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Calcification: The Achilles Heel of Interventional Procedures

The cardiovascular community is primed for a novel and simple solution to enable physicians to address challenging and debilitating calcified vascular occlusions safely and effectively.
Calcification is a dominant hallmark of advanced atherosclerotic disease, and is often underestimated and under-treated. Problematic calcium in the form of stenosis and chronic total occlusions (CTOs) are encountered frequently in patients with both coronary and peripheral artery disease. These occlusions are associated with a higher risk of adverse events, decreased quality of life, worse procedural success and treatment outcomes, and increased healthcare costs. As a result, vessel preparation (crossing CTOs and preparing lesions) has evolved from a mere bailout procedure to an initial revascularization strategy in both coronary and peripheral artery disease treatment.
Plaque modification and CTO crossing devices have enhanced the treatment of moderately calcified cardiovascular lesions. However, highly calcified stenoses and CTOs continue to create challenges for achieving optimal treatment outcomes and pose a management dilemma for physicians due to the technical/procedural complexities and clinical uncertainties.

Peripheral Artery Disease (PAD)

“Far too many amputations are still performed in patients with PAD without considering revascularization before amputation.”
Peripheral artery disease has been associated with significant morbidity and mortality, and it is considered a coronary artery disease risk equivalent. Critical limb ischemia (CLI), the late stage and worst form of peripheral artery disease, is characterized by multilevel and multivessel infrainguinal and tibial-pedal arterial stenoses, and an increasing risk for myocardial infarction, stroke, limb loss, and death.
Peripheral artery disease is a global epidemic affecting 200 million people worldwide, and 20 million people in the United States alone1. Further, it is estimated that 25-30 million people worldwide and >3 million in the United States alone are burdened with CLI1, Prognosis of a CLI patient is poor: within the first year of CLI diagnosis, 25% of patients die and 25% will have a major limb amputation as primary treatment, at a cost of $22 billion in the US alone1,2,3. Two years post below-the-knee (BTK) amputation, 15% will undergo above-the-knee (ATK) amputation and 30% will die.
Moderate to severe calcium is present in 50% of peripheral artery disease patients with severe claudication, and the numbers are even higher (>65%) in CLI patients. Peripheral chronic total occlusions are encountered in up to 50% of peripheral artery disease and CLI patients undergoing endovascular treatment of femoropopliteal (FP) and tibial or below-the-knee (BTK) arteries4-6. These obstructions compromise the viability of the affected tissues and ultimately threaten limb loss (amputations).
Endovascular treatment strategies, which are less invasive than bypass surgery, have evolved to increasingly become the revascularization methods of choice for patients with severe peripheral artery disease and CLI. Successful revascularization significantly reduces the need for amputations.
Despite the emergence of novel technologies, current devices have received low clinical acceptance given their common limitations to safely and effectively address the structural challenges posed by the presence of moderate to severe calcium in complex cases. Failure rates remain high in revascularization procedures, with the biggest failure modality attributed to the inability to cross the tough fibrocalcific chronic total occlusions caps and lesion cores with a conventional guidewire.

There remains a significant unrealized demand for a novel technology solution to safely and effectively address highly fibro-calcific lesions and arrive at the interventional goal: restore flow, promote wound healing and prevent amputations.

References

1. The SAGE Group
2. Abu Dabrh AM, et al. J Vasc Surg. 2015;62(6):1642–1651. [PubMed] [Google Scholar]
3. Norgren L, et al. J Vasc Surg. 2007;45(suppl S):S5–S67. [PubMed] [Google Scholar]
4. Murabito JM et al. Am Heart J. 2002;143(6):961–965. [PubMed] [Google Scholar]
5. Fanelli, J Cardiovasc Surg 2014
6. van der Heijden FH, et al. Br J Surg. 1993

Coronary Artery Disease (CAD)

Coronary artery disease affects 15 million people in the US alone and occurs when the arteries that supply blood to the heart become narrowed or blocked by plaque, often resulting in a heart attack.

The most common treatment for patients is percutaneous coronary intervention (PCI), which involves devices to facilitate angioplasty and stenting. There are one (1) million PCI procedures performed each year in the US alone.

Highly calcified lesions and chronic total occlusions create challenges for achieving optimal outcomes with PCI. Failure to pre-treat calcified lesions may lead to increased major adverse cardiac events (MACE).

It is estimated that 30-40% of patients undergoing PCI have calcification as determined by coronary angiography1,2. Moreover, the prevalence of chronic total occlusions in patients with coronary artery disease is as high as 52%3,4.

Despite the high prevalence, less than 10% of diagnosed chronic total occlusions are treated with PCI (CTO PCI). The low CTO PCI attempt rate is driven primarily by the inability to successfully pass a guidewire across a tough calcific lesion cap and into the true lumen of the distal vessel, and, less commonly, due to complications. Success rates of CTO PCI are only around 50-60% (versus >85% success for non-CTO PCI)4. Higher success rates are reported in the hands of a few dedicated expert operators that use advanced techniques (retrograde or dissection re-entry approaches, for example) which are technically demanding and inherently riskier than traditional non-CTO PCI, imposing a high learning curve upon the operator5. In non-CTO PCI cases with a high calcium burden, plaque modification devices have also seen limited adoption in the coronary setting, due primarily to concerns with their safety and ease of use.

There is demand for safer, simpler, and more effective solutions that can increase the success rate of PCI procedures in complex calcific cases, and ultimately narrow the gap between the expert operators and the other interventional cardiologists.

References

1. Jeroudi OM, et al. Catheter Cardiovasc Interv. 2014
2. Mintz GS, et al. Circulation. 1995
3. Tsai TT, et al. JACC Cardiovasc Interv. 2017
4. Young MN, et al Circ Cardiovasc Interv. 2019;
5. Sakes, A. et al, Cardiovascular Engineering and Technology, 2016

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