 (6), p.684-688
• Main Authors: Al-Zaiti, Salah S., MS, Runco, Kristen N., BSc, Carey, Mary G., PhD
• Format: Article
• Language: English
• Subjects: Adult; Cardiovascular; Electrocardiography, Ambulatory; Exercise Test; Female; Firefighters; Heart Conduction System - physiopathology; Humans; Male; Myocardial ischemia; Myocardial Ischemia - diagnosis; Principal component analysis; Repolarization; T wave complexity
• ISSN: 0022-0736; 1532-8430
• DOI: 10.1016/j.jelectrocard.2011.07.017

Abstract Background Altered ventricular repolarization and cardiovascular mortality are closely correlated, and recent novel findings show that a distorted T wave loop morphology is also strongly correlated with subsequent onset of myocardial infarction among patients with stable angina. Therefore, we hypothesized that an abnormal T wave complexity ratio (CR) can indicate vulnerability to myocardial ischemia in asymptomatic, apparently healthy adults. Methods Healthy firefighters were enrolled in the current investigation where they completed symptom-limited, graded exercise treadmill testing (ETT) and 24-hour Holter electrocardiogram recording. The CR was automatically calculated using principal component analysis of the high-resolution Holter electrocardiogram signal then averaged over 24 hours (CR24h ). End points were manually analyzed from the ETT; recordings revealing horizontal ST-segment depression (≥1 mm) in 2 or more leads for at least 1 minute during the peak of exercise were considered indicators of myocardial ischemia. Results One hundred four firefighters (age, 44 ± 8 years; 96% men) completed both ETT and Holter recording. Firefighters with positive end points (n = 34, or 33%) had higher CR24h compared with those with negative end points (0.14 ± 0.06 vs 0.09 ± 0.04, P < .01); there were no demographic differences between the 2 groups. After controlling for age, smoking status, hypertension, and obesity, an abnormal CR24h (≥20%) significantly predicted exercise-induced myocardial ischemia (odds ratio, 4.6; P = .01). Conclusions Increased T wave CR24h can predict myocardial ischemia in asymptomatic middle-age adults; this suggests that the distorted T wave loop morphology can reflect an altered ventricular repolarization caused by prolonged subclinical myocardial ischemia possibly caused by early coronary artery disease.