Potential factors that affect electrocardiographic progression of interatrial block

Interatrial block (IAB; P wave > or = 110 ms) is associated with atrial tachyarrhythmias and left atrial electromechanical dysfunction. This subtle abnormality is highly prevalent and may exist as partial (pIAB) or advanced IAB (aIAB). Indeed, theoretically pIAB could progress to aIAB with worsening interatrial conduction over time. However, this has been poorly investigated. We retrospectively appraised this phenomenon and also evaluated the influence of common clinical factors such as coronary artery disease (CAD), hypertension (HTN), and use of antihypertensive medications.

Between January 2003 and June 2004, 27 patients who had aIAB on routine 12-lead ECGs were identified. Past serial ECGs of each patient were evaluated for evidence of change in IAB type. Medical records of respective patients were then reviewed for HTN, type of antihypertensive medication used, and other common comorbidities.

Median progression time from pIAB to aIAB was shorter (42 months; mean +/- SD = 39.2 +/- 30.5) compared to that of normal P wave (P-normal) to aIAB (66 months; mean +/- SD = 64.2 +/- 25.6). Use of angiotensin-converting enzyme inhibitors (ACEIs) appeared to significantly delay the progression time in patients who progressed from pIAB to aIAB (50.1 +/- 28.3 vs 10 +/- 10.4 months; P = 0.04). Beta-adrenergic blocker use alone did not significantly affect either progression time but when used in conjunction with ACEIs, appeared to slow such progression.

Progression time from pIAB to aIAB is shorter compared to that of P-normal to aIAB. Given the consequences of IAB, awareness of such progression could be important for clinicians in anticipating potential sequelae.