Primary Stenting of an Anomalous Left Main Trunk Originating from the Right Coronary Artery During Acute Myocardial Infarction

ABSTRACT: In 1.5–2.0% of patients with acute myocardial infarction referred for primary percutaneous coronary intervention, the left main trunk is identified as the culprit vessel. Among the congenital coronary anomalies, an anomalous origin of the left main trunk from the right sinus of Valsalva is very rare. A 73-year-old patient with lateral acute myocardial infarction was referred to primary angioplasty. The initial angiogram showed an anomalous origin of the left main from the right coronary artery, apparently with a septal course, with an angiographic image of intraluminal thrombus; in addition, a severe lesion was present at the distal right coronary artery. The left main and right coronary arteries were successfully treated with direct stenting. The subsequent clinical course during hospitalization was uneventful, and the patient was discharged alive.

Key words: acute myocardial infarction, anomalous coronary artery, coronary stent, left main coronary artery, primary angioplasty

In 1.5–2.0% of patients with acute myocardial infarction (AMI) referred for primary percutaneous coronary intervention (PCI), left main trunk (LMT) is identified as the culprit vessel.^1,2 Although comparative data with urgent surgical revascularization are lacking, PCI at the time of diagnostic coronariographic study is the most frequently accepted treatment in this setting.^1–4 Among the congenital coronary anomalies, an anomalous origin of the LMT from the right sinus of Valsalva is very uncommon.^5,6 We describe a patient with lateral AMI referred for primary PCI in which an anomalous LMT originating from the right coronary artery (RCA) proved to be the infarct-related artery. Direct stenting was used to successfully treat this vessel; subsequently, a tight lesion on the RCA was also treated. Case Report. A 73-year-old patient with prior history of hypertension, smoking, diabetes type II and hypercholesterolemia presented at the emergency room with chest pain lasting approximately 1 hour. Electrocardiogram showed ST-segment elevation in leads I, aVL and aVR, as well as ST-segment depression at the inferior leads and left deviation axis, associated with widening of the QRS complex (Figure 1A). The patient was referred for primary PCI, the first-choice reperfusion therapy for AMI at our institution. As part of our protocol, the non-infarct related artery (RCA) was catheterized first. The initial angiogram showed an anomalous origin of the LMT from the RCA, apparently with a septal course,^7,8 with an angiographic image of intraluminal filling defect highly suggestive of thrombus and a TIMI (Thrombolysis in Myocardial Infarction) flow grade III. In addition, a severe and focal lesion was present at the distal RCA. Figure 2 shows the typical angiographic “eye” sign indicating the septal course of the LMT. A 6 French, Judkins Right guiding catheter (Cordis Corporation, Miami Lakes, Florida) was placed in the LMT, and a Balance Middle Weight™ guidewire (Guidant Corporation, Santa Clara, California) was placed distally. A 2.75 x 9 mm S7 AVE stent (Medtronic AVE, Inc., Minneapolis, Minn.) was directly implanted in the LMT with an excellent angiographic result. Afterward, using the same guiding catheter and guidewire, the RCA was selectively catheterized, and successfully treated with direct implantation of a 3.0 x 12 mm Syncro stent (Sorin Biomedica Cardio, Saluggia, Italy) (Figure 3). After the procedure, chest pain disappeared and the electrocardiogram (ST-segment deviation, interventricular conduction and QRS complex axis) returned to normal (Figure 1B). The subsequent clinical course during hospitalization was uneventful, without recurrent ischemia or heart failure. Peak creatinine-phosphokinase value was 644 IU, and no Q-wave developed on the electrocardiogram. An echocardiographic study showed only mild lateral hypokinesia with preserved left ventricular ejection fraction. Six-month angiographic follow-up showed no restenosis. Discussion. LMT is the infarct-related artery in approximately 1.5% of AMI patients referred for primary PCI;^1,2 this frequency is increased in the presence of left bundle brunch block⁹ or cardiogenic shock.¹⁰ Urgent coronary bypass grafting is associated with very high mortality in this setting,¹¹ and PCI at the time of diagnostic coronariography is the preferred treatment modality in most centers.^1–4 However, despite the achievement of a successful coronary recanalization in most cases, the mortality rate in this challenging situation remains high, ranging from 50–69%.^1–4 This is mainly due to the very high frequency of cardiogenic shock at presentation, since the incidence of other complications is not increased.¹² One of the advantages of primary PCI as a reperfusion strategy for AMI is the immediate knowledge of coronary anatomy. Congenital coronary anomalies are present in approximately 1% of patients referred to cardiac catheterization.^5,6 Although some difficulties in selecting the guiding catheter may complicate the procedure, PCI of anomalous-origin coronary arteries in the scenario of primary angioplasty has already been reported, especially for the RCA.^13,14 In addition, some cases of PCI of an anomalous LMT originating from the RCA have been described, but only in patients with stable or unstable angina.^15,16 A case of primary PCI for an anomalous LMT originating from the RCA is presented herein. The angiographic appearance of the typical “eye” sign in the right anterior oblique view indicated a septal course of the LMT.^7,8 As shown in Figure 2A, the left lateral view allows the visualization of both the anomalous LMT and the RCA in a single projection, and is thus very useful in these cases. Of interest, the typical electrocardiographic sign consisting of ST-segment elevation in aVR > V1, described by Yamaki et al. and highly suggestive of LMT infarction, was present in our patient.17 The favorable clinical course of our patient after the procedure may be explained by the absence of cardiac failure and cardiogenic shock at admission, as well as the short time delay since symptom onset. Finally, due to the technical facility, the RCA was also treated during the same procedure, despite our general rule of treating only the culprit vessel of primary PCI in patients with AMI and multivessel disease.¹⁸ Theoretically speaking, ad hoc treatment of the RCA could be potentially hazardous in a patient with an AMI caused by severe left main disease. However, the excellent result readily obtained in the left main, together with the angiographic severity of the right coronary lesion, encouraged us to proceed with a complete revascularization. Finally, since the infarct-related artery was patent with thrombus in the left main, and the patient was hemodynamically stable, other therapeutic approaches, such as coronary artery bypass grafting, thrombolysis and/or glycoprotein IIb/IIIa inhibitors, could have been considered instead of immediate PCI. However, we applied the latter because: 1) complete occlusion of the left main (if PCI was not applied) could have been potentially lethal; 2) we considered the procedure technically feasible; and 3) coronary stenting in thrombus-containing lesions is associated with very high immediate angiographic success.¹⁹