The progression of left ventricular systolic and diastolic dysfunctions in hypertrophic cardiomyopathy: clinical and prognostic significance

Association of NT-proBNP and hs-cTnT with Imaging Markers of Diastolic Dysfunction and Focal Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Serum biomarkers such as N-terminal prohormone of the brain natriuretic peptide (NT-proBNP) and cardiac troponins are elevated in patients with hypertrophic cardiomyopathy (HCM). At present, it is not clear if these markers are associated with distinct clinical alterations in HCM, such as left ventricular hypertrophy, outflow tract obstruction, myocardial fibrosis and/or diastolic dysfunction (DD), which are associated with adverse cardiovascular outcome. Here we evaluate the association of NT-proBNP and high sensitivity cardiac troponin T (hs-cTnT) to a variety of cardiac imaging parameters in HCM patients in a multivariable regression analysis. This retrospective cross-sectional study included 366 HCM patients who underwent transthoracic echocardiography (TTE), 218 of whom also obtained cardiovascular magnetic resonance (CMR) to assess focal myocardial fibrosis by LGE. Multivariable regression analyses revealed the strongest association of the DD parameters E/E′ mean and E/E′ septal with NT-proBNP (b = 0.06, 95%-CI [0.05−0.07], p < 0.001, R2 = 0.28; b = 0.08, 95%-CI [0.06−0.1], p < 0.001, R2 = 0.25) and LGE size showed the strongest association with hs-cTnT (b = 0.20, 95%-CI [0.15−0.24], p < 0.001, R2 = 0.28). This study indicates that NT-proBNP and hs-cTnT are associated with structural and functional alterations in HCM. NT-proBNP is a stronger predictor for DD, while hs-cTnT is associated with the extent of focal myocardial fibrosis. Both biomarkers might be useful in the diagnostic procedure in addition to imaging parameters.

Effect of Mavacamten on Echocardiographic Features in Symptomatic Patients With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

EXPLORER-HCM (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy) demonstrated that mavacamten, a cardiac myosin inhibitor, improves symptoms, exercise capacity, and left ventricular outflow tract (LVOT) obstruction in patients with obstructive hypertrophic cardiomyopathy (oHCM).

OBJECTIVES

The purpose of this study was to evaluate mavacamten's effect on measures of cardiac structure and function and its association with changes in other clinical measures.

METHODS

Key echocardiographic parameters from serial echocardiograms over 30 weeks from 251 symptomatic oHCM patients (mavacamten [n = 123], placebo [n = 128]) were assessed in a core laboratory.

RESULTS

More patients on mavacamten (80.9%; n = 76 of 94) vs placebo (34.0%; n = 33 of 97) showed complete resolution of mitral valve systolic anterior motion after 30 weeks (difference, 46.8%; P < 0.0001). Mavacamten also improved measures of diastolic function vs placebo, including left atrial volume index (LAVI) (mean ± SD baseline: 40 ± 12 mL/m² vs 41 ± 14 mL/m²; mean change from baseline of -7.5 mL/m² [95% CI: -9.0 to -6.1 mL/m²] vs -0.09 mL/m² [95% CI: -1.6 to 1.5 mL/m²]; P < 0.0001) and lateral E/e' (baseline, 15 ± 6 vs 15 ± 8; change of -3.8 [95% CI: -4.7 to -2.8] vs 0.04 [95% CI: -0.9 to 1.0]; P < 0.0001). Among mavacamten-treated patients, improvement in resting, Valsalva, and post-exercise LVOT gradients, LAVI, and lateral E/e' was associated with reduction in N-terminal pro-B-type natriuretic peptide (P ≤ 0.03 for all). Reduction in LAVI was associated with improved peak exercise oxygen consumption (P = 0.04).

