lncExACT1 and DCHS2 Regulate Physiological and Pathological Cardiac Growth.

BACKGROUND: The heart grows in response to pathological and physiological stimuli. The former often precedes cardiomyocyte loss and heart failure; the latter paradoxically protects the heart and enhances cardiomyogenesis. The mechanisms underlying these differences remain incompletely understood. Although long noncoding RNAs (lncRNAs) are important in cardiac development and disease, less is known about their roles in physiological hypertrophy or cardiomyogenesis. METHODS: RNA sequencing was applied to hearts from mice after 8 weeks of voluntary exercise-induced physiological hypertrophy and cardiomyogenesis or transverse aortic constriction for 2 or 8 weeks to induce pathological hypertrophy or heart failure. The top lncRNA candidate was overexpressed in hearts with adeno-associated virus vectors and inhibited with antisense locked nucleic acid-GapmeRs to examine its function. Downstream effectors were identified through promoter analyses and binding assays. The functional roles of a novel downstream effector, dachsous cadherin-related 2 (DCHS2), were examined through transgenic overexpression in zebrafish and cardiac-specific deletion in Cas9-knockin mice. RESULTS: We identified exercise-regulated cardiac lncRNAs, called lncExACTs. lncExACT1 was evolutionarily conserved and decreased in exercised hearts but increased in human and experimental heart failure. Cardiac lncExACT1 overexpression caused pathological hypertrophy and heart failure; lncExACT1 inhibition induced physiological hypertrophy and cardiomyogenesis, protecting against cardiac fibrosis and dysfunction. lncExACT1 functioned by regulating microRNA-222, calcineurin signaling, and Hippo/Yap1 signaling through DCHS2. Cardiomyocyte DCHS2 overexpression in zebrafish induced pathological hypertrophy and impaired cardiac regeneration, promoting scarring after injury. In contrast, murine DCHS2 deletion induced physiological hypertrophy and promoted cardiomyogenesis. CONCLUSIONS: These studies identify lncExACT1-DCHS2 as a novel pathway regulating cardiac hypertrophy and cardiomyogenesis. lncExACT1-DCHS2 acts as a master switch toggling the heart between physiological and pathological growth to determine functional outcomes, providing a potentially tractable therapeutic target for harnessing the beneficial effects of exercise.

Prognostic role of GDF-15 across the spectrum of clinical risk in patients with NSTE-ACS.

Background Growth differentiation factor (GDF)-15 has been shown to predict cardiovascular (CV) outcomes in acute coronary syndrome (ACS) using non-commercial assays. We evaluated the prognostic performance of GDF-15 measured with the first clinically available assay. Furthermore, we evaluated whether GDF-15 was associated with CV death or heart failure (HF) across the spectrum of risk in non-ST-segment elevation (NSTE)-ACS. Methods We measured baseline GDF-15 (Roche, Elecsys) in 4330 patients with NSTE-ACS enrolled in MERLIN-TIMI 36. Patients were categorized using a priori thresholds of GDF-15 levels (<1200, 1200-1800, ≥1800 ng/L) and stratified according to estimated clinical risk per TIMI risk score (0-2, 3-4, and ≥5). Cox modeling included age, sex, BMI, smoking, HF, diabetes, renal function, NT-proBNP, hsTnT, and hsCRP. Results There were 2286 (53%), 1104 (25%), and 940 (22%) pts with GDF-15 <1200, 1200-1800, and ≥1800 respectively. GDF-15 was significantly associated after multivariable adjustment with CV death/HF modeled either as a categorical (1200-1800 ng/L: Adj hazard ratios [HR] 1.55 [1.09-2.19]; ≥1800 ng/L: Adj HR 1.94 [1.34-2.79]) or continuous variable (Adj HR 1.36 [1.16-1.60] per 1-unit increase in log2-transformed GDF-15). Notably, there was an interaction (Pinteraction=0.003) between TIMI risk score and GDF-15, with GDF-15 identifying the greatest incremental relative risk in those at lowest risk based on the TIMI risk score alone. Conclusions Using a clinically available assay, GDF-15 can be applied using established cut-off points to independently predict risk of CV death/HF in patients with NSTE-ACS. This incremental risk appears to be particularly robust among individuals traditionally identified as low risk.

Improvement in Outcomes After Cardiac Arrest and Resuscitation by Inhibition of S-Nitrosoglutathione Reductase.

