Arterial hypertension was responsible for about 9.4million cases of death in 2010. It is one of the most common cardiovascular risk factors with a global prevalence of 31% in 2010 among adults. It is also one of the most important risk factors of global burden of disease. Treatment of arterial hypertension is regulated by several national and international guidelines. In 10 - 30% of the patients drug refractory hypertension so called 'resistant hypertension' still remains a relevant clinical issue. Interventional approaches such as baroreceptor stimulation or renal sympathetic denervation are an alternative treatment strategy for those patients.
The innovative technology of renal sympathetic denervation has been evaluated in several randomized and non-randomized studies with promising results.
Our pilot study aimed to investigate the possible influence of renal sympathetic denervation on myocardial perfusion reserve. Myocardial perfusion reserve was measured in a semi quantitative approach using the slope of the signal-intensity-time curve of the first pass of a Gadolinium contrast agent in cardiac MRI. In patients with refractory hypertension a reduced ability to improve myocardial perfusion under pathophysiologic conditions at 'stress' has been reported.
We also investigated changes in 24h-holter monitoring as well as changes in cardiac MRI parameters focusing left ventricular function (ejection fraction, stroke volume, endsystolic volume, enddiastolic volume, left ventricular myocardial mass, thickness of interventricular septum)
An adenosine induced cardiac stress MRI as well as an 24h holter monitoring was performed in 15 patients with resistant arterial hypertension prior to and at 3, 6 and 12 months post RSD.
12 months post RSD there were no significant changes in myocardial perfusion reserve index in the examined stratums of the myocardium (apical, midseptal, basal, septal). However, there was a trend towards an increasing myocardial perfusion index in several patients during follow-up. 6 months post RSD there was a significant reduction of mean systolic and diastolic blood pressure in 24h holter monitoring. In individual patients, a reduction of mean systolic blood pressure of > 20mmHg was found. In correlation to blood-pressure lowering we found a significant reduction in left ventricular myocardial mass and in septal wall thickness 12-month post RSD. The number of antihypertensive drugs decreased from 4.67/d to 3.44/d.
In conclusion, there were no significant changes in myocardial perfusion reserve index during one year of follow-up in our patients. However, there was a clear reduction of mean blood pressure in 24h holter monitoring and a significant reduction of left ventricular mass and enddiastolic septal wall thickness. Our findings concerning cardiac MRI parameters revealed by cardiac stress MRI were in line with previous echocardiographic analysis in resistant hypertensive patients undergoing RSD. As a well-known limitation of a pilot study, the number of patients was too small to power statistical significance for several parameters analyzed.
Regarding individual patients of our cohort, there were clear changes in MPRI during 12 months of follow-up after RSD. Thus, a positive correlation between RSD and MPRI might be of relevance in a larger cohort of patients. Future analysis should focus on this clinically important issue.
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