Cracking the Nodular Code
Q&A with Dr. Akiko Maehara about the Disrupt CAD Pooled OCT Calcific Nodules Analysis at TCT21
How do you define a calcific nodule and what makes them so difficult to modify?
Dr. Maehara: As defined by OCT, the eruptive calcific nodule is accumulation of small calcium fragments underlying the calcified plaque typically protruding the lumen. Nodular calcium1 (healed calcified nodule, i.e., calcified nodule with thick fibrous cap) is probably more difficult to modify because calcium is hard structured and because nodules protrude into the lumen which makes fracturing them very difficult with sub-optimal stent expansion.
Why is the Disrupt CAD OCT analysis of calcified nodules relevant to today’s practice?
Dr. Maehara: This analysis is relevant because lesions with calcified nodules present with poor long-term outcomes, even with a good minimum stent area (MSA) at index procedure. There is a very robust recent Japanese article2 published in Atherosclerosis by H. Sugane et al which shows that when we compare severe calcified lesions with or without calcified nodules, the lesions with calcified nodules have poor outcomes compared with the lesions without calcified nodules. While MSA is the most important factor to predict the future event, long-term outcomes are still poor in the presence of calcified nodules regardless of the index MSA. In another Japanese article published in Atherosclerosis by H. Sugane et al using the ISR captured by directional coronary atherectomy3, when they studied the ISR cases, the lesions with calcified nodules showed them protruding through the stent struts, and the calcified nodule was pushed out. This is not something we have seen before, and we are still learning about it.
From your perspective, what did we learn from this study on the impact of coronary IVL on nodular calcium?
Dr. Maehara: The nodular analysis is still a preliminary finding as it is looking at procedural results, so we should acknowledge that we need longer-term clinical follow-up of these patients. That said, my sense looking at this OCT analysis and considering my experience with nodular lesions treated without IVL, is that IVL is disrupting the calcified fragments that are bonded together to create the calcific nodule. IVL seems to be reshaping the calcified nodule which might mean more symmetric stent expansion and less protruding calcium through the struts during follow-up, which theoretically may lead to better long-term outcomes than treatments with other calcium modification therapies. We really have to see clinically good outcomes in the IVL cohort compared to a non-IVL cohort or possibly look into the OCT again in the chronic stage to see if the nodules are protruding inside the stent. That’s kind of the data that is needed to support this type of hypothesis, which will come with longer follow-up.
How would you explain IVL’s ability to successfully modify nodules in this analysis to the interventional cardiologist who do not consider the technology a great tool for this calcium morphology?
Dr. Maehara: We all know these cohorts have very poor outcomes even in comparison to severely calcified lesions without nodules. While the calcified nodule looks like a calcium rock, pathologically, the very dense calcium is small calcium fragments connected with fibrous tissue. As such, the IVL acoustic energy can disrupt the small fragments affecting the calcified nodule. Balloons, on the other hand, are subject to wire bias and are not changing the shape of the calcified nodule. Ablation therapies are polishing only one side of the nodule, just 15% of it4. To be able to ablate more of the nodule with atherectomy, say 50%, you would have to ablate multiple times which we can’t typically do. This is why IVL disrupts calcified nodules much easier than other calcium modification modalities.
Given that these are acute procedural outcomes, what is important to look at next from a research perspective with coronary IVL in calcific nodules?
Dr. Maehara: We have to see clinical outcomes in the long-term. No matter how good stent expansion is, these lesions have poor outcomes because of protruding nodules. Will fracturing the calcified nodule help the long-term outcome? Will the acute appearance correlate with the outcomes? We will see over time.
In addition, we need to better understand different types of calcified nodules and what are the optimal outcomes for each type of nodule, and which calcium treatment device might be ideal for each type.
It is also important to study patients having hemodialysis as they are more likely to have accumulation of calcification, and as a result, more calcified nodules. They are truly a unique cohort with very poor outcomes. This is even more critical to look into for international regions where transplants are not an option.