BACKGROUND: The biological effects of nitric oxide are mediated via protein S-nitrosylation. Levels of S-nitrosylated protein are controlled in part by the denitrosylase, S-nitrosoglutathione reductase (GSNOR). The objective of this study was to examine whether GSNOR inhibition improves outcomes after cardiac arrest and cardiopulmonary resuscitation (CA/CPR). METHODS: Adult wild-type C57BL/6 and GSNOR-deleted (GSNOR-/-) mice were subjected to potassium chloride-induced CA and subsequently resuscitated. Fifteen minutes after a return of spontaneous circulation, wild-type mice were randomized to receive the GSNOR inhibitor, SPL-334.1, or normal saline as placebo. Mortality, neurological outcome, GSNOR activity, and levels of S-nitrosylated proteins were evaluated. Plasma GSNOR activity was measured in plasma samples obtained from post-CA patients, preoperative cardiac surgery patients, and healthy volunteers. RESULTS: GSNOR activity was increased in plasma and multiple organs of mice, including brain in particular. Levels of protein S-nitrosylation were decreased in the brain 6 hours after CA/CPR. Administration of SPL-334.1 attenuated the increase in GSNOR activity in brain, heart, liver, spleen, and plasma, and restored S-nitrosylated protein levels in the brain. Inhibition of GSNOR attenuated ischemic brain injury and improved survival in wild-type mice after CA/CPR (81.8% in SPL-334.1 versus 36.4% in placebo; log rank P=0.031). Similarly, GSNOR deletion prevented the reduction in the number of S-nitrosylated proteins in the brain, mitigated brain injury, and improved neurological recovery and survival after CA/CPR. Both GSNOR inhibition and deletion attenuated CA/CPR-induced disruption of blood brain barrier. Post-CA patients had higher plasma GSNOR activity than did preoperative cardiac surgery patients or healthy volunteers ( P<0.0001). Plasma GSNOR activity was positively correlated with initial lactate levels in postarrest patients (Spearman correlation coefficient=0.48; P=0.045). CONCLUSIONS: CA and CPR activated GSNOR and reduced the number of S-nitrosylated proteins in the brain. Pharmacological inhibition or genetic deletion of GSNOR prevented ischemic brain injury and improved survival rates by restoring S-nitrosylated protein levels in the brain after CA/CPR in mice. Our observations suggest that GSNOR is a novel biomarker of postarrest brain injury as well as a molecular target to improve outcomes after CA.

DECLARE-TIMI 58: Participants' baseline characteristics.

AIM: To describe the baseline characteristics of participants randomized in the Dapagliflozin Effect on CardiovascuLAR Events (DECLARE-TIMI 58) trial, the pivotal study conducted to assess cardiovascular (CV) outcomes with dapagliflozin. METHODS: The DECLARE-TIMI 58 trial will analyse 17 160 patients with type 2 diabetes randomized to treatment with dapagliflozin (10 mg/d) or matching placebo. We analysed their baseline characteristics. RESULTS: The participants' mean ± SD age was 63.8 ± 6.8 years, 62.6% were male, and their mean ± SD diabetes duration was 11.8 ± 7.8 years, glycated haemoglobin 8.3% ± 1.2% (67 mmol/mol ± 9.7 mmol/mol) and body mass index 32.1 ± 6.0 kg/m2 . Randomization included 6971 (40.6%) patients with atherosclerotic CV disease (CVD), and 10 189 (59.4%) patients with multiple risk factors (MRF) for CVD (defined as men age ≥ 55 years or women ≥60 years, with at least one of dyslipidaemia, hypertension or smoking). Patients with CVD compared with patients with MRF were younger (62.5 ± 8.1 vs 64.7 ± 5.6 years), more frequently male (72.1% vs 56.1%), less often used metformin (74.6% vs 81.2%), more often used insulin (44.2% vs 36.4%), and more frequently used statins, aspirin, clopidogrel and ß-blockers (82.2%, 71.1%, 24.7% and 66.6% vs 63.7%, 39.1%, 1.5% and 32.3%, respectively). CONCLUSION: The DECLARE-TIMI 58 trial is expected to provide conclusive data on the effect of treatment with dapagliflozin in addition to standard of care, on CV outcomes in a broad patient population with type 2 diabetes and CVD or MRF for CVD.

Predictors of Long-Term Healthy Arterial Aging: Coronary Artery Calcium Nondevelopment in the MESA Study.

