Does renal denervation impact cardiac parameters in resistant hypertension?

The authors evaluated the effect of renal denervation in resistant hypertension.

Resistant hypertension (high blood pressure) is defined as blood pressure above goal despite the simultaneous use of three or more different antihypertensive drugs, one ideally being a diuretic (causing increased passing of urine), with all drugs prescribed at maximum or maximum tolerated doses. Resistant hypertension can lead to thickening and enlargement of the atria (chambers that collect blood from the body) and ventricles (chambers that expel blood to the body) of the heart, causing strain and dysfunction and increasing risk of cardiovascular events.

Catheter-based renal denervation is a relatively new treatment for resistant hypertension. It is a minimally invasive procedure that strips nerve endings from the wall of blood vessels in the kidney using radiofrequency ablation (removal via heat generated from a high frequency current). It has been shown to reduce the mass of the left wall of the heart and decrease blood pressure.

The present study aimed to evaluate the effects of renal denervation on myocardial (heart muscle) parameters in patients with resistant hypertension.

72 patients were enrolled in the study. 55 patients were treated with renal denervation while 17 subjects were not (controls). Cardiac magnetic resonance (imaging technology to assess structure and function of the heart) was performed at the beginning of the study and after 6 months. The renal denervation group maintained their use of an average of 4.6 antihypertensive drugs throughout the follow-up, while the control maintained their use of an average of 4.5 antihypertensive drugs.

Systolic (pressure when the heart is contracting – the larger number) and diastolic (pressure when the heart is relaxed or filling – the smaller number) blood pressure decreased significantly from an average of 170/90 mmHg at the beginning of the study to 148/82 mmHg 6 months after renal denervation. Blood pressure in the control group also changed from an average of 156/84 mmHg to 145/77 mmHg. 33% of patients were deemed to be non-responders following renal denervation (achieved systolic blood pressure reduction of less than 10 mmHg).

Left ventricular end systolic volume (the volume left in the ventricle chamber of the heart at the end of contraction; used as a measure of adequate emptying of the heart) was reduced from 81 mL to 77 mL. Ejection fraction (the percentage of blood leaving the heart each time it contracts) increased significantly following renal denervation from 55.7% to 57.6% but remained unchanged in the control group. In patients who had left ventricular ejection fraction of less than 50% at the beginning of the study, left ventricular ejection fraction significantly increased by 7.3% in the renal denervation group while there was no improvement in the control group. Left ventricular mass indexed to height (the mass of the left ventricle divided by height) decreased by 7.1% at 6 months following renal denervation.

Circumferential strain (an inward shift of the walls of the heart due to thickening) was improved by 21% in patients with reduced contractility of the heart (ability of the heart to contract) at the beginning of the study. Renal denervation was also associated with a decrease in the size of the left atrium from 29.7 cm² to 28.6 cm².

According to the authors, renal denervation reduced blood pressure and significantly improved left ventricular wall thickness and myocardial function.