Question 1

Are the stents used in these cases metallic stents or bioresorbable scaffolds?

Dr. Subhash Chandra · Accepted Answer

The stents I used in these cases are all drug-eluting stents made of a cobalt chromium or platinum chromium alloy. Some carry a biodegradable polymer, but the majority have a durable polymer, and the drug is usually a limus drug, everolimus or sirolimus. After the Absorb controversy we use bioresorbable scaffolds very sparingly, only in very niche, simple type A lesions. Beyond that, we are not ready to use them in our practice; what we do use more and more are drug-eluting balloons.

Question 2

Prevention is better than cure. For public awareness, what are the general causes of calcified coronary arteries?

Dr. Subhash Chandra · Accepted Answer

Some people presume that taking calcium tablets leads to calcium being deposited in the arteries. That is not how it happens. Atherosclerosis is a process of plaque formation in which the lipid core, macrophages and other cells build the plaque, with a constant cycle of injury and healing. This recurrent healing after injury is what deposits calcium in the vessel wall, so calcium is part and parcel of the healing of plaques that form over decades. Nature also has a balancing act: calcified plaques are largely stable plaques and rarely cause acute coronary syndromes. Soft plaques are the ones susceptible to rupture, and a soft plaque can rupture one fine day and cause an acute coronary syndrome even when the lesion is not significant. That is not the case with thick-capped calcified plaques, which is an advantage.

Question 3

What is the best imaging for assessing the vessels before the procedure?

Dr. Subhash Chandra · Accepted Answer

Beyond a simple angiogram and the stent-enhancement imaging available in the cath lab, intravascular ultrasound (IVUS) is the best option when you want to avoid contrast, because it needs no contrast and so adds no risk of contrast-induced nephropathy. If the patient's kidney function is good, optical coherence tomography (OCT) is perhaps the best tool, because it shows not only the distribution of calcium but also its thickness, which IVUS cannot measure. IVUS at best shows a dark shadow behind the calcium or the napkin-ring calcium, whereas OCT gives a very crisp picture in which the thickness of the calcium comes out clearly. That helps you choose your tools much better than ultrasound alone.

Question 4

If a problem arises during one of these procedures, do you have to open the chest and work on the heart itself, or do you use a technique such as robotic surgery to place the stent?

Dr. Subhash Chandra · Accepted Answer

Opening the chest and robotic surgery are not our domain. We are interventional cardiologists: we do the angioplasty through small punctures with wires and catheters, and the rest is with our cardiac surgical team. If a calcified angioplasty runs into trouble and the patient needs surgery, whether on the heart-lung machine or as beating-heart bypass surgery, that is decided under the heart team concept: the cardiac surgeon, the interventional cardiologist and the anaesthetist decide together what is best for the patient. We try our best not to land in problems while doing these cases, and we work as a team.

Question 5

Is the stent absorbable or metallic? If it is not absorbable, how long can a patient keep it in place before it has to be changed?

Dr. Subhash Chandra · Accepted Answer

Today the majority of stents used worldwide are metallic stents made of cobalt chromium or platinum chromium alloy, coated with a durable or a bioresorbable polymer that controls the release of the drug, which is everolimus or sirolimus. That is how modern stents work. Bioresorbable scaffolds had an era with Absorb, which did not succeed over a period of five or six years and was withdrawn. In India there is a locally made bioresorbable scaffold with 100-micron struts, which is used here occasionally in very niche type A lesions and has done well. We look ahead to the future availability of bioresorbable scaffolds; short of that, drug-eluting balloons are being used more and more, which is a subject for another seminar. A metallic stent never needs to be changed. A cobalt chromium stent, with very thin struts of 60 to 80 microns, stays in the body permanently and after healing becomes covered by a very thin layer of tissue. Where the stent has a bioresorbable polymer, the polymer disappears over the following months along with the drug; a stent with a durable polymer keeps it for life. There is no question about its life and longevity.

Question 6

A patient with Canadian Cardiovascular Society class 2 angina and inducible ischaemia on stress myocardial perfusion imaging has good kidney function, an LDL of 44 and preserved left ventricular function (ejection fraction 60 to 65%), with symptoms that began after earlier cancer treatment. Angiography shows two-vessel coronary disease with 70 to 90% stenoses: multiple lesions in the mid right coronary artery and a calcified LAD and diagonal bifurcation lesion (Medina 1,1,1), with a SYNTAX score of 28. What is the best treatment plan?