OBJECTIVES: This study sought to determine the predictors of healthy arterial aging. BACKGROUND: Long-term nondevelopment of coronary artery calcification (persistent CAC = 0) is a marker of healthy arterial aging. The predictors of this phenotype are not known. METHODS: We analyzed 1,850 participants from MESA (Multi-Ethnic Study of Atherosclerosis) with baseline CAC = 0 who underwent a follow-up CAC scan at visit 5 (median 9.6 years after baseline). We examined the proportion with persistent CAC = 0 and calculated multivariable relative risks and area under the receiver operating characteristic curve for prediction of this healthy arterial aging phenotype. RESULTS: We found that 55% of participants (n = 1,000) had persistent CAC = 0, and these individuals were significantly more likely to be younger, female, and have fewer traditional risk factors (RF). Participants with an ASCVD (Atherosclerotic Cardiovascular Disease Risk Score) risk score <2.5% were 53% more likely to have healthy arterial aging than were participants with an ASCVD score ≥7.5%. There was no significant association between the Healthy Lifestyle variables (body mass index, physical activity, Mediterranean diet, and never smoking) and persistent CAC = 0. The area under the receiver operating characteristic curve incorporating age, sex, and ethnicity was 0.65, indicating fair to poor discrimination. No single traditional RF or combination of other risk factors increased the area under the receiver operating characteristic curve by more than 0.05. CONCLUSIONS: Whereas participants free of traditional cardiovascular disease RF were significantly more likely to have persistent CAC = 0, there was no single RF or specific low-risk RF phenotype that markedly improved the discrimination of persistent CAC = 0 over demographic variables. Therefore, we conclude that healthy arterial aging may be predominantly influenced by the long-term maintenance of a low cardiovascular disease risk profile or yet to be determined genetic factors rather than the absence of any specific RF cluster identified in late adulthood.

Baseline subclinical atherosclerosis burden and distribution are associated with frequency and mode of future coronary revascularization: multi-ethnic study of atherosclerosis.

OBJECTIVES: The aim of this study was to evaluate the impact of coronary artery calcium (CAC) burden and regional distribution on the need for and type of future coronary revascularization-percutaneous versus surgical (coronary artery bypass graft [CABG])-among asymptomatic subjects. BACKGROUND: The need for coronary revascularization and the chosen mode of revascularization are thought to be functions of disease burden and anatomic distribution. The association between the baseline burden and regional distribution of CAC and the risk and type of future coronary revascularization remains unknown. METHODS: A total of 6,540 participants in the MESA (Multi-Ethnic Study of Atherosclerosis) (subjects aged 45 to 84 years, free of known baseline cardiovascular disease) with vessel-specific CAC measurements were followed for a median of 8.5 years (interquartile range: 7.7 to 8.6 years). Annualized rates and multivariate-adjusted hazard ratios for revascularization and revascularization type were analyzed according to CAC score category, number of vessels with CAC (0 to 4, including the left main coronary artery), and involvement of individual coronary arteries. RESULTS: A total of 265 revascularizations (4.2%) occurred during follow-up, and 206 (78% of the total) were preceded by adjudicated symptoms. Revascularization was uncommon when CAC score was 0.0 (0.6%), with a graded increase over both rising CAC burden and increasingly diffuse CAC distribution. The revascularization rates per 1,000 person-years for CAC scores of 1 to 100, 101 to 400, and >400 were 4.9, 11.7, and 25.4, respectively; for 1, 2, 3, and 4 vessels with CAC, the rates were 3.0, 8.0, 16.1, and 24.8, respectively. In multivariate models adjusting for CAC score, the number of vessels with CAC remained predictive of revascularization and mode of revascularization. Independent predictors of CABG versus percutaneous coronary intervention included 3- or 4-vessel CAC, higher CAC burden, and involvement of the left main coronary artery. Risk for CABG was extremely low with <3-vessel baseline CAC. Results were similar when considering only symptom-driven revascularizations. CONCLUSIONS: In this multiethnic cohort of asymptomatic subjects, baseline CAC was highly predictive of future coronary revascularization procedures, with measures of CAC burden and distribution each independently predicting need for percutaneous coronary intervention versus CABG over an 8.5-year follow-up.

Is there a role for coronary artery calcium scoring for management of asymptomatic patients at risk for coronary artery disease?: Clinical risk scores are not sufficient to define primary prevention treatment strategies among asymptomatic patients.

