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Rest and Stress Longitudinal Systolic Left Ventricular Mechanics in Hypertrophic Cardiomyopathy: Implications for
Iraklis Pozios1, Aurelio Pinheiro1, Celia Corona-Villalobos2
1Division of Cardiology, Johns Hopkins University, Baltimore, Maryland.
Insights
Reduced mechanical reserve during exercise in hypertrophic cardiomyopathy (HCM) patients is linked to poorer functional capacity and increased risk of ventricular tachycardia/fibrillation (VT/VF). This highlights the importance of assessing myocardial mechanics during exercise in HCM management.
Area of Science:
- Cardiology
- Cardiovascular Imaging
- Exercise Physiology
Background:
- Exercise intolerance is a primary symptom in hypertrophic cardiomyopathy (HCM).
- The study investigates the link between impaired myocardial mechanics during exercise and patient outcomes in HCM.
Purpose of the Study:
- To determine if the inability to augment myocardial mechanics during exercise impacts functional performance and clinical outcomes in HCM patients.
- To assess the relationship between mechanical reserve and exercise capacity, cardiac structure, and adverse events.
Main Methods:
- Prospective study of 95 HCM patients (categorized by obstruction) and 26 controls.
- Utilized rest and treadmill stress strain echocardiography, with a subset undergoing MRI.
- Defined mechanical reserve (MRES) as the percent change in systolic strain rate (SR) post-exercise.
Main Results:
- HCM patients exhibited lower global strain and SR at rest and post-exercise compared to controls.
- Reduced MRES was observed in nonobstructive and obstructive HCM groups versus labile-obstructive and controls.
- Postexercise SR and MRES correlated with exercise capacity and late gadolinium enhancement (LGE).
Conclusions:
- Nonobstructive and obstructive HCM patients show diminished MRES.
- Exercise SR and MRES are significant predictors of exercise capacity, LGE, and VT/VF risk in HCM.
Background:
Exercise intolerance is the most common symptom in hypertrophic cardiomyopathy (HCM). We examined whether inability to augment myocardial mechanics during exercise would influence functional performance and clinical outcomes in HCM.
Methods:
Ninety-five HCM patients (32 nonobstructive, 32 labile-obstructive, 31 obstructive) and 26 controls of similar age and gender distribution were recruited prospectively. They underwent rest and treadmill stress strain echocardiography, and 61 of them underwent magnetic resonance imaging. Mechanical reserve (MRES) was defined as percent change in systolic strain rate (SR) immediately postexercise.
Results:
Global strain and SR were significantly lower in HCM patients at rest (strain: nonobstructive, -15.6 ± 3.0; labile-obstructive, -15.9 ± 3.0; obstructive, -13.8 ± 2.9; control, -17.7% ± 2.1%, P < .001; SR: nonobstructive, -0.92 ± 0.20; labile-obstructive, -0.94 ± 0.17; obstructive, -0.85 ± 0.18; control, -1.04 ± 0.14 s-1, P = .002); and immediately postexercise (strain: nonobstructive, -15.6 ± 3.0; labile-obstructive, -17.6 ± 3.6; obstructive, -15.6 ± 3.6; control, -19.2 ± 3.1%; P = .001; SR: nonobstructive, -1.41 ± 0.37; labile-obstructive, -1.64 ± 0.38; obstructive, -1.32 ± 0.29; control, -1.82 ± 0.29 s-1, P < .001). MRES was lower in nonobstructive and obstructive compared with labile-obstructive and controls (51% ± 29%, 54% ± 31%, 78% ± 38%, 77% ± 30%, P = .001, respectively). Postexercise SR and MRES were associated with exercise capacity (r = 0.47 and 0.42, P < .001 both, respectively). When adjusted for age, gender, body mass index, E/e', and resting peak instantaneous systolic gradient, postexercise SR best predicted exercise capacity (r = 0.74, P = .003). Postexercise SR was correlated with extent of late gadolinium enhancement (r = 0.34, P = .03). By Cox regression, exercise SR and MRES predicted ventricular tachycardia/ventricular fibrillation (VT/VF) even after adjustment for age, gender, family history of sudden cardiac death, septum ≥ 3 cm and abnormal blood pressure response (P = .04 and P = .046, respectively).
Conclusions:
Nonobstructive and obstructive patients have reduced MRES compared with labile-obstructive and controls. Postexercise SR correlates with LGE and exercise capacity. Exercise SR and MRES predict VT/VF.
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