Defining CLI From the Front Lines of Care

Is critical limb ischemia (CLI) a fast-moving target that is too hard for physicians and health care bodies to catch up to? Or are we just missing “something”? As I put this piece together and read multiple papers, both older and recently published, I find it very intriguing that most of these papers have a similar start and a similar ending. The body of these articles leaves you thinking: what else is going on with CLI?

 

Dr. Eric C. Scott is a very involved CLI operator and has dedicated a large portion of his career to CLI. I am happy to have this chance to share his thoughts and experience with you.

 

 

Eric C. Scott, MD: I define CLI as ischemic rest pain, non-healing wounds in the setting of peripheral arterial disease (PAD), or frank gangrene of the lower extremity. Of these three entities, I find non-healing wounds are really the only component that often require some additional history taking and interrogation to accurately define as CLI or not. Neuropathic ulcers in diabetics, for example, are often identified in the absence of any degree of PAD and do not constitute CLI. However, a foot wound in a diabetic that is not healing, with clinical evidence of PAD, is CLI. The “clinical evidence” of PAD is where perhaps where we have historically gotten tripped up.  

 

For many years, we have tried to incorporate objective testing parameters of circulation into the definition of CLI.  An ankle-brachial index (ABI) had to be less than 0.4 or 0.5 for CLI to exist. A toe pressure had to be less than 50mm Hg. A transcutaneous oxygen measurement had to be less than 50mm Hg. But we now know that these test results are sometimes falsely elevated or erroneous in patients with severe PAD, particularly in diabetic patients. Every time a wound care specialist, podiatrist, primary care physician, or vascular specialist elects to forgo further evaluation of arterial insufficiency in a patient with suspected arterial disease because one of these tests appear normal or “adequate”, an opportunity to heal a wound and maybe even save a limb is lost.  

 

So, in my own practice, I have lowered the threshold to pursue the presence of PAD in patients with non-healing wounds. If pedal pulses are absent or diminished, I still obtain non-invasive testing, but I will proceed to formal angiography with selective popliteal or even tibial imaging, regardless of the non-invasive findings.  There is no doubt in my mind that this is the best way to characterize the arterial circulation and extent of disease. The accompanying case of a 58-year-old diabetic male I recently treated highlights these issues well (Figures 1-4).

 

 

Dr. Scott: The updated guidelines on appropriate use criteria for peripheral arterial interventions from the SCAI align well with what we have discussed above.  The guidelines are focused primarily on differing endovascular treatment modalities and their appropriateness for various clinical scenarios, but attention is paid to the diagnosis of CLI and the limitations of our non-invasive testing. The authors conclude that digital subtraction angiography remains the “gold standard” to visualize lower extremity arterial disease, including in the pedal arch and branch vessels. I completely agree.

 

 

Dr. Scott: I am sure CMS is interested in our treatment of CLI, as these patients consume a disproportionate amount of health care dollars relative to a much larger cohort of Americans with asymptomatic PAD or claudication. From the physician’s perspective, though, I think increasing attention is being paid to CLI because an increasing number of these patients are presenting weekly in our clinics and emergency departments. Not only is the incidence of CLI likely rising given the prevalence of diabetes in our country, the conglomerate awareness of PAD is rising amongst patients, their families, and primary care providers. More patients are coming forward with severe disease today, and hopefully earlier in the disease state.  

 

We already know that amputation is not an appealing therapy for most patients with CLI nor is it cost effective.  This puts increased pressure on vascular specialists to perform often complex endovascular or surgical therapies in an attempt to save limbs. So I think for many of us, CLI has our attention because of the magnitude of the problem and the difficulty in providing clinically beneficial therapies to these challenging patients.  

 

Dr. Scott: I think the field of CLI is moving forward on multiple fronts. First, the medical device industry, working in conjunction with numerous vascular specialists, continues to push the development and testing of new therapies for below-the-knee (BTK) disease. Drug-coated balloon technologies for BTK, “specialty” balloons, and novel atherectomy devices come to mind first and may each push the field forward. Second, there is hardly a national or international vascular symposium that does not devote considerable time and attention to the evaluation and treatment of CLI patients. Through these symposia, valuable therapies, technical details, and data are disseminated worldwide. And finally, over the next five to ten years, the collection of clinical data in multiple, ongoing CLI data registries and clinical trials will hopefully produce a wealth of new information to guide us on selecting the right therapies for the right lesions in the right patients.  

 

 

Dr. Scott: I am fortunate to have such a team assembled at my institution. CLI patients require an extraordinary amount of care initially, as multiple related issues often need to be addressed simultaneously to optimize wound conditions and prepare for revascularization procedures. Regular and frequent follow-up has also been shown to be essential in achieving good outcomes. Honestly, it is too much work and beyond the scope of most physicians to provide all facets of CLI care alone. So a team is essential. What that team looks like though — like politics — is local. In my clinic and hospital, I work very closely with numerous podiatrists who provide excellent care to the entire foot, from wound care to minor amputations. We communicate regularly about challenging patients or acute problems, and do so by phone or secure text to avoid delays in communication. We also utilize the input of infectious disease specialists for detection and treatment of foot infection, and internists for assistance with medical management of diabetes and other vascular risk factors.

 

 

Dr. Scott: I don’t have any major concerns with current CMS policy, but I would certainly caution against additional bundling of tibial and pedal interventions in CLI patients. This could conceivably dissuade interventionalists from pursuing multiple tibial interventions in one setting when certain patients may actually benefit from the additional intervention and circulation.  

 

Disclosure: Dr. Scott reports no conflicts of interest regarding the content herein.

Dr. J.A. Mustapha can be contacted at jihad.mustapha@metrogr.org.
Dr. Eric C. Scott can be contacted at escott@iowaclinic.com.