Study questions prognostic value of myocardial viability in patient selection for PCI
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NEW ORLEANS — PCI may not improve survival or left ventricular recovery among patients with ischemic cardiomyopathy compared with optimal medical therapy alone, regardless of baseline myocardial viability, a speaker reported.
In addition, scar burden, not abundance of dysfunctional-yet-viable segments, was prognostic of LV recovery, independent of baseline LV ejection fraction or CAD severity, according to new data from the REVIVED-BCIS2 trial presented at the American College of Cardiology Scientific Session.
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Divaka Perera MD, FRCP, professor of cardiology at King’s College London, said during a presentation that in a prior meta-analysis, published in the Journal of the American College of Cardiology in 2002, researchers observed that myocardial viability on noninvasive testing may be tied to improved survival after revascularization in patients with chronic CAD and LV dysfunction. However, he said, these findings were challenged 10 years later by an analysis of the STICH trials, published in The New England Journal of Medicine, that did not support the hypothesis that myocardial viability was associated with improved survival after CABG among patients with ischemic cardiomyopathy.
Therefore, the present study had several goals: to assess the prognostic value of myocardial viability for event-free survival, the prognostic value of myocardial viability for LV recovery, the prognostic value of myocardial viability for outcomes after PCI compared with optimal medical therapy and the prognostic value of LV recovery — defined as a median change in EF of 4.7% or more — for event-free survival.
The study included 610 patients with LVEF of 35% or less, severe CAD and either normal or dysfunctional-yet-viable myocardium eligible for PCI (mean age, 69.3 years; 12.3% women). Participants were randomly assigned to PCI plus optimal medical therapy or medical therapy alone.
As Healio previously reported, in the main results of the trial, PCI did not improve clinical outcomes in this population.
Participants classified as having viable myocardium had normal wall motion or dysfunctional wall motion but with myocardial viability established using dobutamine stress echocardiogram, cardiac MRI, PET or single-photon emission CT.
Scar classification was limited to the subset of patients from the study that underwent cardiac MRI.
Among all participants with viable myocardium who underwent PCI — including those with dysfunctional yet viable myocardium — researchers observed a slightly lower risk for death or HF hospitalization compared with those who received optimal medical therapy (adjusted HR per 10% increase in volume = 0.93; 95% CI, 0.87-1; P = .048); however, they observed no significant difference among a subgroup of those with dysfunctional-yet-viable myocardium (aHR per 10% increase in volume = 0.98; 95% CI, 0.93-1.04; P = .56).
When evaluating scar burden, the researchers observed an approximately 18% increase in risk for death and HF hospitalization for every 10% increase in scar volume, independent of baseline LVEF and CAD (aHR = 1.18; 95% CI, 1.04-1.33; P = .009).
In addition, the likelihood of LV recovery at 6 months following PCI among participants with dysfunctional and viable myocardium (OR = 1.01; 95% CI, 0.93-1.11) was primarily driven by those with viable and functional myocardium (OR = 1.22; 95% CI, 1.08-1.37), whereas increased scar burden was associated with lower odds of LV recovery (OR = 0.69; 95% CI, 0.56-0.84).
Compared with patients who did not achieve LV recovery after PCI at 6 months, those who had a median increase in EF of 4.7% or more had lower risk for death or HF hospitalization (aHR = 0.62; 95% CI, 0.41-0.95; P = .029).
“We have shown that characterization by viability assessment doesn’t allow us to a select group of patients who benefit from PCI over medical therapy. There isn’t a ‘Goldilocks zone’ that we have identified,” Perera said during the presentation. “We have also found, and this is perhaps surprising because it challenges the whole theory of characterization, but the abundance of dysfunctional-yet-viable segments is not associated with prognosis or even with LV recovery. However, if you characterize the myocardium in terms of scar or the extent of nonviable myocardium, it’s highly predictive of prognosis and the likelihood of recovery. That is independent of ejection fraction. In fact, if you correct ejection fraction for scar burden, it’s no longer associated with outcome or recovery based on these findings.”
References:
- Allman KC, et al. J Am Coll Cardiol. 2002;doi:10.1016/S0735-1097(02)01726-6.
- Panza JA, et al. N Engl J Med. 2019;doi:10.1056/NEJMoa1807365.
Perspective
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Venkatesh Murthy, MD, PhD, FAHA, FACC, FASNC
The important take-home messages are that the overall study was negative, so secondary analyses like this must be taken with a grain of salt, and that the researchers used a very modern method to assess viability in the form of cardiac MRI in contrast to prior studies, and found no clear predictive ability to identify benefit from revascularization in this population. We now have a better idea of whether to use viability testing before PCI in patients with HF. It is tricky in a study like this because having viability was part of the inclusion criteria. There are not going to be a whole lot of people with no viability. People at the low end of viability were excluded, probably rightfully so.
Another important part of this study was LV recovery. Finding a reduction in a primary endpoint is always challenging in a primary negative study. Here, the researchers did not even find that viability predicted LV recovery at 6 months. That is another factor in the calculus of whether it is even worth doing that kind of testing in these patients, again noting that patients with very minimal viability were not included in the study.
Viability testing has been decreasing in our practice and will probably continue to decrease. That makes sense for the majority of patients with HF who are candidates for revascularization.
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Perera D, et al. Featured Clinical Research I. Presented at: American College of Cardiology Scientific Session; March 4-6, 2023; New Orleans (hybrid meeting).
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