QRS-T morphology measured from exercise electrocardiogram as a predictor of cardiac mortality
Tuomas Kenttä1,*, Mari Karsikas2, M. Juhani Junttila1, Juha S. Perkiömäki1, Tapio Seppänen1, Antti Kiviniemi3, Tuomo Nieminen4, Terho Lehtimäki5, Kjell Nikus6, Rami Lehtinen7, Jari Viik8, Mika Kähönen9 and Heikki V. Huikuri1 + Author Affiliations 1Division of Cardiology, Institute of Clinical Medicine, University of Oulu, PO Box 5000, FI 90014, Oulu, Finland 2Information Processing Laboratory, Technical Department, University of Oulu, Oulu, Finland 3Department of Exercise and Medical Physiology, Verve Research, Oulu, Finland 4Department of Pharmacological Sciences, Tampere University of Technology and Biosensing Competence Centre, Tampere, Finland 5Department of Clinical Chemistry, Tampere University of Technology and Biosensing Competence Centre, Tampere, Finland 6Department of Cardiology, Heart Center, Tampere University Hospital, Tampere, Finland 7Tampere Polytechnic, University of Applied Sciences, Tampere, Finland 8Department of Biomedical Engineering, Tampere University of Technology and Biosensing Competence Centre, Tampere, Finland 9Department of Clinical Physiology, University of Tampere, Tampere, Finland *↵Corresponding author. Tel: +358 8 315 4464; fax: +358 8 315 5599. Email: email@example.com Received August 3, 2010. Accepted November 25, 2010.
Abstract Aims Total cosine R-to-T (TCRT) measured from the standard 12-lead electrocardiogram (ECG) reflects the spatial relationship between depolarization and repolarization wavefronts and a low TCRT value is a marker of poor prognosis. We tested the hypothesis that measurement of TCRT or QRS/T angle from exercise ECG would provide even more powerful prognostic information.
Methods and results The prognostic significances of TCRT and QRS/T angle were assessed from exercise ECG recordings in 1297 patients [age 56 ± 13 years (mean ± SD), 67% males] undergoing a clinically indicated bicycle stress-test and the subsequent follow-up. During an average follow-up of 45 ± 12 months, 74 patients died (5.7%); 34 (2.6%) were cardiac deaths, and 24 (1.9%) were sudden cardiac deaths. Total cosine R-to-T and QRS/T angle exhibited a correlation with the RR intervals in the total cohort, but the individual responses were variable, e.g. median correlation of TCRT-RR was 0.89 with an inter-quartile range from 0.55 to 0.98. A reduced correlation of TCRT-RR during the recovery phase of exercise ECG predicted cardiac death [adjusted heart rate (HR) 3.5, 95% confidence interval (CI): 1.8–6.8, P= 0.001] similarly as the baseline TCRT measured from ECG at rest (adjusted HR 3.4, 95% CI: 1.4–8.1, P= 0.01). The poor correlation between the TCRT-RR both during the exercise and recovery was specifically related to a risk of sudden cardiac death (adjusted HR 6.2, 95% CI: 2.1–17.8, P< 0.001).
Conclusions: Loss of rate-adaptation of the spatial relationship between depolarization and repolarization wavefronts is a strong predictor of cardiac death, especially of sudden cardiac death.
Abstract extraido de EUROPACE mayo 2011, 13 (5)
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