Prevention and treatment of hypertensive left ventricular hypertrophy

PURPOSE OF REVIEW

Left ventricular (LV) hypertrophy (LVH) is a well recognized target organ adaptation to longstanding uncontrolled hypertension and other cardiovascular risk factors. It is also a strong and independent predictor of many cardiovascular disorders.

RECENT FINDINGS

This focused review explores the current concepts in screening, diagnosis, prevention, and treatment of LVH in patients with hypertension. Currently, the primary screening and diagnostic tools for LVH are ECG and 2D echocardiography. Implementing machine learning in the diagnostic modalities can improve sensitivity in the detection of LVH. Lifestyle modifications, blood pressure control with antihypertensive therapy, and management of comorbidities aid in preventing and reversing LV remodeling.

SUMMARY

LVH is a common and often silent complication of hypertension. Prevention and reversal of LV remodeling are crucial for cardiovascular risk reduction in patients with hypertension.

Relationship among Left Ventricular Hypertrophy, Cardiovascular Events, and Preferred Blood Pressure Measurement Timing in Hemodialysis Patients

This study aimed to identify the ideal timing and setting for measuring blood pressure (BP) and determine whether the left ventricular mass index (LVMI) is an independent risk factor associated with increased cardiovascular events in hemodialysis (HD) patients. BP and LVMI were measured at baseline and at 6 and 12 months after HD initiation. BP was monitored and recorded at nine different time points, including before and after HD over a one-week period (HDBP). The mean BP measurement was calculated as the weekly averaged BP (WABP). LVMI was significantly correlated with home BP, in-office BP, HDBP, and WABP. Receiver operating characteristic analysis indicated that the cutoff LVMI value for cardiovascular events was 156 g/m2. LVMI and diabetes mellitus were significant influencing factors for cardiovascular events (hazards ratio (95% confidence interval): diabetes mellitus, 2.84 (1.17,7.45); LVMI > 156 g/m2, 2.86 (1.22,6.99)). Pre-HDBP, post-HDBP, and WABP were independently associated with higher LVMI in the follow-up periods. Hemoglobin and human atrial natriuretic peptide (hANP) levels were associated with LVMI beyond 12 months after HD initiation. Treatment of hypertension, overhydration based on hANP, and anemia may reduce the progression of LVMI and help identify HD patients at high risk for cardiovascular events.

A novel DSN-based fluorescence assay for MicroRNA-133a detection and its application for LVH diagnosis in maintenance hemodialysis patients

Left ventricular hypertrophy (LVH) is the most powerful predictor of cardiovascular mortality in maintenance hemodialysis (MHD) patients. Circulating microRNA-133a (miR-133a) was reported to be a potential biomarker for LVH in MHD patients. The aim of this experiment is to establish a novel DSN (duplex-specific-nuclease)-based fluorescence assay for the ultrasensitive detection of miR-133a and investigate its application for LVH diagnosis in MHD patients. The results indicate DSN enzyme combined with ultrathin metallic MoS₂ nanosheets presents high sensitivity, specificity, and low fluorescence background for miR-133a detection. Then, circulating miR-133a levels in plasma from 40 MHD patients and 20 healthy controls are analyzed by such assay. The levels of miR-133a are down-regulated in MHD patients with LVH compared to MHD patients without LVH and healthy controls, and the ROC (receiver operating characteristic) curve shows strong separation between MHD with LVH patients and MHD without LVH patients. Furthermore, the liner regression analysis shows negative correlation of miR-133a level and interventricular septum thickness (IVS) as well as left ventricular mass index (LVMI), the indicators of LVH. Therefore, our findings reveal DSN-based fluorescence assay for miR-133a is suitable for LVH diagnosis in MHD patients.

Prediction of Left Ventricular Mass Index Using Electrocardiography in Essential Hypertension - A Multiple Linear Regression Model

Background

Current electrocardiography (ECG) criteria indicate only the presence or absence of left ventricular hypertrophy (LVH). LVH is a continuum and a direct relationship exists between left ventricular mass (LVM) and cardiovascular event rate. We developed a mathematical model predictive of LVM index (LVMI) using ECG and non-ECG variables by correlating them with echocardiography determined LVMI.

Patients and Methods

The model was developed in a cohort of patients on treatment for essential hypertension (BP>140/90 mm of Hg) who underwent concurrent ECG and echocardiography. One hundred and forty-seven subjects were included in the study (56.38±11.84 years, 66% males). LVMI was determined by echocardiography (113.76±33.06 gm/m²). A set of ECG and non-ECG variables were correlated with LVMI for inclusion in the multiple linear regression model. The model was checked for multicollinearity, normality and homogeneity of variances.

Results

The final regression equation formulated with the help of unstandardized coefficients and constant was LVMI=18.494+ 1.704 (aLL) + 0.969 (RaVL+SV3) + 0.295 (MBP) + 15.406 (IHD) (aLL – sum of deflections in augmented limb leads; RaVL+SV3 – sum of deflection of (R wave in aVL + S wave in V3); MBP – mean blood pressure; IHD=1 for the presence of the disease, IHD=0 for the absence of the disease).

