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Ischemic-pattern LGE in idiopathic dilated cardiomyopathy might not reflect ischemia

Circulation: Heart Failure
Reuters Health - 30/03/2022 - A significant proportion of patients with idiopathic dilated cardiomyopathy (DCM) and late gadolinium enhancement on cardiovascular magnetic resonance (LGE-CMR) - a finding suggestive of an ischemic etiology - had no evidence of obstructive coronary artery disease on coronary angiography, investigators report.

While the presence LGE- CMR abnormalities, regardless of ischemic or non-ischemic pattern, does not suggest an obstructive atherosclerotic etiology, it does not preclude the presence of either luminal or embolic or hypotensive disease for which aggressive management may still be appropriate, the researchers say.

The Dilated Cardiomyopathy Precision Medicine Study evaluated the likelihood that inherited genetic abnormalities were the most common cause of DCM. Investigators excluded secondary cardiomyopathy on the basis of a detailed history and physical exams to rule out prior myocardial infarction, toxic exposure, infiltrative disease, valvular abnormalities and structural heart disease.

Of the 1,204 enrolled patients with idiopathic DCM, 327 underwent LGE-CMR. LGE was absent in 141 (45.6%), investigators reported in Circulation: Heart Failure. Classical non-ischemic LGE patterns (midmyocardial and epicardial) were seen in 156 patients. Ischemic LGE patterns (subendocardial and transmural) were identified in 22 patients.

Eighteen of those 22 patients had coronary angiography with no evidence of obstructive disease >50%, according to the authors. Thirteen patients had normal studies, three had luminal irregularities and one had a distal coronary thrombus, presumably from a left ventricular thrombus that embolized. A final patient had what was felt to be global ischemia in the setting of IDCM and cardiogenic shock with moderate disease of the major epicardial arteries.

Although patients with ischemic-pattern LGE were statistically older with shorter duration of cardiomyopathy, increased left ventricular end-systolic volume and lower ejection fraction (22% vs 25%), there was no obvious breaking point that would help discriminate the need for further testing for occlusive coronary artery disease.

Despite the fact that 45% of the patients had no LGE, more than 70% of both groups underwent coronary angiography.

"The determination for coronary angiography was made by the heart failure program managing the patient, as part of their routine clinical evaluation for DCM," study leader Dr. Garrie Haas of Ohio State University Medical Center in Columbus, Ohio told Reuters Health by email. "Given the serious diagnosis and poor prognosis of cardiomyopathy in general, it is important to be certain that a potentially treatable condition, like obstructive CAD, is not missed. I would say that most centers will perform coronary angiography to exclude CAD, although there are a few exceptions."

Presently, Dr. Haas believes, computed tomograpy angiography "is adequate if the suspicion for significant/treatable CAD is low."

"There are some situations where cardiac MRI is adequate - for example, the 30 year old patient with new DCM, no coronary risk factors and thus very low suspicion," he added. "In those cases, a cardiac MRI with only non-ischemic fibrosis and no evidence of transmural infarct would suffice to be pretty certain that it's not ischemic cardiomyopathy."

As of now, "No data exist on the prognostic value of LGE consistent with infarction specifically in an idiopathic DCM population where risk of infarction would be considered low," the researchers conclude in their paper.

Dr. Haas suggests, however, that there may be criteria to help differentiate ischemic and nonischemic etiologies of new DCM. "On review of the 22 CMR reports, we also noted that 10 patients had ischemic-pattern LGE in no more than two American Heart Association segments," he said. "In these cases, LV dysfunction appeared out of proportion to the small extent of ischemic-pattern LGE, hence also suggesting that the cardiomyopathy was likely of nonischemic cause."

SOURCE: https://bit.ly/3JStVou Circulation: Heart Failure, online March 4, 2022.

By Austin Kutscher MD FACC

© 2023 The Author(s). Published by Medicom Medical Publishers.
User license: Creative Commons Attribution – NonCommercial (CC BY-NC 4.0)

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