Left ventricular hypertrophy and the risk of subsequent left ventricular remodeling following myocardial infarction

Astragaloside IV derivative HHQ16 ameliorates infarction-induced hypertrophy and heart failure through degradation of lncRNA4012/9456

Reversing ventricular remodeling represents a promising treatment for the post-myocardial infarction (MI) heart failure (HF). Here, we report a novel small molecule HHQ16, an optimized derivative of astragaloside IV, which effectively reversed infarction-induced myocardial remodeling and improved cardiac function by directly acting on the cardiomyocyte to reverse hypertrophy. The effect of HHQ16 was associated with a strong inhibition of a newly discovered Egr2-affiliated transcript lnc9456 in the heart. While minimally expressed in normal mouse heart, lnc9456 was dramatically upregulated in the heart subjected to left anterior descending coronary artery ligation (LADL) and in cardiomyocytes subjected to hypertrophic stimulation. The critical role of lnc9456 in cardiomyocyte hypertrophy was confirmed by specific overexpression and knockout in vitro. A physical interaction between lnc9456 and G3BP2 increased NF-κB nuclear translocation, triggering hypertrophy-related cascades. HHQ16 physically bound to lnc9456 with a high-affinity and induced its degradation. Cardiomyocyte-specific lnc9456 overexpression induced, but knockout prevented LADL-induced, cardiac hypertrophy and dysfunction. HHQ16 reversed the effect of lnc9456 overexpression while lost its protective role when lnc9456 was deleted, further confirming lnc9456 as the bona fide target of HHQ16. We further identified the human ortholog of lnc9456, also an Egr2-affiliated transcript, lnc4012. Similarly, lnc4012 was significantly upregulated in hypertrophied failing hearts of patients with dilated cardiomyopathy. HHQ16 also specifically bound to lnc4012 and caused its degradation and antagonized its hypertrophic effects. Targeted degradation of pathological increased lnc4012/lnc9456 by small molecules might serve as a novel promising strategy to regress infarction-induced cardiac hypertrophy and HF.

Aortic stiffness is associated with elevated high-sensitivity cardiac troponin T concentrations at a chronic stage after ST-segment elevation myocardial infarction

OBJECTIVES

Aortic pulse wave velocity (PWV)--the proposed gold standard for the assessment of aortic stiffness--is a major determinant of left ventricular after-load and coronary perfusion. We aimed to investigate the association between aortic PWV and subclinical elevation of high-sensitivity cardiac troponin T (hs-TnT) concentrations at a chronic stage after acute ST-segment elevation myocardial infarction (STEMI).

METHODS

Seventy-four patients with acute STEMI were included in this cross-sectional single-centre study at the University Hospital of Innsbruck. All patients underwent cardiac MRI for the assessment of left ventricular function, morphology, infarct size and aortic PWV 12 months after acute STEMI. Blood samples were drawn at 12 months by peripheral venipuncture. Levels of hs-TnT were measured by a commercially available immunoassay (Roche Diagnostics).

RESULTS

hs-TnT levels (6.4 ng/l, inter-quartile range 5.0-8.6) were significantly associated with age (r = 0.417, P < 0.001), plasma creatinine levels (r = 0.257, P = 0.027), high-sensitivity C-reactive protein levels (r = 0.281, P = 0.015) and aortic PWV (r = 0.435, P < 0.001). Multiple linear regression analysis revealed aortic PWV (ß = 0.330, P = 0.025), apart from plasma creatinine concentrations (ß = 0.279, P = 0.010), to be independently associated with hs-TnT concentrations (model: R = 0.597, P < 0.001).

CONCLUSION

The present study showed an association of aortic stiffness and hs-TnT concentrations at a chronic stage after STEMI.

N-terminal pro-B-type natriuretic peptide is associated with aortic stiffness in patients presenting with acute myocardial infarction

BACKGROUND

Aortic stiffness is associated with increased left ventricular (LV) afterload, a process which is accompanied by a release of natriuretic peptides. Aortic pulse wave velocity (PWV) has been demonstrated to be the functional surrogate of aortic stiffness. We sought to investigate the impact of aortic PWV on N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations in patients with acute myocardial infarction (AMI).

