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Stress echo could predict PCI efficacy in stable CAD

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Ischemia important to PCI response

Current evidence about the relationship between stress-induced ischemia and the benefits of percutaneous coronary intervention is unclear, and the only sham-controlled trial prior to this one found no effect of PCI on exercise time or angina frequency.

This secondary analysis of data from the ORBITA trial, which finds a reduced frequency of angina in PCI-treated patients with an echocardiographic score at or above 1, is consistent with other studies finding a prompt improvement in angina symptoms above medical therapy alone.

The finding of greater symptom improvement with greater ischemia is intriguing, but what is unclear is whether improvement in symptoms is only likely to be realized above a certain threshold of ischemic severity.

While there remains a question about how effective noninvasive ischemia testing is in guiding decision-making about revascularization, the important take-home message of this study is that ischemia is an important, but not the only, mediator of improvement in patient symptoms after PCI.

Leslee J. Shaw, PhD, is from the Weill Cornell Medical College, New York; Harmony R. Reynolds, MD, is from New York University; and Michael H. Picard, MD, is from Harvard Medical School, Boston. These comments are adapted from an accompanying editorial (Circulation. 2019 Nov 11.). The three authors reported having no conflicts of interest.


 

REPORTING FROM AHA 2019

Dobutamine stress echocardiography could be used to predict which patients with single-vessel stable coronary artery disease are most likely to benefit from percutaneous coronary intervention, according to secondary analysis of data from the ORBITA trial.

In a study to be presented at the American Heart Association scientific sessions on Nov. 16, researchers outline the results of a stress-echo stratification of patients who participated in the Objective Randomized Blinded Investigation with Optimal Medical Therapy of Angioplasty in Stable Angina (ORBITA) trial.

An illustration of a beating heart ©Thinkstock

The original double-blind randomized controlled trial, comparing percutaneous coronary intervention (PCI) to a placebo procedure in 200 patients with stable angina and angiographically severe single-vessel coronary artery disease, found a smaller-than-expected effect size.

“While there was no significant difference between PCI and placebo groups in the patient-reported and physician-assessed symptom and quality of life endpoints, ischemia as assessed by dobutamine stress echocardiography (DSE) wall motion score index showed a clear reduction with PCI,” wrote Rasha K. Al-Lamee, MD, from the National Heart and Lung Institute at Imperial College London, and coauthors.

In their paper, published in Circulation, the researchers analyzed data from 183 patients who underwent prerandomization dobutamine stress echocardiography to see the impact of their stress echo score on the placebo-controlled effect of PCI.

The stress echo score reflects the number of segments that are abnormal at peak stress; akinetic segments count as double and dyskinetic segments count as triple.

The researchers found a significant interaction between the prerandomization stress echo score and the effect of PCI on angina frequency, with the largest placebo-controlled effects of PCI seen in patients with the highest stress echo scores.

Patients with a prerandomization stress echo score at or above 1 were three times more likely to have a lower angina frequency score with PCI than with placebo (odds ratio, 3.18; 95% confidence interval, 1.38, 7.34; P = .007). They were also more than four times more likely to be free from angina with PCI compared to placebo (OR, 4.62; 95% CI, 1.70, 12.60; P = .003).

“We have previously found that there is a clear relationship between invasive physiology and stress echo score but no relationship between invasive physiology and placebo-controlled symptom improvement,” the authors wrote. “The present analysis shows that there is clear evidence of a relationship between ischemia on stress echo and the placebo-controlled efficacy of PCI on frequency of angina.”

The analysis, however, found no detectable interaction between prerandomization stress echo score and the effect of PCI on physical limitation score, quality of life, Canadian Cardiovascular Society angina class score, or treadmill time.

The mean prerandomization stress echo score was 1.56 in the PCI arm and 1.61 in the placebo arm.

The study also looked at the relationship between prerandomization stress echo score and fractional flow reserve. This revealed that, as the stress echo score increased with a greater number of ischemia myocardial segments, the fractional flow reserve value decreased, pointing to a greater degree of ischemia. Researchers also noted that as the stress echo score became larger, the instantaneous wave-free ratio also decreased significantly.

“This stress echo-stratified analysis shows the link between stress-induced myocardial wall motion abnormalities and patient-reported angina frequency,” the authors wrote. “The greater the ischemia on [dobutamine stress echocardiography], the greater the placebo-controlled angina relief from PCI.”

The study was funded by grants from the National Institute for Health Research Imperial Biomedical Research Centre, Foundation for Circulatory Health, Imperial College Healthcare Charity, and in-kind support from Philips Volcano. Two authors declared patents relating to technology used in the study and three declared consultancies, speakers’ fees, and research grants from Philips Volcano. No other conflicts of interest were declared.

SOURCE: Al-Lamee R et al. Circulation. 2019 Nov 11. doi: doi.org/10.1161/CIRCULATIONAHA.119.042918.

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