Acute myocardial infarction in thrombotic microangiopathies--clinical characteristics, risk factors and outcome.
BACKGROUND
Acute myocardial infarction (AMI) has been reported and is associated with poor outcome in the course of thrombotic microangiopathies (TMA). However, data are very limited in regard to the clinical characteristics, risk factors and outcome of AMI during TMA. Furthermore, current AMI definitions based on troponins are more sensitive and specific to detect myocardial injury.


METHODS
We retrospectively analysed 74 consecutive patients with 78 TMA episodes. TMA was defined as platelets below 150 x 10(9)/l, haemolytic anaemia, elevated lactate dehydrogenase (LDH) and increased red cell fragmentation, and AMI as serum troponin I above 1 ng/ml with symptoms of myocardial ischaemia and/or appropriate electrocardiography (ECG) alterations.


RESULTS
AMI occurred in 14 TMA episodes (18%) (9 non- and 5 ST-segment elevation AMI). AMI occurred 5+/-3 days after TMA diagnosis, predominately in clinically suspected thrombotic thrombocytopenic purpura (TTP) as TMA subtype. Independent risk factors for subsequent AMI were TTP (RR 2.2; 95% CI 1.1-5.6), and serum LDH above 1,000 U/l (RR 2.7; 95% CI 1.3-7.2) as well as serum troponin I above 0.20 ng/ml at TMA presentation (RR 13.5; 95% CI 2.6-86.8). LDH above 1,000 U/l together with troponin I above 0.20 ng/ml had a sensitivity of 86% (95% CI 60-96%) and a specificity of 95% (95% CI 86-98%) to predict AMI in the later course of TMA. AMI contributed substantially to morbidity causing left ventricular dysfunction in three of eight survivors and potentially accounted for the death in five of six non-survivors.


CONCLUSIONS
AMI is an early, frequent and severe complication during TMA. AMI occurs especially in TTP, and serum LDH above 1,000 U/l in combination with serum troponin I above 0.20 ng/ml at TMA presentation are excellent predictors of subsequent AMI.
Patschan
Daniel
D
Department of Nephrology, University Hospital, Essen, University of Duisburg-Essen, Germany.
Witzke
Oliver
O
Dührsen
Ulrich
U
Erbel
Raimund
R
Philipp
Thomas
T
Herget-Rosenthal
Stefan
S
D000328:Adult; D015331:Cohort Studies; D005260:Female; D006463:Hemolytic-Uremic Syndrome / Q000150:complications*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology* / Q000401:mortality; D011237:Predictive Value of Tests; D011697:Purpura, Thrombotic Thrombocytopenic / Q000150:complications*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D019210:Troponin I / Q000097:blood; D018487:Ventricular Dysfunction, Left / Q000209:etiology
D019210:Troponin I; D007770:L-Lactate Dehydrogenase