title: Correlation of left atrial size with p-wave duration in interatrial block.
abstract: BACKGROUND
  Interatrial block (IAB) [P-wave duration > or = 110 ms] is associated with left atrial (LA) enlargement (LAE) and pathophysiologic derangements that result in atrial tachyarrhythmias, LA electromechanical dysfunction, and embolism. However, there has been no study addressing the direct correlation of P-wave duration in IAB and LAE.
  
  
  METHODS
  One hundred eighty-one consecutive patients who were admitted to a tertiary care teaching hospital over 5 consecutive days were screened for past transthoracic echocardiogram evaluations and were then matched with ECGs done within 10 days of these echocardiographic investigations. ECGs were evaluated for presence of IAB, and patients were subsequently classified into two groups: control patients and patients with IAB. Patients were also matched for common comorbidities. Mean, SD of age, Pearson correlation coefficient (r), p values, and multivariate and linear regression analyses were analyzed for the investigated variables of LA size, left ventricular hypertrophy (LVH), posterior wall thickness, septal thickness, and P-wave duration.
  
  
  RESULTS
  From the sample (n = 66; mean age +/- SD, 71.3 +/- 13.7; female gender, 48.5%), the mean LA size in the control group was 36.7 +/- 4.01 mm and for the group of patients with IAB (n = 38) was 42.2 +/- 7.25 mm (p = 0.004). Linear regression analysis revealed that P-wave duration was significantly correlated with LA size (p = 0.0002, r = 0.606).
  
  
  CONCLUSIONS
  Degree of conduction delay in IAB (P-wave duration) is an independent, direct correlate of LAE, and the regression equation (LA size [in millimeters] = 2.47 +/- 0.29 x P-wave duration [in milliseconds]) could be used to estimate LAE.
authors.affiliation: Massachusetts Veterans Epidemiology Research and Information Center, Preventive Cardiology, MAVERIC, Veterans Affair Boston Health Care System, and Department of Medicine, 150 South Huntington Ave, Boston, MA 02130, USA. vignendra@hotmail.com
authors.forename: Vignendra
authors.initials: V
authors.lastname: Ariyarajah
authors.forename: Kristin
authors.initials: K
authors.lastname: Mercado
authors.forename: Sirin
authors.initials: S
authors.lastname: Apiyasawat
authors.forename: Puneet
authors.initials: P
authors.lastname: Puri
authors.forename: David H
authors.initials: DH
authors.lastname: Spodick
mesh_terms: D000368:Aged; D016279:Atrial Function, Left / Q000502:physiology; D004452:Echocardiography; D005260:Female; D006325:Heart Atria / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006327:Heart Block / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology*; D006331:Heart Diseases / Q000150:complications; D006801:Humans; D008297:Male; D009929:Organ Size; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications