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08-07-2016 | Acute coronary syndromes | News | Article

Imaging helpful in patients with no obstruction to explain STEMI symptoms

medwireNews: Imaging may reveal an alternative diagnosis in about half of patients who have suspected ST-elevation myocardial infarction (STEMI) but no evidence of obstructive disease, research shows.

Some of the conditions identified in this patient group have an adverse prognosis, and detecting them is important so they can be correctly managed, say Tarun Mittal (Harefield Hospital, London, UK) and co-researchers.

“The use of non-invasive imaging techniques in this group of patients is, therefore, helpful as otherwise important findings could be missed and go untreated”, they write in Heart.

But they add that “not all the diagnoses may be responsible for patients’ presentation and some could be purely coincidental.”

The most common finding was cardiomyopathy, accounting for 43.9% of the 237 patients who received an imaging diagnosis and 18.1% of all the 575 patients who had suspected STEMI but no obstructive disease on angiography. The most common subtypes were hypertrophic cardiomyopathy and Takotsubo cardiomyopathy, at a respective 11.8% and 11.4% of all imaging diagnoses.

Other common diagnoses were myopericarditis, at 20.3%, with myocarditis accounting for 15.2%; myocardial infarction or coronary abnormality, at 11.4%; severe valve disease, at 9.7%; and pulmonary abnormalities, also at 9.7%.

Of the 575 patients overall, no diagnosis was possible in 45.6%, despite imaging, while 41.2% received a diagnosis and 13.2% did not undergo imaging. Patients who receiving imaging underwent cardiac magnetic resonance, chest X-ray, echocardiography and computed tomography. Of note, a diagnosis was more likely if patients had elevated troponin levels, with 74.7% of these 229 patients receiving an imaging diagnosis.

During an average follow-up of 42.6 months, 7% of the patients died, with the most common causes being heart failure, cardiac arrest and stroke. On multivariate analysis, each 10-year increase in age was associated with a 1.39-fold increased mortality risk and having an ejection fraction below 50% conferred a 2.97-fold increased risk. Out-of-hospital cardiac arrest conferred a more than fourfold risk increase, with all these deaths occurring within 35 days of presentation.

Mortality rates during follow-up were highest among patients with severe valve disease (35%) and aortic dissection (50%), whereas patients with cardiomyopathy had more favourable survival, with 9% dying, and only 4% of the patients with myopericarditis died.

The researchers add that the one patient with myocarditis who died “was diagnosed to have giant-cell myocarditis on endocardial biopsy, which is known to have a poor outcome.”

By Eleanor McDermid

medwireNews is an independent medical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2016