Abstract 18854: Concept and Clinical Implications of Mechanical Reserve in Hypertrophic Cardiomyopathy
Background: We hypothesized that inability to augment regional and global mechanics during stress would portend a poor prognosis in hypertrophic cardiomyopathy (HCM).
Methods: Ninety five HCM patients [32 non-obstructive (NO), 32 labile-obstructive (LO), 31 obstructive (Ob)] and 26 age and gender matched controls (Co) underwent conventional and strain echocardiography at rest and after treadmill exercise. Mechanical reserve (MRES) was defined as % change in systolic strain rate (SR) with exercise. Magnetic resonance delayed enhancement (DE) was available in 61 patients.
Results: Exercise capacity was lower in obstructive patients (NO: 10.0±3.7 vs. LO: 11.8±4.4 vs. Ob: 9.1±3.4 vs. Co: 10.9±3.2 METs, p=0.03). Peak global strain and SR were significantly lower in HCM patients both at rest and peak exercise. MRES was lower in non-obstructive and obstructive compared to labile-obstructive and control that had similar values. In univariable analysis, exercise SR and MRES were associated with exercise capacity. In multivariable analysis, exercise SR was found to be the best predictor of exercise capacity when adjusted for age, gender, BMI, E/e’ and resting LVOT gradient. Exercise SR showed a significant correlation with the extent of DE (R=0.342, p=0.03). Cox regression model showed exercise SR and MRES were predictors of VT/VF when adjusted for age, gender, family history of sudden cardiac death, septum ≥3cm and abnormal blood pressure response.
Conclusion: Non-obstructive and obstructive patients have reduced mechanical reserve and exercise capacity compared to labile-obstructive and controls. Exercise SR and mechanical reserve predict exercise capacity and VT/VF.
Author Disclosures: I. Pozios: None. A. Pinheiro: None. C. Corona-Villalobos: None. L.L. Sorensen: None. L.V. Dimaano: None. H. Luo: None. Z. Dardari: None. X. Zhou: None. I. Kamel: None. D.A. Bluemke: None. S.L. Zimmerman: None. M.R. Abraham: None. T.P. Abraham: None.
- © 2014 by American Heart Association, Inc.