title: Relationship between QRS duration and left ventricular mass and volume in patients at high cardiovascular risk.
abstract: OBJECTIVE
  Longer QRS duration on the ECG is associated with increased cardiovascular (CV) mortality. To evaluate potential mechanisms, we examined in this study the relationship between QRS duration and left ventricular (LV) mass and LV end systolic and end diastolic volume in patients with known CV disease or high-risk diabetes.
  
  
  METHODS
  In a substudy of the ONTARGET/TRANSCEND (Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial/Telmisartan Randomised Assessment Study in ACE Intolerant Subjects with Cardiovascular Disease) clinical trials, 368 patients had a cardiac magnetic resonance scan to measure LV mass, LV end systolic volume, LV end diastolic volume and LV ejection fraction at baseline and after 2 years of follow-up. Relationships between QRS duration on the 12-lead ECG and LV mass and volumes were evaluated at both assessments.
  
  
  RESULTS
  Each 10-ms increase in QRS duration both within and above the normal reference range was associated with an 8.3% (95% CI 6.7% to 9.9%) increase in LV mass, a 9.2% (95% CI 7.4% to 10%) increase in LV end diastolic volume and a 7.8% (95% CI 6.4% to 9.3%) increase in LV end systolic volume. QRS duration increased with body size, but associations with LV mass and volumes remained strong after indexing measurements to height(2.7) (p<0.001 for all) and were similar for subjects with an otherwise normal and abnormal ECG.
  
  
  CONCLUSIONS
  A longer QRS duration both within and above the normal reference range is associated with a greater LV mass and larger LV end systolic and end diastolic volumes. This may explain the known association of longer QRS duration with increased CV mortality.
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Private Bag 92024, Auckland 1030, New Zealand. rstewart@adhb.govt.nz
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Stewart
authors.forename: Alistair A
authors.initials: AA
authors.lastname: Young
authors.forename: Craig
authors.initials: C
authors.lastname: Anderson
authors.forename: Koon K
authors.initials: KK
authors.lastname: Teo
authors.forename: Garry
authors.initials: G
authors.lastname: Jennings
authors.forename: Brett R
authors.initials: BR
authors.lastname: Cowan
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000473:pathology* / Q000503:physiopathology; D001827:Body Height / Q000502:physiology; D002318:Cardiovascular Diseases / Q000473:pathology / Q000503:physiopathology; D048909:Diabetes Complications / Q000473:pathology / Q000503:physiopathology; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012306:Risk; D016277:Ventricular Function, Left / Q000502:physiology