Transient Apical Sparing in Hypertensive Heart Disease Explained by Laplace’s Law
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Background
Apical sparing of left ventricular longitudinal strain (LS) is an echocardiographic clue to cardiac amyloidosis but may also occur in hypertensive heart disease (HHD).
Objectives
To determine whether apical sparing in HHD is associated with regional left ventricular wall stress estimated according to Laplace’s law.
Methods
We retrospectively studied 1,559 patients with HHD, 47 with light-chain cardiac amyloidosis (ALCA), and 409 normotensive controls. Artificial intelligence–assisted echocardiography quantified segmental LS, wall thickness, and cavity radius at the basal, midventricular, and apical levels. Wall stress was estimated as mean blood pressure (MBP) × radius/(2 × wall thickness). Apical sparing was defined as a relative regional strain ratio (RRSR)≥1.0.
Results
Apical sparing was present in 14 patients with HHD (0.9%), 13 with ALCA (27.7%), and no controls. Among HHD patients with apical sparing, RRSR decreased from 1.11±0.13 to 0.72±0.10 after antihypertensive treatment ( P <0.001), accompanied by reduced wall stress and improved basal and midventricular LS, with resolution of apical sparing in all 14 patients. In the overall HHD cohort, changes in MBP and left ventricular mass index were independently associated with changes in RRSR. In an exploratory analysis of HHD patients with apical sparing, a reduction in basal wall stress was associated with a reduction in RRSR (β=0.267 for △RRSR×100, 95% CI 0.023–0.511; P =0.036). In ALCA, favorable hematologic response was the only determinant of RRSR reduction.
Conclusions
Apical sparing in HHD was uncommon but reversible and may represent a load-sensitive deformation pattern associated with regional wall stress, consistent with Laplace’s law.
Condensed Abstract
Apical sparing of left ventricular longitudinal strain occurred in 0.9% of patients with hypertensive heart disease and resolved in all affected patients after antihypertensive treatment. Resolution was accompanied by reduced regional wall stress and improved basal and midventricular strain, and reduction in basal wall stress was associated with reduction in the relative regional strain ratio. In contrast, apical sparing was more prevalent in light-chain cardiac amyloidosis and was related to disease stage and hematologic response. These findings support Laplace’s law as a physiologic framework for understanding reversible, load-sensitive apical sparing in hypertensive heart disease.