CONCLUSIONS

Mavacamten significantly improved measures of left ventricular diastolic function and systolic anterior motion. Improvement in LVOT obstruction, LAVI, and E/e' was associated with reduction in a biomarker of myocardial wall stress (N-terminal pro-B-type natriuretic peptide). These findings demonstrate improvement in important markers of the pathophysiology of oHCM with mavacamten. (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy; NCT03470545).

Dysregulation of proangiogeneic factors in pressure-overload left-ventricular hypertrophy results in inadequate capillary growth

Background:

Pressure-overload left-ventricular hypertrophy (LVH) is an increasingly prevalent pathological condition of the myocardial muscle and an independent risk factor for a variety of cardiac diseases. We investigated changes in expression levels of proangiogeneic genes in a small animal model of LVH.

Methods:

Myocardial hypertrophy was induced by transaortic constriction (TAC) in C57BL/6 mice and compared with sham-operated controls. The myocardial expression levels of vascular endothelial growth factor (VEGF), its receptors (KDR and FLT-1), stromal-cell-derived factor 1 (SDF1) and the transcription factors hypoxia-inducible factor-1 and 2 (HIF1 and HIF2) were analyzed by quantitative polymerase chain reaction over the course of 25 weeks. Histological sections were stained for caveolin-1 to visualize endothelial cells and determine the capillary density. The left-ventricular morphology and function were assessed weekly by electrocardiogram-gated magnetic resonance imaging.

Results:

The heart weight of TAC animals increased significantly from week 4 to 25 (p = 0.005) compared with sham-treated animals. At 1 day after TAC, the expression of VEGF and SDF1 also increased, but was downregulated again after 1 week. The expression of HIF2 was significantly downregulated after 1 week and remained at a lower level in the subsequent weeks. The expression level of FLT-1 was also significantly decreased 1 week after TAC. HIF-1 and KDR showed similar changes compared with sham-operated animals. However, the expression levels of HIF1 after 4 and 8 weeks were significantly decreased compared with day 1. KDR changes were significantly decreased after 1, 2, 4, 8 and 25 weeks compared with week 3. After 4 weeks post-TAC, the size of the capillary vessels increased (p = 0.005) while the capillary density itself decreased (TAC: 2143 ± 293 /mm²versus sham: 2531 ± 321 /mm²; p = 0.021). Starting from week 4, the left-ventricular ejection fraction decreased compared with controls (p = 0.049).

Conclusions:

The decrease in capillary density in the hypertrophic myocardium appears to be linked to the dysregulation in the expression of proangiogeneic factors. The results suggest that overcoming this dysregulation may lead to reconstitution of capillary density in the hypertrophic heart, and thus be beneficial for cardiac function and survival.

Alcohol Septal Ablation to Reduce Heart Failure

Hypertrophic cardiomyopathy is a commonly encountered inheritable cardiac disorder with variable phenotypic expression. Although most patients will have no or mild symptoms, 10% will develop heart failure symptoms refractory to medical management. This article discusses the mechanisms through which hypertrophic cardiomyopathy induces heart failure and how alcohol septal ablation can reverse each of these mechanisms to lead to clinical improvement.

Relation of Doppler Tissue Imaging Parameters With Heart Failure Progression in Hypertrophic Cardiomyopathy