Although risk factors have proven to be useful therapeutic targets, they are poor predictors of risk. Traditional risk scores are moderately successful in predicting future CHD events and can be a starting place for general risk categorization. However, there is substantial heterogeneity between traditional risk and actual atherosclerosis burden, with event rates predominantly driven by burden of atherosclerosis. Serum biomarkers have yet to show any clinically significant incremental value to the FRS and even when combined cannot match the predictive value of atherosclerosis imaging. As clinicians, are we willing to base therapy decisions on risk models that lack optimum-achievable accuracy and limit personalization? The decision to treat a patient in primary prevention must be a careful one because the benefit of therapy in an asymptomatic patient must clearly outweigh the potential risk. CAC, in particular, provides a personalized assessment of risk and may identify patients who will be expected to derive the most, and the least, net absolute benefit from treatment. Emerging evidence hints that CAC may also promote long-term adherence to aspirin, exercise, diet, and statin therapy. When potentially lifelong treatment decisions are on the line, clinicians must arm their patients with the most accurate risk prediction tools, and subclinical atherosclerosis testing with CAC is, at the present time, superior to any combination of risk factors and serum biomarkers.

Impact of coronary artery calcium on coronary heart disease events in individuals at the extremes of traditional risk factor burden: the Multi-Ethnic Study of Atherosclerosis.

AIMS: We sought to evaluate the impact of coronary artery calcium (CAC) in individuals at the extremes of risk factor (RF) burden. METHODS AND RESULTS: 6698 individuals from the Multi-Ethnic Study of Atherosclerosis (MESA) were followed for coronary heart disease (CHD) events over mean 7.1 ± 1 years. Annualized CHD event rates were compared among each RF category (0, 1, 2, or ≥3) after stratification by CAC score (0, 1-100, 101-300, and >300). The following traditional modifiable RFs were considered: cigarette smoking, LDL cholesterol ≥3.4 mmol/L, low HDL cholesterol, hypertension, and diabetes. There were 1067 subjects (16%) with 0 RFs, whereas 1205 (18%) had ≥3 RFs. Among individuals with 0 RFs, 68% had CAC 0, whereas 12 and 5% had CAC >100 and >300, respectively. Among individuals with ≥3 RFs, 35% had CAC 0, whereas 34 and 19% had CAC >100 and >300, respectively. Overall, 339 (5.1%) CHD events occurred. Individuals with 0 RFs and CAC >300 had an event rate 3.5 times higher than individuals with ≥3 RFs and CAC 0 (10.9/1000 vs. 3.1/1000 person-years). Similar results were seen across categories of Framingham risk score. CONCLUSION: Among individuals at the extremes of RF burden, the distribution of CAC is heterogeneous. The presence of a high CAC burden, even among individuals without RFs, is associated with an elevated event rate, whereas the absence of CAC, even among those with many RF, is associated with a low event rate. Coronary artery calcium has the potential to further risk stratify asymptomatic individuals at the extremes of RF burden.

Utility of coronary artery calcium scoring in the evaluation of patients with chest pain.

Although coronary artery calcium (CAC) scoring has an established role in risk-stratifying asymptomatic patients at intermediate risk of coronary heart disease (CHD), its utility in the evaluation of patients with chest pain is uncertain. We conducted a literature review of articles investigating the utility of: (1) CAC scoring in elective patients with indeterminate chest pain symptoms, (2) CAC as a "gatekeeper" in the triage of patients presenting to the emergency department (ED) with chest pain, and (3) the cost-effectiveness of the use of CAC scoring in the ED. We also evaluated the predictive accuracy of the absence of CAC in a pooled analysis of applicable studies. Only studies evaluating patients classified as low or intermediate risk were included. Low to intermediate risk was established by Framingham risk scores, Thrombolysis in Myocardial Infarction scores, Diamond-Forrester classification, or by the absence of typical angina symptoms, ischemic electrocardiogram, positive cardiac biomarkers, or a prior history of CHD. In our pooled analysis, the presence of any CAC resulted in a high sensitivity (range 70%-100%) for predicting the presence of obstructive coronary disease among symptomatic patients subsequently referred for coronary angiography. More importantly, a CAC score of 0 in low- and intermediate-risk ED populations with chest pain had a high negative predictive value (99.4%) for CHD events over an average follow-up of 21 months. CAC scoring also seems cost-effective in this population. Although further research is needed, carefully selected ED patients with a normal electrocardiogram, normal cardiac biomarkers, and CAC = 0 may be considered for early discharge without further testing.