Coronary flow reserve impairment in apical vs asymmetrical septal hypertrophic cardiomyopathy

Microcirculatory dysfunction in hypertrophic cardiomyopathy with chest pain assessed by angiography-derived microcirculatory resistance

Chest pain, a common initial symptom in hypertrophic cardiomyopathy (HCM) patients, is closely linked to myocardial ischemia, despite the absence of significant coronary artery stenosis. This study explored microvascular dysfunction in HCM patients by employing angiography-derived microcirculatory resistance (AMR) as a novel tool for comprehensive assessment. This retrospective analysis included HCM patients with chest pain as the primary symptom and control patients without cardiac hypertrophy during the same period. The AMR was computed through angiography, providing a wire-free and adenosine-free index for evaluating microcirculatory function. Propensity score matching ensured balanced demographics between groups. This study also investigated the correlation between the AMR and clinical outcomes by utilizing echocardiography and follow-up data. After matching, 76 HCM patients and 152 controls were analyzed. While there was no significant difference in the incidence of epicardial coronary stenosis, the AMR of three epicardial coronary arteries was markedly greater in HCM patients. The criterion of an AMR ≥ 250 mmHg*s/m was that 65.7% of HCM patients experienced coronary microvascular dysfunction (CMD). Independent risk factors for CMD included increased left ventricular (LV) wall thickness (OR = 1.209, 95% CI 1.013-1.443, p = 0.036). Furthermore, an AMR_LAD ≥ 250 mmHg*s/m had an increased cumulative risk of the endpoint (log-rank p = 0.023) and was an independent risk factor for the endpoint (HR = 11.64, 95% CI 1.13-120.03, p = 0.039), providing valuable prognostic insights.

Major Clinical Issues in Hypertrophic Cardiomyopathy

By actively implementing contemporary management strategies in hypertrophic cardiomyopathy, morbidity and mortality can be substantially reduced. In this review, we discuss the pathophysiology and management of the major clinical issues in hypertrophic cardiomyopathy, including sudden cardiac death, atrial fibrillation and thromboembolism, dynamic left ventricular outflow tract obstruction, and heart failure progression. Although echocardiography and cardiac magnetic resonance imaging currently play an essential and complementary role in the management of hypertrophic cardiomyopathy, further studies are needed to establish how developing techniques such as myocardial deformation and late gadolinium enhancement can provide better risk stratification and guide treatment.

Hypertrophic cardiomyopathy (HCM) is one of the most common inheritable cardiomyopathies. Contemporary management strategies, including the advent of implantable cardioverter-defibrillators and effective anticoagulation, have substantially improved the clinical course of HCM patients; however, the disease burden of HCM is still high in Korea. Sudden cardiac death (SCD), atrial fibrillation and thromboembolic risk, dynamic left ventricular outflow tract (LVOT) obstruction, and heart failure (HF) progression remain important issues in HCM. SCD in HCM can be effectively prevented with implantable cardioverter-defibrillators. However, appropriate patient selection is important for primary prevention, and the 5-year SCD risk score and the presence of major SCD risk factors should be considered. Anticoagulation should be initiated in all HCM patients with atrial fibrillation regardless of the CHA₂DS₂-VASc score, and non-vitamin K antagonist oral anticoagulants are the first option. Symptomatic dynamic LVOT obstruction is first treated medically with negative inotropes, and if symptoms persist, septal reduction therapy is considered. The recently approved myosin inhibitor mavacamten is promising. HF in HCM is usually related to diastolic dysfunction, while about 5% of HCM patients show reduced left ventricular ejection fraction <50%, also referred to as “end-stage” HCM. Myocardial fibrosis plays an important role in the progression to advanced HF in patients with HCM. Patients who do not respond to guideline-directed medical therapy can be considered for heart transplantation. The development of imaging techniques, such as myocardial deformation on echocardiography and late gadolinium enhancement on cardiac magnetic resonance, can provide better risk evaluation and decision-making for management strategies in HCM.

Hypertrophic Cardiomyopathy (HCM): New insights into Coronary artery remodelling and ischemia from FFRCT

INTRODUCTION

Angina, myocardial ischemia, and coronary artery physiology in hypertrophic cardiomyopathy (HCM) are poorly understood. However, coronary computed tomography angiography (CCTA) with fractional flow reserve from CT (FFR_CT) analysis offers a non-invasive method for evaluation of coronary artery volume to myocardial mass ratio (V/M) that may provide insight into such mechanisms. Thus, we sought to investigate changes in V/M in HCM.