Refractory progressive heart failure (HF) is becoming the predominant cause of mortality in nonobstructive hypertrophic cardiomyopathy (HC). To anticipate development of this important and often unpredictable clinical course, we investigated whether left ventricular diastolic dysfunction, assessed by echocardiographic Doppler parameters, could identify a subset of patients with HC without obstruction at rest who would experience progression of HF. Diastolic function parameters, assessed by Doppler tissue imaging (DTI), mitral inflow, and pulmonary venous flow were measured in 274 consecutive adult patients with HC evaluated from 2003 to 2007. DTI and other diastolic and clinical/demographic parameters were measured against the composite end point of HF/death, heart transplantation, or progression to advanced New York Heart Association functional class III/IV symptoms and sudden death (SD)/implantable defibrillator (ICD) interventions. HF end points were reached in 19 of 274 patients (7%) over a follow-up period of 4.0 ± 2.3 years. Variables significantly associated with HF outcome by univariate analysis included male gender, initial New York Heart Association class II, lower ejection fraction, and reduced septal and lateral e' mitral annular tissue velocities. Multivariable analysis showed only a reduced lateral e' mitral annular tissue velocity to be independently associated with the composite HF end points (HR 0.77; 95% CI 0.65 to 0.91; p = 0.003). In addition, estimated pulmonary arterial systolic pressure and extensive late gadolinium enhancement by magnetic resonance were also associated with HF outcome (p = 0.04 and p <0.001, respectively). No Doppler (or clinical) variable was associated with SD/appropriate ICD interventions. In conclusion, in HC without outflow obstruction at rest, diastolic dysfunction, evidenced by DTI-reduced lateral e' mitral annular tissue velocity, was associated with adverse long-term HF outcome but was unrelated to SD. This echocardiographic marker provides a potential noninvasive strategy for anticipating progressive HF in this HC patient group.

How does morphology impact on diastolic function in hypertrophic cardiomyopathy? A single centre experience

OBJECTIVES

It is unclear if morphology impacts on diastole in hypertrophic cardiomyopathy (HCM). We sought to determine the relationship between various parameters of diastolic function and morphology in a large HCM cohort.

SETTING

Tertiary referral centre from Stanford, California, USA.

PARTECIPANTS

383 patients with HCM and normal systolic function between 1999 and 2011. A group of 100 prospectively recruited age-matched and sex-matched healthy participants were used as controls.

PRIMARY AND SECONDARY OUTCOME MEASURES

Echocardiograms were assessed by two blinded board-certified cardiologists. HCM morphology was classified as described in the literature (reverse, sigmoid, symmetric, apical and undefined).

RESULTS

Reverse curvature morphology was most commonly observed (218 (57%). Lateral mitral annular E'<12 cm/s was present in 86% of reverse, 88% of sigmoid, 79% of symmetric, 86% of apical and 81% of undefined morphology, p=0.65. E/E' was similarly elevated (E/E': 12.3±7.9 in reverse curvature, 12.1±6.1 in sigmoid, 12.7±9.5 in symmetric, 9.4±4.0 in apical, 12.7±7.9 in undefined morphology, p=0.71) and indexed left atrial volume (LAVi)>40 mL/m(2) was present in 47% in reverse curvature, 33% in sigmoid, 32% in symmetric, 37% in apical and 32% in undefined, p=0.09. Each morphology showed altered parameters of diastolic function when compared with the control population. Left ventricular (LV) obstruction was independently associated with all three diastolic parameters considered, in particular with LAVi>40 mL/m(2) (OR 2.04 (95% CI 1.23 to 3.39), p=0.005), E/E'>15 (OR 4.66 (95% CI 2.51 to 8.64), p<0.001) and E'<8 (OR 2.55 (95% CI 1.42 to 4.53), p=0.001). Other correlates of diastolic dysfunction were age, LV wall thickness and moderate-to-severe mitral regurgitation.

CONCLUSIONS

In HCM, diastolic dysfunction is present to similar degrees independently from the morphological pattern. The main correlates of diastolic dysfunction are LV obstruction, age, degree of hypertrophy and degree of mitral regurgitation.

Prognostic role of clinical presentation in symptomatic patients with hypertrophic cardiomyopathy

AIMS

To evaluate the long-term prognostic impact of baseline symptoms in a cohort of hypertrophic cardiomyopathy (HCM) patients.

