title: Resting heart rate and measures of effort-related cardiac autonomic dysfunction predict cardiovascular events in asymptomatic type 2 diabetes.
abstract: Autonomic control of the cardiovascular system may be impaired in type 2 diabetes and is associated with increased morbidity and mortality. Parameters obtained during stress testing may reflect early stages of cardiac autonomic dysfunction and provide prognostic information in asymptomatic type 2 diabetes.
  
  
  
  We performed maximal exercise treadmill testing in 594 patients with type 2 diabetes without known coronary heart disease. The prognostic significance of physiological parameters associated with autonomic dysfunction was assessed, including chronotropic incompetence (<80% heart rate reserve), abnormal heart rate recovery at 1 minute <18 beats/minute, and resting tachycardia >100 beats/minute. Cox proportional hazards analysis was used to determine the association of exercise parameters with a composite outcome of all-cause mortality, myocardial infarction or stroke.
  
  
  
  Resting heart rate >100 beats/minute was observed in 18% of patients, chronotropic incompetence in 30% and heart rate recovery at 1 minute <18 beats/minute in 35%. Over 79 ± 16 months, there were 72 (12%) events. Each parameter was significantly associated with event risk in an adjusted multivariate analysis: chronotropic incompetence (hazard ratio 1.89, 95% confidence interval 1.18-3.01; P = 0.008), resting heart rate ≥100 beats/minute (hazard ratio 1.97, 95% confidence interval 1.19-3.26; P = 0.008) and heart rate recovery at 1 minute <18 beats (hazard ratio 1.77, 95% confidence interval 1.12-2.81; P = 0.015). A progressive relationship between the number of abnormal parameters and event risk was observed (log rank P < 0.001).
  
  
  
  Chronotropic incompetence, resting tachycardia and reduced heart rate recovery are independently and additively associated with long-term mortality, myocardial infarction or stroke in type 2 diabetes without known coronary heart disease.
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; the Ruth and Bruce Rappaport School of Medicine, New York, USA barakzmd@gmail.com.
authors.forename: Barak
authors.initials: B
authors.lastname: Zafrir
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; the Ruth and Bruce Rappaport School of Medicine, New York, USA.
authors.forename: Mali
authors.initials: M
authors.lastname: Azencot
authors.affiliation: Department of Cardiology, Bnai Zion Medical Center, Israel.
authors.forename: Idit
authors.initials: I
authors.lastname: Dobrecky-Mery
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; the Ruth and Bruce Rappaport School of Medicine, New York, USA.
authors.forename: Basil S
authors.initials: BS
authors.lastname: Lewis
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; the Ruth and Bruce Rappaport School of Medicine, New York, USA.
authors.forename: Moshe Y
authors.initials: MY
authors.lastname: Flugelman
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; the Ruth and Bruce Rappaport School of Medicine, New York, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Halon
mesh_terms: D000368:Aged; D058070:Asymptomatic Diseases; D001341:Autonomic Nervous System / Q000503:physiopathology*; D002318:Cardiovascular Diseases / Q000150:complications / Q000401:mortality / Q000503:physiopathology*; D002423:Cause of Death / Q000639:trends; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007557:Israel / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012146:Rest / Q000502:physiology*; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends
keywords: Exercise testing; chronotropic incompetence; heart rate; type 2 diabetes