Hypertension-induced Left Ventricular Hypertrophy Research Articles

Impact of changes in left heart geometry on predicting new-onset atrial fibrillation in patients with hypertension

Abstract Background Hypertension-induced left ventricular hypertrophy (LVH) increases end-diastolic LV pressure and contributes to left atrial enlargement (LAE), which are associated with development of atrial fibrillation (AF). However, the impact of LVH and LAE and their regression following antihypertensive therapy on AF incidence remains unclear. Purpose This study aimed to investigate the impact of changes in the LVH and LAE status on the occurrence of new-onset AF (NOAF). Methods This retrospective analysis included patients with sinus rhythm who underwent echocardiography at hypertension diagnosis and after 6–18 months. LVH was defined as LV mass index >115 g/m2 (men) and >95 g/m2 (women), and LAE was defined as LA volume index >42 ml/m2. LVH and LAE regression was defined as the absence of LVH and LAE on follow-up echocardiography, respectively. The occurrence of NOAF was assessed in relation to changes in LVH and LAE status. Results Among the 1,464 patients included in the study, 163 (11.1%) patients developed NOAF during a median follow-up of 63.8 months (interquartile range, 35.9–128.5 months). On average, 12 electrocardiograms per patient were reviewed for AF detection. New-onset LVH (adjusted HR 1.88, 95% CI 1.20–2.94, P=0.006) and LAE (adjusted HR 1.89, 95% CI 1.05–3.40, P=0.034) were significant predictors of NOAF. Conversely, regression of LVH (adjusted HR 0.51, 95% CI 0.280.91, P=0.022) or LAE (adjusted HR: 0.30, 95% CI 0.15–0.63, P=0.001) after antihypertensive therapy was associated with a reduced risk of NOAF. The risk of NOAF was higher in patients with LVH and LAE together (adjusted HR 4.30, 95% CI 2.81–6.56, P<0.001) than in those with either LVH or LAE, or those with neither, as determined by follow-up echocardiography. Conclusion In patients with hypertension and sinus rhythm, regression of LVH and LAE following antihypertensive therapy is associated with a decreased incidence of NOAF, whereas newly developed LVH or LAE is associated with a higher risk of NOAF. The changes in left heart geometry can serve as a predictive marker for NOAF in patients with hypertension.

Impact of changes in left heart geometry on predicting new-onset atrial fibrillation in patients with hypertension.

Hypertension-induced left ventricular hypertrophy (LVH) increases end-diastolic LV pressure and contributes to left atrial enlargement (LAE), which are associated with development of atrial fibrillation. However, the impact of LVH and LAE and their regression following antihypertensive therapy on atrial fibrillation incidence remains unclear. This retrospective analysis included consecutive patients with sinus rhythm who underwent echocardiography at hypertension diagnosis and after 6-18 months between 2006 and 2021 at tertiary care centres in Korea. LVH was defined as LV mass index greater than 115 g/m2 (men) and greater than 95 g/m2 (women), and LAE was defined as LA volume index greater than 42 ml/m2. The occurrence of new-onset atrial fibrillation (NOAF) was assessed in relation to changes in LVH and LAE status. Among the 1464 patients included, 163 (11.1%) developed NOAF during a median 63.8 [interquartile range (IQR) 35.9-128.5] months of surveillance period. New-onset LVH [adjusted hazard ratio (aHR) 1.88, 95% confidence interval (CI) 1.20-2.94, P = 0.006] and LAE (aHR 1.89, 95% CI 1.05-3.40, P = 0.034) were significant predictors of NOAF. Conversely, regression of LVH (aHR 0.51, 95% CI 0.28-0.91, P = 0.022) or LAE (aHR 0.30, 95% CI 0.15-0.63, P = 0.001) was associated with a reduced risk for developing NOAF. Patients with both LVH and LAE at follow-up echocardiography had a higher risk for NOAF (aHR 4.30, 95% CI 2.81-6.56, P < 0.001) than those with either LVH or LAE or those with neither. The changes in left heart geometry can serve as a predictive marker for NOAF in patients with hypertension.

Identification of immune-related genes and small-molecule drugs in hypertension-induced left ventricular hypertrophy based on machine learning algorithms and molecular docking.

