Elevated Heart Rate is Associated with Cardiac Denervation in Patients with Heart Failure: A 123-Iodine-MIBG Myocardial Scintigraphy Study

Abstract

BackgroundIn the Systolic Heart Failure Treatment With the If Inhibitor Ivabradine Trial (SHIFT), heart rate (HR) reduction with ivabradine was associated with improved survival and reduced hospitalizations in patients with heart failure (HF). The mechanisms by which elevated HR increases mortality are not fully understood.ObjectiveTo assess the relationship of baseline HR with clinical, neurohormonal and cardiac sympathetic activity in patients with chronic HF and elevated HR.MethodPatients with chronic HF who were in sinus rhythm and had resting HR>70 bpm despite optimal medical treatment were included in a randomized, double-blind study comparing ivabradine versus pyridostigmine. This report refers to the baseline data of 16 initial patients. Baseline HR (before randomization to one of the drugs) was assessed, and patients were classified into two groups, with HR below or above mean values. Cardiac sympathetic activity was assessed by 123-iodine-metaiodobenzylguanidine myocardial scintigraphy.ResultsMean HR was 83.5±11.5 bpm (range 72 to 104), and seven (43.7%) patients had HR above the mean. These patients had lower 6-min walk distance (292.3±93 vs 465.2±97.1 m, p=0.0029), higher values of N-Terminal-proBNP (median 708.4 vs 76.1, p=0.035) and lower late heart/mediastinum rate, indicating cardiac denervation (1.48±0.12 vs 1.74±0.09, p<0.001).ConclusionElevated resting HR in patients with HF under optimal medical treatment was associated with cardiac denervation, worse functional capacity, and neurohormonal activation.

Hypotension and Renal Dysfunction: The Ghosts of Heart Failure

“…The elevated heart rate (HR) is a marker of severity and is harmful to the patient with HF, and may even be the cause of HF (tachycardiomyopathy). 1 , 17 Since the publication of the study Systolic Heart Failure Treatment With the Inhibitor Ivabradine Trial (SHIFT) it is known that HR is not only a marker of severity, but a therapeutic target in HF, since patients treated with ivabradine, an exclusive HR reducer, showed a reduction in the combined outcome of cardiovascular mortality and hospitalization for HF. 18 Beta blockers prolong the survival of patients with HF and are medicines that reduce HR.…”