What electrocardiographic abnormalities are associated with tuberculosis, especially when there is cardiac involvement such as tuberculous pericarditis or myocarditis?

ECG Changes in Tuberculosis with Cardiac Involvement

When tuberculosis affects the heart, the ECG typically shows widespread ST-segment elevation and PR-segment depression in acute tuberculous pericarditis, with microvoltage being a supportive finding that suggests large pericardial effusion. 1, 2

Primary ECG Abnormalities in Tuberculous Pericarditis

Acute Phase Changes

• Widespread ST-segment elevation (concave upward pattern) is the hallmark ECG finding in acute tuberculous pericarditis, typically accompanied by PR-segment depression in multiple leads 1
• These changes mimic the pattern seen in viral pericarditis but occur in the context of tuberculosis, which is the most common cause of pericardial disease in developing countries 1
• ST-segment elevation was present in 36.6% of patients with tuberculous myopericarditis in one study, making it a significant predictor of myocardial involvement 3

Voltage Abnormalities

• Microvoltage in extremity and/or precordial leads correlates strongly with the presence of large pericardial effusions (>750 mL) 2
• The absence of microvoltage makes the presence of cardiac tamponade unlikely, though its presence does not confirm tamponade 2
• All patients with tuberculous pericarditis in one series had abnormal ECGs, with 83% showing changes of chronic pericarditis 2

ECG Findings in Tuberculous Myopericarditis

When Myocardial Involvement Occurs

• ST-segment elevation is more common when there is concomitant myocardial involvement (myopericarditis), occurring in 36.6% versus 10.8% in isolated pericarditis 3
• ST-segment elevation independently predicts myopericarditis (OR 4.36,95% CI 1.34-17.34) and should prompt evaluation for myocardial involvement 3
• Ventricular and supraventricular arrhythmias may occur, including frequent or complex forms that indicate myocardial inflammation 1
• T-wave inversions can develop, particularly in cases with myocardial involvement 1
• AV blocks or bundle branch blocks (particularly LBBB) may occasionally occur with myocardial involvement 1

Chronic and Constrictive Phase Changes

Evolution Over Time

• Changes of chronic pericarditis were present in 83% of patients with tuberculous pericardial effusion 2
• As constrictive pericarditis develops (tuberculosis is the most common cause in endemic countries), ECG changes may persist or evolve 4
• Pericardial calcification can develop on follow-up imaging, though this is a radiographic rather than ECG finding 5

Clinical Algorithm for ECG Interpretation

Step 1: Identify Pericarditis Pattern

• Look for widespread (not localized) ST-segment elevation with concave upward morphology 1
• Check for PR-segment depression, which distinguishes pericarditis from STEMI 1, 6
• Assess for microvoltage in limb and/or precordial leads suggesting large effusion 2

Step 2: Assess for Myocardial Involvement

• If ST-elevation is present, particularly in the context of low CD4 count in HIV-positive patients, suspect myopericarditis 3
• Check for arrhythmias (ventricular or supraventricular) that suggest myocardial inflammation 1
• Correlate with cardiac biomarkers: elevated troponin occurs in up to 50% of cases with myocardial involvement 1, 3

Step 3: Evaluate Effusion Size and Tamponade Risk

• Microvoltage suggests large effusion (>750 mL) but does not diagnose tamponade 2
• None of the ECG parameters reliably correlate with cardiac tamponade presence—clinical assessment and echocardiography are essential 2
• Electrical alternans, while classically associated with tamponade, was not a reliable finding in tuberculous pericarditis 2

Important Clinical Caveats

Diagnostic Limitations

• The 12-lead ECG is supportive but not diagnostic for cardiac tamponade in tuberculous pericarditis 2
• Normal ECG does not exclude tuberculous pericarditis, though this is rare—all patients in one series had abnormal ECGs 2
• The absence of ST-elevation does not rule out myocardial involvement, as only 36.6% of myopericarditis cases showed this finding 3

Risk Stratification Considerations

• HIV-positive patients with tuberculous pericarditis are more likely to have myopericarditis (81.4% vs 60.5%) and should be monitored more closely 3
• Low CD4 count (<100) increases the likelihood of myocardial involvement when ST-elevation is present 3
• Myopericarditis prevalence reaches 53.1% in tuberculous pericardial effusion, making cardiac biomarker assessment essential 3

Differential Diagnosis Pitfalls

• Do not mistake tuberculous pericarditis for STEMI: the ST-elevation is widespread and concave (saddle-shaped), not localized and convex 1, 6
• ST-T wave alterations can mimic ischemic heart disease, requiring careful clinical correlation 1
• In endemic areas with unexplained pericarditis and systemic symptoms (fever, night sweats, weight loss), consider tuberculosis even with atypical ECG findings 1