COMMENTARY

ORBITA Correctly Positioned in 2019 ESC Guidelines on the Diagnosis and Management of Chronic Coronary Syndromes

Juhani Knuuti, MD, PhD; William Wijns, MD, PhD

Disclosures

September 30, 2019

To the Editor:

In a recent commentary on Medscape, Dr John M. Mandrola strongly criticized that the new ESC guideline on the diagnosis and management of Chronic Coronary Syndromes dismissed ORBITA trial results. In our opinion this is an unfair and incorrect judgement, as the study findings were carefully considered during the guideline development and writing process.

The ORBITA trial enrolled 230 patients with (≥ 70%) single coronary vessel stenoses. After optimized medication, patients were randomized to PCI or placebo procedure, and 6 weeks later the patients were investigated again using exercise testing, dobutamine stress echocardiography, and several questionnaires.

There were no difference in the primary endpoint, which was the exercise time increment. Of the secondary endpoints, no differences were found except that the dobutamine stress echocardiography peak stress wall motion score index improved more with PCI than with placebo (–0.07; 95% CI, –0.11 to –0.04; P <·.0001), indicating that the ischemic wall motion abnormalities were abolished in the PCI arm. There were no differences in outcome, but the study was not powered to this endpoint.

The main question is whether ORBITA trial results should lead to changes in the clinical guideline recommendations.

The Task Force did not think that a parameter such as exercise time obtained in a reasonably small population of patients with single-vessel coronary disease and with 6 weeks of follow-up is a finding that should change clinical guideline recommendations to perform PCI or not.

In our opinion, the ORBITA trial is an important study and the findings are interesting, but taking into account all current evidence, it would be premature to make clear statements based on this single study.

As the authors themselves stated, ORBITA's findings show that placebo-controlled randomised trials remain necessary. Furthermore, they wrote, "the findings of ORBITA do not mean that patients should never undergo PCI for stable angina. Not all patients would be satisfied with taking multiple antianginal agents forever. They might prefer an invasive procedure with a small procedural risk for the potential to need fewer medications."

In ORBITA, the extent of coronary disease (one vessel vs multivessel) was judged visually, as it was regarded as a common practice in diagnostic angiography. Although FFR was performed, it was not used to guide therapy. In ORBITA, 29% of patients had FFR greater than 0.80, and these patients should not be included in a PCI trial in the first place. Based on strong evidence, ESC guidelines emphasize that only functionally significant stenoses should be considered for revascularization.

In the ORBITA trial, the patients who had the placebo procedure had the opportunity to choose to undergo PCI after consultation with their physician. The majority (85%) of sham-arm patients opted for PCI at the end of the 6-week trial period.

Interestingly, Dr Al-Lamee, the principal investigator of the ORBITA trial, participated in the discussion in the SCAI 2018 meeting in San Diego about the controversies over the management of CAD and the findings of the ORBITA trial.

Toward the end of the session, the chairperson asked the panel their thoughts on the potential implications of ORBITA on clinical guidelines. All agreed that any impact would not be with regard to changing treatment recommendations.

"I don't think any one trial changes guidelines," Al-Lamee added. "If ISCHEMIA is negative, maybe we should have that discussion again. It would be nice if we . . . practiced the guidelines that exist."

We agree with Dr Al-Lamee, and while ORBITA results and importance were adequately described in the guideline, new outcome data became available from longer-term follow-up of FFR-guided revascularisation trials. Zimmermann et al analysed individual patient data of the three available randomized trials of contemporary FFR-guided PCI vs medical therapy in patients with acute (non-culprit stenoses) or chronic coronary syndromes. After a median follow-up of 35 months, there was a significant reduction in the composite of cardiac death or spontaneous myocardial infarction with FFR-guided PCI as compared with medical therapy (hazard ratio, 0.72; 95% CI, 0.54-0.96; P = .02). This difference between randomisation groups was driven by a 2.8% absolute reduction in the incidence of myocardial infarction.

This important analysis reinforces the recommendation for combined anatomical and functional evaluation of hemodynamic stenosis severity, when revascularization is considered on top of medical care for optimized symptomatic and prognostic outcomes.

The authors chair the Task Force on 2019 ESC guidelines on the diagnosis and management of chronic coronary syndromes.

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