Gizmo idolatry can be defined as the willingness to accept, in fact to prefer, unproven, technologically oriented medical measures. [2] J. Robert Oppenheimer, at the hearing before the Personnel Security Board of the U.S. Atomic Energy Commission (USAEC) in 1954, humbly acknowledged: “When you see something that is technically sweet, you go ahead, and do it, and you argue about what to do about it only after you have had your technical success.”[3] A high-tech approach often bestows a halo of expertise and pre-eminence on the gizmologist, and despite uncertainty or lack of benefits, incentives can be considerable. And, as stated above, in the context of leeches for medical use, the theatrics are undeniable.[1]
Antihypertensive Drug Therapy
The more bromidic a medical issue, the easier it will be hijacked by a high-tech approach whenever the opportunity presents itself. As such, run-of-the-mill antihypertensive therapy can be considered as an ideal target: Ever since the National Heart, Lung, and Blood Institute advocated the stepped-care approach, antihypertensive therapy has lost its highbrow luster to clinicians; over years, if not decades, little if any change in prescription patterns has occurred. With >80 million prescriptions per year, lisinopril remains the most common used antihypertensive in the United States, followed by amlodipine and hydrochlorothiazide. Prescribing these drugs is not exactly a cognitive challenge for most physicians, although despite wide-available medications and lifestyle interventions, blood pressure (BP) control rates remain precariously low.[4]
The arrival of renal denervation (RDN) in 2011 is what allowed the redefinition of antihypertensive therapy as a high-tech item rather than something mundane like prescribing a pill or 2. After the initial excitement sparked by uncontrolled studies waned, a subsequent decade of intense research has provided reliable data allowing the assessment of RDN’s efficacy and safety. In November of last year, the U.S. Food and Drug Administration (FDA) approved 2 renal denervation systems for the treatment of hypertension.
Efficacy
The FDA’s approval of antihypertensive drugs is solely based on a surrogate endpoint, that is, BP criteria. Clinicians often are impressed by the profound BP response immediately after RDN. However, in the data submitted to the FDA,[5] the decrease in systolic BP after 2 months amounted to <5 mm Hg compared with sham, after 6 months, it was 3 mm Hg. Long-term durability remains uncertain because in the pivotal trials, patients and physicians were at liberty to change medications. Also, up to one-third of patients do not respond, with BP remaining unchanged or even rising.[6] Intense efforts to identify responders and nonresponders have not proved to be successful. This means that many patients will undergo a painful invasive procedure without having benefits. There also is concern that the lesioned renal nerves may regenerate, thereby possibly reversing the BP lowering effect.[7]
By contrast, a well-established antihypertensive such as amlodipine does lower systolic BP by >10 mm Hg in a day, and does so in a week, in a month, in a year, and in 10 years. Importantly, the drug not only lowers the surrogate of BP but also decisively reduces outcome, that is, the risk of stroke, heart attack, and death. No such information is available with RDN, and with its FDA approval, it is unlikely that there ever will be. RDN allegedly lowers BP by interfering with sympathetic activity, a mechanism akin to beta blockade. Compared with other antihypertensive drug classes, beta-blockers, despite lowering BP, have consistently demonstrated little if any efficacy in reducing outcomes in hypertensive cardiovascular disease.[8]
Safety
Based on the limited number of procedures done so far, RDN appears to be safe. Despite its lesioning the renal arteries, no subsequent stenoses were reported. [6] This holds true when the bar was set at the deceptively high level of >70% occlusion. However, closer scrutiny of the computed tomography angiography/ magnetic resonance angiography data set in the FDA executive summary reveals 3 patients with a 31% to 50% occlusion and 2 patients with a 51% to 70% occlusion, corresponding to 2.7% and 1.8% of the patient population, respectively.[5] These figures are of concern for a procedure poised to be used in a prevalent condition such as treatment-resistant hypertension. There is wide variability in the reported prevalence of treatment-resistant hypertension with rates from 3% to 30% of hypertensive patients.[9,10]
With the FDA approval, RDN companies intend to immediately begin widespread commercialization. News media in the United States have recently touted RDN as “game-changing” for people with uncontrolled hypertension. How much of a game-changer is an invasive procedure that lowers systolic BP on average by a 3 to 4 mm Hg after 6 months and is ineffective in many patients?
While pondering this and similar questions, clinicians may want to take a fresh look at antihypertensive therapy, however mundane it may be perceived. What your attending was teaching you a few years ago may no longer be state-of-the-art. In many a patient with so-called resistant hypertension, BP levels can be lowered by improving adherence and simply using a more synergistic treatment strategy.
Guidelines
Most national and international hypertension guidelines were published before FDA approval of RDN. They either sidestep the topic of RDN or approach it carefully and leave recommendations open-ended. A recent exception is the just published 2024 hypertension guidelines of the European Society of Cardiology (ESC).[11] They suggest that device-based therapy should be considered in selected patients with resistant hypertension who express a preference to undergo RDN after a shared risk-benefit discussion and multidisciplinary assessment of the BP-lowering effect. However, despite this, the guideline’s verdict remains: “Use of device-based therapies is not recommended for the routine treatment of hypertension... until further evidence regarding their safety and efficacy becomes available.”[11] Thus, ESC guidelines consider RDN Class IIb for treatment of resistant hypertension or for patients with uncontrolled hypertension and high cardiovascular disease risk.
Refractory Hypertension
The predominant mechanism underlying resistant hypertension is fluid-volume retention, mediated most often by mineralocorticoid excess.[12] By contrast, the rare patients with refractory hypertension, defined as a phenotype of antihypertensive treatment failure in which BP remains uncontrolled despite maximal therapy, often exhibit increased sympathetic nervous system activity.[12] Most clinicians regard refractory hypertension as an end-of-the-rope situation; I certainly consider it to be an appropriate clinical indication for resorting to RDN.
Conclusion
Gizmo idolatry is a pervasive phenomenon, not restricted to medicine. It consists in glorifying gadgets as more than just tools and elevating them to a level of importance or reverence that goes far beyond their documented risk-benefit ratio. Before becoming too ensnared by RDN as innovative antihypertensive therapy, we should remember the statement of the chairman of the FDA advisory committee, Dr Richard Lange, who on August 23, 2023, had to break the member’s split vote on RDN approval: “At the end of the day, I can’t honestly look patients in the eye and tell them that the benefit outweighs the risk for the population at large.”[13]
J Am Coll Cardiol. 2025;85(6) © 2025
Cite this: Renal Denervation: Antihypertensive or Gizmo Idolatry? - Medscape - Mar 20, 2025.