Optical coherence tomography 'reducing heart attacks'

21 May 2015

Imaging technique appears to improve outcomes for cardiac patients being fitted with coronary stents, finds large-scale trial.

OCT guidance

Clinical trials to assess the effectiveness of optical coherence tomography (OCT) imaging ahead of cardiac stent surgery is helping physicians make better interventions, and leading to better patient outcomes – including a reduced rate of heart attacks.

That’s according to St Jude Medical (SJM), the US-based medical equipment company whose OCT technology is currently the subject of two large-scale studies.

In those trials, conducted on more than 400 patients, OCT and other imaging techniques are used before surgery. The idea is to help surgeons better visualize individual anatomies, and decide exactly which size of stent should be used, and where it should be placed to best restore blood flow to the heart.

Announcing the findings as a late-breaking paper at the EuroPCR 2015 conference taking place this week in Paris, France, SJM said: “Taken together, the findings from both studies show that with resolution up to ten times higher than intravascular ultrasound, OCT imaging can help improve stent selection and deployment, better support clinical decision-making, and improve patient outcomes.”

“The ILUMIEN I and ILUMIEN II clinical studies provide important additional data and information to the body of clinical evidence supporting the use of OCT imaging guidance to optimize percutaneous coronary intervention (PCI, also known as coronary angioplasty),” added Mark Carlson, SJM’s chief medical officer. “These studies validate the important contribution of OCT in PCI treatment planning, and show a correlation between OCT imaging guidance and improved patient outcomes.”

Trial data
Precise planning of the intervention is crucial, because badly fitting stents can damage tissues surrounding blood vessels. Alternatively, if they are under-expanded once in place the stents can cause blood clots, or allow the original narrowing of the artery to recur.

The first of the trials, ILUMIEN I, represents the largest study to date on OCT’s impact in clinical decision-making and patient outcomes in the cardiology field. In it, 418 patients with angina – a symptom indicative of constricted coronary arteries – were assessed. The trial began in late 2012, at no fewer than 36 hospitals and clinics around the world.

SJM says that when OCT imaging was performed ahead of surgery, it altered treatment plans in 55 per cent of patients, leading to changes in the sizes of the stents being fitted. The company added:

“OCT imaging was associated with a reduction of in-hospital myocardial infarction (MI, the clinical term for a heart attack) when used pre- and post-PCI to change the procedural strategy.” SJM did not quantify the degree to which heart attack incidences were reduced.

“Perfecting” PCI
William Wijns, a co-director of the Cardiovascular Centre in Aalst, Belgium, said of the results: “Many physicians have long suspected that OCT’s higher resolution could support treatment planning and PCI procedural technique, and the ILUMIEN I study is another important step toward confirming OCT can contribute to the perfection of PCI.”

The second trial, on 940 patients, has been designed to determine whether OCT imaging yields the same degree of stent expansion as the more conventional ultrasound technique. Based on data from ILUMIEN I and also results from another trial of a new type of stent, it found OCT to be no different to ultrasound.

Gregg W. Stone, a professor of medicine at the Columbia University Medical Center and the chairman of that follow-up study, said: “The results of ILUMIEN II address long-standing questions regarding the ability of OCT guidance to achieve comparable stent expansion, more precise measurements and a greater level of vascular visualization than first-generation imaging tools such as intravenous ultrasound.”

That is not the end of the clinical trials, however. Up next is the multi-center and randomized ILUMIEN III study, in which stent implantation using guidance by angiography [X-ray], ultrasound and OCT imaging will all be evaluated against each other.

• SJM gained its OCT expertise with the 2010 acquisition of LightLab Imaging, the Massachusetts Institute of Technology spin-out started up by Jim Fujimoto and Eric Swanson, among others.

In 2011, when the company received European CE Mark approval for the ILUMIEN system, Fujimoto commented that the emergence of high-speed CCD sensors had been one of the critical technological developments to enable real-time OCT imaging for cardiovascular applications.