title: Impact of electrocardiographic interpretability on outcome in patients referred for stress testing.
abstract: BACKGROUND
  There is limited insight into the association of electrocardiographic interpretability with outcome in patients referred for stress testing.
  
  
  METHODS
  Exercise echocardiography was performed in 8226 patients with known or suspected coronary artery disease. Electrocardiograms were considered uninterpretable in the presence of left bundle-branch block (LBBB), left ventricular hypertrophy (LVH) with strain, repolarization abnormalities because of digitalis therapy, ventricular paced rhythm, preexcitation or ST depression ≥ 0.1 mV because of other causes. End points were all-cause mortality, cardiac death and hard cardiac events (i.e. cardiac death or nonfatal myocardial infarction).
  
  
  RESULTS
  A total of 2450 patients had uninterpretable electrocardiograms. During a follow-up period of 4.1 ± 3.5 years, there were 1011 deaths (of which 478 were cardiac deaths) and 1069 patients experienced a hard cardiac event. The 5-year rates of death, cardiac death and hard cardiac events were, respectively, 18.7%, 10.9% and 18.8% in patients with uninterpretable ECGs, compared with 9.5%, 4.1% and 10.9% in those with interpretable ECGs (P < 0.001). After covariate adjustment, lack of ECG interpretability remained an independent predictor of all-cause mortality (hazard ratio [HR] 1.25, 95% confidence interval [CI] 1.08-1.44, P = 0.002), cardiac death (HR 1.63, 95% CI 1.32-2.01, P < 0.001) and hard cardiac events (HR 1.28, 95% CI 1.11-1.47, P < 0.001). When the specific ECG abnormalities were included as covariates, LBBB, LVH and digitalis therapy remained predictors of cardiac death; LBBB and LVH were predictors of hard cardiac events, and LVH remained predictive of all-cause mortality.
  
  
  CONCLUSIONS
  Uninterpretable ECGs portend a worse prognosis in patients referred for stress testing.
authors: Department of Cardiology, Hospital Universitario A Coruña, A Coruña, Spain. alberto.bouzas.mosquera@sergas.es
authors: Alberto
authors: A
authors: Bouzas-Mosquera
authors: Jesús
authors: J
authors: Peteiro
authors: Francisco J
authors: FJ
authors: Broullón
authors: Elizabet
authors: E
authors: Méndez
authors: Gonzalo
authors: G
authors: Barge-Caballero
authors: Manuel
authors: M
authors: López-Pérez
authors: Angela
authors: A
authors: López-Sainz
authors: Nemesio
authors: N
authors: Alvarez-García
authors: Alfonso
authors: A
authors: Castro-Beiras
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000401:mortality; D004452:Echocardiography / Q000379:methods; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D015996:Survival Rate; D013997:Time Factors