METHODS

This prospective observational study included 86 consecutive patients undergoing percutaneous coronary intervention for AMI. Aortic PWV was determined 47 h (interquartile range (IQR) 27-64 h) after AMI using an established oscillometric device. NT-proBNP values were measured using a commercially available immunoassay.

RESULTS

The mean age of the study cohort was 60±11 years; 19% were female. Median aortic PWV was 7.8 m/s (IQR 6.8-9.4 m/s). Patients with a PWV above the median showed significantly higher NT-proBNP peak concentrations (median=1330 ng/l, IQR: 729-3180 ng/l vs median=498 ng/l, IQR: 124-1575 ng/l, p=0.001). Aortic PWV (beta=0.373, p=0.014) was independently associated with NT-proBNP peak concentrations even after correction for LV function, cardiac troponin T levels, heart rate, blood pressure, body mass index and the primary prevention European Society of Cardiology (ESC) SCORE (model: R=0.542, p=0.014).

CONCLUSION

In patients with AMI, aortic PWV is independently associated with NT-proBNP concentrations. This finding suggests an impact of aortic PWV on myocardial wall stress after AMI.

Use and limitations of cardiac magnetic resonance derived measures of aortic stiffness in patients after acute myocardial infarction

INTRODUCTION

Cardiac magnetic resonance (CMR) is a unique method to determine regional and local aortic stiffness parameters. Although various methods have been validated, there are no data in patients after acute ST-segment elevation myocardial infarction (STEMI). In the present study we assessed the feasibility of different CMR derived measures of aortic stiffness in patients after first acute STEMI for the first time.

METHODS

CMR derived aortic pulse wave velocity (PWV) determined by the regional transit-time (PWVTT) and local flow-area (PWVQA) method as well as local distensibility coefficients (DCs) was analyzed in 22 healthy young volunteers and 28 patients with recent acute STEMI.

RESULTS

PWVTT and DC of the ascending aorta differed significantly between healthy subjects and STEMI patients (all p<0.001). PWVQA at thoracic levels of aorta was not different between groups (p>0.520) and did not correlate with age (p>0.149) and PWVTT (p>0.310). Intra- and interobserver variability was high for PWVTT (r=0.970, p<0.001 and r=0.920, p<0.001), acceptable for DC (all r>0. 809, p<0.001 and all r>0.510, p<0.001) but low for thoracic PWVQA (all r<0.330 and all r<0.372).

CONCLUSION

PWVTT and local DC are robust methods for the assessment of aortic stiffness in patients after acute STEMI.

Relation of plasma adiponectin levels and aortic stiffness after acute ST-segment elevation myocardial infarction

BACKGROUND

Pulse wave velocity is a measure of aortic stiffness and an independent predictor of cardiovascular morbidity and mortality. Adiponectin is involved in atherosclerosis and inflammation. In the present study we aimed to explore the association between plasma adiponectin concentrations and pulse wave velocity in the acute phase after ST-segment elevation myocardial infarction (STEMI).

METHODS

Forty-six consecutive STEMI patients (mean age 57 ± 11 years) treated with primary percutaneous coronary intervention (PCI) were enrolled in this cross-sectional study. Plasma adiponectin was measured 2 days after index event by enzyme-linked immunosorbent assay. Aortic pulse wave velocity (PWV) was calculated by the transit-time method with the use of a velocity-encoded, phase-contrast cardiac magnetic resonance protocol.

RESULTS

Median plasma adiponectin concentration was 2385 ng/ml (interquartile range 1735-5403). Males had lower plasma adiponectin values than females and current smokers had lower values than non-smokers (all p<0.02). Adiponectin was significantly associated with PWV (r=0.505, p<0.001), age (r=0.437, p=0.002), and total cholesterol (r=0.468, p=0.001). Multiple linear regression analysis revealed adiponectin as a predictor of PWV independently of age, sex, smoking status, total cholesterol, and N-terminal pro-B-type natriuretic peptide (p=0.027).

