SCAI: HERCULES shows BNP as weak predictor of systolic BP response

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BALTIMORE—There is no evidence of correlation between pre-procedural brain natriuretic peptide (BNP) levels, change in BNP levels and clinically important reduction in systolic blood pressure following renal artery stenting, based on the late-breaking HERCULES trial presented May 5 at the 2011 Society for Cardiovascular Angiography and Interventions (SCAI) scientific sessions. However, the RX Herculink Elite renal stent system (Abbott Vascular), which is not FDA approved, was shown to be safe.

The study’s lead author Michael R. Jaff, DO, from Massachusetts General Hospital in Boston, explained that controversy has persisted regarding the role of endovascular renal artery stent revascularization for patients with atherosclerotic renal artery stenosis (ARAS).

Therefore, the HERCULES investigators sought to examine whether they could predict outcomes from renal artery stent revascularization using quantitative measures prior to intervention. According to Jaff, the HERCULES trial included the largest prospective series evaluating the role of BNP as a predictor of systolic blood pressure response following renal artery stenting.

In this prospective, multi-center trial, the researchers enrolled 202 patients (241 total lesions; 39 bilateral lesions) between August 2007 and October 2009.

The primary endpoint was nine-month binary restenosis rate as determined by duplex ultrasound and/or angiographic analysis. Secondary endpoints included changes in blood pressure, anti-hypertensive medications and renal function between baseline and nine months. BNP was measured at baseline, 24 hours and 30 days post procedure.

Jaff et al found that the systolic blood pressure decreased after stenting with no change in medications. Sixty-six percent of patients had BNP of greater than 80pg/mL. Baseline serum creatinine was 1.2, and 61.5 percent of the participants had epidermal growth factor receptor (eGFR) of less than 60. eGFR was stable at nine months.

Despite a reduction in mean systolic blood pressure, mean BNP levels remained elevated at one month, Jaff reported. There was no evidence of a correlation between BNP levels at baseline and SBP reduction, or between BNP reduction and systolic blood pressure response.

The restenosis rate was 10.5 percent at nine months.

The study device, procedure and clinical success rates were 96 percent, 99.2 percent and 98 percent, respectively. Freedom from major adverse events and re-intervention was 94.8 percent.

Based on the results, the researchers concluded that the trial demonstrated clinically and statistically significant systolic blood pressure reduction in patients with multi-drug uncontrolled hypertension associated with low in-stent restenosis and complication rates.

However, elevated pre-treatment BNP levels were not predictive of reduction in systolic blood pressure.

Therefore, Jaff suggested that further studies of predictors of systolic blood pressure response after renal artery stenting are needed. He added that this study was “disappointingly negative” for BNP as a biomarker, and “we are struggling to find any solid data that a particular biomarker could help us predict systolic blood pressure response.”

Abbot Vascular sponsored the trial.