Difference in myocardial flow reserve between patients with dilated cardiomyopathy and those with dilated phase of hypertrophic cardiomyopathy: evaluation by 15O-water PET

Insights and Challenges of Multi-Scale Modeling of Sarcomere Mechanics in cTn and Tm DCM Mutants-Genotype to Cellular Phenotype

Dilated Cardiomyopathy (DCM) is a leading cause of sudden cardiac death characterized by impaired pump function and dilatation of cardiac ventricles. In this review we discuss various in silico approaches to elucidating the mechanisms of genetic mutations leading to DCM. The approaches covered in this review focus on bridging the spatial and temporal gaps that exist between molecular and cellular processes. Mutations in sarcomeric regulatory thin filament proteins such as the troponin complex (cTn) and Tropomyosin (Tm) have been associated with DCM. Despite the experimentally-observed myofilament measures of contractility in the case of these mutations, the mechanisms by which the underlying molecular changes and protein interactions scale up to organ failure by these mutations remains elusive. The review highlights multi-scale modeling approaches and their applicability to study the effects of sarcomeric gene mutations in-silico. We discuss some of the insights that can be gained from computational models of cardiac biomechanics when scaling from molecular states to cellular level.

Myocardial blood volume reserve by intravenous contrast echocardiography predicts improvement in left ventricular function in patients with nonischemic dilated cardiomyopathy

BACKGROUND

Impaired myocardial perfusion has been shown in nonischemic dilated cardiomyopathy (DCM). Intravenous myocardial contrast echocardiography (MCE) has been introduced to examine myocardial blood volume (MBV) noninvasively. This study was designed to evaluate if MBV reserve assessed by intravenous MCE with adenosine triphosphate (ATP) can predict efficacy of optimal medical therapy in patients with DCM.

METHODS AND RESULTS

Fifteen DCM patients and 8 control subjects underwent conventional echocardiography and intravenous MCE. We obtained the change in peak contrast integrated backscatter intensity (∆PI) by ATP on the left ventricular (LV) anteroseptal myocardium. After 3 months of optimal medical therapy in DCM patients, we reperformed conventional echocardiography. A good responder to therapy was defined as a decrease in LVDd >5 mm to final LVDd <55 mm and increase in LVEF >20 % to final LVEF >45 %. In DCM patients, ∆PI was lower compared to controls (p < 0.001). Good responders to therapy (n = 6) had higher ∆PI than poor responders (n = 9) (p < 0.05).

CONCLUSIONS

The present study demonstrates that the response to the medical therapy in DCM is predicted by the assessment of dilator reserve in MBV. Intravenous MCE with ATP may provide useful information to evaluate MBV reserve.

Clinical Characteristics and Prognosis of End-stage Hypertrophic Cardiomyopathy

Background:

End-stage hypertrophic cardiomyopathy (HCM) is complicated by substantial adverse events. However, few studies have focused on electrocardiographic features and their prognostic values in HCM. This study aimed to evaluate the clinical manifestations and prognostic value of electrocardiography in patients with end-stage HCM.

Methods:

End-stage HCM patients were enrolled from a total of 1844 consecutive HCM patients from April 2002 to November 2013 at Fuwai Hospital. Clinical data, including medical history, electrocardiography, and echocardiography, were analyzed. Cox hazards regression analysis was used to assess the risk factors for cardiovascular mortality.

Results:

End-stage HCM was identified in 99 (5.4%) patients, averaged at 52 ± 16 years old at entry. Atrial fibrillation was observed in 53 patients and mural thrombus in 19 patients. During 3.9 ± 3.0 years of follow-up, embolic stroke, refractory heart failure, and death or transplantation were observed in 20, 39, and 51 patients, respectively. The incidence of annual mortality was 13.2%. Multivariate Cox hazards regression analysis identified New York Heart Association Class (NYHA) III/IV at entry (hazard ratio [HR]: 1.99; 95% confidence interval [CI]: 1.05–3.80; P = 0.036), left bundle branch block (LBBB) (HR: 2.80; 95% CI: 1.47–5.31; P = 0.002), and an abnormal Q wave (HR: 2.21; 95% CI: 1.16–4.23; P = 0.016) as independent predictors of cardiovascular death, in accordance with all-cause death and heart failure-related death.

Conclusions:

LBBB and an abnormal Q wave are risk factors of cardiovascular mortality in end-stage HCM and provide new evidence for early intervention. Susceptibility of end-stage HCM patients to mural thrombus and embolic events warrants further attention.

[Vascular functional alterations in hypertrophic cardiomyopathy]

Hypertrophic cardiomyopathy is a hereditary, not uncommon cardiac disease, which is associated with asymmetric thickening and hypertrophy of the interventricular septum unrelated to hemodynamic reasons. Despite hypertrophic cardiomyopathy is considered to be a disorder of the heart muscle, several associated vascular alterations have been described. The aim of the present review is to summarize vascular functional alterations in hypertrophic cardiomyopathy.

Myocardial radionuclide imaging in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is defined as a primary and familial cardiac disorder characterized by heterogeneous expression, unique pathophysiology and considerable diversity in clinical presentation. Clinical diagnosis was mainly based on the performance of ECG. In addition, cardiovascular MRI or ECG plays an important role in the diagnosis. Nevertheless, myocardial radionuclide imaging, which could provide detailed information on myocardial perfusion, metabolism and neurological function, is a valuable method for exploring the inter-relationship between the morphological, pathophysiological and functional changes in hypertrophic cardiomyopathy. It is also helpful in evaluating the effect of transcoronary ethanol septal ablation and prognosis in patients with hypertrophic cardiomyopathy, which suggests that it is an important imaging method in the comprehensive evaluation of hypertrophic cardiomyopathy.