Abstract 15574: High Frequency of Anti-Heart and Anti-Intercalated Disk Autoantibodies in Acute Myocardial Infarction with Normal Coronary Arteries: Evidence for Unsuspected Immune-Mediated Myocarditis
Acute myocardial infarction with angiographically normal coronary arteries (MINC) is a poorly understood and likely heterogeneous entity. Although acute biopsy-proven myocarditis (My) may present as MINC, differential diagnosis is often not undertaken. Anti-heart (AHA) and anti-intercalated disk autoantibodies (AIDA) are specific serum markers of immune-mediated My.
Hypothesis: To assess whether MINC may represent unsuspected immune-mediated My, we compared features at diagnosis (dgn), including AHA and AIDA, in consecutive patients (pts) with MINC vs pts with biopsy-proven My and pseudo-ischemic presentation (chest pain and abnormal troponin I).
Methods: We studied 147 MINC pts (100 male, aged 37± 17 years, follow-up (f-u) 33 ± 32 months) and 53 My pts (40 male, aged 35 ± 15 years, f-u 66± 39 months). Coronary angiogram was always normal. Biopsy-proven My (Dallas criteria) was lymphocytic in 46 pts, giant cell in 3, other in 4. AHA and AIDA were detected by indirect immunofluorescence on human myocardium and skeletal muscle. Controls for AHA included 141 pts with angiographically proven coronary heart disease (CAD) (131 male, aged 51 ± 12 years) and 270 normal blood donors (NBD) (123 male, 35 ± 11 years).
Results: At presentation angiographic left ventricular ejection fraction (LVEF) was higher in MINC than in My (65 ± 10% vs 58 ± 13%, p=0.009). Peak troponin I was lower in MINC than in My (11±12 vs 20±21, p=0.003). History of chest pain with abnormal troponin I prior to the index episode occured in MINC (9%) and in My (30%, p=0.0001). AHA were found in 34% of MINC and in 59% of My pts (p=0.003). AHA frequency was higher in MINC or My than in CAD (7%) or in NBD (8%) (p=0.0001). AIDA were found in 11% of MINC and in 25% of My pts (p=0.03). AIDA frequency was higher in MINC or My than in CAD (3%) or in NBD (0%) (p=0.0001). At f-u 2% of MINC and My pts were dead or transplanted; all survivors were in NYHA I but 4 My pts who were in NYHA II (p=0.0001), echocardiographic LVEF at last f-u was higher in MINC than in My (p=0.02).
Conclusions: The high frequency of AHA and AIDA suggests that in about 34% of pts MINC may represent mild unsuspected immune-mediated My with pseudo-ischemic presentation. Long term follow-up in MINC is needed as relapse, death or transplant may occur, similar to My.
- © 2010 by American Heart Association, Inc.