LAS VEGAS, NV – New angiographic data from the Preventive Angioplasty in Acute Myocardial Infarction (PRAMI) trial show that the degree of stenosis in nonculprit arteries is associated with risk of subsequent events, but that even patients with moderate blockages not treated at the time of primary PCI went on to have events.

The findings imply that using only high-percentage stenosis as a cut point when deciding whether to open a nonculprit lesion during primary PCI may lead to a large proportion of preventable subsequent events being "missed," Dr Keith Oldroyd (Golden Jubilee National Hospital, Glasgow, Scotland) said.

Oldroyd presented the new PRAMI results here at the Society for Cardiovascular Angiography and Intervention (SCAI) 2014 Scientific Sessions .

Current guidelines advise against the treatment of nonculprit lesions—a recommendation called into question by the main PRAMI results released at the European Society of Cardiology (ESC) 2013 Congress . PRAMI, which was published simultaneously in the New England Journal of Medicine, showed that treatment of nonculprit lesions during primary PCI reduced the risk of major adverse cardiac events (cardiac death, nonfatal MI, and refractory angina with ischemia).

In his presentation at the SCAI meeting, Oldroyd zeroed in on the group of patients whose nonculprit lesions were not treated, stratified by the degree of stenosis in the most severe, nonculprit lesion in each patient. All measurements were by in-lab quantitative coronary angiography (QCA) by the operator, not core-lab QCA, he cautioned.

Analyzed according to risk of MACE, patients with the most severe blockages (95%–99% stenosis) were the most likely to go on to have a MACE (47% of patients). However, patients with vessels with 75%–94% stenosis and even 50%–74% stenosis also experienced primary outcome events, at a rate of 23% and 14%, respectively.

"You may say, okay, I will only do the really severe lesions; I don't want to do touch anything that's severe or only moderately severe," Oldroyd observed. "But, if you cut it off at 95% to 99%, you will identify only 20% of the subsequent events, and you will miss 80% of the events. If you move the cutoff to 75%, this time you pick up 80% of the events, but you still miss 20%. So by sticking with a 50% [cutoff], you will pick up all the events as identified in the trial."

He also stressed that all MIs were spontaneous and not periprocedural troponin spikes, which were not counted as part of the primary end point in PRAMI. Moreover, the benefit of preventive PCI of nonculprit lesions appeared within the first month following the first treatment—a finding with implications for staged procedures.

The Next Burning Questions

In a panel discussion following Oldroyd's presentation, moderator Dr Ajay Kirtane (Columbia University, New York, NY) called this lesion-level data "probably the predominant thing people wanted to see" from the PRAMI investigators, following the presentation of the primary results. "What you've demonstrated is, not only were these spontaneous events not periprocedural events, but that there was perhaps a gradient effect leading to these events. That's a really important finding. For me, that's the first time I've ever seen this."

The next burning question, according to panelist Dr David Cohen (St Luke's Health System, Kansas City, MO), is whether those lesions need to be treated in the same setting "or, as many of us do occasionally in the United States, can you stage it two or three days later?" It will be important to tease out the "timing of benefit," he said.

Dr Michael Kim (Northshore University Hospital, Manhasset, NY), also on the panel, commented that most operators today will "fix" a >95% lesion at the time of PCI. These new data from PRAMI, and particularly the fact that MACE-event curves appear to separate almost immediately after the index admission, are enough to convince him to consider treating less severe lesions as well. "If that's true . . . I would probably now fix [those lesions] at the same time" as the culprit lesion," he said.

By contrast, Dr David Cox (Lehigh Valley Heart Specialists, Allentown, PA) said he won't change his practice on the basis of a single study. "At a busy center, I want to get my culprit gone and move on to the next MI that I know is coming an hour or two later," he said, prompting appreciative chuckles from the panel and audience. "The other issue is that, I think sometimes when you bring those folks back, that 75% looks like about 57%, and I wonder if a lot of those people will come back asymptomatic."

A lot hinges on whether nonculprit lesions in an "AMI milieu" are more vulnerable than comparable stenosis in stable CAD. "We commonly hear from our noninvasive colleagues that, after we treat the culprit lesion, that patient is now a COURAGE patient, and therefore the remainder of the disease does not need revascularization," Kirtane said. "The biggest lesson from [PRAMI] for me, and it needs to be substantiated, is that these are really different types of patients."

Survey Says

Oldroyd also showed results from a survey of US and non-US physicians that asked whether they believed preventive angioplasty of all non–infarct-related coronary stenoses >50% that are amenable to PCI prevent future MIs and adverse cardiovascular events.

Only 15% of both the US and non-US physicians answered yes, while 31% of US and 47% of non-US physicians said no (the remainder answered "unsure"). They also had similar responses with regard to how nonculprit lesions should be managed, with roughly one-third in both groups saying they would treat these medically, and over 50% of both groups saying they'd do a staged PCI. Where they differed was in the timing of that staged PCI. In the US, the largest group—42%—said they would do these procedures during the index admission. That's identical to the proportion of non-US operators who said they would do these procedures four to six weeks later.

Asked how UK operators have responded to the PRAMI results, Oldroyd said that treating nonculprit vessels during primary PCI has "not been accepted as standard of care," probably to the same degree as was seen in the survey results.

"In our own center, there is also some variable enthusiasm, depending on the time of the day or the weekend or whether there is another STEMI coming in. But I can speak for myself and for one of my colleagues who is the audience and say that we have fully adopted this strategy following the results of the trial."

Oldroyd and colleagues are hoping to pull the funding together for PRAMI 2, a study that could take a closer look at the timing of nonculprit-lesion PCI in STEMI. Another larger randomized controlled trial, named Complete vs Culprit-only Revascularization to Treat Multi-vessel Disease After Primary PCI for STEMI (COMPLETE), is currently enrolling in Canada and the US, aiming to recruit almost 4000 patients.

Cohen disclosed being an advisory board/board member for and receiving grant or research support from Medtronic, Eli Lilly, and AstraZeneca, as well as being on the speaker's bureau for AstraZeneca. Cox disclosed being an advisory board/board member for Medtronic, Boston Scientific, and Abbott Vascular. Kim disclosed grants/research support from Philips Healthcare. Oldroyd disclosed being on the speaker's bureau for AstraZeneca and St Jude Medical and receiving grants/research support from St Jude.

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