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Coronary stenting with stable CHD: no advantages over placebo?

 An analysis of  stents in patients with stable single vessel coronary artery disease 

Percutaneous Coronary Interventions (PCI) play a major role in cardiology, as they are the gold standard for the treatment of narrowed (stenosed) coronary vessels. However, the highly acclaimed stents are the target of new criticism.

The ORBITA study recently published in the Lancet shows that a stent implant provides no advantage over a placebo heart catheter in patients with stable coronary heart disease and pectanginal complaints. This is causing an uproar in the world of cardiology, as until now, it has been believed that dilating narrowed blood vessels is the solution for the treatment of coronary heart disease.

The fact is that many patients with stable angina pectoris report an improvement in their symptoms after a stent PCI. Previous unblinded studies also show an improvement in PCI performance, for example by increasing training time in spiroergometry by an average of 96 seconds. However, whether this effect is a placebo has not yet been determined.

Rather, the widespread opinion was that a dilated coronary artery improves the blood flow to the heart and therefore helps the patient. However, the authors of the ORBITA study wanted to get to the bottom of this and investigated the effect of PCI compared to placebo PCI in stable heart disease in a multicenter double-blind randomized study.

230 patients with stable single-vessel CHD examined

The study was conducted at five hospitals in the UK from 2014 to 2017. 230 patients were included, with coronary single-vessel disease and stable angina pectoris as inclusion criteria. Previous myocardial infarction or multiple vascular diseases were already a criterion for exclusion. The authors explain that "sicker" patients would have benefited more from PCI and a possible placebo effect would have been irrelevant in this case.

The study participants first went through a six-week optimization phase of their previous therapy, during which the antianginal medication was discontinued in accordance with the guidelines but at the highest possible dosage. Subsequently, functional examinations were performed (vital parameters, ECG, spiroergometry and stress echocardiography) and the patients were asked about their symptoms.

Then came the randomization. 104 patients received a PCI with stent implantation and 91 patients received a placebo PCI. Doctors and patients did not know which procedure was used on them or their patients. After six weeks of follow-up, the tests were repeated.

No difference between the PCI and placebo groups

Both groups recorded an average increase in physical performance due to an increase in training time according to spiroergometry observations. The PCI group could reach 28.4 seconds and the placebo group managed 11.8 seconds of training time average.

However, a statistically significant difference between the two groups could not be shown (p = 0.2). There was also no difference with other parameters such as the time to the 1mm-ST reduction and the maximum oxygen absorption. If the patients were interviewed, half of them expressed an improvement in their symptoms, the other half no change or deterioration. There was no difference between the groups here either.

Microvascular changes as a possible explanation

If one takes a look at the PCI data of the group treated with a stent, stent implantation is quite effective. The constrictions were reduced and blood flow was significantly improved, as a measurement of the fractional flow reserve (FFR) before and after stent PCI showed.

However, it seems that patients do not always benefit subjectively or notice an improvement in their symptoms although no treatment has taken place. The simple assumption that dilatation of a narrowed blood vessel alleviates the patient's symptoms does not always seem to apply.

Several factors seem to play a role, including the placebo effect. The authors also suspect that, in addition to the visible macrovascular narrowing of a vessel, microvascular changes in the apparently unaffected cardiovascular system may also be decisive.

The placebo-controlled study is also important for interventional procedures

The ORBITA study shows the strength of placebo-controlled examinations. Even widely accepted procedures such as a cardiac catheter examination can be put to the test. What has long been a standard in drug therapy, now also seems to be establishing itself in interventional procedures, even if the procedure involves higher hurdles than with conventional drugs.

It should be noted that the results of this study only apply to patients with stable coronary artery disease. Patients with unstable angina pectoris, multiple vascular disease, and myocardial infarction continue to benefit fully from PCI.

In addition, the study participants received an average of three antianginal medications, which may prove difficult in clinical routine due to the adherence of the patients. Also, the short follow-up of six weeks does not allow any conclusion on the long-term effect of a placebo-PCI. The authors refer here to the ISCHEMIA study, which will address this problem.

Source:
Al-Lamee R et al. Percutaneous coronary intervention in stable angina (ORBITA): A double-blind, randomised controlled trial. Lancet 2017 Nov 2;[e-pub]. (http://dx.doi.org/10.1016/S0140-6736(17)32714-9).