Cardiomegaly is NOT a Contraindication to Rifapentine and Isoniazid
Cardiomegaly alone does not contraindicate the use of rifapentine and isoniazid for tuberculosis treatment or latent TB infection. The major guidelines and drug safety literature do not list cardiomegaly as a contraindication to these medications.
Actual Contraindications to Rifapentine-Based Regimens
The CDC and National Tuberculosis Controllers Association identify specific contraindications that do NOT include cardiomegaly 1:
- Drug-drug interactions with rifamycins (particularly protease inhibitors and certain NNRTIs) 1, 2
- Drug intolerance to rifamycins or isoniazid 1
- HIV infection with CD4 count <100 cells/μL when using once-weekly rifapentine/isoniazid for active TB 1
- Pregnancy (rifapentine not recommended) 3
- Age <2 years for the 3HP regimen 2
- Previous rifamycin resistance 4
Cardiac Considerations That Matter
While cardiomegaly itself is not a contraindication, you should consider:
- Hepatic function monitoring is more relevant than cardiac status, as both isoniazid and rifapentine can cause hepatotoxicity 1, 5, 6
- Baseline liver function tests (AST, ALT, bilirubin, alkaline phosphatase) should be obtained before treatment 1, 7
- Monthly clinical evaluations for adverse effects are recommended regardless of cardiac status 2, 7
Clinical Decision Algorithm
Proceed with rifapentine/isoniazid treatment if:
- No significant drug-drug interactions present 1
- Liver function is adequate for monitoring 1, 7
- Patient can complete the regimen (3 months for 3HP vs 6-9 months for isoniazid alone) 1, 2
Choose alternative regimen only if:
Common Pitfall to Avoid
Do not confuse cardiomegaly with conditions that actually matter for rifapentine use. The concern with fluoroquinolones (like moxifloxacin) regarding cardiotoxicity 8 does not apply to rifapentine or isoniazid. These drugs do not have significant cardiac toxicity profiles that would make cardiomegaly relevant 5, 6.