From the Guidelines
Biphasic QRS complexes in leads III, aVF, and V2 are indicative of ventricular conduction abnormalities and require further evaluation to determine the underlying cause, which could be a bundle branch block, ventricular hypertrophy, or myocardial infarction. The presence of biphasic QRS complexes in these leads suggests altered ventricular depolarization pathways, leading to a positive-negative or negative-positive deflection pattern in the QRS complex 1. According to the AHA/ACCF/HRS recommendations, a complete left bundle branch block is characterized by a QRS duration greater than or equal to 120 ms in adults, with specific patterns in leads I, aVL, V5, and V6 1. However, the biphasic QRS complexes in leads III, aVF, and V2 do not specifically meet the criteria for a complete left bundle branch block, and therefore, a complete 12-lead ECG interpretation by a cardiologist is recommended to determine the underlying cause of these findings. Additional diagnostic testing, such as echocardiography, may be valuable to assess ventricular function and structure, especially if these findings are new compared to previous ECGs 1. It is also important to consider clinical correlation, including patient symptoms, medical history, and cardiac biomarkers, to determine the best course of action for further evaluation and management. The international recommendations for electrocardiographic interpretation in athletes provide guidance on abnormal ECG findings, including T wave inversion, ST-segment depression, and pathologic Q waves, which may be relevant in certain cases 1. However, the primary concern with biphasic QRS complexes in leads III, aVF, and V2 is to rule out underlying cardiac conditions that may impact morbidity, mortality, and quality of life, and therefore, prompt evaluation and further testing are recommended. Some key points to consider in the evaluation of biphasic QRS complexes include:
- Clinical correlation, including patient symptoms and medical history
- Comparison to previous ECGs to determine if the findings are new
- Additional diagnostic testing, such as echocardiography, to assess ventricular function and structure
- Consideration of abnormal ECG findings, such as T wave inversion and ST-segment depression, which may indicate underlying cardiac conditions 1. In summary, biphasic QRS complexes in leads III, aVF, and V2 require further evaluation to determine the underlying cause, and a complete 12-lead ECG interpretation by a cardiologist, along with clinical correlation and additional diagnostic testing, is recommended to assess ventricular function and structure and to rule out underlying cardiac conditions.
From the Research
Biphasic QRS Complex
- A biphasic QRS complex in leads 3, aVF, and V2 can be an indicator of various cardiac conditions, including myocardial infarction and accessory pathways.
- According to 2, a positive QRS complex in limb lead 2 with a negative QRS in lead 3 can be predictive of an anterior location of right-sided accessory pathways.
- However, the provided studies do not directly address the significance of a biphasic QRS complex in leads 3, aVF, and V2.
Detection of Myocardial Ischemia
- Exercise echocardiography can detect myocardial ischemia and predict functional recovery early after acute myocardial infarction, as shown in 3.
- A biphasic response during exercise echocardiography can be an indicator of reversible dysfunction, with a higher sensitivity than a worsening response.
- Stress cardiac magnetic resonance imaging (CMR) is a noninvasive test that can accurately assess myocardial ischemia, myocardial viability, and cardiac function, as discussed in 4.
Assessment of Myocardial Viability
- Echocardiographic techniques, such as dobutamine stress echocardiography, can identify hibernation and assess myocardial viability, as mentioned in 5.
- A biphasic response to dobutamine can indicate the presence of viable myocardium, with low doses detecting inotropic reserve and high doses surpassing the ischemic threshold.
- Quantitative stress perfusion cardiac MRI can quantify myocardial blood flow and assess ischemic burden, as described in 6.