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An Unusual Case Of Recurrent Atrial Fibrillation

An Unusual Case Of Recurrent Atrial Fibrillation. Mark Linzer MD Section of GIM Scholars GIM Conference 4-16-08. Financial Disclosure. No support for this talk. Learning Objectives. To learn an uncommon cause of recurrent atrial fibrillation More objectives after the case report.

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An Unusual Case Of Recurrent Atrial Fibrillation

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  1. An Unusual Case Of Recurrent Atrial Fibrillation Mark Linzer MD Section of GIM Scholars GIM Conference 4-16-08

  2. Financial Disclosure • No support for this talk

  3. Learning Objectives • To learn an uncommon cause of recurrent atrial fibrillation • More objectives after the case report

  4. Case Report • Robust 73 yo man with mild HBP, lipid d/o • Develops episodic afib 2003, ETT neg. Echo dilated LA, EF 60%; TSH 2 • Started on amiodarone and coumadin • Chest pain in 2005; LAD stent • Did well until 2007; usual HR 50-60

  5. 2007: Abnormal Liver Function Tests • 7/07 ALT 160, AST 80; amio discontinued. • 10/07 frequent afib, SOB, anxiety. • PMH: CAD, BPH, GERD, lipids, OA • Meds: ASA, lipitor, doxazosin, lisinopril, metoprolol, PPI, warfarin • PE: BP 130/70, pulse 60-80, o/w neg

  6. Next steps? (Don’t turn page)

  7. Objectives: • Know two types of amiodarone-induced thyrotoxocosis (AIT) • Know how to attempt to distinguish them • Know the treatments

  8. Work Up • TSH 0, FT4 high; LFTs near nl; amio zero • Paged Endocrine, bumped beta blockers • Scan arranged for Txgiving wkend • Uptake 1% (very low) • Dx: amiodarone induced thyroiditis (likely) • Rx: high doses steroids, beta blockers

  9. Amio-induced thyrotoxicosis (AIT) • Prevalence 3% (2-3 yrs after Rx onset) • Type 1: exacerbation of latent Graves • Type 2: drug-induced thyroiditis (majority) • Some patients have mixed picture • Amio half life 100 days • Note amio and hyperthyroidism can increase sensitivity to warfarin* • Kurnik et al. Medicine. 2004;83:107-113.

  10. Amio and iodine • Very high iodine content (20x usual)* • Can cause hypo or hyperthyroidism • Has beta blocking properties and decreases T4 to T3 conversion: • can mask hyperthyroidism • stopping amio may make sx worse. • *UpToDate, Ross DS. Amio and thyroid dysfunction. 2008.

  11. Type 1 vs. Type 2 AIT • Type 1: Exacerbation latent Graves: usually with MNG; due to excess Iodine. Can (but may not) have high scan uptake • Type 2: Destructive thyroiditis, amio toxicity follicular cells, excess release T4. Scan uptake low. • Remember: patients must not be pregnant if scanned

  12. Ways to distinguish • Thyroid scan: low uptake Type 2 (thyroiditis); can be low Type 1 (amio competes with tracer) • Other methods*: • Color flow doppler: 80% sensitive Type 1 due to increased vascularity • Goiter (type 1) • IL-6 elevated in Type 2 • Amio duration longer (>2 yrs) in Type 2 • Response to prednisone implies Type 2 • *Basaria S, Cooper DC. Amiodarone and the thyroid. Am J Med. 2005;118:706-14

  13. Basaria S, Cooper DC. Amiodarone and the thyroid. Am J Med. 2005;118:706-14.

  14. Treatment • “AIT… complex Dx and Rx challenge*.” • Type 1: antithyroid meds, beta blockers • Type 2: prednisone 40 mg x 1-3 months, slow taper • Mixed or uncertain: antithyroid meds and steroids • Other Rx: surgery, plasmapharesis • *Rajeswaran. Swiss Med Wkly 2003;133:579-85

  15. Clinical course for my patient • Prednisone 40 mg daily x 2 wks; tapered • Free T4 fell, TSH 0 (can lag). • Relapsed, with free T4 rising. Refer Endo. • Re-Rx with prednisone, longer taper. • After 4 weeks, TSH 1, Free T4 normal. BMD osteopenia • Next time: Color flow doppler; IL-6, longer prednisone Rx, early Endo.

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