Conclusion

In the model, 50.4% of the variability in LV mass is explained by the variables used. The findings warrant further studies for the development of better and validated models that can be incorporated in microprocessor-based ECG devices. The determination of LVMI with ECG only will be a cost-effective and readily accessible tool in patient care.

Test characteristics of electrocardiography for detection of left ventricular hypertrophy in asymptomatic emergency department patients with hypertension

OBJECTIVES

The objective was to evaluate the diagnostic test characteristics of three validated electrocardiographic (ECG) criteria for the diagnosis of left ventricular hypertrophy (LVH) in undifferentiated, asymptomatic emergency department (ED) patients with hypertension (HTN).

METHODS

This was a prospective cohort study of ED patients with asymptomatic HTN at a single tertiary care facility. Patients 35 years of age or older with systolic blood pressure (sBP) ≥ 140 mm Hg or diastolic blood pressure (dBP) ≥ 90 mm Hg on two separate readings (at least 1 hour apart) were eligible for inclusion. At enrollment, ECGs were obtained for all patients. Presence of LVH on ECG was defined using Cornell voltage, Cornell product, and Minnesota Code 3.1/3.2 criteria. Echocardiography was then performed, with LVH defined by the presence of one or more of the following validated criteria: interventricular septal or posterior wall thickness ≥ 1.3 cm, LV mass ≥ 225 g (male) or ≥ 163 g (female), or LV mass indexed to height raised to the power of 2.7 ≥ 48 g/m(2.7) (male) or ≥ 45 g/m(2.7) (female). Descriptive statistics and diagnostic characteristics (i.e., sensitivity and specificity) with corresponding 95% confidence intervals (CIs) for each of the three ECG criteria were derived for both the composite and the individual echocardiographic determinants of LVH. Logistic regression was also used to model LVH before and after subsequent inclusion of clinically relevant variables.

RESULTS

A total of 161 patients (93.8% African American; mean [±SD] age = 49.8 [±8.3] years) were enrolled, and LVH was present in 89 patients (55.2%, 95% CI = 47.6% to 62.8%). On ECG analysis, mean Cornell voltage (21.5 mV vs. 28.7 mV; difference = -7.2 mV, 95% CI = -3.8 to -10.7 mV) and Cornell product (1868.4 msec × mV vs. 2616.4 msec × mV; difference = -748.0 msec × mV, 95% CI = -401.2 to -1094.8 msec × mV) were significantly lower among those without LVH on echocardiography. Subjects without LVH on echocardiography were less likely to meet Cornell voltage (30.5% vs. 48.3%; difference = -17.8%, 95% CI = -2.5% to -31.7%) or Cornell product (26.4% vs. 49.4%; difference = -23.0%, 95% CI = -8.0% to -36.5%) criteria for LVH. The diagnosis of LVH by Minnesota Code was less common (18.1% vs. 25.8%; difference = -7.7%, 95% CI = -20.1% to 5.3%) with no difference by group. Sensitivity and specificity were as follows: for the Cornell voltage, sensitivity 25.4% (95% CI = 15.3% to 37.9%), specificity 50.0% (95% CI = 67.6% to 93.2%); for the Cornell product, sensitivity 25.4% (95% CI = 15.3% to 37.9%), specificity 75.0% (95% CI = 19.4% to 99.4%); and for the Minnesota code, sensitivity 26.9% (95% CI = 16.6% to 39.7%), specificity 75.0% (95% CI = 19.4% to 99.4%). On logistic regression, the c-statistics for Cornell voltage and Cornell product were equivalent (0.67), with only marginal improvement after the addition of body mass index (BMI; 0.69 and 0.70, respectively), B-type natriuretic peptide (BNP; 0.68 and 0.69, respectively), or both (0.71 and 0.72, respectively) to the models.

CONCLUSIONS

In this cohort of predominately African American ED patients with asymptomatic HTN, sensitivity and specificity of standard ECG criteria were relatively poor for the diagnosis of LVH on echocardiography. Thus, ECG is of limited use for LVH risk stratification in asymptomatic ED patients with elevated blood pressure, with additional clinical information only modestly strengthening its predictive value.

