What is the significance of biphasic P waves in leads V1 to V3 on an electrocardiogram (ECG)?

From the Guidelines

Biphasic P waves in leads V1 to V3 are indicative of left atrial enlargement or abnormality, and further cardiac evaluation, including echocardiography, is warranted to confirm structural changes and assess for underlying pathology. This ECG finding is characterized by an initial positive deflection followed by a negative terminal component of the P wave, creating a "notched" or "M-shaped" appearance. The negative terminal force in V1 (the product of the depth and duration of the negative component) greater than 0.04 mm-sec is particularly significant, as noted in the study by 1. This pattern occurs because the left atrium is positioned posteriorly in the heart, and its depolarization travels away from the right precordial leads (V1-V3), creating the negative deflection.

Key Points to Consider

• Left atrial enlargement is commonly associated with conditions that increase left atrial pressure or volume, such as mitral valve disease, hypertension, heart failure, and coronary artery disease, as discussed in 1.
• The study by 1 highlights that a prolonged activation time of the atrium, indicated by the total duration of the P wave of 120 ms or more, is present in a large majority of patients with electrocardiographic signs that are considered to represent left atrial abnormalities.
• Management focuses on treating the underlying cause rather than the ECG finding itself, and it's essential to correlate ECG findings with clinical findings and imaging studies for definitive diagnosis, as ECG criteria alone have limited sensitivity and specificity, as noted in 1.

Important Considerations for Diagnosis and Management

• The presence of biphasic P waves in V1-V3 suggests left atrial abnormality, but correlation with clinical findings and imaging studies is necessary for definitive diagnosis.
• Echocardiography is a crucial diagnostic tool to confirm structural changes and assess for underlying pathology.
• Treatment should focus on addressing the underlying cause of left atrial enlargement or abnormality, rather than the ECG finding itself.

Summary of Recommendations

• Further cardiac evaluation, including echocardiography, is warranted to confirm structural changes and assess for underlying pathology.
• Correlation with clinical findings and imaging studies is necessary for definitive diagnosis.
• Management should focus on treating the underlying cause rather than the ECG finding itself.

From the Research

Biphasic P Waves in V1 to V3

• Biphasic P waves in leads V1 to V3 can be an indicator of left atrial enlargement or abnormality, as suggested by studies 2, 3.
• The presence of biphasic P waves in lead V1 has been associated with increased morbidity and mortality in patients with myocardial infarction, particularly those with three-vessel disease and bypass 2.
• Echocardiographic evaluation of left atrial size and function can provide valuable information on the prognostic implications of left atrial enlargement, including the risk of cardiac and cerebrovascular disease 4, 5, 6.
• The correlation between ECG findings, including biphasic P waves, and echocardiography or cardiac magnetic resonance imaging (CMR) findings is not well defined, and updating current waveform criteria may improve diagnostic accuracy 3.

Clinical Implications

• Biphasic P waves in leads V1 to V3 may be a determining parameter for acute coronary syndromes in terms of three-vessel disease, bypass, and mortality 2.
• Left atrial enlargement, which can be indicated by biphasic P waves, is a marker of hypertensive heart disease associated with increased cardiovascular risk 6.
• Echocardiographic assessment of left atrial function can provide incremental prognostic information in patients with atrial fibrillation, stroke, heart failure, and ischemic and valvular heart disease 5.

ECG Criteria

• ECG criteria for left atrial enlargement, including p-wave duration and negative p-wave deflection, have been correlated with transthoracic echocardiograms and CMR findings, although the correlation is not strong 3.
• The Romhilt-Estes criteria for left ventricular hypertrophy (LVH) have been shown to demonstrate the strongest correlation with transthoracic echocardiograms and CMR findings 3.