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PARIS -- More abnormal physiology was more likely to benefit from percutaneous coronary intervention (PCI) in reducing ischemia in stable angina, according to an updated analysis of the ORBITA trial, although still confirming the lack of advantage for symptoms.

Dobutamine stress echocardiography (DSE) scores improved more for patients randomized to PCI versus sham stenting (ANCOVA estimate 1.07, 95% CI 0.70 to 1.44, P<0.00001) in the new analyses to further account for baseline differences between treatment groups in their sham-controlled trial, confirming what had been seen in the primary analysis for this secondary endpoint.

But in an analysis of physiological measurements taken before randomization, that advantage with PCI was limited to those with more abnormal physiology, Rasha Al-Lamee, MD, of Imperial College London, reported here at the meeting.

Patients with lower fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) had an advantage in the DSE score with PCI versus the sham arm (P<0.00001 for interaction for both). But initial values exceeding 0.6-0.7 were not associated with a greater reduction on ischemia with the real procedure, according to Al-Lamee's presentation at the late-breaking trial session.

Thus, Al-Lamee concluded, "FFR and iFR predict the placebo-controlled PCI effect on stress echocardiography." Average FFR and iFR were identical between the two treatment arms (0.69 and 0.76, respectively). Operators were blinded to physiologic assessment.

Notably, as in the primary analysis, stenting provided neither greater symptom relief (reported as a continuous variable on the Seattle Angina Questionnaire) nor extra exercise time over a sham procedure among the trial's 200 PCI-eligible patients with severe single-vessel disease on angiography.

FFR and iFR did not predict the effect of PCI on symptoms or treadmill exercise time, Al-Lamee reported in the updated ORBITA data, which were also published simultaneously online in .

Importantly, what interventionalists will see is a disconnect between physiologic assessment and anginal symptoms even after PCI, said session panelist David Capodanno, MD, PhD, of Ferrarotto Hospital in Italy.

Another discussant discussed his doubts over the validity of ORBITA's primary endpoint of exercise time at 6 weeks.

"I really wonder if the exercise time endpoint is the legitimate endpoint under these circumstances," said Martin Leon, MD, also of Columbia University Medical Center/New York-Presbyterian Hospital, suggesting that the investigators would have been better off with ischemia-driven DSE given that it is much more controlled and quantitative a measure.

Al-Lamee's response: she "absolutely" agreed that if she could do it all over, she wouldn't choose exercise time as the primary endpoint for ORBITA -- and would opt for a binary one at that.

Nevertheless, "these observations illustrate that the clearly demonstrated physiologic effect of PCI over sham as assessed by FFR and iFR does not easily translate into downstream clinical observations within the trial, highlighting the subjective and multifactorial nature of angina symptoms," according to an by Ajay Kirtane, MD, SM, of Columbia University Medical Center/New York-Presbyterian Hospital in New York City.

It is clear that epicardial coronary physiology isn't the sole determinant of clinical symptom relief, particularly among patients whose angina is well-controlled on intensive medical therapy, Kirtane emphasized.