What is the significance of high voltage on an electrocardiogram (ECG)?

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Last updated: March 28, 2025View editorial policy

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From the Guidelines

High voltage on an electrocardiogram (ECG) is a significant finding that may indicate left ventricular hypertrophy (LVH), which is a major risk factor for cardiovascular morbidity and mortality. The significance of high voltage on an ECG can be assessed using various criteria, including the Sokolow-Lyon criteria, which involve measuring the sum of the S wave in V1 and the R wave in V5 or V6 1. According to the American Heart Association, the ECG is a fundamental tool for diagnosing and monitoring various cardiovascular conditions, including LVH, and its interpretation can lead to the recognition of electrolyte abnormalities and genetically mediated cardiac abnormalities 1.

Some key points to consider when interpreting high voltage on an ECG include:

  • The ECG is a non-invasive and widely available diagnostic tool that can provide valuable information about cardiac structure and function 1
  • High voltage on an ECG can be caused by various factors, including LVH, which is often associated with hypertension, valvular heart disease, or cardiomyopathy 1
  • The sensitivity of the ECG for detecting LVH is moderate, ranging from 50-60%, and therefore, echocardiography may be recommended for confirmation if LVH is suspected clinically despite a normal ECG 1
  • Serial ECGs may be useful in monitoring patients with cardiovascular conditions, including those undergoing antiarrhythmic drug therapy, coronary angioplasty, or other intracardiac invasive procedures 1

In terms of clinical implications, high voltage on an ECG should prompt further evaluation and management to reduce the risk of cardiovascular morbidity and mortality. This may involve lifestyle modifications, such as blood pressure control and lipid management, as well as pharmacological interventions, such as antiarrhythmic or antihypertensive medications 1. Additionally, patients with high voltage on an ECG may require closer monitoring and follow-up to detect any changes in their cardiac condition or to adjust their treatment plan as needed 1.

From the Research

Significance of High Voltage on an ECG

  • High voltage on an ECG can be indicative of various cardiac conditions, including left ventricular hypertrophy and cardiomyopathies 2, 3.
  • In patients with hypertrophic cardiomyopathy (HCM), an abnormal ECG may be the only manifestation of disease at an early stage, and specific electrical anomalies may differentiate HCM from phenocopies such as cardiac amyloidosis and glycogen storage diseases 3.
  • The interpretation of high voltage on an ECG should be done in conjunction with clinical assessment and comparison to previous ECGs, as it may also be secondary to nonischemic etiologies 2.
  • Triage nurses can accurately interpret the ECG, including identifying patterns indicative of time-dependent conditions correlated with major acute cardiovascular events, and have a moderate ability in identifying alterations in specific components of the ECG 4.
  • A simple, five-step method for evaluating the main components of cardiac rhythm can help emergency nurses understand and interpret the cardiac rhythms commonly encountered on ECGs in EDs 5.

Ischemic Patterns on an ECG

  • The ECG is a useful diagnostic tool that allows clinicians to rapidly evaluate patients for acute coronary syndrome, and various guidelines provide criteria to aid in recognizing ischemia and help dictate patient management 6.
  • Not all ischemic patterns requiring emergent management present within the classic definition of an STEMI, and it is critical for clinicians to be able to accurately recognize these ischemic patterns to allow timely and appropriate cardiovascular care 6.
  • High voltage on an ECG can be indicative of ischemia, and the ECG should be read along with the clinical assessment of the patient to determine the significance of high voltage 2.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The role of the ECG in diagnosis, risk estimation, and catheterization laboratory activation in patients with acute coronary syndromes: a consensus document.

Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc, 2014

Research

Electrocardiograms: a guide to rhythm recognition for emergency nurses.

Emergency nurse : the journal of the RCN Accident and Emergency Nursing Association, 2018

Research

The Ischemic Electrocardiogram.

Emergency medicine clinics of North America, 2022

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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