A specific combination of P wave duration and morphology accurately predicts the presence of left atrial low voltage area in patients with atrial fibrillation.

Background: Since low voltage area (LVA) impairs not only intra atrial conduction velocity but also intra atrial propagate direction, these alternates may reflect the P wave duration (PWD) and morphology. We examined the relationship between the PWD, morphology and LVA.

Methods: Consecutive 127 AF patients were divided into 2 groups depending on the presence of LVA (35 subjects LVA positive group, 92 subjects LVA negative group). P wave morphologies were divided into 3 categories, normal: P-wave duration<120 ms, partial interatrial block (IAB): P wave duration≥120 ms, advanced IAB: PWD ≥ 120 ms with biphasic P waves in inferior leads. LVA was defined as a voltage amplitude<0.5 mV, and qualitatively assessed to be categorized into three grades (mild<10%, 10% ≤ moderate<30%, 30% ≤ extensive).

Results: LVA was significantly highly detected in patients of advanced age, female, comorbidities of hypertension, prior brain infarction, LA enlargement. PWD was correlated with LA volume in the LVA negative group, but not in the LVA positive group. Advanced IAB was significantly accumulated in the LVA positive group while partial IAB was found in both LVA positive and negative groups. Receiver-operating characteristics curve revealed that a combination of IAB and biphasic P wave in any inferior lead identified the presence of LVA with 83% sensitivity and 98% specificity. PWD and the presence of advanced IAB were independent predictors of LVA as determined by multivariate logistic regression analysis.

Conclusion: Advanced IAB is a favorable parameter for the presence of LVA.