What does a wide S wave on an electrocardiogram (ECG) indicate?

From the Guidelines

A wide S wave on an electrocardiogram (ECG) is most commonly associated with right bundle branch block, but can also indicate left ventricular hypertrophy, particularly when seen in leads V5 or V6, as noted in the American Heart Association recommendations 1.

Key Points to Consider

• The presence of a wide S wave in leads I, aVL, V5, and V6, often accompanied by an RSR' pattern in leads V1 and V2, suggests a conduction delay or block in the heart's electrical pathway.
• The normal S wave duration should be less than 0.04 seconds, and widening beyond this threshold suggests abnormal ventricular depolarization.
• According to the American Heart Association electrocardiography and arrhythmias committee, council on clinical cardiology, the presence of prominent S waves in V5 or V6, right axis deviation, unusually tall biphasic R/S complexes in several leads, and signs of right atrial abnormality are useful signs that right ventricular hypertrophy (RVH) may also be present in the context of left ventricular hypertrophy (LVH) 1.
• In patients with congenital heart defects and RVH, the presence of combined tall R waves and deep S waves in leads V2 to V6, with combined amplitude greater than 60 mm (6.04 mV), suggests the presence of LVH 1.

Diagnostic Criteria

• For the diagnosis of right bundle branch block (RBBB), criteria include an rsr, rsR, or rSR pattern in leads V1 or V2, an S wave of greater duration than the R wave or greater than 40 ms in leads I and V6 in adults, and a normal R peak time in leads V5 and V6 but greater than 50 ms in lead V1, as outlined in the AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram 1.

Clinical Implications

• The finding of a wide S wave on an ECG warrants clinical correlation with the patient's symptoms and medical history, as it may represent either a benign variant or a significant cardiac abnormality requiring treatment depending on the underlying cause.
• It is essential to consider the patient's overall clinical context, including symptoms, medical history, and other diagnostic findings, when interpreting the significance of a wide S wave on an ECG.

From the Research

Wide S Wave on an Electrocardiogram (ECG)

A wide S wave on an electrocardiogram (ECG) can be an indicator of several conditions, but the provided studies do not directly address the wide S wave. However, we can look at related information on left ventricular hypertrophy (LVH), which might be associated with changes in ECG readings.

Left Ventricular Hypertrophy (LVH)

• LVH is a maladaptive response to chronic pressure overload and an important risk factor for atrial fibrillation, diastolic heart failure, systolic heart failure, and sudden death in patients with hypertension 2.
• Controlling arterial pressure, sodium restriction, and weight loss can facilitate the regression of LVH 2.
• The choice of antihypertensive agents is important when treating a patient with hypertensive LVH, with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers being effective in facilitating the regression of LVH 2, 3.

Treatment Approaches

• Both ACE inhibitors and AT1 antagonists can benefit the regression of LVH in diabetic patients who start dialysis therapy 3.
• Combination therapy with ACE inhibitors and AT1 antagonists may provide more beneficial effects on LVH than monotherapy 3.
• Beta-blockers and ACE inhibitors have been shown to cause left ventricular hypertrophy regression in hypertensive patients 4.

Diagnosis and Prognosis

• LV geometrical changes, including concentric remodeling, concentric or eccentric LV hypertrophy, are major independent risk factors for CVD morbidity and mortality, as well as all-cause mortality and neurological pathologies 5.
• Blood pressure control with lifestyle changes and antihypertensive agents has been demonstrated to prevent and regress LVH 5, 6.