Longitudinal Strain Patterns in Stress (Takotsubo) Cardiomyopathy: Evidence of Global Myocardial Injury and Incomplete Recovery

Stress cardiomyopathy develops after abrupt sympathetic stimulation, likely from catecholamine-induced myocardial toxicity. The evolution of myocardial strain during and after an episode have not been previously characterized. We aimed to determine whether preexisting contractile abnormalities may explain the observed regional dysfunction during an acute episode and to investigate the persistence of strain abnormalities after clinical recovery. We identified patients who were diagnosed with stress cardiomyopathy and had an echocardiogram performed before their episode, during their episode, and within 1 year after. The diagnosis was confirmed based on the absence of obstructive coronary lesions. Left ventricular (LV) longitudinal strain was calculated using speckle-tracking software and compared between baseline, episode, and follow-up echocardiograms. The LV strain analysis was performed on 23 patients. The LV ejection fraction was 64 ± 8.7% at baseline, 45 ± 12% during the episode, and 5 9 ± 10% after a median follow-up of 46 days. The LV global longitudinal strain was 24 ± 4.7% at baseline, 11 ± 4.9% during the episode, and 19 ± 4.6% after the follow-up. The mean ejection fraction (p <0.01) and global longitudinal strain (p <0.001) remained below baseline levels at follow-up. Longitudinal strain was reduced (<18%) in 80 ± 23% of myocardial segments during an episode and 41 ± 21% of myocardial segments at follow-up. During the acute episode, 35 ± 6% of the abnormal segments were in the base, outside of the region of ballooning. Our findings suggests that stress cardiomyopathy is associated with global rather than regional myocardial injury and that contractile abnormalities persist after clinical improvement. These findings challenge our previous understanding of stress cardiomyopathy and may guide future pathophysiologic understanding of this complex disease.

Global Longitudinal Strain as Predictor of Inducible Ischemia in No Obstructive Coronary Artery Disease in the CIAO-ISCHEMIA Study

BACKGROUND

Global longitudinal strain (GLS) is a sensitive marker for identifying subclinical myocardial dysfunction in obstructive coronary artery disease (CAD). Little is known about the relationship between GLS and ischemia in patients with myocardial ischemia and no obstructive CAD (INOCA).

OBJECTIVES

To investigate the relationship between resting GLS and ischemia on stress echocardiography (SE) in patients with INOCA.

METHODS

Left ventricular GLS was calculated offline on resting SE images at enrollment (n = 144) and 1-year follow-up (n = 120) in the CIAO-ISCHEMIA (Changes in Ischemia and Angina over One year in International Study of Comparative Health Effectiveness with Medical and Invasive Approaches trial screen failures with no obstructive CAD on computed tomography [CT] angiography) study, which enrolled participants with moderate or severe ischemia by local SE interpretation (≥3 segments with new or worsening wall motion abnormality and no obstructive (<50% stenosis) on coronary computed tomography angiography.

RESULTS

Global longitudinal strain values were normal in 83.3% at enrollment and 94.2% at follow-up. Global longitudinal strain values were not associated with a positive SE at enrollment (GLS = -21.5% positive SE vs GLS = -19.9% negative SE, P = .443) or follow-up (GLS = -23.2% positive SE vs GLS = -23.1% negative SE, P = .859). Significant change in GLS was not associated with positive SE in follow-up (P = .401). Regional strain was not associated with colocalizing ischemia at enrollment or follow-up. Changes in GLS and number of ischemic segments from enrollment to follow-up showed a modest but not clinically meaningful correlation (β = 0.41; 95% CI, 0.16, 0.67; P = .002).

CONCLUSIONS

In this cohort of INOCA patients, resting GLS values were largely normal and did not associate with the presence, severity, or location of stress-induced ischemia. These findings may suggest the absence of subclinical myocardial dysfunction detectable by echocardiographic strain analysis at rest in INOCA.

Exercise Ventricular Reserve Among Women With a History of Peripartum Cardiomyopathy

Peripartum cardiomyopathy (PPCM) is associated with highly variable clinical outcomes. Small series suggest postpartum variation in exercise capacity and ventricular reserve. We describe limitations in exercise capacity and/or ventricular reserve in asymptomatic women who had recovered from PPCM and underwent a detailed physiologic assessment by cardiopulmonary exercise testing. (Level of Difficulty: Intermediate.)

Echocardiography for the Pregnant Heart

Purpose of review

Pregnancy is associated with significant hemodynamic changes, making it a potentially high-risk period for women with underlying cardiovascular disease. Echocardiography remains the preferred modality for diagnosis and monitoring of pregnant women with cardiovascular disease as it is widely available and does not require radiation. This paper reviews the role of echocardiography along the continuum of pregnancy in at-risk patients, with a focus on key cardiac disease states in pregnancy.