Left ventricular hypertrophy (LVH) is a common consequence of hypertension and can lead to heart failure. The immune response plays an important role in hypertensive LVH; however, there is no comprehensive method to investigate the mechanistic relationships between immune response and hypertensive LVH or to find novel therapeutic targets. This study aimed to screen hub immune-related genes involved in hypertensive LVH as well as to explore immune target-based therapeutic drugs. RNA-sequencing data from a mouse model generated by angiotensin II infusion were subjected to weighted gene co-expression network analysis (WGCNA) to identify core expression modules. Machine learning algorithms were applied to screen immune-related LVH characteristic genes. Heart structures were evaluated by echocardiography and cardiac magnetic resonance imaging (CMRI). Validation of hub genes was conducted by RT-qPCR and western blot. Using the Connectivity Map database and molecular docking, potential small-molecule drugs were explored. A total of 1215 differentially expressed genes were obtained, most of which were significantly enriched in immunoregulation and collagen synthesis. WGCNA and multiple machine learning strategies uncovered six hub immune-related genes (Ankrd1, Birc5, Nuf2, C1qtnf6, Fcgr3, and Cdca3) that may accurately predict hypertensive LVH diagnosis. Immune analysis revealed that fibroblasts and macrophages were closely correlated with hypertensive LVH, and hub gene expression was significantly associated with these immune cells. A regulatory network of transcription factor-mRNA and a ceRNA network of miRNA-lncRNA was established. Notably, six hub immune-related genes were significantly increased in the hypertensive LVH model, which were positively linked to left ventricle wall thickness. Finally, 12 small-molecule compounds with the potential to reverse the high expression of hub genes were ruled out as potential therapeutic agents for hypertensive LVH. This study identified and validated six hub immune-related genes that may play essential roles in hypertensive LVH, providing new insights into the potential pathogenesis of cardiac remodeling and novel targets for medical interventions.

Relationship between four insulin resistance surrogates and left ventricular hypertrophy among hypertensive adults: a case-control study.

Hypertension-induced left ventricular hypertrophy (LVH) is intricately linked to insulin resistance (IR). This research aimed to elucidate the relationship of advanced indices, namely the triglyceride-glucose (TyG) index, the TyG adjusted for body mass index (TyG-BMI), the triglycerides-to-high-density lipoprotein cholesterol ratio (TG/HDL-c), and the metabolic score for IR (METS-IR), with LVH in hypertensive cohorts. This analytical case-control investigation encompassed 800 individuals aged 18 or above from the Cardiology Department of the Second Affiliated Hospital of Baotou Medical College over a span from January 2021 to April 2022. Data extraction was conducted from inpatient records. The nexus between the four metrics and LVH susceptibility was ascertained via logistic regression models. Furthermore, the receiver operating characteristic (ROC) curve's area (AUC) shed light on the discriminative capacities of the distinct IR indicators for LVH, considering other concomitant risk variables. Post multifaceted covariate adjustments, the fourth quartile figures for TyG-BMI emerged as the most starkly significant (OR: 5.211, 95% CI: 2.861-9.492), succeeded by METS-IR (OR: 4.877, 95% CI: 2.693-8.835). In juxtaposition with other IR-derived indices (TyG and TG/HDL-c), TyG-BMI manifested the paramount AUC (AUC: 0.657; 95% CI: 0.606-0.708). Concurrently, METS-IR exhibited commendable predictive efficacy for LVH (AUC: 0.646; 95% CI: 0.595-0.697). TyG-BMI and METS-IR displayed superior discriminative capabilities for LVH, underscoring their potential as supplementary indicators in gauging LVH peril in clinical settings and prospective epidemiological research.

Assessment of papillary muscle free strain in hypertrophic cardiomyopathy and hypertension-induced left ventricular hypertrophy.

We aimed to evaluate and compare papillary muscle free strain in hypertrophic cardiomyopathy (HCMP) and hypertensive (HT) patients. Global longitudinal strain (GLS), and longitudinal myocardial strain of the anterolateral (ALPM) and posteromedial papillary muscles (PMPM) were obtained in 46 HCMP and 50 HT patients. Interventricular septum (IVS)/posterior wall (PW) thickness ratio, left ventricular mass index (LVMI), left atrial anteroposterior diameter (LAAP) and mitral E/E' were found to be increased in patients with HCMP compared to HT patients. Left ventricular cavity dimensions were smaller in HCMP patients. GLS of HCMP and HT patients were - 14.52 ± 3.01 and -16.85 ± 1.36%, respectively (p < 0.001). Likewise, ALPM and PMPM free strain values were significantly reduced in HCMP patients over HT patients [-14.00% (-22 to -11%) and -15.5% (-24.02 to -10.16%) vs -23.00% (-24.99 to -19.01%) and -22.30% (-26.48 to -15.95%) (p = 0.016 and p = 0.010)], respectively. ALPM free strain showed a statistically significant correlation with GLS, maximal wall thickness, IVS thickness and LVMI. PMPM free strain showed a significant correlation with GLS, IVS thickness and LAAP. The GLS value of - 13.05 had a sensitivity of 61.9% and a specificity of 97.4% for predicting HCMP. ALPM and PMPM free strain values of -15.31 and -17.17% had 63 and 76.9% sensitivity and 85.7 and 76.9% specificity for prediction of HCMP. Besides other echocardiographic variables, which were investigated in earlier studies, papillary muscle free strain also could be used in HCMP to distinguish HCMP- from HT-associated hypertrophy.

Assessing Myocardial Strain and Myocardial Work as a Marker for Hypertensive Heart Disease: A Meta-Analysis.

