From left to right: Superficial almost 360 degree calcium; Calcific nodule from 12-3 o’clock and from 8-10 o’clock; Superficial 360 degree concentric calcium that’s fractured at 3, 6 and 9 o’clock.

OCT imaging can effectively characterize the degree of calcification and inform optimal device selection and assess treatment efficacy.¹

The most important aspect of addressing the calcium problem is to recognize and classify calcium with OCT imaging. By addressing the degree of calcific burden, you can select the right lesion preparation strategy which impacts treatment strategy.

In LightLab Clinical Initiative,⁵ physicians changed lesion prep strategy in nearly 1/3 of lesions after they assessed lesion morphology and severity with OCT. When a change in vessel prep strategy occurred, calcification was the predominant morphology as seen with OCT.

In the LightLab case, pre-PCI angio assessment and planned treatment approach (left image) was changed after performing pre-PCI OCT (right image).

The impactful changes include:

1. angiographic underestimation of lesion calcification (identified calcific nodule)
2. change in vessel prep (changed from compliant balloon to NC balloon, added rotational atherectomy)
3. change in stent size: +6mm

OCT classification of calcium

The use of intravascular imaging allows for more specific characterization and quantification of calcification compared to angiographic calcium classification as mild, moderate, or severe.

OCT classifies calcium into deep, superficial and nodular, as well as eccentric or concentric calcium. Morphology and calcium assessment which are performed in the first step of MLD MAX workflow, M -Morphology, are important factors in determining the optimal treatment approach because different types of calcium requires a different treatment technique.¹

OCT calcium score: Rule of 5s

Measuring calcium depth w/ an OCT-based calcium score algorithm can help identify calcific lesions that would benefit from plaque modification before stent implantation.⁶ This algorithm looks at calcium thickness, calcium angle and calcium length which are among the most important parameters used to predict the need and success of calcium modification devices.

• Thickness >0.5 mm
• Angle >50% vessel arc
• Length >5 mm

Lesions at risk of stent under-expansion have a calcium score of 4:⁶

Evaluation of calcium thickness is key in predicting stent expansion.⁷ With IVUS, the sound waves bounce off calcium and create a dark shadow. With OCT, the light can penetrate calcium thus evaluate its thickness.⁷

How to diagnose and treat calcified lesions with OCT

1. Start PCI with the MLD MAX workflow
2. Assess Morphology (M) to determine the type of plaque
3. For calcific plaque, apply OCT-guided treatment of Calcified lesions algorithm.¹ The algorithm guides physicians from assessment of calcific burden to lesion preparation and through treatment.
   Such approach relies on OCT’s ability to accurately recognize and access calcific burden to inform vessel preparation (device selection, stent sizing) to ensure adequate stent expansion.

Watch Video: OCT-Guided Treatment of Calcified Lesions.

In this video, Dr. Tej Sheth discussed how to apply MLD MAX algorithm to identify and treat calcified lesions. 

How does OCT imaging compare to other modalities used for calcified lesions?

OCT is the best imaging modality to detect, localize and quantify coronary calcium.⁸

Coronary angiography, coronary computed tomography (CT), intravascular ultrasound (IVUS), radiofrequency (RF), intravascular ultrasound-virtual histology (IVUS-VH), and optical coherence tomography (OCT) can all detect and attempt to localize and quantify calcium, albeit with very different diagnostic accuracies, as concluded by Gary Mintz after 20 years of intravascular imaging studies of the relationship between calcium and coronary atherosclerosis.⁸

Successful PCI and reduction in future revascularizations are closely tied to final stent expansion.¹ Coronary artery calcification is often underappreciated by angiography because angiography underestimates morphological lesion severity which impacts treatment strategy.⁵

Using OCT imaging with MLD MAX workflow to guide PCI helps to determine the right treatment approach and achieve optimal stent expansion. In LightLab, operators achieved 80% minimal stent expansion on average when following MLD MAX workflow.

References

1. Shlofmitz, E., Sosa, F. A., Ali, Z. A., Waksman, R., Jeremias, A., & Shlofmitz, R. (2019). OCT-Guided Treatment of Calcified Coronary Artery Disease: Breaking the Barrier to Stent Expansion. Current Cardiovascular Imaging Reports, 12(8), 32.
2. Dean Kereiakes, Disrupt CAD III: Lithotripsy for Vessel Preparation in Calcified Coronary Arteries Prior to Stenting, CLD. Dec 29, 2020.
3. Madhavan MV, Tarigopula M, Mintz GS, Maehara A, Stone GW, Généreux P. Coronary artery calcification: pathogenesis and prognostic implications. J Am Coll Cardiol. 2014 May 06;63(17):1703-14.
4. Räber L, et al. Clinical use of intracoronary imaging. Part 1: guidance and optimization of coronary interventions. An expert consensus document of the European Association of Percutaneous Cardiovascular Interventions. Eur Heart J. 2018;39(35):3281-3300.
5. Croce, K. et al: Optical Coherence Tomography Influences Procedure and Vessel Preparation Decisions During Percutaneous Coronary Intervention– Insights from the LightLab Initiative. TCTConnect2020 Presentation.
6. Fujino, A et al. A new optical coherence tomography-based calcium scoring system to predict stent underexpansion. EuroIntervention. 2018 Apr 6;13(18):e2182-e2189. doi: 10.4244/EIJ-D-17-00962.
7. Wang, X et al. In vivo calcium detection by comparing optical coherence tomography, intravascular ultrasound, and angiography. JACC Cardiovasc Imaging. 2017 Aug;10(8):869-879. doi: 10.1016/j.jcmg.2017.05.014.
8. Mintz,G. Intravascular Imaging of Coronary Calcification and its Clinical Implications. JACC Cardiovascular Imaging, 2015. http://dx.doi.org/10.1016/j.jcmg.2015.02.003