An Unusual Case Of Recurrent Atrial Fibrillation

Mark Linzer MDSection 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

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

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

Next steps? (Don’t turn page)

Objectives:

Know two types of amiodarone-induced thyrotoxocosis (AIT)

Know how to attempt to distinguish them

Know the treatments

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

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.

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.

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

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

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

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

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.