CABG Provides ‘Good Value’ in Ischemic Cardiomyopathy

Performing CABG on top of optimal medical therapy is a cost-effective treatment option for patients with ischemic cardiomyopathy and reduced LV function, an analysis based on STICH/STICHES data indicates.

The incremental cost-effectiveness ratio (ICER) for CABG versus medical therapy alone was $63,989 per quality-adjusted life-year (QALY) gained, suggesting surgery is “economically favorable” when using a societal willingness-to-pay threshold of $100,000 per QALY gained.

Researchers led by Derek Chew, MD (University of Calgary, Canada, and Duke Clinical Research Institute, Durham, NC), report their results in a paper published last week in Circulation. “Together with the improved clinical outcomes seen in the 10-year extended follow-up of STICH, these findings provide additional economic support for the use of CABG in patients with ischemic cardiomyopathy eligible for STICH,” they write.

The extension study STICHES showed that the addition of CABG to optimal medical therapy improved outcomes over a decade of follow-up compared with medical therapy alone, which was hinted at, but not proven, in the 5-year STICH results.

Whether the greater initial costs were justified had not been evaluated before now, Chew told TCTMD.

“The long-term economic consequences of CABG hadn’t been reported, but in STICH patients with ischemic cardiomyopathy and an EF less than 35%, routine use of CABG not only showed quality-of-life benefits but also a mortality benefit for a reasonable up-front cost, so it represented good value for healthcare in an American system,” he said.

Considering the Economic Impact

Ischemic cardiomyopathy accounts for roughly half of all cases of heart failure (HF) with reduced LV function, and “the relevance of ischemic cardiomyopathy as a public health issue is anticipated to become even more urgent in the context of an aging population and rising prevalence of coronary artery disease and HF,” Chew et al write. “Thus, it is critical to understand the relative value of high-cost surgical interventions by considering the downstream economic and clinical consequences.”

To explore this question for CABG in the setting of ischemic cardiomyopathy, the investigators turned to the STICH trial, which included 1,212 patients who had reduced LV function and coronary disease suitable for surgery; they were randomized to CABG plus optimal medical therapy or optimal medical therapy alone. The initial results, based on a median follow-up of 56 months, did not show a difference in mortality between the two arms, although an advantage for CABG emerged over longer-term follow-up in STICHES.

Based on resource use and clinical data from the trial, Chew et al employed simulation models to estimate the lifetime costs and benefits of CABG and medical therapy from the perspective of the US healthcare system. The estimated a gain of 6.53 QALYs at a lifetime cost of $140,059 for CABG and a gain of 5.52 QALYs at a lifetime cost of $74,896 for medical therapy alone.

There was an 87% likelihood that the addition of CABG would be cost-effective at a willingness-to-pay threshold of $100,000 per QALY gained, and a 97% likelihood at a threshold of $150,000. The ICER of $63,989 per QALY gained would place CABG in this setting within the “intermediate-value” range ($50,000 to < $150,000 per QALY gained) according to a framework established by the American College of Cardiology/American Heart Association.

In subgroup analyses, the ICER for CABG versus medical therapy alone was more favorable in patients with LVEFs of 28% or lower and in those with three-vessel versus less-widespread disease.

“Our model found that patients assigned to the CABG group had greater total costs than medical therapy, driven by higher initial costs associated with surgery. However, the up-front costs were offset by sufficient gains in life expectancy and quality of life to represent good value,” Chew et al write. They note that their cost-effectiveness estimates “were not substantially affected by changes to health resource unit costs, discount rate, quality-of-life weighting, or the assumptions related to extrapolation of clinical effectiveness.”

Importance of Medical Therapy

Commenting for TCTMD, James Fang, MD (University of Utah Health, Salt Lake City), said, “I think the findings are not entirely surprising, and I think that they are consistent with what the evidence shows for the benefits of bypass surgery for the management of heart failure.”

As for whether an analysis demonstrating the cost-effectiveness of CABG in patients with ischemic cardiomyopathy and reduced LV function will have an impact on clinical practice, Fang was skeptical. “It’s more relevant to insurance companies, healthcare economists, and others,” he said. “I don’t think it’s going to really make any difference to patients or their providers as to what they would recommend.”

He noted that when the original STICH results were published in the New England Journal of Medicine in 2011, he wrote the accompanying editorial that highlighted the power of medical therapy. In the trial, CABG was performed in addition to—and not instead of—optimal medical therapy, he underscored. “That point I think is worth driving home—that background medical therapy really is important,” Fang said, adding that it’s unclear whether the findings would remain the same on the background of current therapies, including sacubitril/valsartan (Entresto; Novartis) and the sodium-glucose cotransporter 2 (SGLT2) inhibitors.

Another key factor to include when counseling patients on the possibility of CABG is the early risk of mortality with surgery before the advantage tips in its favor over the long term, Fang said.

Though the current cost-effectiveness analysis is unlikely to sway considerations around the use of CABG in this population very much, it is relevant to explore these issues, Fang said, “because there’s not a limitless amount of money to take care of people, and I do think that we have to do things that have high value.”

For his part, Chew said: “I’m hoping it shifts people’s thoughts [around CABG]. It’s hard to foresee the long-term benefit when you have such an expensive up-front cost, but when you actually account for all the downstream benefits, CABG is just as cost-effective as some of the latest greatest medications out there.”