RESUMO
The exercise heart rate (HR) profile and its relation to cardiac function and arrhythmias were investigated in patients with hypertrophic cardiomyopathy (HC). Chronotropic response (CR) and heart rate recovery (HRR) were computed during and after treadmill exercise testing in 273 patients with HC and 95 age-matched healthy controls. Patients with HC had higher prevalence of chronotropic incompetence and lower HRR1-5min compared with controls. Exercise capacity, diastolic function (assessed by E/e') and left atrial volume index were associated with HRR1min and CR in HC. Septal myectomy was associated with reduction in chronotropic incompetence but did not affect HRR1min. In conclusion, impaired CR and HRR1min are associated with advanced disease and do not appear to be independent clinical markers indicating high-risk status in HC. Improving CR by titrating doses of negative chronotropic agents, myectomy, and atrial pacing may be useful to increase exercise capacity in patients with HC.
Assuntos
Cardiomiopatia Hipertrófica/fisiopatologia , Eletrocardiografia , Exercício Físico/fisiologia , Frequência Cardíaca/fisiologia , Ventrículos do Coração/fisiopatologia , Recuperação de Função Fisiológica , Função Ventricular Esquerda/fisiologia , Cardiomiopatia Hipertrófica/diagnóstico , Ecocardiografia Doppler em Cores , Teste de Esforço/métodos , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons , Prognóstico , Estudos Retrospectivos , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios XRESUMO
Accurate localization of myocardial viability is important in diagnosis of infarction. Regional strain function provides excessive information for clinical decision making but comparison of strain tensor profiles across differing tissue types is usually difficult due to multivariate nature of tensors. It is desirable to describe tensors with simplified scalar indices which are more mathematically and statistically intuitive. In this work, anisotropy of tensors in healthy and experimental infarct regions in a large animal model is assessed and compared to directional components of strain tensors which are currently the most popular indices in active use. Myocardial strain tensors are computed using zHARP, a magnetic resonance (MR) tagging technique that provides quantification of cardiac function with direct computation of three-dimensional tensors from two-dimensional short axis MR images. Fractional anisotropy of strain tensors shows high correlation with late gadolinium enhanced images and is capable of discrimination between healthy and infarcted regions.