1348342 - A Case of Intramyocardial Dissection with Contained Left Ventricular Free Wall Rupture

Description of Clinical Presentation: A 59 year old man with a history late-presenting acute myocardial infarction (AMI) treated with 2 drug eluting stents delivered to the mid left anterior descending artery and distal left circumflex artery 2 months prior presented to the emergency department (ED) with positional chest discomfort.  The discomfort was worse with lying supine. It was not exacerbated by exertion and there was no associated dyspnea, syncope, or pre-syncope. His other co-morbidities included hypertension, hyperlipidemia, and atrial fibrillation. A recent outpatient echocardiogram showed a small endocardial deformity in the left ventricular (LV) mid inferolateral segment concerning for a sub-epicardial aneurysm. There was no extravasation of microbubble contrast into the pericardial space. The patient’s vitals and physical examination in the ED were unremarkable. An electrocardiogram showed normal sinus rhythm, left axis deviation, LV hypertrophy, incomplete right bundle branch block, and non-specific ST-T abnormalities in the inferolateral leads. His laboratory studies were normal, though cardiac biomarkers were not checked. He underwent computed tomography cardiac angiogram (CTCA) followed by cardiac magnetic resonance (CMR) for further investigation.

Diagnostic Techniques and Their Most Important Findings: The CTCA demonstrated a central cleft-like excrescence of contrast in the inferolateral LV wall extending beyond the epicardium and into the pericardium with pericardial thickening, adhesions, and a small effusion. The coronary stents were patent. These findings were concerning for an intramyocardial dissection (ID) with focal myocardial rupture. The CMR images from delayed post-contrast inversion-recovery sequences demonstrated delayed cardiac enhancement involving the basilar to mid LV inferolateral wall consistent with infarct. There was an inferolateral LV wall defect measuring 13 x 7 x 12 mm with a neck orifice of 14 mm and thin linear channel extending to the sub-epicardium adjacent to a small localized pericardial effusion. This confirmed ID with possible free wall rupture.

Learning Points from this Case: The patient underwent surgical repair of the free wall rupture with a bovine pericardial patch and did well at 1-year follow-up. LV ID is a rare complication of AMI with the potential to cause LV rupture. It occurs due to dissection among the spiral myocardial fibers with the influx of blood and creation of a neo-cavity.¹ The dissection may result from rupture of intramyocardial vessels and an ensuing decrease in tensile strength of the infarcted area.² Echocardiography is usually performed first, but is limited in differentiating ID from thrombus or pseudoaneurysm.³ Due to excellent contrast resolution, CMR can help distinguish ID from pseudoaneurysm by displaying an intact epicardium.¹ Delayed cardiac enhancement may show an intramyocardial hematoma surrounded by bright, hyperintense infarcted myocardium and dissecting endocardial flap^.4  Surgery is reserved for patients with low ejection fraction, hemodynamic compromise, or worsening features.⁴