title: QTc prolongation prior to angiography predicts poor outcome and associates significantly with lower left ventricular ejection fractions and higher left ventricular end-diastolic pressures.
abstract: BACKGROUND
  QT prolongation on the surface ECG is associated with sudden cardiac death. The cause of QT prolongation in ischaemic heart disease (IHD) patients remains unknown, but may be due to a complex interplay between genetic factors and impaired systolic and/or diastolic function through as yet unexplained mechanisms. It was hypothesised that QT prolongation before elective coronary angiography is associated with an increased mortality at six months.
  
  
  METHODS
  Complete records of 321 patients who underwent coronary angiography were examined for QT interval corrected for heart rate (QTc), left ventricular ejection fraction (LVEF), left ventricular end-diastolic pressure (LVEDP) and known ischaemic heart disease risk factors. Patients were designated long QTc (LQTc) when they had prolonged QTc intervals or normal QTc (NQTc) when the QTc interval was normal. Patients with atrial fibrillation, bundle branch blocks, no ECG in the 24 hours before angiography, or a creatinine level > 200 µmol/l were excluded. Survival was determined telephonically at six months.
  
  
  RESULTS
  Twenty-eight per cent of the total population had LQTc. During follow up, 15 patients (4.7%) died suddenly, 73% of whom had a LQTc. LQTc was significantly associated with mortality (LQTc 12% vs NQTc 1.7%; p < 0.01), and with lower but normal LVEF (LQTc 52.9 ± 15.4% vs NQTc 61.6 ± 13.6%; p < 0.01), higher LVEDP at LVEF > 45% (LQTc 19.2 ± 9.0 mmHg vs NQTc 15.95 ± 7.5 mmHg; p < 0.05), hypercholesterolaemia and a negative family history of IHD.
  
  
  CONCLUSIONS
  In patients with sinus rhythm and normal QRS width, QTc prolongation before coronary angiography predicted increased mortality at six months. QTc also associated strongly with left ventricular systolic and diastolic dysfunction, hypercholesterolaemia and a negative family history of IHD.
authors.affiliation: Division of Cardiology, Department of Medicine, Stellenbosch University and Tygerberg Academic Hospital, Western Cape, South Africa.
authors.forename: P
authors.initials: P
authors.lastname: van der Bijl
authors.forename: M
authors.initials: M
authors.lastname: Heradien
authors.forename: A
authors.initials: A
authors.lastname: Doubell
authors.forename: P
authors.initials: P
authors.lastname: Brink
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D017023:Coronary Angiography; D016757:Death, Sudden, Cardiac / Q000209:etiology; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008133:Long QT Syndrome / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D011379:Prognosis; D012307:Risk Factors; D013318:Stroke Volume; D016019:Survival Analysis; D055815:Young Adult