METHODS AND RESULTS

We considered 84 HCM patients symptomatic at diagnosis: 26 (31%) with heart failure (group 1), 34 (40%) with syncope/palpitations (group 2) and 24 (29%) with chest pain (group 3). During a median follow-up of 102 (53-187) months, 25 (30%) patients died/underwent heart transplant (HTx), 14 of 26 (54%) in group 1, 10 of 34 (29%) in group 2 and one of 24 (4%) in group 3. At 12, 60 and 120 months, HTx-free survival rates were 100, 79 and 52% in group 1, vs. 100, 97 and 69% in group 2, vs. 96, 96 and 96% in group 3, respectively (P = 0.008). At multivariate analysis, heart failure [hazard ratio (HR) 2.59, confidence interval (CI) 95% 1.09-6.17, P = 0.032] and left atrium diameter (HR 1.83, CI 95% 1.16-2.89, P = 0.009) emerged as independent predictors of death/HTx, with incremental prognostic power with respect to echo Doppler variables of left ventricular systolic and diastolic dysfunction [area under the curve (AUC) of receiver operating characteristics (ROC) curves at 5 years: 0.90 vs. 0.78, respectively, P = 0.03].

CONCLUSION

Clinical presentation emerged as a relevant prognostic tool in HCM patients symptomatic at onset, as heart failure was associated with a particularly poor outcome. Heart failure and left atrium diameter at diagnosis showed incremental prognostic power compared with echo Doppler assessment of left ventricular systolic and diastolic dysfunction.

Fibroblast growth factor-23 and interleukin-6 are risk factors for left ventricular hypertrophy in peritoneal dialysis patients

BACKGROUND

Left ventricular hypertrophy (LVH) is a major risk factor for cardiovascular death in dialysis patients. Fibroblast growth factor-23 (FGF-23) and interleukin-6 (IL-6) were thought to be related to cardiovascular diseases (CVDs) in dialysis.

METHODS

To determine the relationship between FGF-23, IL-6 and LVH in continuous ambulatory peritoneal dialysis (CAPD) patients, serum FGF-23 and IL-6 levels as well as standard laboratory parameters were assessed in 62 CAPD patients and 30 healthy controls. LVH was determined by echocardiography in dialysis patients.

RESULTS

Serum FGF-23 and IL-6 levels were significantly higher in CAPD patients than in healthy controls, whereas both were higher in patients with LVH than in patients without LVH. FGF-23 was found to be positively associated with left ventricle mass index (LVMI) and serum phosphate. IL-6 level was positively associated with LVMI and negatively correlated with serum albumin and hemoglobin. Serum FGF-23 level was positively correlated with IL-6 level.

CONCLUSION

FGF-23 and IL-6 are independent risk factors for LVH in CAPD patients and both collaborated in causing LVH in CAPD.

Cardiologists' workflow in small to medium-sized German hospitals: an observational work analysis

AIMS

Due to recent changes in national health policy and a subsequent increase in clinicians' workload, medical residents in Germany feel that the growing burden of documentation duties leaves too little time for direct patient care. Thus, to describe the daily workflow in cardiology wards with more accuracy, this real-time observational study detailed all tasks performed by resident cardiologists during daily shifts at German hospitals.

METHODS

Daily routines of 20 resident cardiologists at four German hospitals were observed and recorded in real time during the study period from September 2009 to January 2010. Each participant was shadowed during three entire day shifts by an observer, who recorded all tasks performed by the cardiologist.

RESULTS

During the study period, 60 workdays (512 h) of observation took place. On average, doctors worked 08:31 h per day (SD = 00:32 h). Most time was spent on meetings (2:51 h), on administration duties (1:22 h), on ward rounds and admission to hospital (0:42 h) and on breaks (0:30 h). Doctors were interrupted every 16 min and spent 16.20% of each workday multitasking.

CONCLUSION

Ward rounds, meetings and administrative duties took up two-thirds of an average workday. Little time was spent on direct patient care relative to other clinical tasks such as paperwork and management. High rates of interruptions and multitasking were found. As the medical workforce is valuable, changes in the organization of workflow should be made in order to minimize residents' administrative duties and paperwork; thus, cardiologists' job satisfaction might increase.