What are the diagnostic and prognostic values of abnormal electrocardiogram (EKG) results?

Diagnostic and Prognostic Value of Abnormal Electrocardiogram Results

Abnormal ECG findings have significant diagnostic and prognostic value in identifying underlying cardiovascular conditions and predicting adverse outcomes, requiring comprehensive cardiac evaluation based on the specific abnormalities detected. 1, 2

Diagnostic Value of Abnormal ECG Findings

Identification of Specific Cardiac Conditions

• ECG abnormalities can identify specific cardiovascular pathologies including arrhythmias, conduction disorders, ischemia, cardiomyopathies, and channelopathies 2
• Specific ECG patterns may suggest underlying conditions such as:
  • T-wave inversion patterns (anterolateral, inferolateral, anterior, lateral) may indicate cardiomyopathy 1
  • ST-segment depression ≥0.5 mm in two or more contiguous leads suggests myocardial ischemia 1
  • Pathologic Q waves may indicate previous myocardial infarction 1
  • Ventricular pre-excitation (PR interval <120 ms with delta wave) suggests Wolff-Parkinson-White syndrome 1
  • Prolonged QT interval may indicate congenital or acquired long QT syndrome 1
  • Epsilon waves may suggest arrhythmogenic right ventricular cardiomyopathy 1

Evaluation of Specific Patient Populations

• In athletes, abnormal ECG findings require careful interpretation as some patterns represent normal physiological adaptation while others indicate pathology 1
  • Early repolarization patterns are common in athletes and generally considered benign when present in isolation 1
  • Complete right bundle branch block (CRBBB) is more prevalent in males and athletes (0.25% vs. 0.14%) but requires evaluation when accompanied by other abnormalities or QRS duration ≥130 ms 3
• In patients with syncope, an ECG is a crucial diagnostic tool, although it provides a definitive diagnosis in only approximately 5% of cases 1

Prognostic Value of Abnormal ECG Findings

Prediction of Adverse Outcomes

• Abnormal ECG findings are associated with increased risk of all-cause mortality at 1 year in patients presenting with syncope 1
• Specific ECG abnormalities carrying prognostic significance include:
  • Atrial fibrillation, intraventricular conduction disturbances, voltage criteria for left ventricular hypertrophy, and ventricular pacing are associated with increased risk of death 1
  • P-wave amplitude in lead II of ≥0.25 mV is associated with a 2.8-fold greater risk of death over a 6-year follow-up period in patients with pulmonary arterial hypertension 1
  • Each additional 1 mm of P-wave amplitude in lead III corresponds with a 4.5-fold increased risk of death in PAH patients 1

Risk Stratification

• ECG abnormalities are included in most multivariate risk scores used to predict adverse outcomes in patients with syncope 1
• The presence of an abnormal ECG is a multivariate predictor for arrhythmia or death within 1 year 2
• Cardiac imaging of regional function and perfusion offers substantially greater diagnostic and prognostic information for early cardiac events in patients presenting with chest pain and no ST elevation than routine assessment including ECG 4

Clinical Management Based on ECG Findings

Immediate Evaluation Required

• Ventricular arrhythmias or high-grade AV block require immediate intervention 2
• Left ventricular hypertrophy with repolarization abnormalities requires urgent evaluation within 24 hours 2
• Right bundle branch block with right axis deviation requires urgent evaluation within 24 hours 2

Follow-up Evaluation Required

• Asymptomatic competitive athletes with substantial ECG abnormalities but normal initial clinical evaluation should be followed with longitudinal clinical surveillance (including imaging) 1
• Isolated axis deviation or voltage criteria for atrial enlargement require outpatient follow-up 2
• Early repolarization pattern without other abnormalities requires outpatient follow-up 2
• First-degree AV block without symptoms requires outpatient follow-up 2

Special Considerations

• In pre-operative settings, abnormal ECG findings may necessitate postponement of elective procedures until cardiac evaluation is complete 2
• For athletes with abnormal ECGs, temporary restriction from physical activity may be warranted until a complete cardiac evaluation is performed 2
• Competitive athletes with Wolff-Parkinson-White pattern should undergo cardiac evaluation including physical examination, personal and family history, and echocardiogram 1

Limitations of ECG as a Diagnostic Tool

• The ECG lacks sufficient sensitivity to serve as a screening tool for certain conditions like pulmonary arterial hypertension (sensitivities of right-axis deviation and right ventricular hypertrophy were only 73% and 55%, respectively) 1
• In large population screening programs, false-positive ECGs can create excessive and costly second-tier testing 1
• The positive predictive value of ECG is poor when the population prevalence of the disorder being tested is low 1
• Physiological alterations in ECGs often overlap with pathological patterns, particularly in physically active children and adolescents 1

Conclusion on Clinical Utility

• A resting 12-lead ECG is an essential component of the initial evaluation of patients with known or suspected bradycardia or conduction disorder 1
• ECG interpretation in athletes should follow current consensus recommendations, with clinical evaluation tailored to address the specific cardiovascular pathology suggested by the ECG abnormality 1
• Abnormal ECG findings should be correlated with clinical symptoms, as syncope, chest pain, palpitations, or dyspnea significantly increases the likelihood of cardiac pathology 2