Dec 27, 2013
Hypertension affects 78 million adults in the US. According to national data 82% of those with hypertension are aware that they have it. 75% are being treated but on 50% are under control. The degree of control is variable across different groups. Effective blood pressure control is essential to the successful reduction of heart attack, stroke and renal failure risks.
Importantly, of those control over 85% report having a usual source of health care and having insurance. Given the importance of this issue, the American Heart Association has made this a primary focus area of its 2014-17 campaign with a goal to reduce the death rate from heart attack and stroke by 20% in 2020.
Achieving this goal will require a mulipronged approach directed at systems changes, care provider education to ensure compliance with best evidence treatment approaches, and effective patient engagement to stimulate the highest level of patient education and participation.
Still, up to 20% of patients may have poorly controlled blood pressure despite being on three agents at maximally tolerated dosages, one of which is a diuretic. In this group of patients, the risk of heart attack, heart failure, stroke and renal failure are up to 3 times greater. Renal artery sympathetic ablation or renal denervation, represents a technology with potential benefit to better control blood pressures in this challenging group.
Research has shown that patients with this problem suffer from higher circulating levels of norepinephrine levels which are regulated by the nerves to and from the kidney. These nerves are also responsible for regulating salt and water absorption and blood vessel tone. Increased salt absorption and increase vascular constriction both elevate blood pressure.
Selectively interrupting these nerve pathways causes a reduction in blood pressure. The SimplicityI 1 Trial showed a reduction of 30/17 at one year which continued out to 3 years in a subset of patients followed out that far.
84% of patients responded.
The next level of studies will be better controlled with a placebo arm (patients not receiving the treatment to reduce the impact of the "placebo affect"). The trial will also have larger numbers. The questions that remain to be answered include who it works in and just as important, who doesnt it work in. Are there any mid and long term side affects on artery integrity.
For a patient group that has limited options and significantly elevated stroke and heart attack risk--denervation trial enrollment represents an important immediate and future treatment option.