Treating Calcified Coronary Arteries

In calcified coronary arteries, atherosclerotic plaque has hardened with calcium deposits, making angioplasty and stenting far harder than in soft disease. Treating calcified coronary arteries well depends on planning: assessing heart function and haemodynamic support, choosing access and guiding catheters, imaging the calcium with intravascular ultrasound (IVUS) or optical coherence tomography (OCT), and preparing the vessel with the right calcium modification tool before any stent is placed.

Dr. Subhash Chandra, Chairman - Interventional Cardiology - Cardiology & Structural Heart Disease, BLK-Max Super Speciality Hospital, New Delhi, India, describes heavily calcified lesions as a real challenge for the interventional fraternity. The challenge is growing. Interventional cardiologists now see more patients whom surgeons have declined, more very elderly and high-risk patients, and more families who choose not to proceed with bypass surgery. For these patients, angioplasty is often the only revascularisation on offer, and its success rests on two things he names together: the operator's skill set and the tools at the operator's disposal.

This guide sets out the full approach, from why calcium forms to the planning checklist, the toolkit and the choice between stenting and surgery. Two companion articles go deeper: one on coronary calcium imaging with IVUS and OCT and how to choose a calcium modification tool, and one on rotational atherectomy, its complications and the bailout lessons from eight cases.

Why calcium forms in coronary arteries

Coronary calcium is a product of atherosclerosis, not of dietary calcium. Some patients assume that calcium tablets cause calcium to be deposited in their arteries. Dr. Chandra is clear that this is not the mechanism. Atherosclerotic plaque forms as a lipid core, macrophages and other cells accumulate in the vessel wall, and the plaque goes through a constant cycle of injury and healing. Calcium is laid down as part of that repeated healing. Because plaques form over decades, calcification is in effect a record of how long the disease has been present.

That is why calcified disease is most common in older patients, in people with diabetes and in those with chronic kidney disease, the same groups who are often poor candidates for surgery. The overlap is what makes calcified coronary disease such a practical problem.

Calcified plaque is usually stable plaque

Calcified plaques are largely stable and rarely cause acute coronary syndromes. Dr. Chandra calls this nature's balancing act. Soft, lipid-rich plaques are the ones that rupture: a soft plaque can rupture one day and cause a heart attack even when the narrowing it produces is not significant. Thick-capped calcified plaques do not behave that way.

This has a direct consequence for treatment. A calcified plaque that is not critically narrowing the artery can be managed medically, with dual antiplatelet therapy and a good dose of statin. Unless the patient has angina, or there is objective evidence of ischaemia on a stress scan or thallium perfusion imaging, he sees no need to rush into treating these lesions. Intervention is reserved for calcified disease that is flow-limiting and causing symptoms or ischaemia.

Planning angioplasty for calcified coronary arteries

In Dr. Chandra's words, planning is the most important part of doing angioplasty of a calcified lesion. His planning sequence runs in a fixed order.

1. Haemodynamic status and left ventricular function

The first question is how well the left ventricle is working. If a complication occurs during the procedure, the patient's ability to survive it depends largely on robust left ventricular function. Where left ventricular function is poor, the team must have haemodynamic support ready, in the form of an intra-aortic balloon pump, an Impella heart pump or another device.

2. Pharmacology

Patients should be loaded with dual antiplatelet therapy before the procedure. Dr. Chandra's preference is ticagrelor with aspirin, together with a statin. European guidelines name clopidogrel as the default P2Y12 inhibitor with aspirin for elective percutaneous coronary intervention (PCI, angioplasty with stenting) in chronic coronary syndromes, and allow ticagrelor or prasugrel to be considered in selected high-risk procedures, such as complex left main or multivessel stenting.

3. Access

His team performs almost 90% of interventions through the radial artery at the wrist. Complex calcified cases can be different. Here he may choose femoral access with a sheath of at least 7 French, because the procedure may need bulky equipment: a rotational atherectomy system, an intravascular lithotripsy balloon, or two stents (or a stent and a balloon) delivered together in a complex bifurcation. A wide-bore guiding catheter is a dictum for these cases. If the aorta is tortuous, a long sheath that extends up to the aortic arch keeps the system stable.

