What are the electrocardiogram (ECG) findings indicative of left ventricular hypertrophy (LVH)?

From the Guidelines

Left ventricular hypertrophy (LVH) on ECG is a significant finding that indicates underlying cardiac stress, and its diagnosis should be confirmed with an echocardiogram to assess the degree of hypertrophy and guide management. The most reliable ECG criteria for LVH include voltage criteria such as the Sokolow-Lyon index (S wave in V1 + R wave in V5 or V6 > 35 mm) and the Cornell criteria (R wave in aVL + S wave in V3 > 28 mm in men or > 20 mm in women) 1. Other findings may include left axis deviation, prolonged QRS duration, ST segment depression with T wave inversion in leads V5-V6 (strain pattern), and left atrial enlargement.

The sensitivity of ECG for detecting LVH is relatively low (around 50-60%) but specificity is high (85-90%), meaning that when LVH criteria are met on ECG, it's likely a true finding 1. However, the combination of an abnormal ECG, any signs and symptoms of heart disease, and a positive family history for premature cardiac death warrants further evaluation 1.

Some key points to consider in the diagnosis and management of LVH include:

• The ECG is widely available, inexpensive, and has high specificity but poor sensitivity for detection of LVH 1
• LVH is more prevalent in blacks and is an independent predictor of diminished cardiovascular survival 1
• People with larger body size and blacks may have an increase in wall thicknesses on echocardiography, which should be correlated with ECG, clinical signs and symptoms, and family history before they are advised against participation in competitive sports 1
• It is rare for physiological increased left ventricular wall thicknesses to exceed 13 mm and indicates the advisability of a referring the patient for further evaluation for hypertrophic cardiomyopathy with ECG, clinical assessment, and family history 1

Finding LVH should prompt investigation into its cause, with aggressive management of underlying conditions like hypertension using appropriate medications such as ACE inhibitors, ARBs, or beta-blockers to prevent further cardiac remodeling and reduce cardiovascular risk. The goal of treatment is to reduce morbidity, mortality, and improve quality of life by controlling blood pressure, reducing left ventricular mass, and preventing cardiovascular events 1.

From the Research

Left Ventricular Hypertrophy on ECG

• Left ventricular hypertrophy (LVH) is a common condition and a powerful independent risk factor for coronary heart disease, congestive heart failure, and other cardiac morbidity 2.
• The most common cause of LVH is hypertension, and many antihypertensive agents induce regression of LVH 2, 3.
• Angiotensin-converting enzyme (ACE) inhibitors have been shown to reverse LVH by a mechanism that is not yet fully understood, but may involve reduction in afterload, blocking of adrenergic action, and suppression of sympathetic nervous system influences 2, 3.

ECG Criteria for LVH

• The electrocardiogram (ECG) criteria for LVH include voltage, repolarization abnormalities, left atrial abnormality, and ventricular conduction time 4.
• An increase in left ventricular mass (LVM) has a significant effect on all four ECG criteria, with the frequency of voltage criteria for LVH increasing from 52% to 83% as LVM increases from <400g to >600g 4.
• Increased wall thickness and ventricular diameter do not correlate with the overall ECG score or significantly influence the frequency of any of the four ECG criteria for LVH when LVM is held relatively constant 4.

Relationship between ECG and Cardiovascular Magnetic Resonance Imaging

• Conventional assessment of LVH using the ECG has relied on assessing changes in the amplitude and/or duration of the QRS complex to quantify LV mass 5.
• Cardiovascular magnetic resonance imaging (CMR) has emerged as a tool to not only quantify LV mass but also detect and quantify the extent and severity of focal or diffuse myocardial fibrosis, edema, inflammation, and other pathological changes 5.
• CMR techniques such as late gadolinium enhancement, T1 mapping, and extracellular volume fraction mapping can provide additional information on myocardial tissue characteristics beyond LV mass 5.

Regression of LVH with ACE Inhibitors

• Prolonged therapy with ACE inhibitors has been shown to induce a regression of LVH in dialyzed uremic patients independently of hypotensive effects 6.
• ACE inhibitors may be able to reverse LVH by mechanisms independent of their antihypertensive effects, such as reducing angiotensin II-mediated protein synthesis in myocardial myocytes 2, 6.