Introduction Elevated Cardiac enzymes are associated with high morbidity and mortality. A significant subset of patients referred to the cardiac service has raised troponin levels and normal coronary angiography. This subset is distinctive from patients with type 2 myocardial infarction (MI). It includes patients with no active medical conditions who present with clinical and electrocardiographic features similar to that of acute coronary syndrome. In this report we describe a cohort of patients, in whom the diagnosis of type 1 myocardial infarction was very likely, but subsequently had normal angiogram.
Purpose of study The aim of the study is to identify a diagnostic approach for patients who display features of MI with no evidence of obstructive coronary artery pathology.
Methods The study included all patients with suspected with MI (STEMI or NSTEMI) with raised troponin, abnormal ECG and normal coronary angiography who attended the PCI centre at the University Hospital Limerick between September 2015 to January 2016. All patients received the standard diagnostic pathway of acute coronary syndrome. Data collected included baseline characteristics, ECG on presentation, laboratory profile, Grace score, cardiac imaging results, recurrence of symptoms and hospital readmission over 3–6 months period. All patients included in this study had normal coronary angiogram.
Result A total of 26 patients included in this study, 13 (50%) patients were men and the mean age was 51 years old. 6.7 (26.9%) patients presented as STEMI while 19 (73.0%) patients had ST segment depression on presenting ECG. Mean troponin level on admission was 285.9 ng/dl with mean Grace score of 100.04. 69% of the patients had normal EF on Echocardiogram and 11 (42%) patients had cardiac MRI (CMR) and one patient under went optical coherence tomography (OCT) during coronary angiography.
Confirmed diagnosis post-appropriate investigations included acute myocarditis (34.6%), acute myocardial ischemia on CMR (15.3%), Takotsubo syndrome (7.6%), pulmonary embolus (3.8%), Hypertrophic cardiomyopathy (11.5%) and severe aortic stenosis (3.8%). 4 (15.3%) patients had recurrent hospital admission with similar presentation while 84% had experienced no further symptoms or hospital admission.
Conclusion Establishing a definitive diagnosis in patients with raised troponin and normal coronary angiogram is challenging, but using imaging modalities such as CMR and OCT provides a valuable insight to guide diagnosis and management.
Acute myocarditis is the most common cause of raised troponin and normal angiogram in this cohort.
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