METHODS

A retrospective analysis was performed on 37 HCM patients and 37 controls matched for age, sex, and cardiovascular risk factors; CCTA-derived coronary artery lumen volume (V) and myocardial mass (M) were used to determine V/M. FFR_CT values were calculated for the left anterior descending (LAD), left circumflex (LCx) and right coronary (RCA) arteries as well as the 3-vessel cumulative FFR_CT values.

RESULTS

HCM patients had significantly increased myocardial mass (176 ± 84 vs. 119 ± 27 g, p < 0.0001) and total coronary artery luminal volume (4112 ± 1139 vs. 3290 ± 924 mm³, p < 0.0001) that resulted from increases in segmented luminal volumes of both the left and right coronary artery systems. However, HCM patients had significantly decreased V/M (23.8 ± 5.9 vs. 26.5 ± 5.3 mm³/g; p = 0.026) which was further decreased when restricting V/M analysis to those HCM patients with septal hypertrophy (22.4 mm³/g, p = 0.01) that was mild-moderately predictive of HCM (AUC = 0.68). HCM patients also showed significantly lower nadir FFR_CT values in the LCx (0.87 ± 0.06 vs. 0.91 ± 0.06, p = 0.02), and cumulative 3-vessel FFR_CT values (2.58 ± 0.18 vs. 2.63 ± 0.14, p = 0.006).

CONCLUSIONS

HCM patients demonstrate significantly greater coronary volume. Despite this, HCM patients suffer from decreased V/M. Further prospective studies evaluating the relationship between V/M, angina, and heart failure in HCM are needed.

Usefulness of Serum Omentin-1 Levels for the Prediction of Adverse Cardiac Events in Patients with Hypertrophic Cardiomyopathy

OBJECTIVE

To investigate the association between serum omentin-1 levels and adverse cardiac events in patients with hypertrophic cardiomyopathy (HCM).

SUBJECTS AND METHODS

This prospective, observational study included 87 patients with HCM and 50 age- and sex-matched control subjects. Serum omentin-1 and brain natriuretic peptide (BNP) levels were measured in all subjects, using enzyme-linked immunosorbent assay and electrochemiluminescence, respectively. Patients with HCM were divided into 2 groups according to their omentin levels, i.e., low: ≤291 ng/mL (n = 48) and high: > 291 ng/mL (n = 39). Cardiac mortality, hospitalization due to heart failure, and implantable cardioverter-defibrillator (ICD) implantation were considered adverse cardiac events. Statistical analysis included uni- and multivariant logistic regression, receiver-operating characteristic (ROC) analysis, and the Kaplan-Meier method.

RESULTS

Serum omentin-1 levels were significantly lower in the obstructive (253.9 ± 41.3 ng/mL) and nonobstructive (301.9 ± 39.8 ng/mL) HCM groups than in the control group (767.1 ± 56.4 ng/mL), p < 0.001, respectively. The BNP levels were higher in the obstructive and nonobstructive HCM groups than in the control group (269.5 ± 220, 241.0 ± 227, and 24.0 ± 18.9 pg/mL, respectively, p < 0.001). The Kaplan-Meier analysis indicated that patients with low omentin-1 levels showed a significantly higher (48.2%) 2-year cumulative incidence of overall adverse cardiac events than those with high omentin-1 levels (16.2%) (log-rank test, p  =  0.001). In the multivariate logistic regression analysis, omentin-1, interventricular septum (IVS) thickness, and male gender were independent predictors of adverse cardiac events in the follow-up.

CONCLUSION

Omentin-1 levels were lower in patients with HCM than in the control group, and this was associated with worse cardiac outcomes.

Distribution and Clinical Significance of High Signal Intensity of the Myocardium on T2-Weighted Images in 2 Phenotypes of Hypertrophic Cardiomyopathy

OBJECTIVE

The aim of this study was to evaluate distribution and clinical significance of high signal intensity of the myocardium on T2-weighted images (T2-HI) in 2 phenotypes of hypertrophic cardiomyopathy (HCM).

METHODS

Thirty-six patients with asymmetrical septal HCM (ASH) and 18 patients with apical HCM (APH) and their 864 myocardial segments were investigated. The distribution of T2-HI was compared with that of late gadolinium enhancement (LGE), and the relationships between T2-HI and clinical risk markers were evaluated. T2 values of the T2-HI were estimated with T2 mapping.

RESULTS

The T2-HI was observed in 18 segments (3.1%) in 13 patients with ASH (36.1%) and in 12 segments (4.2%) in 8 patients with APH (44.4%). It was often localized outside LGE. The presence of T2-HI was related to syncope in ASH (P = 0.016). Furthermore, it had higher T2 values (61.1 milliseconds) than the reference myocardium (47.3 milliseconds).