The main objective of this study was to determine whether myocardial strain and myocardial work are altered in hypertension and whether the strain is independent of hypertension-induced left ventricular hypertrophy. Two systematic literature searches were conducted using Medline and EMBASE through to June 30, 2022. In the first, search terms left ventricular strain or speckle tracking AND hypertension and left ventricular hypertrophy were used in conjunction with Boolean operators to identify articles reporting left ventricular strain in patients with hypertension. In the second, the terms Global cardiac or myocardial work AND hypertension were used to identify articles. Publication bias was assessed by examination of funnel plots and calculation of the Failsafe N and Duval and Tweedie's Trim and fill. The results were presented as Forrest plots. Global longitudinal strain (GLS) was significantly lower in patients with hypertension compared to those without hypertension with a mean difference of 2.0 0.1 (standard error of mean(SEM)) in the fixed effect model. Global circumferential strain (GCS) was significantly lower in hypertension. The mean difference between the hypertensive and non-hypertensive groups was 1.37 0.17. Global radial strain (GRS) was significantly (p 0.05) greater in hypertension. However, this difference was significant in only 3 and of borderline significance in 3 of 14 studies where GRS was measured. The mean difference between the hypertensive and non-hypertensive groups was 1.5 0.5 using the fixed effects model. There was a significant relationship between GLS and GCS as well as between GCS and GRS but no significant relationship between GLS and GRS. There was no significant difference in left ventricular ejection fraction (LVEF) between the hypertension and no hypertension groups. There was no significant relationship between LVEF and either GLS or GCS but a significant negative correlation was found between LVEF and GRS. GLS was further reduced in persons with hypertension and left ventricular hypertrophy (LVH) compared to hypertension without LVH. In contrast, there were no or minimal differences in GCS and GRS for individuals with hypertension and LVH compared to those without LVH. Global myocardial work index (GWI) and Global constructive work (GCW) were significantly greater in patients with hypertension compared to controls. Global wasted work (GWW) indicated significantly less wasted work in controls compared to hypertension. In contrast, Global work efficiency (GWE) was significantly lower in hypertension compared to the control. There was a significant reduction in GLS and GCS in hypertension while GRS was increased. The reduction in GLS in hypertension was not dependent on the presence of LVH. GLS was further reduced in persons with hypertension when LVH was present. In contrast, there were no or minimal differences in GCS and GRS for individuals with LVH compared to those without LVH. GLS was independent of left ventricle (LV) ejection fraction. GWI, GCW and GWW were greater in hypertension while GWE was lower in hypertension compared to controls. These data support the contention that GLS and indices of global work are early markers of hypertensive heart disease.

PS-BPB02-8: CURCUMIN, AN INHIBITOR OF P300-HAT ACTIVITY, PREVENTS HYPERTENSION-INDUCED CARDIAC HYPERTROPHY WITH PRESERVED SYSTOLIC FUNCTION IN DAHL RATS

Background: Hypertension causes left ventricular hypertrophy (LVH) with a preserved systolic function. While LVH might be a compensatory process, its presence of LVH is associated with an increased incidence of cardiovascular events and heart failure. Recently, we found that curcumin, a major curcuminoid isolated from Curcuma longa, inhibits the histone acetyltransferase (HAT) activity of p300 as well as the p300-induced acetylation of histones and a hypertrophy-responsive transcription factor, GATA-4, in cultured cardiomyocytes. Furthermore, curcumin prevents deterioration of the systolic function in rat heart failure models in vivo. However, whether curcumin prevents the development of hypertension-induced LVH at an early stage of hypertension is unclear. Objective: To solve this problem, we have utilized a salt-sensitive Dahl rat (DS) model of hypertension. Methods: We randomized 6-week-old DS (n = 19) and control salt-resistant Dahl rats (DR, n = 10) to curcumin or the vehicle group. Then, these rats were given a high-salt diet and subjected to daily oral treatment with 50 mg/kg/day of curcumin or its vehicle (1% Gum arabic) for 6 weeks. Results: There were no differences between curcumin and vehicle in any data examined before treatment (6 weeks of age). The high-salt diet-induced a similar degree of hypertension in these two groups of DS compared with DR. At 12 weeks of age, transthoracic echocardiography in the vehicle group showed that the LV wall thickness, LV mass, and LV fractional shortening were significantly higher in DS compared with DR, and the LV systolic and diastolic dimensions were significantly smaller in DS than DR. Curcumin treatment significantly (p &lt; 0.01) decreased the LV wall thickness in DS but not DR. Curcumin also significantly (p &lt; 0.01) decreased the LV mass in DS, but not in DR. However, LV fractional shortening in DS was similar between the two groups. Curcumin also prevented the increases in hypertension-induced myocardial cell hypertrophy and perivascular fibrosis. Furthermore, curcumin significantly attenuated the up-regulation of hypertrophy-response gene transcriptions as well as acetylation of GATA4 but not phosphorylation of ERK1/2 and GATA4 in the heart. Conclusions: The natural compound, curcumin, inhibits the development of hypertension-induced concentric LVH without affecting the systolic function through inhibition of GATA4-acetylation. Thus, this compound might be applicable to patients with early-stages hypertensive heart diseases.

