The Road to Conquering Complexity in CAD Despite the Unknowns

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 - The Diamondback 360
The Diamondback 360 Coronary Orbital Atherectomy System.
Source: Cardiovascular Systems

For physicians who treat patients with coronary artery disease (CAD), the complex has become more and more commonplace. CAD patients with comorbidities, challenging anatomical features and sometimes a combination of the two now have options beyond medical management. But what they often lack is data from randomized, controlled clinical trials, making some treatment decisions a challenge.

No simple definition

Many physicians agree about the basic factors that constitute complexity in patients with CAD. They include comorbidities such as heart failure, high blood pressure, diabetes, chronic kidney disease and obesity that ramp up risk as well as anatomical and physiological features such as multivessel disease, bifurcations, severely calcified lesions and chronic total occlusions (CTOs). Like a Jackson Pollack drip painting, these factors can exist as a fairly straightforward solo splatter on a bare canvas or as a tangle of intermingling conditions and situations piled thickly atop each other. Based on trend lines, interventional cardiologists, cardiothoracic surgeons and other physicians should anticipate more intermingling in coming years.

“There is no question that in North America the prevalence of diabetes, hypertension, hypertriglyceridemia and metabolic syndrome has increased tremendously,” says Roxana Mehran, MD, director of interventional cardiovascular research and clinical trials at Mount Sinai Hospital in New York City. “We are right in the middle of an epidemic of high burden of atherosclerotic disease.”

According to the Centers for Disease Control and Prevention (CDC), the prevalence of coronary heart disease has edged down slightly in the U.S. but still remains high at 6 percent. At the same time, the number of adults in the U.S. with diagnosed diabetes tripled between 1980 and 2011, from 5.5 million to 19.5 million. Almost 17 percent of children and 35 percent of adults were obese in 2012. While overall prevalence has remained mostly stable since 2003, the morbidly obese posted steep gains through 2010.  

Complexity doesn’t end with comorbidities and vessels. Age, left ventricular function, valvular disease and severity of disease can come into play as well. “When I think of a com plex patient, I think of someone with many comorbidities who is on multiple medications that would require many different specialists in consultation while he or she is in house recovering from any procedure,” says Terry Shih, MD, a surgeon at the University of Michigan in Ann Arbor. “I also think of patients who have extreme severity of disease, those patients who go into severe heart failure after a heart attack, who have to be on a balloon pump or need a lot of intensive care even before moving toward CABG.”

Changes in clinical practice also can contribute to the growing pool of complex patients. When the COURAGE trial (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) found no benefit to PCI in addition to medical management in patients with stable CAD, some cardiologists began to defer elective PCIs and CABGs, notes Ajay Kirtane, MD, SM, director of the cardiac catheterization laboratories at NewYork-Presbyterian Hospital/Columbia University Medical Center in New York City. One analysis of practices before and after COURAGE found a steep drop in PCIs in patients with stable angina and 16 percent decline in the overall use of PCIs (Circ Cardiovasc Qual Outcomes 2011; 4[3]:300-305).

“What this means is that we typically are seeing patients with more advanced stages at their presentation,” Kirtane says. “In our experience at a tertiary center where we get lots of referrals, the complexity has definitely increased, which is probably a good thing as long as you are not underdiagnosing. If you are not underdiagnosing, the patients you can help most are those who are more complex as opposed to those with single-vessel disease, who might be fine with medical therapy.”

Excluded but in need

How to optimally treat complex patients sometimes boils down to clinical judgment rather than top-notch evidence, though. Complex patients often are not invited to the party when recruiters seek out patients for randomized clinical trials. By design, some trials exclude complex patients for ethical reasons or to ensure feasibility. Other trials may include patients with comorbidities or other factors that make them more complex but in too few numbers to be statistically significant.

Researchers can turn to registry