Registries & Randomization

We appear to be poised on a new era for treating a variety of cardiovascular conditions with renal artery denervation, a percutaneous technique that disrupts the renal sympathetic nervous system using ablation. In this issue of Cardiovascular Business, we talk with interventional cardiologists and electrophysiologists about its potential as a treatment for drug-resistant hypertension, atrial fibrillation and heart failure. While not approved in the U.S., the technique already has been approved for refractory hypertension in parts of Europe and Australia. 

Many randomized clinical trials are ongoing to evaluate safety, efficacy and short- and long-term outcomes for patients who receive this treatment. It will be important to know if the benefits seen for hypertension hold up beyond three years, for instance, or if the delayed response seen with hypertensive patients manifests in heart failure patients. In the former group, this trend toward lowering of blood pressure is a benefit, but in the latter, it could be a complication.  

Randomized controlled trials often get criticized for not representing the real-world patients who get treated in clinical practice. In fact, enrollers often can’t conduct an all-comers trial for ethical or practical reasons. Studies using administrative data and registries help to fill those gaps by including a broader selection of patients, settings and physicians. These, too, have their faults; since patients aren’t randomized, the findings are subject to unmeasured confounders.

The good news is that administrative and registry databases are becoming increasingly robust. In this issue, we also provide an update on ICD-10 coding for thoracic surgery. These codes will provide granularity that may be a treasure trove for researchers. Some organizations also have taken a proactive approach by investing in registries to track outcomes.  

In the case of renal denervation, physicians in Europe who have performed the procedure encourage their colleagues to participate in a registry to identify potential complications. Medtronic, whose Symplicity renal denervation system has been used to treat more than 5,000 patients, launched a global registry in 2012 to evaluate its use in clinical practice. That’s a start.