Is There a Right Way to do PCI for STEMI? Variations in the Step-by-Step Approach to STEMI Patients in the Cath Lab: Results from a Survey of SCAI Operators

You’re called into the cath lab for an ST-elevation myocardial infarction (STEMI).  On arrival you learn your ‘favorite’ attending physician is not covering tonight. Dr. Newguy is going to be the operator. What equipment should you pull out? What order of the procedure does this individual use? Is he a radial-first operator? Will he do left ventriculography (LV gram) or a right heart cath? Is there a right or wrong way to do percutaneous coronary intervention (PCI) for a STEMI?

What determines the appropriate steps for STEMI PCI?

The step-by-step mechanics of treating STEMI patients depend not only on the presentation of the patient but also on the operator’s preferences, biases, skill set and habits, and perhaps the cath lab traditions and routines.  As one might expect in the practice of medicine, if the techniques used in the cath lab are the only way or the unequivocal best way to do something, there is no debate. On the other hand, many things in the cath lab that we do and the order in which we may do them are open to discussion, since there may be no data to support better outcomes with one method or the other. I’m sure one of my colleagues will remind me that we don’t need a randomized trial to test the value of parachutes when jumping out of an airplane. But how about the value of an LV gram before or after PCI for STEMI?

How should angiography and PCI be done in the routine STEMI patient?

Before going into the variations of the approach to STEMI, here’s one method that we use for routine, uncomplicated STEMI patients. Starting in the emergency department (ED), the patient and his electrocardiogram (ECG) are confirmed to be an acute STEMI presentation. A history and physical exam should exclude any contraindications to proceeding immediately to the cath lab. The patient is consented and further prepared with the application of radiolucent ECG leads, and good, working IVs.  Groin access preparation (despite our radial-first approach) is completed by ED staff. These steps are done while the cath lab team and operator are in transit. The patient is transferred to the cath lab as soon as possible.

In the cath lab, our team sets up for radial artery access unless informed otherwise. After vascular access is achieved, a universal catheter (like a Jacky [Terumo] or its equivalent) is advanced and the non-culprit artery imaged, quickly followed by an angiogram of the culprit artery. A guide catheter is then exchanged and advanced to the culprit coronary ostium, followed by PCI, occasional thrombectomy, and after an uncomplicated stent placement, left ventriculography. Vascular closure is then performed. It is important to recall that the appropriate pharmacology before PCI includes heparin, clopidogrel or ticagrelor, and use of bivalirudin, now popular among our small group of operators. After PCI, only the P2Y12 drug and aspirin are continued and the patient receives other routine medications for coronary artery disease (CAD), hypertension, hyperlipidemia, diabetes, and other conditions as clinically indicated.  

Operator variations in the approach to STEMI PCI

However, as every cath team member is aware, in the cath lab there is usually more than one way to perform almost any intervention, including STEMI PCI.  Is there one right way to proceed for the STEMI patient, especially as there is pressure to reduce the door-to-balloon time? With the help of the Society for Cardiovascular Angiography and Interventions (SCAI), Chiang et al¹ conducted a survey of SCAI members asking for their preferred step-by-step mechanics of treating the STEMI patients. The results are enlightening. Let’s see what the SCAI operators said.

Preferences for initial access and angiographic approach

Of the 2910 members receiving the survey, 326 responded that their preferred access approach was femoral (83%) compared to radial (17%). When asked should you do diagnostic image of the non-culprit artery first, 58% said yes. In thinking about this, some operators would say you may be delaying the door-to-balloon (DTB) time by performing angiography of the non-culprit vessel before getting down to the business of the reperfusion (i.e., achieving shortest DTB). Like most in the survey, I prefer knowing how much CAD the patient has before proceeding.  While this knowledge will not likely change my decision to proceed with the culprit PCI, it does add information about risk if the non-culprit artery is totally occluded, an uncommon scenario. But more complete coronary angiography could be a critical piece of information during the PCI should no reflow or some other complication occur. It is noteworthy that 23% of respondents also performed complete diagnostic angiography before inserting a guide catheter (Figure 1). One advocate for this approach reports complete angiography gives the whole picture of disease and also gives information on what guide catheter may be best suited for the PCI.

Left ventriculography in the STEMI patient

Among the steps with wide agreement was the timing and use of the LV gram. Only 9% perform an LV gram before PCI. Most respondents (66%) perform ventriculography during or after PCI. Twenty-five percent (25%) said they never do an LV gram in the STEMI patient (Figure 2). From my view, the LV gram after the PCI provides two pieces of information which may help in the post procedure care: 1) the LV end diastolic pressure (EDP) and 2) extent of wall motion abnormalities. LVEDP provides some guidance for management of the patient’s volume status and the potential for heart failure and possible causes of low blood pressure relative to the LVEDP. The LV function (i.e., left ventricular ejection fraction [LVEF]) predicts outcome. An LV gram at the end of the procedure is safe (safer when using a pigtail catheter rather than end-hole catheter — see below) and gives the operator an immediate and complete understanding of wall motion abnormalities, filling pressure and mitral regurgitation. Most of the time in the routine STEMI PCI, the LV gram will change little, but waiting for the same information by echo later that night or the next morning may delay appreciation of causes of low output or hypotension.

