Jani T Tikkanen1, Tuomas Kentta1, Kimmo Porthan2, Olli Anttonen3, Antti Eranti1, Aapo L Aro4, Tuomas Kerola3, Harri A Rissanen5, Paul Knekt5, Markku Heliövaara5, Arttu Holkeri1, Anette Haukilahti1, Teemu Niiranen6, Jussi Hernesniemi7, Antti Jula5, Markku S Nieminen4, Robert J Myerburg8, Christine M Albert9, Veikko Salomaa5, Heikki V Huikuri1, M Juhani Junttila10. 1. Research Unit of Internal Medicine, Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland. 2. Department of Medicine, University of Helsinki and Minerva Foundation Institute for Medical Research, Helsinki, Finland. 3. Research Unit of Internal Medicine, Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland; Päijät-Häme Central Hospital, Lahti, Finland. 4. Division of Cardiology, Heart and Lung Center, Helsinki University Hospital, Helsinki, Finland. 5. THL-Finnish Institute for Health and Welfare, Helsinki, Finland. 6. Department of Medicine, Turku University Hospital and University of Turku, Turku, Finland. 7. Tays Heart Hospital, Tampere University Hospital, Tampere, Finland. 8. Division of Cardiology, Miller School of Medicine, University of Miami, Miami, Florida. 9. Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts. 10. Research Unit of Internal Medicine, Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland. Electronic address: juhani.junttila@oulu.fi.
Abstract
BACKGROUND: QRS duration and corrected QT (QTc) interval have been associated with sudden cardiac death (SCD), but no data are available on the significance of repolarization component (JTc interval) of the QTc interval as an independent risk marker in the general population. OBJECTIVE: In this study, we sought to quantify the risk of SCD associated with QRS, QTc, and JTc intervals. METHODS: This study was conducted using data from 3 population cohorts from different eras, comprising a total of 20,058 individuals. The follow-up period was limited to 10 years and age at baseline to 30-61 years. QRS duration and QT interval (Bazett's) were measured from standard 12-lead electrocardiograms at baseline. JTc interval was defined as QTc interval - QRS duration. Cox proportional hazards models that controlled for confounding clinical factors identified at baseline were used to estimate the relative risk of SCD. RESULTS: During a mean period of 9.7 years, 207 SCDs occurred (1.1 per 1000 person-years). QRS duration was associated with a significantly increased risk of SCD in each cohort (pooled hazard ratio [HR] 1.030 per 1-ms increase; 95% confidence interval [CI] 1.017-1.043). The QTc interval had borderline to significant associations with SCD and varied among cohorts (pooled HR 1.007; 95% CI 1.001-1.012). JTc interval as a continuous variable was not associated with SCD (pooled HR 1.001; 95% CI 0.996-1.007). CONCLUSION: Prolonged QRS durations and QTc intervals are associated with an increased risk of SCD. However, when the QTc interval is deconstructed into QRS and JTc intervals, the repolarization component (JTc) appears to have no independent prognostic value.
BACKGROUND: QRS duration and corrected QT (QTc) interval have been associated with sudden cardiac death (SCD), but no data are available on the significance of repolarization component (JTc interval) of the QTc interval as an independent risk marker in the general population. OBJECTIVE: In this study, we sought to quantify the risk of SCD associated with QRS, QTc, and JTc intervals. METHODS: This study was conducted using data from 3 population cohorts from different eras, comprising a total of 20,058 individuals. The follow-up period was limited to 10 years and age at baseline to 30-61 years. QRS duration and QT interval (Bazett's) were measured from standard 12-lead electrocardiograms at baseline. JTc interval was defined as QTc interval - QRS duration. Cox proportional hazards models that controlled for confounding clinical factors identified at baseline were used to estimate the relative risk of SCD. RESULTS: During a mean period of 9.7 years, 207 SCDs occurred (1.1 per 1000 person-years). QRS duration was associated with a significantly increased risk of SCD in each cohort (pooled hazard ratio [HR] 1.030 per 1-ms increase; 95% confidence interval [CI] 1.017-1.043). The QTc interval had borderline to significant associations with SCD and varied among cohorts (pooled HR 1.007; 95% CI 1.001-1.012). JTc interval as a continuous variable was not associated with SCD (pooled HR 1.001; 95% CI 0.996-1.007). CONCLUSION: Prolonged QRS durations and QTc intervals are associated with an increased risk of SCD. However, when the QTc interval is deconstructed into QRS and JTc intervals, the repolarization component (JTc) appears to have no independent prognostic value.