Recent findings

In the preconception stage, risk stratification scores such as CARPREG II, ZAHARA and the modified WHO remain central to counseling and planning. As such, echocardiography serves an important role in assessing the severity of pre-existing structural disease. Among women with pre-existing cardiovascular disease who become pregnant-as well as those who develop cardiovascular symptoms during pregnancy-echocardiography is a key imaging tool for assessment of hemodynamic and structural changes and is recommended as the first-line imaging modality when appropriate by both the American College of Obstetricians and Gynecologists (ACOG) and the Food and Drug Administration (FDA). However, routine screening intervals during pregnancy for various cardiac lesions are not well defined, resulting in clinical heterogeneity in care.

Summary

Echocardiography is the imaging modality of choice for defining, risk stratifying, and monitoring cardiovascular changes throughout pregnancy. Once identified, at-risk patients should receive careful individual counseling and follow-up with a multidisciplinary team. Echocardiography serves as a widely available tool for serial monitoring of pregnant women with cardiovascular disease throughout pregnancy and the postpartum period.

Neonatal Micro-RNA Profile Determines Endothelial Function in Offspring of Hypertensive Pregnancies

Offspring of hypertensive pregnancies are at increased risk of developing hypertension in adulthood. In the neonatal period they display endothelial cell dysfunction and altered microvascular development. MicroRNAs, as important endothelial cellular regulators, may play a role in this early endothelial dysfunction. Therefore we identified differential microRNA patterns in endothelial cells from offspring of hypertensive pregnancies and determined their role in postnatal vascular cell function. Studies were performed on human umbilical vein endothelial cell (HUVECs) samples from 57 pregnancies. Unbiased RNA-sequencing identified 30 endothelial-related microRNAs differentially expressed in HUVECs from hypertensive compared to normotensive pregnancies. Quantitative reverse transcription PCR (RT-qPCR) confirmed a significant higher expression level of the top candidate, miR-146a. Combined miR-146a targeted gene expression and pathway analysis revealed significant alterations in genes involved in inflammation, angiogenesis and immune response in the same HUVECs. Elevated miR-146a expression level at birth identified cells with reduced ability for in vitro vascular tube formation, which was rescued by miR-146a inhibition. In contrast, miR-146a overexpression significantly reduced vascular tube formation in HUVECs from normotensive pregnancies. Finally, we confirmed that mir146a levels at birth predicted in vivo microvascular development during the first three postnatal months. Offspring of hypertensive pregnancy have a distinct endothelial regulatory microRNA profile at birth, which is related to altered endothelial cell behaviour, and predicts patterns of microvascular development during the first three months of life. Modification of this microRNA profile in vitro can restore impaired vascular cell function.

Association of Maternal Antiangiogenic Profile at Birth With Early Postnatal Loss of Microvascular Density in Offspring of Hypertensive Pregnancies

Offspring of hypertensive pregnancies are more likely to have microvascular rarefaction and increased blood pressure in later life. We tested the hypothesis that maternal angiogenic profile during a hypertensive pregnancy is associated with fetal vasculogenic capacity and abnormal postnatal microvascular remodeling. Infants (n=255) born after either hypertensive or normotensive pregnancies were recruited for quantification of postnatal dermal microvascular structure at birth and 3 months of age. Vasculogenic cell potential was assessed in umbilical vein endothelial cells from 55 offspring based on in vitro microvessel tube formation and proliferation assays. Maternal angiogenic profile (soluble fms-like tyrosine kinase-1, soluble endoglin, vascular endothelial growth factor, and placental growth factor) was measured from postpartum plasma samples to characterize severity of pregnancy disorder. At birth, offspring born after hypertensive pregnancy had similar microvessel density to those born after a normotensive pregnancy, but during the first 3 postnatal months, they had an almost 2-fold greater reduction in total vessel density (-17.7±16.4% versus -9.9±18.7%; P=0.002). This postnatal loss varied according to the vasculogenic capacity of the endothelial cells of the infant at birth (r=0.49; P=0.02). The degree of reduction in both in vitro and postnatal in vivo vascular development was proportional to levels of antiangiogenic factors in the maternal circulation. In conclusion, our data indicate that offspring born to hypertensive pregnancies have reduced vasculogenic capacity at birth that predicts microvessel density loss over the first 3 postnatal months. Degree of postnatal microvessel reduction is proportional to levels of antiangiogenic factors in the maternal circulation at birth.

Clinical cardiovascular risk during young adulthood in offspring of hypertensive pregnancies: insights from a 20-year prospective follow-up birth cohort

OBJECTIVES

Offspring of hypertensive pregnancies have increased cardiovascular risk factors during childhood. We hypothesised that offspring of hypertensive pregnancies would demonstrate increased clinical levels of hypertension by young adult life, which would be proportional to the severity of the pregnancy complication.

