A European multi‐center trial investigating the anti‐restenotic effect of intravascular sonotherapy after stenting of de novo lesions (EUROSPAH: EUROpean Sonotherapy Prevention of Arterial Hyperplasia)

Randomized trials of invasive cardiovascular interventions that include a placebo control: a systematic review and meta-analysis

AIMS

The difference in the benefit of invasive cardiovascular interventions compared with placebo controls has not been analysed systematically.

METHODS AND RESULTS

MEDLINE and Web of Science were searched through 29 March 2020. Randomized, placebo-controlled trials of invasive cardiovascular interventions (including catheter-based interventions and pacemaker-like devices) investigating predefined primary outcomes were included. Standardized mean differences (SMD) and odds ratios were calculated for continuous and dichotomous outcomes, respectively. Meta-regression analyses were performed to assess whether estimates of treatment effects were associated with methodological characteristics of trials. Thirty trials, including 4102 patients, were analysed. The overall risk of bias was judged to be low in only 43% of the trials. Ten trials (33%) demonstrated statistically significant superiority of invasive interventions over placebo controls for the respective predefined primary outcomes. In almost half of the 16 trials investigating continuous predefined primary outcomes, the SMD between the active and placebo procedure indicated a small (n = 4) to moderate (n = 3) treatment effect of active treatment over placebo. In contrast, one trial indicated a small treatment effect in favour of the placebo procedure. In the remaining trials, there was no relevant treatment effect of active treatment over placebo. In trials with a protocol-mandated stable and symmetrical use of co-interventions, the superiority of active procedures vs. invasive placebo procedures was significantly larger as compared with trials with frequent or unbalanced changes in co-interventions (P for interaction 0.027).

CONCLUSIONS

The additional treatment effect of invasive cardiovascular interventions compared with placebo controls was small in most trials.

Evaluating the importance of sham-controlled trials in the investigation of medical devices in interventional cardiology

Cardiovascular medicine is one of the specialties that has relied most heavily on evidence from randomised clinical trials in determining best practice for the management of common disease conditions. When comparing treatment approaches, trials incorporating random allocation are the most appropriate method for protecting against treatment allocation bias. In order to protect against performance and ascertainment bias, trial designs including placebo control are preferable where feasible. In contrast to testing of medicines, treatments based on procedures or use of medical devices are more challenging to assess, as sham procedures are necessary to facilitate blinding of participants. However, in many cases, ethical concerns exist, as individual patients allocated to sham procedure are exposed only to risk without potential for benefit. Accordingly, the potential benefits to the general patient population must be carefully weighed against the risks of the exposed individuals. For this reason, trial design and study conduct are critically important to ensure that the investigation has the best chance of answering the study question at hand. In the current manuscript, we aim to review issues relating to the conduct of sham-controlled trials and discuss a number of recent examples in the field of interventional cardiology.

Diagnosis and treatment of coronary vulnerable plaques

Thin-capped fibroatheroma is the morphology that most resembles plaque rupture. Detection of these vulnerable plaques in vivo is essential to being able to study their natural history and evaluate potential treatment modalities and, therefore, may ultimately have an important impact on the prevention of acute myocardial infarction and death. Currently, conventional grayscale intravascular ultrasound, virtual histology and palpography data are being collected with the same catheter during the same pullback. A combination of this catheter with either thermography capability or additional imaging, such as optical coherence tomography or spectroscopy, would be an exciting development. Intravascular magnetic resonance imaging also holds much promise. To date, none of the techniques described above have been sufficiently validated and, most importantly, their predictive value for adverse cardiac events remains elusive. Very rigorous and well-designed studies are compelling for defining the role of each diagnostic modality. Until we are able to detect in vivo vulnerable plaques accurately, no specific treatment is warranted.