PS-BPB02-2: POLYMORPHISM OF DNA REPAIR GENE IS ASSOCIATED WITH HYPERTENSION-INDUCED LEFT VENTRICULAR HYPERTROPHY - ROLE OF DNA DAMAGE AND CELL SENESCENCE

Objective: Deficiency of X-ray repair cross-complementing protein 3 (XRCC3), a DNA-damage repair molecule, and 241Met variant of XRCC3 are prone to increase endoreduplication, resulting in pathological polyploidy. In this study we investigated the impact of XRCC3 polymorphism on the incidence of hypertension-induced left ventricular hypertrophy (LVH) and underlying mechanisms. Design and method: Patients under hemodialysis (n = 77) were genotyped for XRCC3 Thr241Met polymorphism. LVH was determined by echocardiography. To investigate the possible mechanisms for LVH, human XRCC3 cDNA of 241Thr or that of 241Met was introduced into cultured cells. The surface area of the cells was measured and spontaneous DNA double-strand breaks were detected by immunofluorescent study with anti-53BP1 antibody. The mRNA levels of basal and TNF-α-stimulated MCP-1 were quantified by real-time RT PCR. FACS analysis was performed to count the percentage of polyploidy. Results: In patients under hemodialysis, XRCC3 241Thr/Met genotype was more frequent in LVH (+) group than in LVH (-) group (42.3% vs. 13.7%, χ2 = 7.85, p = 0.0051). To investigate the possible mechanisms for LVH, following in vitro experiments were performed. The surface area of Chinese hamster ovary cells expressing XRCC3 241Met variant was larger than those expressing 241Thr. The accumulation of spontaneous DNA double-strand breaks (DSBs) was increased in NIH3T3 cells expressing 241Met (3T3–241Met) than those expressing 241Thr (3T3–241Thr). Ionizing radiation-induced cell senescence was significantly enhanced in 3T3–241Met than in 3T3–241Thr. The mRNA levels of basal and TNF-α-stimulated MCP-1 were higher in 3T3–241Met variant than 3T3–241Thr. Finally, FACS analysis revealed that the cell percentage in G2/M phase including polyploidy was significantly increased in 3T3–241Met compared with 3T3–241Thr. In addition, the basal mRNA level of MCP-1 was positively correlated with the cell percentage in G2/M phase and polyploidy. Conclusion: The current study suggests that XRCC3 241Met variant increases the risk of LVH via the accumulation of DNA damage, alteration of cell cycle progression, and induction of cell senescence and proinflammatory phenotype.

MiRNA-29b and miRNA-497 Modulate the Expression of Carboxypeptidase X Member 2, a Candidate Gene Associated with Left Ventricular Hypertrophy.

Left ventricular hypertrophy (LVH) is a major risk factor for adverse cardiovascular events. Recently, a novel candidate gene encoding the carboxypeptidase X member 2 (CPXM2) was found to be associated with hypertension-induced LVH. CPXM2 belongs to the M14 family of metallocarboxypeptidases, yet it lacks detectable enzyme activity, and its function remains unknown. Here, we investigated the impact of micro (mi)RNA-29b, miRNA-195, and miRNA-497 on the posttranscriptional expression control of CPXM2. Candidate miRNAs for CPXM2 expression control were identified in silico. CPXM2 expression in rat cardiomyocytes (H9C2) was characterized via real-time PCR, Western blotting, and immunofluorescence. Direct miRNA/target mRNA interaction was analysed by dual luciferase assay. CPXM2 was expressed in H9C2 and co-localised with z-disc associated protein PDZ and LIM domain 3 (Pdlim3). Transfection of H9C2 with miRNA-29b, miRNA-195, and miRNA-497 led to decreased levels of CPXM2 mRNA and protein, respectively. Results of dual luciferase assays revealed that miRNA-29b and miRNA-497, but not miRNA-195, directly regulated CPXM2 expression on a posttranscriptional level via binding to the 3′UTR of CPXM2 mRNA. We identified two miRNAs capable of the direct posttranscriptional expression control of CPXM2 expression in rat cardiomyocytes. This novel data may help to shed more light on the—so far—widely unexplored expression control of CPXM2 and its potential role in LVH.

Pharmacotherapy for hypertension-induced left ventricular hypertrophy.