CONCLUSIONS

Plasma adiponectin concentrations are strongly associated with aortic stiffness in patients after acute STEMI treated with primary PCI. Our data support a possible role for adiponectin as an independent risk marker for increased aortic stiffness in STEMI patients.

Hypertension and acute myocardial infarction: an overview

History of hypertension is a frequent finding in patients with acute myocardial infarction (AMI) and its recurring association with female sex, diabetes, older age, less frequent smoking and more frequent vascular comorbidities composes a risk profile quite distinctive from the normotensive ischemic counterpart.Antecedent hypertension associates with higher rates of death and morbid events both during the early and long-term course of AMI, particularly if complicated by left ventricular dysfunction and/or congestive heart failure. Renin-angiotensin-aldosterone system blockade, through either angiotensin-converting enzyme inhibition, angiotensin II receptor blockade or aldosterone antagonism, exerts particular benefits in that high-risk hypertensive subgroup.In contrast to the negative implications carried by antecedent hypertension, higher systolic pressure at the onset of chest pain associates with lower mortality within 1 year from coronary occlusion, whereas increased blood pressure recorded after hemodynamic stabilization from the acute ischemic event bears inconsistent relationships with recurring coronary events in the long-term follow-up.Whether antihypertensive treatment in post-AMI hypertensive patients prevents ischemic relapses is uncertain. As a matter of fact, excessive diastolic pressure drops may jeopardize coronary perfusion and predispose to new acute coronary events, although the precise cause-effect mechanisms underlying this phenomenon need further evaluation.

Body size adjustments for left ventricular mass by cardiovascular magnetic resonance and their impact on left ventricular hypertrophy classification

Methods to index left ventricular (LV) mass, measured by cardiovascular magnetic resonance (CMR), for body size have not been investigated. The purposes of this study were to develop allometric indices for LV mass measured by CMR and compare estimates of the prevalence and predictive value of LV hypertrophy defined by a new allometric height-weight index, LV mass/body surface area (BSA), height indices (a new allometric height index; and previously derived indices from echocardiographic measurements: LV mass/height(2), LV mass/height(2.7)), and non-indexed LV mass. 5,004 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with CMR measurements of LV mass and no clinical cardiovascular disease at baseline were followed for a median of 4.1 years. The new indices and limits for hypertrophy (95th percentile) were derived from 822 normal-weight, normotensive, non-diabetic MESA participants. 107 events (coronary heart disease or stroke) were observed. The estimated prevalence of hypertrophy at baseline and hazard ratio for event associated with hypertrophy were 8% and 2.4 with the new allometric height-weight index, 11% and 2.2 with LV mass/BSA, 23-24% and 2.0-2.1 with height indices, and 20% and 1.7 with non-indexed LV mass. A statistically significant difference was detected between the hazard ratios based on the new height-weight index and non-indexed LV mass. The prevalence of hypertrophy is higher for indices that do not account for weight. The predictive value of hypertrophy is significantly better with the new allometric height-weight index than with non-indexed LV mass and may be better than indices without weight.

Clinical impact of left ventricular hypertrophy and implications for regression

Left ventricular hypertrophy (LVH) is an independent risk factor and predictor of cardiovascular (CV) events and all-cause mortality. Patients with LVH are at increased risk for stroke, congestive heart failure, coronary heart disease, and sudden cardiac death. Left ventricular hypertrophy represents both a manifestation of the effects of hypertension and other CV risk factors over time as well as an intrinsic condition causing pathologic changes in the CV structure and function. We review the risk factors for LVH and its consequences, concentric remodeling, and its prognostic significance, clinical benefits and supporting evidence for LVH regression, and its implications for management. We conclude our review summarizing the various pharmacological and nonpharmacological therapeutic options approved for the treatment of hypertension and LVH regression and the supporting clinical trial data for these therapeutic strategies.

