Angina Is as Subjective as Any Other Pain

Almost 80% of all patients randomized in this study reported Canadian Cardiovascular Society class II or III angina, and almost all of them (97%) had more than 1 positive non-invasive ischemia test that matched the area of their single diseased coronary vessel. Beyond fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR), the study randomized patients to undergo angioplasty or a sham procedure (placebo group). We might have expected angioplasty patients to resolve their symptoms and placebo patients to continue with the same angina functional class. It should be noted that all patients were symptomatic and they all had single-vessel disease, with ischemia shown in more than one functional study.

Our expectations turned out to be quite different from reality, since almost half the patients who underwent angioplasty continued with angina and, more interestingly, 31.5% of placebo patients (i.e., those who underwent a sham procedure) reported being symptom-free. That is a significant difference, which leads us to conclude that, while angioplasty does actually improve symptoms, some things we are yet to understand.

Before randomization, all patients were assessed with iFR and FFR, while results were blinded. Mean FFR was 0.69 ± 0.16 and mean iFR was 0.76±0.22 (undoubtedly, all subjects were ischemic patients) in 196 study patients, among whom 103 underwent angioplasty and 93 underwent a placebo procedure.

Angioplasty clearly improved stress echocardiography scores (p < 0.0001) and its effect was progressively more evident with decreasing FFR and iFR (p for interaction < 0.00001). That is the expectable, logical result for this study.

However, angioplasty did not improve angina frequency scores significantly more than placebo, and there was no detectable evidence of interaction with FFR (p = 0.849) or iFR (p = 0.783) results.

Despite all of the above, as it was mentioned at the beginning of this article, angioplasty was associated with more freedom from angina (49.5% versus 31.5%; odds ratio [OR]: 2.47; 95% confidence interval [CI]: 1.30 to 4.72; p = 0.006), although neither FFR nor iFR could predict this effect.

This is undoubtedly one of the most interesting studies ever published on ischemic heart disease and, despite its scarce 196 patients, it is certainly bound to start a debate.

Original title: Fractional Flow Reserve and Instantaneous Wave-Free Ratio as Predictors of the Placebo-Controlled Response to Percutaneous Coronary Intervention in Stable Single-Vessel Coronary Artery Disease. Physiology-Stratified Analysis of ORBITA.

Reference: Al-Lamee R et al. Circulation. 2018 May 22. Epub ahead of print.