Hypertension is the leading preventable risk factor for cardiovascular disease and premature death worldwide. One of the clinical effects of hypertension is left ventricular hypertrophy (LVH), a process of cardiac remodelling. It is estimated that over 30% of people with hypertension also suffer from LVH, although the prevalence rates vary according to the LVH diagnostic criteria. Severity of LVH is associated with a higher prevalence of cardiovascular disease and an increased risk of death. The role of antihypertensives in the regression of left ventricular mass has been extensively studied. However, uncertainty exists regarding the role of antihypertensive therapy compared to placebo in the morbidity and mortality of individuals with hypertension-induced LVH. To assess the effect of antihypertensive pharmacotherapy compared to placebo or no treatment on morbidity and mortality of adults with hypertension-induced LVH. Cochrane Hypertension's Information Specialist searched the following databases for studies: Cochrane Hypertension Specialised Register (to 26 September 2020), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library; 2020, Issue 9), Ovid MEDLINE (1946 to 22 September 2020), and Ovid Embase (1974 to 22 September 2020). We searched the World Health Organization International Clinical Trials Registry Platform and the ClinicalTrials.gov for ongoing trials. We also searched Epistemonikos (to 19 February 2021), LILACS BIREME (to 19 February 2021), and Clarivate Web of Science (to 26 February 2021), and contacted authors and funders of the identified trials to obtain additional information and individual participant data. There were no language restrictions. Randomised controlled trials (RCTs) with at least 12 months' follow-up comparing antihypertensive pharmacological therapy (monotherapy or in combination) with placebo or no treatment in adults (18 years of age or older) with hypertension-induced LVH were eligible for inclusion. The trials must have analysed at least one primary outcome (all-cause mortality, cardiovascular events, or total serious adverse events) to be considered for inclusion. Two review authors screened the search results, with any disagreements resolved by consensus amongst all review authors. Two review authors carried out the data extraction and analyses. We assessed risk of bias of the included studies following Cochrane methodology. We used the GRADE approach to assess the certainty of the body of evidence. We included three multicentre RCTs. We selected 930 participants from the included studies for the analyses, with a mean follow-up of 3.8 years (range 3.5 to 4.3 years). All of the included trials performed an intention-to-treat analysis. We obtained evidence for the review by identifying the population of interest from the trials' total samples. None of the trials provided information on the cause of LVH. The intervention varied amongst the included trials: hydrochlorothiazide plus triamterene with the possibility of adding alpha methyldopa, spironolactone, or olmesartan. Placebo was administered to participants in the control arm in two trials, whereas participants in the control arm of the remaining trial did not receive any add-on treatment. The evidence is very uncertain regarding the effect of additional antihypertensive pharmacological therapy compared to placebo or no treatment on mortality (14.3% intervention versus 13.6% control; risk ratio (RR) 1.02, 95% confidence interval (CI) 0.74 to 1.40; 3 studies; 930 participants; very low-certainty evidence); cardiovascular events (12.6% intervention versus 11.5% control; RR 1.09, 95% CI 0.77 to 1.55; 3 studies; 930 participants; very low-certainty evidence); and hospitalisation for heart failure (10.7% intervention versus 12.5% control; RR 0.82, 95% CI 0.57 to 1.17; 2 studies; 915 participants; very low-certainty evidence). Although both arms yielded similar results for total serious adverse events (48.9% intervention versus 48.1% control; RR 1.02, 95% CI 0.89 to 1.16; 3 studies; 930 participants; very low-certainty evidence) and total adverse events (68.3% intervention versus 67.2% control; RR 1.07, 95% CI 0.86 to 1.34; 2 studies; 915 participants), the incidence of withdrawal due to adverse events may be significantly higher with antihypertensive drug therapy (15.2% intervention versus 4.9% control; RR 3.09, 95% CI 1.69 to 5.66; 1 study; 522 participants; very low-certainty evidence). Sensitivity analyses limited to blinded trials, trials with low risk of bias in core domains, and trials with no funding from the pharmaceutical industry did not change the results of the main analyses. Limited evidence on the change in left ventricular mass index prevented us from drawing any firm conclusions. We are uncertain about the effects of adding additional antihypertensive drug therapy on the morbidity and mortality of participants with LVH and hypertension compared to placebo. Although the incidence of serious adverse events was similar between study arms, additional antihypertensive therapy may be associated with more withdrawals due to adverse events. Limited and low-certainty evidence requires that caution be used when interpreting the findings. High-quality clinical trials addressing the effect of antihypertensives on clinically relevant variables and carried out specifically in individuals with hypertension-induced LVH are warranted.

Curcumin, an Inhibitor of p300-HAT Activity, Suppresses the Development of Hypertension-Induced Left Ventricular Hypertrophy with Preserved Ejection Fraction in Dahl Rats.

We found that curcumin, a p300 histone acetyltransferase (HAT) inhibitor, prevents cardiac hypertrophy and systolic dysfunction at the stage of chronic heart failure in Dahl salt-sensitive rats (DS). It is unclear whether curcumin suppresses the development of hypertension-induced left ventricular hypertrophy (LVH) with a preserved ejection fraction. Therefore, in this study, we randomized DS (n = 16) and Dahl salt-resistant (DR) rats (n = 10) at 6 weeks of age to either curcumin or vehicle groups. These rats were fed a high-salt diet and orally administrated with 50 mg/kg/d curcumin or its vehicle for 6 weeks. Both curcumin and vehicle treatment groups exhibited similar degrees of high-salt diet-induced hypertension in DS rats. Curcumin significantly decreased hypertension-induced increase in posterior wall thickness and LV mass index, without affecting the systolic function. It also significantly reduced hypertension-induced increases in myocardial cell diameter, perivascular fibrosis and transcriptions of the hypertrophy-response gene. Moreover, it significantly attenuated the acetylation levels of GATA4 in the hearts of DS rats. A p300 HAT inhibitor, curcumin, suppresses the development of hypertension-induced LVH, without affecting blood pressure and systolic function. Therefore, curcumin may be used for the prevention of development of LVH in patients with hypertension.