Susceptibility to systolic dysfunction in the myocardium from chronically infarcted spontaneously hypertensive rats

We explored whether the hypertensive heart is susceptible to myocardial dysfunction in viable noninfarcted tissue post-myocardial infarction (MI), the potential mechanisms thereof, and the impact of these changes on pump function. Six to seven months after the ligation of the left anterior descending coronary artery, left ventricular (LV) myocardial systolic function, as assessed from the percent shortening of the noninfarcted lateral wall segmental length determined over a range of filling pressures (ultrasonic transducers placed in the lateral wall in anaesthetized, open-chest, ventilated rats) and the percent thickening of the posterior wall (echocardiography), was reduced in infarcted spontaneous hypertensive rats (SHR-MI) ( P < 0.05) but not in normotensive Wistar-Kyoto (WKY-MI) animals compared with corresponding controls [SHR-sham operations (Sham) and WKY-Sham]. This change in the regional myocardial function in SHR-MI, but not in WKY-MI, occurred despite a similar degree of LV dilatation (increased LV end-diastolic dimensions and volume intercept of the LV end-diastolic pressure-volume relation) in SHR-MI and WKY-MI rats and a lack of difference in LV relative wall thinning, LV wall stress, apoptosis [terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling (TUNEL)], or necrosis (pathological score) between SHR-MI and WKY-MI rats. Although the change in regional myocardial function in the SHR-MI group was not associated with a greater reduction in baseline global LV chamber systolic function [end-systolic elastance (LV Ees) and endocardial fractional shortening determined in the absence of an adrenergic stimulus], in the presence of an isoproterenol challenge, noninfarct-zone LV systolic myocardial dysfunction manifested in a significant reduction in LV Ees in SHR-MI compared with WKY-MI and SHR and WKY-Sham rats ( P < 0.04). In conclusion, these data suggest that with chronic MI, the hypertensive heart is susceptible to the development of myocardial dysfunction, a change that cannot be attributed to excessive chamber dilatation, apoptosis, or necrosis, but which in turn contributes toward a reduced cardiac adrenergic inotropic reserve.

Effect of antecedent hypertension and follow-up blood pressure on outcomes after high-risk myocardial infarction

The influence of blood pressure on outcomes after high-risk myocardial infarction is not well characterized. We studied the relationship between blood pressure and the risk of cardiovascular events in 14 703 patients with heart failure, left ventricular systolic dysfunction, or both after acute myocardial infarction in the Valsartan in Myocardial Infarction Trial. We assessed the relationship between antecedent hypertension and outcomes and the association between elevated (systolic: >140 mm Hg) or low blood pressure (systolic: <100 mm Hg) in 2 of 3 follow-up visits during the first 6 months and subsequent cardiovascular events over a median 24.7 months of follow-up. Antecedent hypertension independently increased the risk of heart failure (hazard ratio [HR]: 1.19; 95% CI: 1.08 to 1.32), stroke (HR: 1.27; 95% CI: 1.02 to 1.58), cardiovascular death (HR: 1.11; 95% CI: 1.01 to 1.22), and the composite of death, myocardial infarction, heart failure, stroke, or cardiac arrest (HR: 1.13; 95% CI: 1.06 to 1.21). While low blood pressure in the postmyocardial infarction period was associated with increased risk of adverse events, patients with elevated blood pressure (n=1226) were at significantly higher risk of stroke (adjusted HR: 1.64; 95% CI: 1.17 to 2.29) and combined cardiovascular events (adjusted HR: 1.14; 95% CI: 1.00 to 1.31). Six months after a high-risk myocardial infarction, elevated systolic blood pressure, a potentially modifiable risk factor, is associated with an increased risk of subsequent stroke and cardiovascular events. Whether aggressive antihypertensive treatment can reduce this risk remains unknown.

