Data supporting the long-term safety and effectiveness of renal sympathetic denervation in treating patients with chronic hypertension were presented on 25 September 2009 at the Transcatheter Cardiovascular Therapeutics (TCT) conference in San Francisco, US. The data were presented at a late-breaking trial session and showed that patients in the study maintained a clinically significant reduction in blood pressure at one -year following treatment.
The results stemmed from the Symplicity I trial which was the first clinical study to evaluate a catheter-based treatment for chronic hypertension. The study enrolled patients who had persistent elevated blood pressure despite taking an average of 4.7 medications. The multicentre study was conducted in Australia and Europe, using the Symplicity Catheter System manufactured by Ardian. Early results from this same trial were also recently reported in The Lancet (11 April) and The New England Journal of Medicine (27 August).
The study’s co-principal investigator, Henry Krum, director of the Center of Cardiovascular Research & Education in Therapeutics, Monash University, Melbourne, Australia, reported that the simple, 40-minute procedure safely produced a mean blood pressure reduction of -27/-17mmHg at 12 months in the study cohort. These findings suggest that the single, catheter-based intervention may achieve a durable, clinically important reduction in blood pressure in this very difficult to treat population.
Both vascular and renal safety were also carefully assessed in the study and reported during the conference. Renal vascular safety was assessed by imaging treated arteries both acutely and chronically for up to 9 months. No evidence of treatment-related abnormalities or stenoses was reported. Kidney function was assessed with serial measures of serum creatinine and calculation of glomerular filtration rate (GFR). The mean GFR in the study cohort remained stable at 12 months.
Commenting on these results, Krum stated, “I am very excited by these latest findings. These data demonstrate that the reductions in blood pressure we observed at 12 months in our initial Lancet paper have been found to be durable amongst a much larger cohort of patients who have now completed the study.”
Based on these results Ardian has initiated the Symplicity HTN-2 trial, a prospective, multicentre randomised study comparing patients treated with renal denervation to those receiving rigorous medical therapy. The trial will enrol 110 patients with blood pressure over 160mmHg, despite taking three or more anti-hypertensive medications. The primary endpoint for the trial will be blood pressure reduction at six months. Kidney function, vascular safety and additional efficacy measures will also be assessed. Patients will be followed for three years.
Ardian’s Symplicity Catheter System delivers radiofrequency energy from within the renal artery to block conduction in the surrounding renal nerves, thereby counteracting chronic activation of the sympathetic nervous system. In addition to blood pressure reduction, this treatment has shown promising results for chronic kidney disease, heart failure and metabolic syndrome. The treatment is performed in the catheterisation laboratory using routine interventional techniques similar to those used in renal stent procedures. The 40-minute treatment is minimally invasive and does not involve a permanent implant. The Symplicity Catheter System has received CE mark approval in Europe but remains investigational in the US.