Acute Anterior Wall Myocardial Infarction in a Young Patient with Thrombotic Occlusion of the Left Anterior Descending Coronary Artery

In the previous issue of this publication, the INFUSE-AMI [Intracoronary Abciximab Infusion and Aspiration Thrombectomy in Patients Undergoing Percutaneous Coronary Intervention for Anterior ST Segment Elevation Myocardial Infarction (MI)] trial was discussed¹ and a representative case presented². Herein, another case of anterior wall ST-elevation MI percutaneous coronary intervention (PCI) is discussed where the patient’s presentation is beyond four hours. In this case report, we would like to highlight some of the differences that an operator may encounter in patients presenting beyond four hours and possible solutions.

Case Report

A 49-year-old gentleman with histThe patient is a 46-year-old gentleman with no prior history of coronary artery disease who presented to the emergency room with six hours of chest pain and an electrocardiogram (EKG) consistent with acute anterior wall myocardial infarction (Figure 1). He was seen in the emergency room, received aspirin 325 mg and was sent emergently to the cardiac catheterization laboratory for primary PCI. The patient was given 180 mg of ticagrelor at the start of the procedure. Coronary angiography revealed total occlusion of the proximal left anterior descending coronary artery (LAD) at the origin of diseased diagonal branch (Figure 2). All other vessels were patent with mild disease and ejection fraction (EF) was 40%. At this point, intravenous (IV) bivalirudin was started and a 7 French (Fr) extra back-up (EBU) 3.5 guide catheter (Medtronic) was used from the right femoral approach. A 0.014-inch Balance Middleweight (BMW) wire (Abbott Vascular) was utilized to cross the total occlusion of the LAD and another wire was placed in the diagonal branch. Aspiration thrombectomy of the LAD was performed with the Xpress-Way RX extraction catheter (Atrium Medical) (Figure 3). This was followed by localized, super-selective administration of abciximab in the lesion using a 1.5x20 mm ClearWay therapeutic infusion catheter (Atrium Medical) (Figure 4).

Post abciximab infusion, the LAD had normal flow with significant angiographic reduction in thrombus burden (Figure 5). At this point, a drug-eluting stent in the LAD had been planned; however, we were concerned about plaque shift and loss of the diagonal artery. As a result, balloon dilation of the diagonal artery was performed. Subsequent to the balloon dilation, a 3x38 mm Xience Prime drug-eluting stent (Abbott Vascular) was implanted in the LAD. This stent was examined with an Eagle Eye Platinum intravascular ultrasound catheter (Volcano Corporation) (Figure 6). Based on the intravascular ultrasound finding, the stent was post dilated in proximal segment to 4 mm with the Trek NC balloon (Abbott Vascular). At this point, a dissection was noted in the diagonal artery proximal segment. Due to the dissection, a 2.5x15 mm Xience V drug-eluting stent was implanted in the diagonal proximal segment using the provisional T And small Protrusion (TAP) technique (Figure 7). Post diagonal stent, a kissing inflation in the LAD and diagonal artery was performed using a 2.5x20 mm Trek NC balloon in the diagonal and a 3.5x20 mm Trek NC balloon in the LAD. The final result was excellent, with TIMI-3 flow and a myocardial blush grade of 3 in the LAD (Figure 8). A follow-up EKG demonstrated resolution of ST changes (Figure 9).

The patient had an uneventful recovery and was discharged on aspirin 81 mg and ticagrelor 90 mg twice daily for one year, in addition to other cardiovascular medications.

Discussion

The “delayed presenter” during STEMI PCI presents challenges beyond recanalization of the infarct-related artery. These patients likely have more fibrotic thrombus, which isn’t necessarily apparent on angiography. The additional risk of case complications, such as embolization, slow flow/no reflow, poor EF, TIMI flow, myocardial blush grade, and lack of ST resolution, are magnified in this patient population, leading to increased mortality.³ Using a plain old balloon angioplasty technique in this scenario to re-establish flow is likely to set the stage for managing serious adverse events during recanalization of the artery.

In this case example, the patient presented at approximately 6 hours from onset of chest pain. Patients presenting beyond 4 hours will likely have larger clot burdens and more fibrous clot, which may reduce the effectiveness of complete thrombus removal via manual extraction catheter. It is our observation that the technique of utilizing localized delivery of a IIb/IIIa bolus delivered via the ClearWay super-selective drug delivery catheter as a first-line thrombus management strategy has a softening effect on fibrous clot. Super-selective administration of a IIb/IIIa agent delivered in high concentrations causes dissolution of thrombus via platelet dissagregation⁴, which then may make clot removal via manual aspiration more amenable. Figure 10 describes the stratification protocol used in our lab to ensure successful revascularization when treating late-presenting patients.

Recent trials using the newest optical coherence tomography (OCT) devices available^5,6 showed significant clot burden being left behind after manual extraction and plain old balloon angioplasty. It is important, then, to consider the drugs that will be chosen pre-emptively to manage case complications that may result from thrombus protruding through stent struts or debris that may likely become embolized during PCI in this patient population. Despite mortality benefit, neither the TAPAS trial (IV administration of abciximab), nor the HORIZONS-AMI trial (IV administration of heparin + IV abciximab or IV bivalrudin) showed reduction in the infarct size.^7,8 The fact that a reduction in infarct size was not observed in these trials could be explained by the inclusion of patients out to 12 hours, some of which may have had organized thrombus burden which did not respond to IV administration of IIb/IIIa or IV bivalrudin.

In the two arms of INFUSE-AMI⁹ that received intracoronary administration of bolus-only abciximab via the ClearWay catheter, the reduction in infarct size was significant versus IV administration of bivalrudin alone. It seems that the high concentration of intracoronary, bolus-only abciximab offers protective effects in resolving residual clot that remains after either plain old balloon angioplasty or extraction, resulting in preservation of the greatest amount of heart muscle through reduction in infarct size. However, INFUSE-AMI enrollment criteria included only patients with onset of chest pain out to five hours (with the average onset to device time of 99 minutes). The question remains, would the successful strategy employed in INFUSE-AMI also translate for patients presenting later, and/or in other territories? In our experience, the combination of both thrombus management strategies in patients presenting beyond five hours results in less adverse case complications and better long-term outcomes.

Dr. Dave can be contacted at rdintervention@yahoo.com.

Disclosure: Dr. Dave reports consultant, research and training honoraria from Atrium Medical, speaking honoraria from Lilly/Daichi Sankyo, and research, training and speaking honoraria from Abbott Vascular.

References

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