Cardiac and pulmonary arterial remodeling after sinoaortic denervation in normotensive rats

Blood pressure variability (BPV) and baroreflex dysfunction may contribute to end-organ damage process. We investigated the effects of baroreceptor deficit (10 weeks after sinoaortic denervation - SAD) on hemodynamic alterations, cardiac and pulmonary remodeling. Cardiac function and morphology of male Wistar intact rats (C) and SAD rats (SAD) (n=8/group) were assessed by echocardiography and collagen quantification. BP was directly recorded. Ventricular hypertrophy was quantified by the ratio of left ventricular weight (LVW) and right ventricular weight (RVW) to body weight (BW). BPV was quantified in the time and frequency domains. The atrial natriuretic peptide (ANP), alpha-skeletal actin (α-skelectal), collagen type I and type III genes mRNA expression were evaluated by RT-PCR. SAD did not change BP, but increased BPV (11±0.49 vs. 5±0.3 mmHg). As expected, baroreflex was reduced in SAD. Pulmonary artery acceleration time was reduced in SAD. In addition, SAD impaired diastolic function in both LV (6.8±0.26 vs. 5.02±0.21 mmHg) and RV (5.1±0.21 vs. 4.2±0.12 mmHg). SAD increased LVW/BW in 9% and RVW/BW in 20%, and augmented total collagen (3.8-fold in LV, 2.7-fold in RV, and 3.35-fold in pulmonary artery). Also, SAD increased type I (~6-fold) and III (~5-fold) collagen gene expression. Denervation increased ANP expression in LV (75%), in RV (74%) and increased α-skelectal expression in LV (300%) and in RV (546%). Baroreflex function impairment by SAD, despite not changing BP, induced important adjustments in cardiac structure and pulmonary hypertension. These changes may indicate that isolated baroreflex dysfunction can modulate target tissue damage.

In vitro studies of early cardiac remodeling: impact on contraction and calcium handling

Cardiac remodeling, hypertrophy, and alterations in calcium signaling are changes of the heart that often lead to failure. After a hypertrophic stimulus, the heart progresses through a state of compensated hypertrophy which over time leads to decompensated hypertrophy or failure. It is at this point that a cardiac transplant is required for survival making early detection imperative. Current experimental systems used to study the remodeling of the heart include in vivo systems (the whole body), isolated organ and sub-organ tissue, and the individual cardiac muscle cells and organelles.. During pathological remodeling there is a derangement in the intracellular calcium handling processes. These derangements are thought to lead to a dysregulation of contractile output. Hence, understanding the mechanism between remodeling and dysregulation is of great interest in the cardiac field and will ultimately help in the development of future treatment and early detection. This review will center on changes in contraction and calcium handling in early cardiac remodeling, with a specific focus on findings in two different in vitro model systems: multicellular and individual cell preparations.

Cardiovascular changes in spontaneously hypertensive rats are improved by chronic treatment with zofenopril

BACKGROUND AND PURPOSE

The aim of this study was to investigate the effect of chronic treatment with antihypertensive and non-antihypertensive doses of zofenopril on cardiovascular changes in spontaneously hypertensive rats (SHR).

EXPERIMENTAL APPROACH

Male SHR were treated with 0.5 or 10 mg kg(-1) per day of zofenopril (Z(0.5) and Z(10)) for 3 months. SHR and Wistar-Kyoto rats (WKY) receiving vehicle were used as controls. Systolic blood pressure was measured using the tail cuff method. Left ventricular weight/body weight ratio was calculated as cardiac hypertrophy index. Angiotensin converting enzyme (ACE) activity was determined in plasma and tissues by a fluorimetric method. Vascular reactivity was evaluated on aortic rings by acetylcholine and sodium nitroprusside relaxations. Effects on vascular structure were assessed by lumen diameter, wall thickness and medial cross-sectional area determination. Superoxide anion generation was quantified using lucigenin-amplified chemiluminescence in aorta.

RESULTS

Long-term daily administration of zofenopril (10 mg kg(-1)) to SHR reduced blood pressure to WKY values, decreased cardiac hypertrophy, improved the acetylcholine-induced relaxant response and reversed the vascular remodelling. ACE inhibition and antioxidant activity were involved in these effects. 0.5 mg kg(-1) per day of zofenopril slightly modified blood pressure and the other effects were weaker.

CONCLUSIONS AND IMPLICATIONS

Antihypertensive effects of chronic treatment with zofenopril were accompanied by recovery of endothelial function and improvement of cardiovascular structure. Low-dose zofenopril had little effect on blood pressure, with some benefits on cardiovascular structure and function. Inhibition of ACE and antioxidant activity were involved in these effects.

Left ventricular hypertrophy and renin-angiotensin system blockade

The renin-angiotensin system (RAS), an important control system for blood pressure and intravascular volume, also causes left ventricular hypertrophy (LVH) and fibrosis. The main causal mechanism is the increase in blood pressure, which leads to increased left ventricular wall stress; however, aldosterone release from the adrenals and (more controversially) the direct action of angiotensin II on the cardiomyocytes also play a role. Large clinical trials evaluating the blockade of the RAS with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have demonstrated an ability to prevent progression and induce regression of left ventricular mass, thereby reducing the significant and independent cardiovascular risk conferred by LVH. Regression of left ventricular mass is also achieved by other medication classes, but the RAS blockers have an additional beneficial effect for the same blood pressure reduction, for which the mechanism is not entirely clear. Studies comparing the efficacy of angiotensin-converting enzyme inhibitors versus angiotensin receptor blockers to achieve LVH regression have not demonstrated any clear benefit of one class over the other.