Tag Archives: blood pressure

Promising One Year Results For Renal Denervation In Resistant Hypertension Spark Hype Reply

by • Interventional Cardiology & Surgery, People, Places & Events, Policy & Ethics, Prevention, Epidemiology & Outcomes • Tags: , , ,

Denervation of the renal sympathetic nerve may become an important new tool in the fight against resistant hypertension.  Previously, the main results of the Symplicity HTN-2 trial demonstrated that in selected patients renal denervation resulted in a large and highly significant reduction in systolic blood pressure (BP) at six months. Now, longer followup from the trial, published in Circulation, demonstrates that the benefits at 6 months extend to one year, and that control patients who crossed over to renal denervation also experienced large reductions in BP.

For 47 patients with resistant hypertension, the reduction in systolic BP at one year (−28.1 mm Hg) was similar to the reduction at 6 months (31.7 mm Hg). For 35 control patients  who crossed over to renal denervation after six months, mean systolic BP dropped from 190.0±19.6 before the procedure to 166.3±24.7 mm Hg. The authors reported one case of renal artery dissection in the crossover group, which was fixed with renal artery stenting, and one episode of hypotension, which was fixed with a medication adjustment.

The results, according to a clinical perspective accompanying the article, suggest that “radiofrequency ablation of renal nerves can significantly lower blood pressure in patients with systolic blood pressures >160 mm Hg with no loss of treatment effect through 1 year and thus may provide a safe and effective adjunctive therapy for treatment-resistant hypertensive patients.”

Comment: Excitement about renal denervation has been growing in recent years. At least some of the optimism may well be warranted. But, for now, the greatest danger is hype. Here’s the #4 item on the AHA’s list, released just this week, of the top advances of 2012:

“Disconnecting” the kidneys might be the key to treating high blood pressure

What does that mean, “the key to treating high blood pressure?” As an invasive procedure, renal denervation will never be more than a important therapeutic option after lifestyle and polypharmacy have failed. I applaud the AHA for highlighting this important new technology, but I think it should have used more cautious wording.

Get ready for much worse. Gullible or naive reporters and editors have already fallen into the trap. Here’s the headline and opening sentences of a story that appeared earlier today in TheStar.com:

Zapping kidneys with radio waves could cure high blood pressure, study finds

In what’s being described as a potential public health miracle, a new study shows that zapping the kidneys with radio waves can safely and dramatically lower blood pressure.

“It makes one dizzy to think about the next set of benefits that follow,” said Dr. Clyde Yancy, head of cardiology at Chicago’s Northwestern University.

This is almost a textbook example of how science and medicine stories should not be reported. It’s important to activate your BS detector whenever you see words like “cure” and “miracle” in a health story. Renal denervation is not a cure and it’s not a miracle. If things work out, it may represent a welcome and significant advance for some patients with resistant hypertension.

To be fair, the rest of the story contains some great quotes and perspective from Clyde Yancy. But by then the damage has been done. It’s impossible to be rational in the presence of cures and miracles. Of course, any reporter can slip at some point and buy into the hype. We’re not perfect. But it helps if the reporter has some prior knowledge and experience in the field. I’m assuming this reporter had little background in this field, since no experienced health reporter would describe renal denervation as “bathing the kidneys in radio waves.” It’s hard enough for physicians and grizzled journalists to figure this kind of stuff out. This is no spot for learning on the job.

But let’s not blame the reporter. He was probably just doing his job as best he could, on a deadline and with few resources. He should be congratulated for getting a good interview with Clyde Yancy. The larger problem here is the way most media treat health, medicine and science stories. Breakthroughs and cures aren’t everyday events, except in the filler pages of tabloids, and on news broadcasts and websites, where scientific inflation is an everyday occurrence. In this context, scientific reporting becomes, essentially, worthless. If everything is a breakthrough then nothing is a breakthrough.
Click here to read the Medtronic press release…

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Should Body Weight Influence Choice of Antihypertensive Therapy? 1

by • Heart Failure, Prevention, Epidemiology & Outcomes • Tags: , , , , , ,

The hypertension field has been troubled by repeated observations that normal weight patients have more cardiovascular (CV) events than obese patients. Now a new analysis of a large hypertension trial confirms this finding but also suggests that it may be explained by either an adverse effect of diuretics or a protective effect of calcium-channel blockers in non-obese hypertensives.

Michael Weber and colleagues analyzed data from more than 11,000 patients randomized in the ACCOMPLISH trial to shed light on this problem. In 2008 the main results of the trial showed that the combination of benazepril and amlodipine (calcium channel blocker group, CCB) was superior to the combination of benazepril and hydrochlorothiazide (diuretic group) in reducing CV events in high risk hypertensive patients.

The new analysis, published online in the Lancet, confirmed earlier observations and found significant differences in outcome based on weight. However, the differences in outcome occurred mostly in the diuretic group. In the diuretic group, the rate for the primary endpoint was significantly different between the groups (30.7 events per 1,000 patient-years in normal weight patients, 21.9 in overweight patients, and 18.2 in obese patients, p=0.0034). In the CCB group the rates were not significantly different (18.2, 16.9, and 16.5).

To explain their finding the investigators proposed that “hypertension in obese and lean patients is probably mediated by different forms of underlying pathophysiology.” Obese patients, who are more likely to have increased plasma volume and cardiac output, will be responsive to diuretics, while lean patients are more likely to have involvement of the sympathetic and renin-angiotensin systems. They concluded that “diuretic-based regimens seem to be a reasonable choice in obese patients in whom excess volume provides a rationale for this type of treatment, but thiazides are clearly less protective against cardiovascular events in patients who are lean. An alternative therapeutic regimen that includes a calcium channel blocker such as amlodipine, which works equally well across all BMI categories, provides an advantage with respect to clinical outcomes in patients who are not obese.”

In an accompanying comment, Franz Messerli and Sripal Bangalore write that the effectiveness of hydrochlorothiazide in obese people in ACCOMPLISH “has little if anything to do with obesity per se, but simply reflects the fact that among obese patients there was a preponderance of individuals at risk for heart failure who were prone to respond well to diuretic treatment.” They argue that “amlodipine-based treatment should be used irrespective of body size” for the indication of hypertension. Diuretics, on the other hand, should be used for the prevention of left-ventricular dysfunction.
Click here to read the press release from the Lancet…