- 1 Torii et al, Pathology of Calcified Nodule J A C C V O L . 7 7 , N O . 1 3 , 2 0 2 1 A P R I L 6 , 2 0 2 1 : 1 5 9 9 – 6 1 1
2 H. Sugane et al, Atherosclerosis, https://doi.org/10.1016/j.atherosclerosis.2020.11.005
3 Nakamura et al, J Am Heart Assoc. 2020;9:e016595. DOI: 10.1161/JAHA.120.016595 1
4 Yamamoto et al, Catheter Cardiovasc Interv. 2018;1–8.
Dr. Maehara is a paid consultant for Shockwave Medical.
Important Safety Information
Please contact your local Shockwave representative for specific country availability and refer to the Shockwave C2 instructions for use containing important safety information.
Indications for Use—The Shockwave Intravascular Lithotripsy (IVL) System with the Shockwave C2 Coronary IVL Catheter is indicated for lithotripsy-enabled, low-pressure balloon dilatation of severely calcified, stenotic de novo coronary arteries prior to stenting.
Contraindications—The Shockwave C2 Coronary IVL System is contraindicated for the following: This device is not intended for stent delivery. This device is not intended for use in carotid or cerebrovascular arteries.
Warnings— Use the IVL Generator in accordance with recommended settings as stated in the Operator’s Manual. The risk of a dissection or perforation is increased in severely calcified lesions undergoing percutaneous treatment, including IVL. Appropriate provisional interventions should be readily available. Balloon loss of pressure was associated with a numerical increase in dissection which was not statistically significant and was not associated with MACE. Analysis indicates calcium length is a predictor of dissection and balloon loss of pressure. IVL generates mechanical pulses which may cause atrial or ventricular capture in bradycardic patients. In patients with implantable pacemakers and defibrillators, the asynchronous capture may interact with the sensing capabilities. Monitoring of the electrocardiographic rhythm and continuous arterial pressure during IVL treatment is required. In the event of clinically significant hemodynamic effects, temporarily cease delivery of IVL therapy.
Precautions— Only to be used by physicians trained in angiography and intravascular coronary procedures. Use only the recommended balloon inflation medium. Hydrophilic coating to be wet only with normal saline or water and care must be taken with sharp objects to avoid damage to the hydrophilic coating. Appropriate anticoagulant therapy should be administered by the physician. Precaution should be taken when treating patients with previous stenting within 5mm of target lesion.
Potential adverse effects consistent with standard based cardiac interventions include– Abrupt vessel closure – Allergic reaction to contrast medium, anticoagulant and/or antithrombotic therapy-Aneurysm-Arrhythmia-Arteriovenous fistula-Bleeding complications-Cardiac tamponade or pericardial effusion-Cardiopulmonary arrest-Cerebrovascular accident (CVA)-Coronary artery/vessel occlusion, perforation, rupture or dissection-Coronary artery spasm-Death-Emboli (air, tissue, thrombus or atherosclerotic emboli)-Emergency or non-emergency coronary artery bypass surgery-Emergency or non-emergency percutaneous coronary intervention-Entry site complications-Fracture of the guide wire or failure/malfunction of any component of the device that may or may not lead to device embolism, dissection, serious injury or surgical intervention-Hematoma at the vascular access site(s)-Hemorrhage-Hypertension/Hypotension-Infection/sepsis/fever-Myocardial Infarction-Myocardial Ischemia or unstable angina-Pain-Peripheral Ischemia-Pseudoaneurysm-Renal failure/insufficiency-Restenosis of the treated coronary artery leading to revascularization-Shock/pulmonary edema-Slow flow, no reflow, or abrupt closure of coronary artery-Stroke-Thrombus-Vessel closure, abrupt-Vessel injury requiring surgical repair-Vessel dissection, perforation, rupture, or spasm.
Risks identified as related to the device and its use: Allergic/immunologic reaction to the catheter material(s) or coating-Device malfunction, failure, or balloon loss of pressure leading to device embolism, dissection, serious injury or surgical intervention-Atrial or ventricular extrasystole-Atrial or ventricular capture.
Prior to use, please reference the Instructions for Use for more information on warnings, precautions and adverse events. https://shockwavemedical.com/IFU