Abstract 17781: Spironolactone Improves Left Atrial Function and Atrioventricular Coupling in Resistant Hypertension

Abstract

Purpose: To determine the blood pressure independent effects of spironolactone on left atrial (LA) size and function in patients with resistant hypertension (RHTN). Methods: Patients with RHTN (N=36, 55±7 years) were prospectively recruited. Spironolactone was initiated at 25 mg/day and increased to 50 mg/day after four weeks. Other antihypertensives were withdrawn to maintain constant blood pressure. Cardiac magnetic resonance imaging was performed at baseline and after six months of spironolactone treatment and changes in LA functional metrics were assessed (Figure 1). The statistical analysis was conducted using two-sided tests of significance. Results: LA size and function parameters improved from baseline to month-six: LA volumes indexed to body surface area (LAVI) were reduced (LAVI max 41.4±12 vs 33.2±9.7 ml/m 2 ; LAVI pre-A 32.6±9.8 vs 25.6±8.1 ml/m 2 ; LAVI min 18.5 [13.9 - 24.8] vs 14.1 [10.9 - 19.2] ml/m 2 ; all p < 0.05); left atrioventricular coupling index was reduced (28.2±11.5 vs 22.7±9.2 %, p < 0.05); LA emptying fractions (LAEF) were increased (total LAEF 52.4 [48.7 - 60.3] vs 55.9 [50.3 - 61.1] %; active LAEF 40.2±8.6 vs 43.1±7.8 %, both p < 0.05). There was a substantial increase in reservoir strain (29.1 ± 8.5 % vs 30.9 ± 5.5 %, p = 0.068) whereas active strain was significantly increased from baseline (16.3 ± 4.1 % vs 17.8 ± 4.2 %, p < 0.05). Changes in passive strain and strain rates were not statistically significant (p > 0.1). The effect of spironolactone was similar in patients with high (N = 18) and normal (N = 18) aldosterone status (defined by plasma renin activity and 24-hour urine aldosterone). Conclusion: Treatment of RHTN with spironolactone is associated with improvements in LA size and function regardless of whether aldosterone levels were normal or high. This study suggests the need for larger prospective studies examining effects of mineralocorticoid receptor antagonists on atrial function and atrioventricular coupling.