SCAI Releases Practical, Technical Advice for Primary PCI in STEMI

The Society for Cardiovascular Angiography and Interventions (SCAI) has released a new expert consensus statement on the management of patients with STEMI referred for primary PCI.

The statement, which was led by writing chair Jacqueline Tamis-Holland, MD (Cleveland Clinic, OH), and co-chair Yader Sandoval, MD (Minneapolis Heart Institute/Abbott Northwestern Hospital, MN), provides practical advice for working physicians, including directions on how to handle trickier clinical scenarios, such as dealing with a large thrombus burden or no-reflow phenomenon encountered during the procedure.

“Clinical guidelines have really become very patient-oriented, but they don’t get into details regarding technical aspects of care,” Tamis-Holland told TCTMD. “They also don’t go into things that don’t have a lot of evidence, such as activating the cath lab before hospital arrival or when to bypass the emergency department. We felt it was important to emphasize the way we should manage these STEMI patients, particularly in the cath lab where there's very few guideline recommendations and a lot of variability from physician to physician.”

Published this week in JSCAI, the paper outlines standard equipment required of every cardiac catheterization laboratory performing primary PCI, including plaque modification tools, microcatheters, transvenous pacing, guide extension devices, and aspiration catheters. It’s also recommended that centers have intravascular ultrasound or optical coherence tomography on hand to assess lesion morphology and to guide PCI. Mechanical support for cases of refractory shock also is strongly recommended.

“If you’re doing primary PCI, we felt you shouldn’t be treating STEMI if you don’t have some type of support device and imaging,” said Tamis-Holland.

Intracoronary imaging is necessary to understand the mechanisms underlying stent thrombosis or stent failure when it occurs, the statement notes. In situations where it’s thought STEMI might have a nonatherosclerotic origin, such as in cases of epicardial vasospasm, spontaneous coronary artery dissection, coronary embolism, or MI without obstructive coronary arteries, intracoronary imaging can also help in assessing lesions and understanding the cause of the infarction.

‘Achilles’ Heel of STEMI Care’

In the current US guidelines, radial access is preferred to a femoral approach in patients with ACS and stable ischemic heart disease, and the SCAI experts recommend transradial access as the default strategy. In line with the practical nature of the statement, however, Tamis-Holland said there will be extenuating circumstances—absent radial pulse or pulsatility on ultrasound, need for an 8-Fr sheath or larger, prior CABG with bilateral left internal mammary artery graft and left radial graft, among other situations—when radial access doesn’t work.   

“We really did focus on the fact that it's okay if you do femoral access in certain situations,” she said. “We didn't want the practitioner to struggle with radial access only to say, ‘Oh, I have to do this way because the SCAI consensus document says so.’ Radial access is default, but there are circumstances where you could use femoral access and that's okay because it's best for the patient.”

In addition, the SCAI experts offer practical direction on how best to manage thrombus during PCI. In situations where there is total or subtotal occlusion, the assessment of thrombus grade should happen once the coronary wire has crossed the lesion. If the thrombus is small (grade 0-3), operators are advised to proceed with balloon dilation and stent placement (and to consider direct stenting if there is no calcium). If the thrombus is large, bailout aspiration thrombectomy is an acceptable strategy, while parenteral (or intracoronary) antiplatelet agents can be used for refractory thrombus.   

Additionally, the writing group gives advice on how to manage coronary reflow during primary PCI. If no-reflow is observed, the goal is to reverse vasoconstriction and treat microvascular thrombosis. Intracoronary arteriolar vasodilators, such as adenosine, nitroprusside, calcium channel blockers, or diluted epinephrine, should be delivered to the distal coronary bed as necessary.

Tamis-Holland said large thrombus and no-reflow are sticky situations made challenging because there isn’t a lot of data. The practical recommendations around how to best deal with these scenarios are the “meat of the document,” she added, because dealing with large thrombus and no-reflow remain the “Achilles’ heel of STEMI care.”  

The SCAI group also outlines suggestions for managing key anatomical subsets, such as patients with coronary calcification, bifurcation lesions, and coronary aneurysms/ectasia. Plaque modification for calcified lesions can help with stent placement and expansion while a provisional one-stent strategy in bifurcation lesions is recommended. Restoration of flow is the most important goal of managing coronary artery aneurysms, the group says, and this might require advanced techniques to manage the thrombus, such as mechanical or manual aspiration thrombectomy or the use of intravenous glycoprotein IIb/IIIa receptor inhibitors.

Time to Reperfusion

The consensus statement lays out appropriate reperfusion times for primary PCI, with the recommendations in line with clinical performance and quality metrics from the American College of Cardiology/American Heart Association.

For the patient with symptoms who calls 9-1-1 or goes directly to a PCI-capable hospital, an ECG by emergency medical services (EMS) or hospital staff should be performed within 10 minutes and PCI should be performed within 90 minutes. If the patient goes to a non-PCI-capable hospital, an ECG should be taken within 10 minutes and they should be transported to a PCI-ready hospital within 45 minutes. In this scenario, PCI should be done within 120 minutes of first presenting to the non-PCI-capable hospital. If PCI can’t be done within 120 minutes of first medical contact, fibrinolysis is recommended, but it has significant limitations compared with revascularization, according to the SCAI experts. 

Prehospital activation of the lab is also recommended for patients presenting via EMS, say the SCAI experts. When it comes to prehospital activation of the cath lab by EMS or the emergency department (ED), Tamis-Holland said there is some regional variability, but the transmission of the 12-lead ECG, which is recommended, allows physicians to review the findings, agree with the diagnosis, and anticipate potential diagnostic and therapeutic interventions. Physician review also cuts down the risk of false-positive activations. Bypassing the ED and going straight to the cath lab is recommended for stable STEMI patients, too.

“There are ways we can improve the whole team-based approach to reducing time, and I think that's really important, but I also think it’s important that we spend time [in our document] indicating that you shouldn't rush so much that you miss an obvious aortic dissection or something else,” said Tamis-Holland. 

Finally, the SCAI writing group highlights emerging approaches for reducing infarct size, noting that bigger infarcts are associated with a higher risk of MACE. These include the approved use of supersaturated oxygen to reduce infarct size in patients with anterior STEMI undergoing primary PCI within 6 hours of symptom onset. Mild hypothermia and left ventricular unloading have also been explored as possible means to reduce infarct size, but there are very limited data to support any adjunctive approach, including supersaturated oxygen, as part of routine first-line therapy during primary PCI of STEMI patients.