title: Limited utility of interatrial block in predicting ischemia on coronary angiography in patients with suboptimal exercise performance.
abstract: BACKGROUND
  Interatrial block (P waves > or = 110 ms) is thought to be associated with underlying myocardial ischemia during exercise but has not been extensively investigated in patients with suboptimal or borderline exercise tolerance tests (< 3 min exercise). We utilized coronary angiography to assess the relationship of both, the resting baseline and exercise induced increase in P-wave duration with coronary artery disease among patients who had undergone such tests.
  
  
  METHODS
  We prospectively identified 51 consecutive patients with interatrial block who had coronary artery disease and hypertension but not atrioventricular valvular heart disease, and had undergone coronary angiography to evaluate myocardial ischemia after a suboptimal exercise tolerance test. A control group of 64 consecutive exercise tolerance test patients with similar preliminary characteristics but without interatrial block at rest was used for comparison. Patients from both groups were then appraised for significant obstructive lesions (> 70%) on coronary angiography that were suggestive of myocardial ischemia.
  
  
  RESULTS
  Obstructive coronary artery lesions suggestive of myocardial ischemia were more frequent among interatrial block patients but this was not statistically significant (p=0.25). However, change in P-wave duration of > 20 ms occurred more frequently in interatrial block patients in the presence of a positive exercise tolerance test. Among patients without interatrial block at baseline, more patients who developed new interatrial block had significant disease on coronary angiography.
  
  
  CONCLUSIONS
  The utility of using interatrial block toward predicting myocardial ischemia among patients with suboptimal exercise tolerance tests is limited. However, further investigation on the early change in P-wave duration in patients with interatrial block and the development of new interatrial block during exercise could be helpful in optimizing exercise tolerance tests, particularly when borderline or suboptimal.
authors.affiliation: Preventive Cardiology, Massachusetts Veterans Epidemiology Research and Information Center, Veterans Affairs Boston Healthcare System, 150 South Huntington Avenue, Boston, Massachusetts 02130, USA. vignendra@hotmail.com
authors.forename: Vignendra
authors.initials: V
authors.lastname: Ariyarajah
authors.forename: David H
authors.initials: DH
authors.lastname: Spodick
authors.forename: Jaxon
authors.initials: J
authors.lastname: Fernandes
authors.forename: Sirin
authors.initials: S
authors.lastname: Apiyasawat
mesh_terms: D000368:Aged; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004562:Electrocardiography; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012848:Sinoatrial Block / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*