CONCLUSIONS

High signal intensity of the myocardium on T2-weighted images often locates outside LGE and reflects myocardial damage, which is related to syncope in ASH.

Increased Transforming Growth Factor-β Levels Associated With Cardiac Adverse Events in Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a common genetic heart disease characterized by ventricular hypertrophy, myocardial fibrosis, and impaired ventricular relaxation. The exact mechanisms by which fibrosis is caused remain unknown.

HYPOTHESIS

Circulating TGF-β is related to poor prognosis in HCM.

METHODS

We compared TGF-β levels of 49 HCM patients with those of 40 non-HCM patients. We followed the patients with HCM for 18 months and divided them into 2 groups: low TGF-β (≤ 4877 pg/mL) and high TGF-β (> 4877 pg/mL). We compared the 2 groups in terms of brain natriuretic peptide (BNP), echocardiographic parameters, and clinical outcomes including myocardial infarction, arrhythmias, implantable cardioverter-defibrillator implantation, hospitalization, New York Heart Association (NYHA) class, acute heart failure, and mortality.

RESULTS

The HCM patients had higher TGF-β levels than those in the control group (P = 0.005). In the follow-up, those in the high TGF-β group had higher BNP levels, larger left-atrial size, thicker interventricular septum, NYHA class, more hospitalizations, and a greater number of clinical adverse events (P < 0.001, P = 0.01, P < 0.001, P = 0.002, P < 0.001 and P = 0.003, respectively). TGF-β level of > 4877 pg/mL can predict adverse events with a specificity of 75% and a sensitivity of 72% (P = 0.014). In multivariate regression analysis, TGF-β, BNP, and interventricular septum thickness were significantly associated with adverse events (P = 0.028, P = 0.030, and P = 0.034, respectively).

CONCLUSIONS

The TGF-β level is higher in HCM patients and associated with a poor prognosis in HCM.

Targets for therapy in sarcomeric cardiomyopathies

To date, no compounds or interventions exist that treat or prevent sarcomeric cardiomyopathies. Established therapies currently improve the outcome, but novel therapies may be able to more fundamentally affect the disease process and course. Investigations of the pathomechanisms are generating molecular insights that can be useful for the design of novel specific drugs suitable for clinical use. As perturbations in the heart are stage-specific, proper timing of drug treatment is essential to prevent initiation and progression of cardiac disease in mutation carrier individuals. In this review, we emphasize potential novel therapies which may prevent, delay, or even reverse hypertrophic cardiomyopathy caused by sarcomeric gene mutations. These include corrections of genetic defects, altered sarcomere function, perturbations in intracellular ion homeostasis, and impaired myocardial energetics.

[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.

Differences of left ventricular systolic deformation in hypertensive patients with and without apical hypertrophic cardiomyopathy

BACKGROUND

We tested the hypothesis that the apical myocardial mechanics differ from those of other ventricular segments in hypertensive patients with and without apical hypertrophic cardiomyopathy (ApHCM).

METHODS

We retrospectively studied hypertensive patients with and without ApHCM. Left ventricular longitudinal, circumferential, and radial strains were examined by two-dimensional speckle-tracking echocardiography at the basal, middle, and apical walls of the parasternal short-axis and apical 2-, 3- and 4-chamber views.

RESULTS

Fourteen consecutive patients with hypertension and ApHCM and 14 patients with hypertension without ApHCM were studied. Lower mitral annular peak systolic velocity and greater diastolic dysfunction were present in hypertensive patients with ApHCM than in hypertensive patients without ApHCM. Compared with hypertensive patients without ApHCM, hypertensive patients with ApHCM had significantly lower apical longitudinal (-13.9% vs -21.9%, p = 0.010) and radial strains (4.4% vs 11.5%, p = 0.017) without the base-to-apex gradient. The global longitudinal (-15.6% vs -18.8%, p = 0.027) and circumferential strains (-16.1% vs -19.2%, p = 0.019) were significantly lower in hypertensive patients with ApHCM than in hypertensive patients without ApHCM. Among systolic parameters, the global longitudinal strain was independently associated with hypertension with ApHCM (odds ratio, 1.457; 95% confidence interval, 1.002-2.119; p = 0.049).

CONCLUSIONS

Reduced apical longitudinal and radial strains without a base-to-apex gradient were present in hypertensive patients with ApHCM. The global longitudinal strain was independently associated with ApHCM in hypertensive patients.