Long-term effect of aldosterone inhibition on cardiac structural abnormality as assessed with analysis of ultrasonic radio frequency signals

Background: Aldosterone antagonists are considered as one of interventions that may provide additional benefits to standard therapy of congestive heart failure. Experimental studies have suggested that aldosterone inhibition provides benefits through effects on cardiac structure; however, the confirmation of these experimental results in patients has been difficult because of limited tools for assessment of LV structure. Recently, we have reported that analysis of ultrasonic radio-frequency (RF) signals obtained from myocardium may have a potential of detecting structural damage noninvasively. Methods and Results: To assess long-term effect of aldosterone inhibition on cardiac structure, myocardial RF signals were analyzed in 15 patients with LV hypertrophy (LV mass index>120g/m2) before and after 6 and 12 month-administration of spironolactone. There were no changes in LV end-diastolic diameter, ejection fraction and LV mass index throughout the study protocol. Attractors constructed from RF signals formed a thin ring-like structure consisting of a relatively empty, roughly circular core (quasi-periodic pattern) before the administration and changed to chaotic pattern 6 and 12 months after the administration. The mean value of correlation dimension (CD) calculated from the RF signals of all the subjects increased towards a normal level (2.6±0.1 vs. 3.0±0.2, p