Dr. Subhash Chandra · Accepted Answer

At a SYNTAX score of 28 this would definitely be a case more favourable for bypass surgery. If the SYNTAX score were less than 23, angioplasty and bypass would be in equipoise and angioplasty could have been done. Here nothing precludes surgery: kidney function is good and left ventricular function is good, so most things favour a straightforward bypass operation. If the patient chooses angioplasty, then with modern tools even angioplasty of this 1,1,1 bifurcation, which is the most crucial lesion, is possible, and the other lesions, including the diffuse or multiple plaques in the right coronary artery, can be dealt with easily. My first choice is bypass surgery; short of that, angioplasty is also possible.

Question 7

Diffuse plaque with heavy intracoronary calcium is often missed as significant coronary disease. How should it be managed?

Dr. Subhash Chandra · Accepted Answer

Calcified plaques that are not critically blocking the artery have the advantage of being very stable. They can be managed with dual antiplatelet therapy and a good dose of statins, and unless they cause angina or there is objective evidence of ischaemia on a stress scan or thallium imaging, one need not rush to treat them. If the plaque is diffuse and the lesions are significant because of the underlying calcium, something needs to be done, but you should not put stents everywhere in the coronary arteries. Today we use a hybrid approach: in the major arteries we place stents after preparing the bed with rotablation or intravascular lithotripsy, and in the diffusely diseased distal vessels we use a cutting balloon followed by a drug-eluting balloon, which works much like a stent there. Too much metal in small-calibre arteries is not a good idea because it brings more restenosis. That is how I treat them.

Question 8

For the same patient, the team has planned staged PCI of the calcified LAD and first diagonal bifurcation: rotablation and a drug-eluting stent for the long calcified LAD segment, and a drug-coated balloon for the diagonal. Is there any guidance on this plan?

Dr. Subhash Chandra · Accepted Answer

That is the way to do it. We use drug-coated balloons in more and more bifurcations these days to treat the diagonal branch. The sequence can change, and you can treat the diagonal branch first, but most of the time we place the stent in the main vessel, recross the side branch, pre-treat it very well so that its ostium is fully opened, and finally inflate a drug-coated balloon for 1 minute or 90 seconds, and then you are done, with no further intervention on the side branch. This has become a default approach for us, especially for the distal left main with the circumflex as the side branch: instead of a simple balloon angioplasty of the side branch, we treat it with a drug-coated balloon after a provisional stent in the main artery. So I quite agree with this approach.

Question 9

When standard angiography underestimates calcification, which IVUS or OCT parameters, such as calcium arc, length or thickness, make you switch from standard balloon predilatation to advanced calcium modification?

Dr. Subhash Chandra · Accepted Answer

On OCT, a calcium arc of more than 180 degrees, a calcium thickness of more than 0.5 mm and a calcium length of more than 5 mm would definitely take the lesion beyond non-compliant balloons, to rotablation, orbital atherectomy or intravascular lithotripsy. If there is calcium deep in the vessel wall as well, intravascular lithotripsy is the best choice; otherwise rotablation. One may try a cutting balloon when the arc is around 180 degrees, but if the arc is 360 degrees, a napkin ring all the way round, you will definitely not succeed with simple non-compliant balloon angioplasty and must rely on one of these tools. That is how we approach it.

Question 10

In thick, deep, concentric calcification compared with superficial calcified nodules, how do you decide between intravascular lithotripsy and rotational or orbital atherectomy?

Dr. Subhash Chandra · Accepted Answer

Intraluminal calcium is amenable mainly to rotablation or orbital atherectomy. Orbital atherectomy works with a whipping, orbital motion, so the chance of the device getting stuck is very small; it is withdrawn backwards once it has crossed the lesion. Rotablation uses a front-loaded diamond burr that spins on its axis, and once it has crossed a lesion there is a chance that it gets stuck and does not come back. For calcium in the vessel wall, intravascular lithotripsy is perhaps the best tool: it is like cracking a deep-seated rock in a mountain. The calcified nodule is the biggest bane for the interventional cardiologist. Orbital atherectomy has some data for nodules, especially at the ostia or at bends, and intravascular lithotripsy has also shown remarkable results in calcified nodules. Some very recalcitrant nodules may, after everything else has been done, still need a super-high-pressure balloon to achieve a good minimal stent area. That is how we choose between the tools for calcium in the coronary arteries.

Live Discussion with Dr. Subhash Chandra