Should OCT be done routinely in MI Patients- Experts Opine

Medical science is evolving and so is Cardiology. A news report has emphasized role of optical coherence tomography (OCT) in delianeating cases of MI where PCI can be avoided.

There is a huge report in the Times of India in which doctors at the Surana Hospital in Chembur have used OCT (optical coherence tomography) along with angiography to treat 3 of their patients without Stenting since their patients were having plaque erosion and not rupture they could defer stenting. The news sparked a burst of views from many cardiology experts. Many responses criticized the inappropriateness of the headline and demanded that the Times of India retract the article.

This observation confirms EROSION Study presented at the European Society of Cardiology in 2016. The study published in the journal Circulation showed that ACS patients who have been screened by OCT and were found to have plaque erosion and not rupture could safely be treated with antithrombotic instead of stenting. The study found that 92.5% of the 53 patients who completed 12 months of follow up and were managed with ticagrelor and aspirin without stenting remained free of major adverse cardiovascular events (MACE).

The findings of the Surana Hospital doctors confirming EROSION Study have raised a very pertinent question which is that "Whether OCT imaging should be carried out routinely in all patients of myocardial infarction (MI) to obviate stenting in established cases of plaque erosion.

Explaining the logic behind doing OCT in MI patients, Dr Sandeep Mishra, Cardiologist and the Professor of Cardiology at AIIMS, New Delhi, told Medical Dialogues that "Myocardial infarction (MI) aka Heart Attack is a serious cardiac condition associated with significant morbidity and even mortality. Atherosclerosis is the underlying pathology, although immediate predisposition is plaque rupture in the majority of the cases. Aggressive medical therapy including thrombolysis can stabilize the plaque in most cases, but this plaque is prone to re-rupture contributing to a risk of recurrent MI. Angioplasty with stenting is the only definitive treatment in this case. However, in a minority of cases (up to 25%) MI may be caused by a calcified nodule or plaque erosion with thrombus formation on the top of it. Plaque erosions are especially commoner in very young patients like those between the age group of 20-30 years. Since in case of plaque erosion, there is no risk of re-occlusion; the treatment often involves only pharmacological or sometimes mechanical extraction of thrombus, with no need for stenting; the majority of cases (>90% ) be managed with just anti-thrombotic therapy. "

He adds "optical coherence tomography(OCT) is an invasive imaging technology which utilizes light to optimally visualize intimal aspects of vessel lumen including coronary artery. It can discriminate among the various abnormalities of intimal surface; dissection, erosion, thrombus formation and some sub-intimal problems as well. Thus, optical coherence tomography(OCT) is an important tool for evaluating the cause of MI but only in those cases where the chance of finding erosions is higher for e.g. very young MI patients (< 30 years)."

Elaborating on the limitation of OCT Dr. Mishra said “Currently major limitation of OCT is its cost. After price regulation while a drug-eluting stent costs only Rs 25,000 / - or so, at the moment cost of OCT is upwards of Rs 60,000 / - Thus while unnecessary stenting is always an issue, it may still turn out cheaper than the cost of doing OCT. Furthermore, excessive use of contrast required to do OCT can be a serious issue in renally compromised patients (renal function tests are often not available in acute situations like heart attack).”

Dr Mishra concluded that “While optical coherence tomography(OCT ) may not be useful in all cases of MI, it could be a useful test in those patients where the likelihood of plaque erosions is high like for instance MI patients in the age group 20- 30 year. “

Taking a cue from the EROSION study Dr. Ajay Jagannath Swami, Cardiologist at the Army Hospital, Indian Air Force, told medical dialogues that “ It is true that among acute MI patients taken up for primary PCI, those with TIMI 3 flow after plain balloon or thrombosuction, optical coherence tomography(OCT ) can help to elucidate the pathology in some cases. Contrast clearing to obtain interpretable images may not be always possible in absence of TIMI 3 flow. However, it leads to the use of additional contrast and adds procedure time that could be detrimental to patients. 3. It is premature and inappropriate to rush to the conclusion that every Primary PCI should undergo OCT. A balanced approach to perform OCT in the patients who have no residual stenosis after plain balloon or thrombosuction may be candidates for OCT. This would on an estimate be only about 20 per cent of all primary PCI”