Heart failure and left ventricular remodeling after reperfused acute myocardial infarction in patients with hypertension

In the thrombolytic era, hypertension has been shown to adversely affect the development of heart failure after acute myocardial infarction (AMI). We sought to examine the relation between antecedent hypertension and heart failure after mechanical reperfusion and to test the impact of postinfarction left ventricular remodeling on heart failure in hypertensive patients. A series of 953 patients (324 hypertensives) with AMI treated with successful primary percutaneous coronary intervention underwent a 5-year follow-up. A subgroup of 325 subjects underwent 2D echocardiography at admission, 1 month, and 6 months. From day 1 to 6 months, despite similar improvement in regional and global left ventricular function and similar 6-month infarct artery patency rate, left ventricular end-diastolic volume increased in the normotensives (122+/-36 mL to 131+/-47 mL; P<0.001) but not in the hypertensives (127+/-41 mL to 128+/-31 mL; P=0.768). At 6 months, the incidence of left ventricular remodeling in hypertensive and normotensive patients was not different (22% versus 28%; P=0.210). However, at 5 years, the incidences of hospitalization for heart failure (7% versus 3%; P=0.014) and of New York Heart Association functional class > or =2 (53% versus 40%; P<0.001) were higher in hypertensive as compared with normotensive patients. Hypertension was found to be a predictor of heart failure (hazard ratio, 2.23; P=0.015). In conclusion, patients with antecedent hypertension are at higher risk to develop heart failure after AMI, even when successfully reperfused by primary percutaneous coronary intervention. However, the increased incidence of heart failure in hypertensive patients is not associated with a greater propensity to postinfarction left ventricular remodeling.

Effect of antecedent systemic hypertension on subsequent left ventricular dilation after acute myocardial infarction (from the Survival and Ventricular Enlargement trial)

Whether antecedent systemic hypertension influences the risk of subsequent left ventricular (LV) dilation in patients after an acute myocardial infarction with LV systolic dysfunction is unclear. We assessed echocardiographic evidence of ventricular remodeling from baseline (mean +/- SD 11 +/- 3 days) to 2 years after an acute myocardial infarction in 122 hypertensive (defined as a history of treated hypertension, baseline systolic blood pressure > or =140 or baseline diastolic blood pressure > or =90 mm Hg) and 334 nonhypertensive patients in the Survival and Ventricular Enlargement echocardiographic substudy. Compared with nonhypertensives, baseline heart size, defined as the sum of the average short- and long-axis LV cavity areas, was similar (70.1 +/- 11.9 vs 68.8 +/- 11.2 cm(2), p = 0.33 at end-diastole; 50.1 +/- 11.3 vs 48.8 +/- 10.8 cm(2), p = 0.31 at end-systole), but short-axis LV myocardial area (24.7 +/- 4.3 vs 25.7 +/- 5.0 cm(2), p = 0.043) and wall thickness (1.15 +/- 0.16 vs 1.21 +/- 0.17 cm, p = 0.004) at end-diastole were greater among hypertensives. The myocardial infarct segment lengths were similar in the 2 groups (p = 0.22). Although LV cavity areas increased significantly in the 2 groups from baseline to 2 years (p < or =0.001), the increase was significantly greater in hypertensives than in nonhypertensives (+5.6 +/- 11.5 vs +2.2 +/- 10.7 cm(2), p = 0.005 at end-diastole; +6.23 +/- 12.75 vs +2.94 +/- 11.4 cm(2), p = 0.012 at end-systole). There was no concomitant difference in the change in LV myocardial area or LV wall thickness between the 2 groups (p >0.30). After adjusting for known confounders, antecedent hypertension was associated with a doubling of the risk of LV dilation (50.8% vs 37.7%, odds ratio 2.09, 95% confidence interval 1.27 to 3.45, p = 0.004). This association was not modified by diabetes mellitus, myocardial infarct segment length, or captopril use (all p values for interaction >0.10). We conclude that antecedent hypertension is associated with subsequent LV dilation in patients after acute myocardial infarction with LV systolic dysfunction.