Atypical ST-Segment—Elevation Infarction in a Patient With Bicuspid Aortic Valve
We report the case of a 51-year-old man who was admitted to our hospital with ST-segment–elevation myocardial infarction and normal epicardial coronary arteries. To the best of our knowledge, this is the first documented case of a myocardial infarction caused by intermittent occlusion of the right coronary artery by an adhering cardiac tumor on a bicuspid aortic valve.
The patient presented with sudden onset of typical anginal chest pain radiating into the left arm and throat, accompanied by nausea and diaphoresis. He had no previous cardiac history, and smoking was his only cardiovascular risk factor. As a result of ST-segment elevations in the lateral precordial leads in a 12-lead surface ECG (Figure 1) and his typical clinical presentation, he was medically treated according to the ST-segment–elevation myocardial infarction guidelines by the emergency physician and directly transported to the catheterization unit in our hospital.
Myocardial infarction was confirmed by an increase in cardiac enzymes, reaching a peak of 4.2 ng/mL for high-sensitivity cardiac troponin T (normal, <0.01 ng/mL) and 171 U/L for creatine kinase-MB (normal, <25 U/mL) 6 hours after admission. Inflammation markers were negative (C-reactive protein level <0.16 mg/dL [normal, 0 to 0.5 mg/dL]; white blood cell count, 10×103/μL [normal, 4.6 to 10.2×103/μL]). Surprisingly, cardiac catheterization directly after admission showed normal epicardial coronary arteries (Movie IA and IB in the online-only Data Supplement). A coronary thromboembolic event also was ruled out.
A subsequent transthoracic echocardiogram (Philips ie33 3D) demonstrated a moderate aortic valve stenosis (Vmax, 3.6 m/s; dPmean, 29 mm Hg; calculated planimetric opening area, 1.3 cm2) caused by a congenital bicuspid aortic valve (Figure 2). Additionally, a floating mass adhering to the fused right coronary cusp (Figure 3A and Movie II in the online-only Data Supplement) was observed.
Transesophageal echocardiography confirmed the moderate aortic valve stenosis caused by a bicuspid valve configuration, with fusion of the right and left cusps presenting massive degenerative changes, whereas the opening between the left cusp and noncoronary cusp was normal (Movie III in the online-only Data Supplement). The 20-mm-long adherent mass was floating into the aortic root, regularly intubating and closing the ostium of the right coronary artery (Figure 4and Movie IVA and IVB in the online-only Data Supplement). The patient was operated on the next day; the bicuspid valve was removed and a mechanical aortic valve was implanted (St. Jude Medical; 23 mm).
A macroscopic pathological examination of the specimen showed a highly degenerated and ulcerated bicuspid valve (Figure 5) with neovascularization and nodal calcification. The valve tissue was infiltrated with plasma cells and lymphocytes, indicating a chronic inflammatory process. The floating mass (Figure 6) was initially suspected to be a fibroelastoma, but no elastic filaments were detectable on microscopic examination (Figure 7, elastic van Gieson stain). It was classified as an unspecific degenerative adhesion at the edge of the degenerative aortic valve.
The patient presented no further complications. Left ventricular function remained only slightly impaired, with a localized hypokinesia of the inferior wall 12 days after surgery.
Establishing the correct diagnosis in a patient with ST-segment–elevation myocardial infarction and normal coronary arteries is challenging. Severe aortic valve stenosis in both the tricuspid and bicuspid valves typically causes anginal chest pain, but severe aortic valve stenosis after enzymatic myocardial infarction resulting from a fixed cardiac output through the valve is exceptional, to the best of our knowledge. This is not likely to be the reason in our patient, because dPmean was 29 mm Hg and calculated planimetric opening area was 1.3 cm2, yielding only a mild to moderate aortic valve stenosis.
Multiple conditions can cause myocardial enzyme elevation, such as myocarditis, takotsubo syndrome, blunt chest trauma, coronary embolization, or coronary spasm. Given that the patient was admitted directly to the catheterization laboratory 30 minutes after the onset of symptoms and no embolus was obvious in the coronary angiography, coronary embolization is unlikely. Coronary spasm cannot be ruled out as a differential diagnosis, but there was no evidence for coronary spasm when intubating the coronary ostia and applying contrast medium. Before this presentation, the patient had no angina-like symptoms, as would be likely in vasospastic angina. We did not test agents provoking vasospasm because this test is not typically used in clinical routine and is controversial because of safety concerns. Summing up these findings, and according to lex parsimoniae, (ie, the simplest explanation is usually the correct one), we have to assume that an intermittent occlusion of the right coronary ostium caused the myocardial infarction.
We have demonstrated that a systematic and accurate transthoracic echocardiogram and a transesophageal echocardiogram may be helpful in resolving atypical cases like ours. To the best of our knowledge, this is the first case of an echocardiographically documented floating degeneration on the fused cusps of a bicuspid valve that slid in and out of a coronary artery, causing an occlusive ST-segment–elevation infarction.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/123/13/e392/DC1.
- © 2011 American Heart Association, Inc.