Prevalence and significance of relative apical sparing in aortic stenosis: insights from an echo and cardiovascular magnetic resonance study of patients referred for surgical aortic valve replacement

Aims: This study aims to assess the prevalence of relative apical sparing pattern (RASP) in patients with severe symptomatic aortic stenosis (AS), referred for surgical aortic valve replacement (AVR), to evaluate its significance, possible relation to amyloid deposition, and persistence after surgery. Methods and results: Prospective study of 150 consecutive patients [age 73 (interquartile range: 68-77), 51% women], with severe symptomatic AS referred to surgical AVR. All patients underwent cardiac magnetic resonance (CMR) before surgery. RASP was defined by [average apical longitudinal strain (LS)/(average basal LS + average mid LS)] > 1 by echocardiography. AVR was performed in 119 (79.3%) patients. Both Congo red and sodium sulphate-Alcian blue (SAB) stain were used to exclude amyloid on septal myocardial biopsy. LV remodelling and tissue characterization parameters were compared in patients with and without RASP. Deformation pattern was re-assessed at 3-6 months after AVR. RASP was present in 23 patients (15.3%). There was no suspicion of amyloid at pre-operative CMR [native T1 value 1053 ms (1025-1076 ms); extracellular volume (ECV) 28% (25-30%)]. None of the patients had amyloid deposition at histopathology. Patients with RASP had significantly higher pre-operative LV mass and increased septal wall thickness. They also had higher N-terminal pro b-type natriuretic peptide (NT-proBNP) levels [1564 (766-3318) vs. 548 (221-1440) pg/mL, P = 0.010], lower LV ejection fraction (53.7 ± 10.5 vs. 60.5 ± 10.2%, P = 0.005), and higher absolute late gadolinium enhancement (LGE) mass [9.7 (5.4-14.1) vs. 4.8 (1.9-8.6) g, P = 0.016] at CMR. Follow-up evaluation after AVR revealed RASP disappearance in all except two of the patients. Conclusion: RASP is not specific of cardiac amyloidosis. It may also be found in severe symptomatic AS without amyloidosis, reflecting advanced LV disease, being mostly reversible after surgery.