Percutaneous renal denervation in patients with treatment-resistant hypertension: final 3-year report of the Symplicity HTN-1 study

BACKGROUND

Renal denervation (RDN) with radiofrequency ablation substantially reduces blood pressure in patients with treatment-resistant hypertension. We assessed the long-term antihypertensive effects and safety.

METHODS

Symplicity HTN-1 is an open-label study that enrolled 153 patients, of whom 111 consented to follow-up for 36 months. Eligible patients had a systolic blood pressure of at least 160 mm Hg and were taking at least three antihypertensive drugs, including a diuretic, at the optimum doses. Changes in office systolic blood pressure and safety were assessed every 6 months and reported every 12 months. This study is registered with ClinicalTrials.gov, numbers NCT00483808, NCT00664638, and NCT00753285.

FINDINGS

88 patients had complete data at 36 months. At baseline the mean age was 57 (SD 11) years, 37 (42%) patients were women, 25 (28%) had type 2 diabetes mellitus, the mean estimated glomerular filtration rate was 85 (SD 19) mL/min per 1·73 m(2), and mean blood pressure was 175/98 (SD 16/14) mm Hg. At 36 months significant changes were seen in systolic (-32·0 mm Hg, 95% CI -35·7 to -28·2) and diastolic blood pressure (-14·4 mm Hg, -16·9 to -11·9). Drops of 10 mm Hg or more in systolic blood pressure were seen in 69% of patients at 1 month, 81% at 6 months, 85% at 12 months, 83% at 24 months, and 93% at 36 months. One new renal artery stenosis requiring stenting and three deaths unrelated to RDN occurred during follow-up.

INTERPRETATION

Changes in blood pressure after RDN persist long term in patients with treatment-resistant hypertension, with good safety.

FUNDING

Ardian LLC/Medtronic Inc.

International expert consensus statement: Percutaneous transluminal renal denervation for the treatment of resistant hypertension

Catheter-based radiofrequency ablation technology to disrupt both efferent and afferent renal nerves has recently been introduced to clinical medicine after the demonstration of significant systolic and diastolic blood pressure reductions. Clinical trial data available thus far have been obtained primarily in patients with resistant hypertension, defined as standardized systolic clinic blood pressure ≥ 160 mm Hg (or ≥ 150 mm Hg in patients with type 2 diabetes) despite appropriate pharmacologic treatment with at least 3 antihypertensive drugs, including a diuretic agent. Accordingly, these criteria and blood pressure thresholds should be borne in mind when selecting patients for renal nerve ablation. Secondary forms of hypertension and pseudoresistance, such as nonadherence to medication, intolerance of medication, and white coat hypertension, should have been ruled out, and 24-h ambulatory blood pressure monitoring is mandatory in this context. Because there are theoretical concerns with regard to renal safety, selected patients should have preserved renal function, with an estimated glomerular filtration rate ≥ 45 ml/min/1.73 m(2). Optimal periprocedural management of volume status and medication regimens at specialized and experienced centers equipped with adequate infrastructure to cope with potential procedural complications will minimize potential patient risks. Long-term safety and efficacy data are limited to 3 years of follow-up in small patient cohorts, so efforts to monitor treated patients are crucial to define the long-term performance of the procedure. Although renal nerve ablation could have beneficial effects in other conditions characterized by elevated renal sympathetic nerve activity, its potential use for such indications should currently be limited to formal research studies of its safety and efficacy.

The rationale and design of the Glycemic Effects in Diabetes Mellitus Carvedilol-Metoprolol Comparison in Hypertensives (GEMINI) trial

Beta-blockers utilized in the Type 2 diabetic patient result in an even greater decrease in cardiac events than in the nondiabetic patient. Unfortunately, first-and second-generation beta-blockers are associated with the worsening of insulin resistance, deterioration of glycemic control, peripheral vasoconstriction, potentially worsening peripheral vascular disease, and more frequent and severe hypoglycemia. The third-generation beta-blockers have unique properties, including alpha1-blockade, and have been shown to lower insulin resistance, improve glycemic control, and vasodilate resistance arterioles. The Glycemic Effects in Diabetes Mellitus: Carvedilol-Metoprolol Comparison in Hypertensives (GEMINI) trial has been designed to compare a third-generation (carvedilol) with a second-generation beta-blocker (metoprolol) in a cohort of participants with hypertension and Type 2 diabetes. The primary outcome measure of the study is change in the HbA1c. The study is powered to detect a difference in HbA1c of 0.3 units (%) between the groups. Secondary endpoints include changes in insulin resistance, fasting glucose, and the lipid profile. Differences in the side-effect profile (cold extremities, fatigue, impotence, and hypoglycemia) will also be assessed. The GEMINI trial, therefore, is the first large randomized trial to assess whether utilizing a third-generation beta-blocker yields a favorable metabolic profile in the patient with Type 2 diabetes and hypertension.

Safety of intravenous gadolinium (Gd-BOPTA) infusion in patients with renal insufficiency

The safety of gadolinium (Gd-benzyloxypropionictetra-acetate [BOPTA] dimeglumine) infusion was evaluated in 32 patients with severe or moderate chronic renal failure in a prospective, randomized, double-blind, placebo-controlled study. Renal failure was defined as severe if creatinine clearance was between 10 and 29 mL/min, and as moderate if creatinine clearance was between 30 and 60 mL/min. Serum creatinine level and 24-hour urine samples for creatinine clearance were followed up serially for 7 days after the administration of either gadolinium (Gd-BOPTA dimeglumine), 0.2 mmol/kg, or a saline infusion. No patient experienced a significant change in renal function, defined as an increase in serum creatinine level greater than 0.5 mg/dL more than baseline, and no patient required hospitalization or dialysis during the study period. Gadolinium (Gd-BOPTA dimeglumine) appears to be well tolerated in patients with moderate to severe renal failure.