Effect of a Combined Treatment with Ivabradine and Spironolactone on Cardiac Structure and Function in Hypertensive Dahl Salt‐Sensitive Rats

Introduction Hypertension-induced left ventricular (LV) hypertrophy and myocardial fibrosis provide structural basis for diastolic dysfunction. It has been previously reported that aldosterone receptor antagonist spironolactone (SL) can prevent myocardial fibrosis and, hence, alleviate hypertension-induced diastolic dysfunction, whereas treatment with heart rate lowering drug ivabradine (IVA) can improve cardiac function during development of hypertension-induced hypertrophy. Hypothesis We hypothesize that a combination of a heart rate-lowering drug IVA and a competitive mineralocorticoid receptor antagonist SL would alleviate adverse LV structural alterations and diastolic dysfunction in animals with chronic hypertension. Methods Seven-week-old, male Dahl salt-sensitive rats were fed a high-salt diet (8% NaCl) to induce sustained hypertension. After 7 weeks on a high-salt diet, in order to reduce the risk of death by stroke, the hypertensive (HT) rats were switched to a low-salt diet (0.3% NaCl) and randomly divided into two experimental groups: 1) treated with IVA (10 mg/kg/day) and SL (20 mg/kg/day) (HT-T) and 2) subjected to a vehicle only (HT-V). A mixture of dimethyl sulfoxide and propylene glycol (50%:50%, v/v) was used as a vehicle to deliver the drugs for 8 weeks by intraperitoneal ALZET osmotic pumps. The rats fed a low-salt diet only were used as an age-matched normotensive controls (NT). Heart rate and blood pressure were evaluated every week using the CODA tail-cuff plethysmography system. At the end of experiment, the hemodynamic parameters and LV function were assessed using a Millar micro-tip pressure catheter and a PowerLab data acquisition system. Subsequently, rats were euthanized, and their hearts were processed to paraffin for morphological evaluation. Serial sections from each heart were stained with various histological techniques. Images were captured using either a MicroScan D2 slide scanner or a Leica DM IRE2 microscope and analyzed by Image-Pro Analyzer v.7.0 software. Statistical analysis was performed using Prism 6 software. Results At the beginning of treatment, HT rats demonstrated a 42.3% increase in mean arterial blood pressure (MAP) and a 17.1% rise in heart rate compared to NT rats. During 8 weeks of treatment, the MAP remained comparably elevated in both HT groups, whereas heart rate had been persistently reduced in treated rats on average by 37.5% and 26.9% in comparison with HT-V and NT rats, respectively. At the end of a treatment period, rats in both HT groups had a significantly increased Tau constant, suggesting an analogous impairment of active relaxation. At the same time, all groups showed a similar level of LV end-diastolic pressure, indicating a preservation of passive myocardial stiffness. The examination of hearts has confirmed that chronic hypertension caused significant LV hypertrophy (P≤0.001) and myocardial fibrosis (P≤0.01) compared to NT rats. More important, HT rats in treated group revealed more pronounced concentric hypertrophy than animals in HT-V group. Conclusion Our findings establish that a combined treatment with IVA and SL augmented concentric LV hypertrophy and did not alleviate the hypertension-induced diastolic dysfunction.

Hypertension induces compensatory left ventricular hypertrophy by a mechanism involving gap junction lateralization and overexpression of CD36, PKC and MMP-2.

Hypertension-induced left ventricular hypertrophy evolves initially as an adaptive response meant to minimize ventricular wall stress. The mechanisms involved in the preservation of the cardiac function during the “compensatory” phase of the left ventricular hypertrophy are still unclear. Therefore, we aimed at uncovering fine changes that aid the heart to cope with the increased stress in hypertension. Male golden Syrian hamsters were given NG-nitro-L-arginine methyl ester (L-NAME) for 16 weeks, and they became hypertensive (HT), developing left ventricular hypertrophy with no impaired contractility or fibrosis. As compared to age-matched control hamsters, the hypertrophied left ventricles in L-NAME-induced HT hamsters exhibited the following structural and molecular changes: (i) accumulation of lipid droplets (LDs) within cardiomyocytes and relocation of gap junctions to the lateral membrane of cardiomyocytes or close to mitochondria (revealed by electron microscopy); (ii) overexpression of the cluster of differentiation 36 (CD36) fatty acid transporter, protein kinase C (PKC), and matrix metalloproteinase-2 (MMP-2), enhanced activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway, and unchanged expression of the connexin 43 (Cx43) and N-cadherin junctional proteins (assessed by Western blot); (iii) increased protein carbonyl content, assessed with a 2,4-Dinitrophenylhydrazine (DNPH)-based spectrophotometric assay, indicative of an enhanced reactive oxygen species (ROS) production; and (iv) augmented MMP-2 activity (determined by gelatin zymography). These changes may participate in an orchestrated adaptive hypertrophic growth response that helps to maintain cardiac performance, in HT hamsters. Together, these findings could provide support for designing future strategies meant to prevent the transition from compensatory left ventricular hypertrophy to decompensated heart failure.