Routine thrombectomy?

The use of aspiration thrombectomy for STEMI has swung from one end of the spectrum to the other based on results of large trials that have produced contradictory information.^2,3 The TAPAS study² said manual aspiration of thrombus should accompany all STEMIs, whereas the TASTE³ trial recently published came to the opposite conclusion. The uncertainty involved in the outcomes of such practices about thrombectomy is reflected in the respondents’ answers. When asked, “Do you routinely use thrombus aspiration for STEMI?”, 49% said yes routinely, 43% selective only, 8% said rarely or never (Figure 3). If aspiration of thrombus had clear benefit, it’s likely we all would be using it.  

Part of the problem with the contradictory results of the thromboaspiration studies is that the thrombus is not the only factor that determines the patient’s outcome. We should recall that the most important variable of improved outcome in the STEMI patient is the ischemic time, the time from onset of ischemia to reperfusion, and not necessarily the DTB or removal of thrombus. Reduction of true ischemic time likely plays the biggest role in saving myocardium. Considering the ischemic time, we know why a reduction of DTB time of 15 minutes has not translated into better outcomes. The answer can be easily understood. For example, if the patient had 10 hours of ischemic time before coming to the hospital and then a 60-minute DTB time, he might do worse than a patient with a 2-hour onset of pain (ischemic time) and a 90-minute DTB time. The outcomes with thrombectomy for the STEMI patient must content with appreciating and incorporating the ischemic time as a key variable. My bias is that a very large thrombus burden will produce slow flow during stenting if we don’t attempt to debulk the thrombus load.

Are there STEMI practices that should be avoided?

Any practice that has potential harm with little or no benefit obviously should be carefully considered and avoided, especially in the STEMI patient. Unnecessary delay should be avoided to give the patient a chance with a short DTB time, but never at the expense of the institution of appropriate support measures including intubation, pacemaker insert, LV support device application, or other needed therapies. A right heart cath is rarely needed and was almost never done before PCI. Routine insertion of a pacemaker has long been abandoned. Routine use of large-size guides (e.g., 8 French) is unnecessary without a specific plan for large therapeutic device application (like Rotablator, but not in STEMI patients).  

I have heard of some very unusual idiosyncratic approaches to STEMI patients, with one operator performing the procedure only under fluoroscopy and other odd techniques. Finally, on my polling many cath lab directors across the country and several in Europe, LV angiography should not be done with end-hole catheters.⁴ 

The bottom line

I highly recommend that reviewing the paper by Dr. Chiang and colleagues to gain insights on the practices of the different operators in your lab. My bottom line is that the PCI approach to STEMI across a large variety of presentations and patients has only a modest variation of step-by-step mechanics and has resulted in good if not great outcomes. The reduction of morbidity and mortality of the STEMI patient through the efforts of the many diligent cath lab teams and operators remains a testament to our (all of our) lab’s dedication to improving the lives of our patients.

References

1. Chiang A, Gada H, Kodali SK, Lee Jeremias A, Pinto DS, Bangalore S, Yeh RW, Henry TD, Lopez-Cruz G, Mehran R, Kirtane AJ. Procedural variation in the performance of primary percutaneous coronary intervention for ST-elevation myocardial infarction: A SCAI-based survey study of US interventional cardiologists. Catheter Cardiovasc Interv. 2014 Apr 1; 83(5): 721-726. doi: 10.1002/ccd.25276.
2. Vlaar PJ, Svilaas T, van der Horst IC, et al. Cardiac death and reinfarction after 1 year in the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS): A 1-year follow-up study. Lancet. 2008; 371: 1915-1920.
3. Frobert O, Lagerqvist B, Gudnason T, et al. Thrombus Aspiration in ST-Elevation myocardial infarction in Scandinavia (TASTE trial). A multicenter, prospective, randomized, controlled clinical registry trial based on the Swedish angiography and angioplasty registry (SCAAR) platform. Study design and rationale. Am Heart J. 2010; 160: 1042-1048.
4. Kern M, with Bailey S, Babb J, Bell M, Bittl J, Chambers C, DeBruyne B, Garrett K, Jeremias A, Klein LW, Krucoff M, Pichard G, Rizik D, Stone G, Tommaso C, Uretsky B, Ver Lee P, Vetrovec G, Vidovich MI, Weiner B, Welt F, White C. Conversations in cardiology: the end of end-hole left ventriculography – a consensus of operators. Cath Lab Digest. 2013 Nov; 21(11): 4-14.