4. Guiding catheter engagement

Engagement matters because the guiding catheter provides the backup force that pushes devices through resistant calcium. Dr. Chandra's default for the left coronary artery is an extra-backup guiding catheter. For a right coronary artery with a shepherd's crook origin, which loops sharply upwards before descending, he may choose an Amplatz left 2 (AL2) catheter. Operators must be well versed in handling the AL2, because at the ostium of the right coronary artery it can cause dissection in inexperienced hands.

5. Imaging and target lesions

Once the guiding catheter is engaged, the angiogram must be studied thoroughly. Dr. Chandra estimates that 30 to 40% of angiograms miss significant calcium, which is why intravascular imaging with IVUS or OCT is essential before embarking on a calcified intervention. The target lesions must also be determined. Not every calcified lesion needs to be opened: the priority is the arteries that supply large territories of heart muscle.

6. Guide wires, lesion preparation, physiology and closure

Conventional workhorse guide wires suffice in many cases, but extra-support wires may be needed to straighten calcified, tortuous arteries. Lesion preparation then escalates as needed from non-compliant balloon angioplasty to cutting balloons, orbital atherectomy, rotational atherectomy and intravascular lithotripsy. Physiology, such as fractional flow reserve (FFR, a pressure-wire measurement of how much a narrowing limits flow), or repeat imaging can confirm the result. Closure of the femoral puncture is the final step, and he singles it out as one of the most important.

Bed preparation before any stent in calcified arteries

The central principle of calcified angioplasty is that the vessel bed must be prepared before a stent is placed. No constrained segments should remain. A stent deployed into undilated calcium cannot expand fully, and an underexpanded stent is a leading cause of later stent failure through restenosis or stent thrombosis. Preparing the bed properly is what secures the longevity of the procedure.

Dr. Chandra puts the attitude bluntly. One should never start half-heartedly on a calcific lesion in the optimistic hope that a balloon alone will succeed. He titles one of his cases "when you fail to prepare, you are preparing to fail", and the lesson recurs across his cases: when the calcium is heavy, the atherectomy device should be used from the front, not as a rescue after balloons have failed.

The calcified coronary toolkit

Calcified angioplasty needs a broad set of tools on the table before the case begins. Dr. Chandra's list covers:

• Non-compliant balloons, which hold their size at high pressure.
• Scoring and cutting balloons, with blades or wires that concentrate force to fracture calcium.
• Super-high-pressure non-compliant balloons, which he says can be inflated to 40 to 50 atmospheres, for a discrete, resistant segment that remains after stenting. These pressures exceed the manufacturer's rated burst pressure, so they are an operator's off-label choice.
• Rotational atherectomy (rotablation), a diamond-coated burr spinning at high speed that ablates calcium.
• Orbital atherectomy, an eccentric diamond-coated crown that sands calcium as it orbits.
• Intravascular lithotripsy (IVL), a balloon that emits acoustic pressure waves to crack calcium deep in the vessel wall.
• Excimer laser coronary atherectomy (ELCA).
• Long sheaths, extra-support guiding catheters and guide extension catheters, which can be advanced up to the lesion when a stent will not cross.
• Covered stents and pericardiocentesis equipment, ready in case of perforation.

Dr. Chandra regards rotational atherectomy as the best tool for heavily calcified lesions without contraindications, and in his experience it has emerged as the best tool for non-crossable lesions. Intravascular lithotripsy is an effective tool for breaking calcium within the vessel wall, facilitating stent expansion while minimising slow flow. Combining the two, with rotablation creating a channel and IVL cracking the deeper calcium, is known as rotatripsy, a hybrid approach.