Reactivation of fatty acid oxidation by medium chain fatty acid prevents myocyte hypertrophy in H9c2 cell line.

Metabolic shift is an important contributory factor for progression of hypertension-induced left ventricular hypertrophy into cardiac failure. Under hypertrophic conditions, heart switches its substrate preference from fatty acid to glucose. Prolonged dependence on glucose for energy production has adverse cardiovascular consequences. It was reported earlier that reactivation of fatty acid metabolism with medium chain triglycerides ameliorated cardiac hypertrophy, oxidative stress and energy level in spontaneously hypertensive rat. However, the molecular mechanism mediating the beneficial effect of medium chain triglycerides remained elusive. It was hypothesized that reduction of cardiomyocyte hypertrophy by medium chain fatty acid (MCFA) is mediated by modulation of signaling pathways over expressed in cardiac hypertrophy. The protective effect of medium chain fatty acid (MCFA) was evaluated in cellular model of myocyte hypertrophy. H9c2 cells were stimulated with Arginine vasopressin (AVP) for the induction of hypertrophy. Cell volume and secretion of brain natriuretic peptide (BNP) were used for assessment of cardiomyocyte hypertrophy. Cells were pretreated with MCFA (Caprylic acid) and metabolic modulation was assessed from the expression of medium-chain acyl-CoA dehydrogenase (MCAD), cluster of differentiation-36 (CD36) and peroxisome proliferator-activated receptor (PPAR)-α mRNA. The signaling molecules modified by MCFA was evaluated from protein expression of mitogen activated protein kinases (MAPK: ERK1/2, p38 and JNK) and Calcineurin A. Pretreatment with MCFA stimulated fatty acid metabolism in hypertrophic H9c2, with concomitant reduction of cell volume and BNP secretion. MCFA reduced activated ERK1/2, JNK and calicineurin A expression mediated by AVP. In conclusion, the beneficial effect of MCFA is possibly mediated by stimulation of fatty acid metabolism and modulation of MAPK and Calcineurin A.

Pharmacotherapy for hypertension-induced left ventricular hypertrophy

Pharmacotherapy for hypertension-induced left ventricular hypertrophy

Treatment of Hypertensive Left Ventricular Hypertrophy.

The development and risk potential of hypertension-induced left ventricular (LV) hypertrophy has been well described in epidemiological studies. Regression of LV hypertrophy reduces cardiovascular morbidity and mortality. However, the best treatment strategy is still debated, as well as the appropriate blood pressure target in these patients. We here review the treatment of LV hypertrophy and the potential benefit on clinical outcomes, against a background of the epidemiology and pathophysiology. Both hemodynamic and non-hemodynamic mechanisms contribute to hypertensive LV hypertrophy, which is characterized by an inappropriate myocardial fibrosis. Stringent blood pressure control reduces LV hypertrophy. Blockers of the renin-angiotensin-aldosterone system may have valuable effects on cardiac and electrophysiological remodelling beyond the effects of blood pressure reduction. Thus, they represent a cornerstone in the treatment of hypertensive LV hypertrophy, but most often other antihypertensive drug classes need to be added. Current guidelines indicate a blood pressure target in most patients with hypertensive LV hypertrophy of 120-130/80 mmHg. LV hypertrophy and myocardial fibrosis are important characteristics of hypertensive heart disease and associated with untoward prognosis. Regression of LV hypertrophy reduces cardiovascular morbidity and mortality. New drugs under development may add additional benefit.

Acetyltransferase p300 inhibitor reverses hypertension-induced cardiac fibrosis.

Epigenetic dysregulation plays a crucial role in cardiovascular diseases. Previously, we reported that acetyltransferase p300 (ATp300) inhibitor L002 prevents hypertension‐induced cardiac hypertrophy and fibrosis in a murine model. In this short communication, we show that treatment of hypertensive mice with ATp300‐specific small molecule inhibitor L002 or C646 reverses hypertension‐induced left ventricular hypertrophy, cardiac fibrosis and diastolic dysfunction, without reducing elevated blood pressures. Biochemically, treatment with L002 and C646 also reverse hypertension‐induced histone acetylation and myofibroblast differentiation in murine ventricles. Our results confirm and extend the role of ATp300, a major epigenetic regulator, in the pathobiology of cardiac hypertrophy and fibrosis. Most importantly, we identify the efficacies of ATp300 inhibitors C646 and L002 in reversing hypertension‐induced cardiac hypertrophy and fibrosis, and discover new anti‐hypertrophic and anti‐fibrotic candidates.

