STICH Analysis by Age Shows Benefit of CABG in Ischemic Heart Failure Across the Decades

ROME, Italy—The choice of CABG over medical therapy in patients with ischemic cardiomyopathy and reduced ejection fraction yields a more substantial benefit in terms of all-cause mortality in younger patients, as compared with older adults, but patients of all ages can still derive some benefit, a new analysis of the STICH trial shows. 

Presenting the results here at the European Society of Cardiology Congress 2016, Eric Velazquez, MD (Duke Clinical Research Institute, Durham, NC), noted that it is not known whether the survival benefit of CABG—which took 10 years to emerge in STICH—was seen across all ages in that trial. Velazquez presented the main 10-year results at the American College of Cardiology 2016 Scientific Sessions earlier this year.

The implication from the current post-hoc analysis, he said, “is that cardiologists and cardiac surgeons can offer patients CABG, in addition to optimal medical therapy, with the knowledge that CV mortality is reduced by CABG across all age groups included in the trial, through 10 years follow-up.”

The STICH age-group study was simultaneously published today in Circulation.

A STICH in Time

As previously reported by TCTMD, STICH originally enrolled a total of 1,212 patients who had ejection fractions of 35% or less and coronary artery disease that could be treated with bypass surgery, typically with no or minimal angina symptoms. While no difference was seen between CABG and medical therapy in the main analysis at a median of 56 months, a significant difference emerged favoring CABG between 5 and 10 years in the STICH Extension Study (STICHES).

Seeking to see whether this benefit differed across age groups, Velazquez, along with first author Mark Petrie, MD (University of Glasgow, Scotland), reviewed outcomes by quartiles of age. The four age categories were 54 and younger, 54 to 60 years, 60 to 67 years, and over age 67.

While all-cause mortality was higher in older than in younger patients regardless of whether patients were assigned to medical therapy (79% vs 60% for the oldest vs youngest; log-rank P = 0.005) or to CABG (68% vs 48%, respectively; log-rank P < 0.001), no such difference by age was seen for cardiovascular mortality in either treatment group. Not surprisingly, cardiovascular deaths accounted for a greater proportion of the deaths among younger subjects than in older subjects (79% vs 62%) for whom other age-related morbidity played a bigger role. The benefit of CABG over medical therapy for all-cause mortality “tended to diminish with increasing age,” the researchers report, “whereas the benefit of CABG on cardiovascular mortality was consistent over all ages.”

For the combined endpoint of all-cause mortality or cardiovascular hospitalization, CABG was associated with better outcomes than was medical therapy in the younger but not the older patients.

“CABG added to medical therapy has a consistent beneficial effect on cardiovascular mortality regardless of age,” Velazquez concluded. “Among older patients, the benefit of CABG on cardiovascular mortality should be considered carefully due to the risk of age and comorbidities and the competing risk of noncardiovascular death.

In discussion following the STICH presentation today, Velazquez was asked whether he and his colleagues have landed on an age cutoff that could be used to determine when CABG is not likely to be of benefit. He replied: “I don’t think we have a definitive answer, but based on these data, assuming that the data have no substantial suggestion of increased noncardiac risk, we would expect that the effect of CABG over medical therapy is consistent really regardless of age.”

To this point, session moderator Stephan Achenbach, MD (University of Erlangen, Germany), pointed out that the patients enrolled in STICH were actually very young and very sick, something Velazquez characterized as “an important comment.”

“Clearly I am not aware of any drug or approach that avoids deaths completely and at some point death occurs,” Velazquez said. “So there is a point at which the non-CVD risk may predominate, [but] in the population that we studied in STICH, we did not see that. I can’t speak to whether these trial results would apply in the very elderly such as those 90 and above, which we did not study.

By the same token, it’s also important to consider the implications for younger patients—a full 330 patients were age 54 or younger in this trial.

“These data [offer] an important lesson in the younger population a well,” Velazquez noted. “We saw a roughly 40% relative risk reduction between the two treatments by age. My interpretation of that data is that it is probably not too appropriate, based on these analyses, to avoid CABG in a younger patient [opting instead] for another therapy, when you see this level of mortality in the very young.” This observation, he added, reflects his personal opinion and goes “above and beyond the data” in STICH.

Source:

• Petrie MC, Jhund PS, She L, et al. Ten-year outcomes after coronary artery bypass grafting according to age in patients with heart failure and left ventricular systolic dysfunction. Circulation 2016; Epub ahead of print.

Disclosures:

• Velazquez and others report grants from the National Heart, Lung, and Blood Institute and Alynlam Pharmacetucials and Pfizer as well as grants and personal fees from Merck and Expert Exchange.  

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• Less Is Not Always More: Screening for Coronary Disease Underused in Patients With Heart Failure
• CABG Beats Medical Therapy in CAD Patients With Severe LV Dysfunction: STICH 10-Year Results