How to choose among these tools, and the IVUS and OCT thresholds that trigger a switch from balloons to advanced calcium modification, are covered in detail in the companion article on IVUS and OCT criteria for calcium modification.

Bypass surgery or angioplasty for calcified multivessel disease

The decision between bypass surgery and angioplasty depends on the complexity of the disease, measured by the SYNTAX score (an angiographic score of how complex coronary disease is), and on what the patient's condition allows. Answering a case presented during the session (two-vessel disease with a calcified left anterior descending (LAD) artery and diagonal bifurcation, a SYNTAX score of 28, good kidney function and good left ventricular function), Dr. Chandra said this would be a case more favourable for bypass surgery. Below a SYNTAX score of 23, he said, angioplasty and bypass are in equipoise. European guidelines apply these SYNTAX thresholds to left main and three-vessel disease; for one- or two-vessel disease involving the proximal LAD, they recommend angioplasty and bypass surgery equally. With nothing precluding surgery, his first choice was bypass; if the patient chose angioplasty, modern tools would make it possible even for the complex bifurcation.

The decision is made by a heart team, in which the cardiac surgeon, the interventional cardiologist and the anaesthetist decide together what is best for the patient. For readers comparing the evidence on stenting and surgery more broadly, Dr. Biswarup Purkayastha's guide to left main coronary disease and when bypass beats a stent covers the trial data. Patients weighing the procedures themselves can see indicative ranges for angioplasty with stent and for coronary artery bypass grafting.

Diffuse calcified disease: the hybrid approach

Not every diseased segment should be stented. For diffuse calcified disease, Dr. Chandra's practice is a hybrid approach: stents in the major arteries after the bed has been prepared with rotablation or IVL, and, in diffusely diseased distal vessels, a cutting balloon followed by a drug-eluting balloon, which works much like a stent in those segments. Too much metal in small-calibre arteries is not a good idea, he explains, because it brings more restenosis.

Drug-coated balloons are also changing bifurcation treatment. His default approach for many bifurcations, particularly the distal left main with the circumflex as side branch, is a provisional stent in the main vessel, recrossing and thoroughly pre-treating the side branch, and then a drug-coated balloon inflated for 1 minute or 90 seconds, with no further intervention on the side branch.

Stents and scaffolds used today

Modern drug-eluting stents are metallic. Dr. Chandra's cases used stents made of cobalt chromium or platinum chromium alloy, carrying either a durable or a biodegradable polymer and a limus drug (everolimus or sirolimus). A metallic stent is never replaced: its thin struts, 60 to 80 microns in the platforms he describes, become covered by a thin layer of tissue after healing and remain in the body permanently. A biodegradable polymer dissolves over the following months once the drug has been released.

Fully bioresorbable scaffolds have had a difficult history. Absorb, the first widely used scaffold, was withdrawn after it failed to deliver over several years of follow-up. A locally made bioresorbable scaffold with 100-micron struts is used occasionally for very niche, simple type A lesions. For now, drug-eluting balloons are increasingly used as an alternative to leaving metal behind.

Key principles for treating calcified coronary arteries

Dr. Chandra's conclusions reduce to a short set of principles:

1. Diffuse plaque with heavy intracoronary calcium is often missed as significant disease on the angiogram.
2. Physiological and imaging assessment of the coronaries makes robust planning possible.
3. Rotational atherectomy prepares the bed in heavily calcified lumens; IVL cracks calcium within the wall and helps stents expand with less slow flow.
4. Rotablation has a steep learning curve and needs dedicated training and judgement for safe outcomes.
5. All these tools, IVL included, are bulky and expensive.
6. Cutting balloons, super-high-pressure balloons and guide extension catheters belong in every calcified coronary toolkit.

The questions doctors asked during the session, including the choice between IVL and atherectomy for calcified nodules, are answered in full in the Live Discussion. Dr. Chandra's first masterclass, on structural heart intervention, is summarised in the complete guide to TAVI for aortic stenosis, and his background is on his doctor profile. More heart content is collected on the cardiology hub.