Carvacrol Ameliorates Pathological Cardiac Hypertrophy in Both In-vivo and In-vitro Models.

Hypertension-induced left ventricular hypertrophy is the most important risk factor for heart failure. This study aimed at investigating the effects of monoterpenoid phenol, carvacrol, on myocardial hypertrophy using both in-vivo and in-vitro models. Male Wistar rats were divided into the control (Ctl), un-treated hypertrophy (H), and carvacrol-treated hypertrophy groups (25, 50 and 75 mg/kg/day, Car+H). In the hypertrophy groups animals underwent abdominal aorta banding. Blood pressure (BP) was recorded via carotid artery cannulation. TUNEL assay and Masson’s trichrome staining were used to assess apoptosis and fibrosis, respectively. The 2-2-diphenyl 1-picril-hydrasil )DPPH( radical scavenging activity and malondialdehyde (MDA) level were estimated by biochemical tests. In in-vitro study H9c2 cardiomyoblasts were treated with angiotensin II (Ang II) to promote hypertrophy. Cell size was measured using crystal violet staining. Gene expression was evaluated by real-time RT-PCR technique. In the carvacrol-treated rats BP, heart rate, and heart weight to the body weight ratio were significantly decreased. In-vitro study showed that H9c2 cell size was significantly reduced compared to Ang II-treated cells. Both in-vivo and in-vitro studies demonstrated that carvacrol decreased atrial natriuretic peptide )ANP( mRNA level significantly (vs. H groups). The number of apoptotic cells increased in H group, while it was decreased in the Car50+H and Car75+H. In Car+H groups, in comparison with H group, the serum concentration of MDA was decreased and DPPH was increased significantly. Our findings demonstrated that carvacrol decreases hypertrophy markers in in-vivo and in-vitro models of hypertrophy.

The Significance of Interstitial Fibrosis on Left Ventricular Function in Hypertensive versus Hypertrophic Cardiomyopathy

Extracellular volume (ECV) has been validated as a surrogate measure of interstitial fibrosis, that is increased in both hypertension-induced left ventricular hypertrophy (H-LVH) and hypertrophic cardiomyopathy (HCM). We aimed to explore the correlation between ECV and left ventricular cardiac function. Eighty-one patients with HCM, 44 with H-LVH and 35 controls were prospectively enrolled. Even among patients with normal diastolic function, patients in HCM group had increased- ECV. In terms of diastolic dysfunction (DD), a similar increase in ECV was associated with a larger percentage of patients with severe or moderate-to-severe DD in HCM group. In addition, there was a compensatory increase in the left ventricular ejection fraction (LVEF) in HCM, but no hyperdynamic LVEF was observed in H-LVH. ECV was negatively correlated with LVEF in the late gadolinium enhancement (+) (LGE+) subgroups in the H-LVH group, while no significant linear correlation was observed in HCM group. The increased ECV in HCM patients with normal diastolic function warrants further exploration of the prognostic value of ECV assessments in the early stages of HCM. The associations between ECV and left ventricular functional parameters differed and taking both LGE and ECV into account might be reasonable way to differentiate between the two disorders.

XRCC3 polymorphism is associated with hypertension-induced left ventricular hypertrophy.

Deficiency of X-ray repair cross-complementing protein 3 (XRCC3), a DNA-damage repair molecule, and the 241Met variant of XRCC3 have been reported to increase endoreduplication, which induces polyploidy. The aims of this study were to determine the impact of the XRCC3 polymorphism on the incidence of hypertension-induced left ventricular hypertrophy (LVH) and to investigate the mechanisms underlying any potential relationship. Patients undergoing chronic hemodialysis (n = 77) were genotyped to assess for the XRCC3 Thr241Met polymorphism. The XRCC3 241Thr/Met genotype was more frequent in the LVH (+) group than in the LVH (-) group (42.3 vs. 13.7%, χ2 = 7.85, p = 0.0051). To investigate possible mechanisms underlying these observations, human XRCC3 cDNA of 241Thr or that of 241Met was introduced into cultured CHO cells. The surface area of CHO cells expressing XRCC3 241Met was larger than that expressing 241Thr. Spontaneous DNA double-strand breaks accumulated to a greater degree in NIH3T3 cells expressing 241Met (3T3-241Met) than in those expressing 241Thr (3T3-241Thr). DNA damage caused by radiationinduced cell senescence more frequently in 3T3-241Met. The levels of basal and TNF-α-stimulated MCP-1 mRNA and protein secretion were higher in 3T3-241Met. Finally, FACS analysis revealed that the cell percentage in G2/M phase including polyploidy was significantly higher in 3T3-241Met than in 3T3-241Thr. Furthermore, the basal level of MCP-1 mRNA positively correlated with the cell percentage in G2/M phase and polyploidy. These data suggest that the XRCC3 241Met increases the risk of LVH via accumulation of DNA damage, thereby altering cell cycle progression and inducing cell senescence and a proinflammatory phenotype.