Acute Myocardial Infarction Caused by Spontaneous Coronary Intramural Hematoma

Abstract: A 49-year-old male presented to our emergency department with sudden anterior chest pain. His electrocardiogram revealed ST-segment elevations in leads II, III and aVF. An inferior acute myocardial infarction was suspected. Emergent coronary angiography (CAG) showed there was a long lesion in the right coronary artery (RCA), which continued from the proximal to the distal part of RCA with 50% stenosis and narrowed further to 99% stenosis at the distal end. Intravascular ultrasound (IVUS) examination demonstrated a diffuse intramural hematoma raging from the proximal to the distal part of the RCA. No visualization of the intimal flap was identified by IVUS, indicating coronary artery dissection as a pathogenesis of this hematoma formation. After intracoronary injection of isosorbide dinitrate, the 99% stenosis regressed to 50% spontaneously. Neither balloon angioplasty nor stenting was performed. He was discharged home free from symptoms 9 days after the procedure. Thirty-day follow-up CAG revealed an almost normal finding of the RCA and IVUS delineated a complete restoration of the intramural hematoma.

J INVASIVE CARDIOL 2012;24(12):692-693

Key words: coronary artery dissection, isosorbide dinitrate

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Spontaneous coronary intramural hematoma is extremely uncommon and the possible pathogenic mechanisms are poorly understood. However it is an important cause of acute coronary syndrome and can be discriminated from secondary hematoma following coronary artery dissection. IVUS is useful and essential modality for diagnosing this usual pathological condition.

Case Description

A 49-year-old male with light smoking history presented to our emergency department with sudden anterior chest pain. An electrocardiogram documented > 0.1mV ST-segment elevation in leads II, III, and aVF, suspected of being inferior acute myocardial infarction. Emergent coronary angiography (CAG) showed a long moderate stenosis originating from the proximal right coronary artery. At the distal end of the diffuse non-significant narrowing, a severe stenosis was located (Figure 1). Intravascular ultrasound (IVUS) demonstrated a long intramural hematoma which ranged from the proximal to the distal segment of the right coronary artery, concentrically compressing the true lumen (Figure 1). IVUS identified no visualization of an intimal tear which suggested any entry point of coronary artery dissection.¹ After intracoronary injection of isosorbide dinitrate, the severe stenosis regressed to moderate spontaneously. As no flow limit and no observation indicating ongoing ischemia were recognized, neither balloon angioplasty nor stenting were performed. His 9-day hospital stay was uneventful and without recurrent episodes of angina. We performed a follow-up coronary angiography at 30 days after the index procedure without any abnormal finding of the right coronary artery. IVUS delineated a complete restoration of the intramural hematoma (Figure 2). No inducible coronary spasm was observed by means of an intracoronary ergonovine maleate.

Discussion

Spontaneous coronary intramural hematoma is a unique type of spontaneous coronary artery dissection that is limited to the medial-adventitial layers or within media, causing subsequent hematoma formation without intimal flap.¹ Several underlying conditions have been proposed such as atherosclerosis, women in the peri- or postpartum period, coronary spasm, predisposing weakness of medial structure, vasculitis, and particular agents like oral contraceptives. However, a large number of cases are found to be idiopathic. The present case was a younger male that had little presence of an atherosclerotic coronary artery and no evidence of a vasospastic component. Vessels with minor atherosclerotic involvement without medial atrophy or scarring appear more vulnerable to extension of the dissection,² which may account for triggering the diffuse long hematoma formation in the present case. Clear therapeutic strategies have not been established.³ We obtained a good result from the observation without percutaneous coronary intervention because there was some possibility of the coronary hematoma being spontaneously absorbed. 

References 

1. Maehara A, Mintz GS, Castagna MT, et al. Intravascular ultrasound assessment of spontaneous coronary artery dissection. Am J Cardiol. 2002; 89(4):466-468
2. Khan NU, Miller MJ, Babb JD, et al. Spontaneous coronary artery dissection. Acute Card Care. 2006;8(3):162-171.
3. Kamran M, Guptan A, Bogal M. Spontaneous coronary artery dissection: case series and review. J Invasive Cardiol. 2008;20(10):553-559.

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From the Department of Cardiology, Niigata City General Hospital, Niigata, Japan.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted June 1, 2012, and accepted June 19, 2012

Address for correspondence: Ryutaro Ikegami, MD, Department of Cardiology, 

Niigata City General Hospital,Shumoku 463-7, Chuo-ku, Niigata 950-1197, Japan

Email: ryutaro.i.0820@gmail.com