DESIGN

Prospective birth cohort study

SETTING

Tertiary obstetric hospital.

PARTICIPANTS

2868 young adult offspring of women enrolled during pregnancy into the Western Australia Pregnancy Cohort (Raine) Study.

MAIN OUTCOME MEASURES

Cardiovascular risk, including incidence of hypertension and metabolic disease, in those born to hypertensive compared to normotensive pregnancies.

RESULTS

Young adult offspring of hypertensive pregnancies were 2.5 times (95% CI 1.32 to 4.56, p=0.004) more likely to have global lifetime risk (QRISK) scores above the 75th centile. Thirty per cent of 20 year olds with hypertensive blood pressures were born following a hypertensive pregnancy. Pre-eclampsia or hypertension resulting in preterm birth associated with a threefold (95% CI 1.3 to 7.0, p=0.01) greater risk of being hypertensive by age 20 years, with no differences in body mass index. Whereas pregnancy-induced hypertension associated with a smaller 3 ± 1 mm Hg blood pressure rise (p=0.001) and a twofold (95% CI 1.5 to 2.8, p=0.001) greater risk of being obese or overweight. Risk factor associations were consistent throughout early life and independent of other birth-factors.

CONCLUSIONS

Incidence of offspring hypertension was significantly increased in those whose mothers had a more complicated pregnancy history, including preterm birth and pre-eclampsia.

Elevated blood pressure in preterm-born offspring associates with a distinct antiangiogenic state and microvascular abnormalities in adult life

Preterm-born individuals have elevated blood pressure. We tested the hypothesis that this associates with an enhanced antiangiogenic circulating profile and that this association is mediated by variations in capillary density. We studied 204 adults aged 25 years (range, 20-30 years), of which 102 had been followed up prospectively since very preterm birth (mean gestational age, 30.3±2.5 weeks) and 102 were born term to uncomplicated pregnancies. A panel of circulating biomarkers, including soluble endoglin and soluble fms-like tyrosine kinase-1, were compared between groups and related to perinatal history and adult cardiovascular risk. Associations with cardiovascular phenotype were studied in 90 individuals who had undergone detailed assessment of microvascular, macrovascular, and cardiac structure and function. Preterm-born individuals had elevations in soluble endoglin (5.64±1.03 versus 4.06±0.85 ng/mL; P<0.001) and soluble fms-like tyrosine kinase-1 (88.1±19.0 versus 73.0±15.3 pg/mL; P<0.001) compared with term-born individuals, proportional to elevations in resting and ambulatory blood pressure, as well as degree of prematurity (P<0.05). Maternal hypertensive pregnancy disorder was associated with additional increases in soluble fms-like tyrosine kinase-1 (P=0.002). Other circulating biomarkers, including those of inflammation and endothelial activation, were not related to blood pressure. There was a specific graded association between soluble endoglin and degree of functional and structural capillary rarefaction (P=0.002 and P<0.001), and in multivariable analysis, there were capillary density-mediated associations between soluble endoglin and blood pressure. Preterm-born individuals exhibit an enhanced antiangiogenic state in adult life that is specifically related to elevations in blood pressure. The association seems to be mediated through capillary rarefaction and is independent of other cardiovascular structural and functional differences in the offspring.

Right ventricular systolic dysfunction in young adults born preterm

BACKGROUND

Young adults born preterm have distinct differences in left ventricular mass, function, and geometry. Animal studies suggest that cardiomyocyte changes are evident in both ventricles after preterm birth; therefore, we investigated whether these young adults also have differences in their right ventricular structure and function.

METHODS AND RESULTS

We studied 102 preterm-born young adults followed up prospectively since birth and 132 term-born control subjects born to uncomplicated pregnancies. We quantified right ventricular structure and function by cardiovascular magnetic resonance on a 1.5-T Siemens scanner using Argus and TomTec postprocessing software. Preterm birth was associated with a small right ventricle (end diastolic volume, 79.8±13.2 versus 88.5±11.8 mL/m(2); P<0.001) but greater right ventricular mass (24.5±3.5 versus 20.4±3.4 g/m2; P<0.001) compared with term-born controls, with the severity of differences proportional to gestational age (r=-0.47, P<0.001). Differences in right ventricular mass and function were proportionally greater than previously reported for the left ventricle. This was most apparent for systolic function; young adults born preterm had significantly lower right ventricular ejection fraction (57±8% versus 60±5%; P=0.006). Indeed, 21% had values below the lower limit observed in the term-born adults and 6% had mild systolic dysfunction (<45%). Postnatal ventilation accounted for some of the variation in mass but not function.

CONCLUSIONS

Preterm birth is associated with global myocardial structural and functional differences in adult life, including smaller right ventricular size and greater mass. The changes are greater in the right ventricle than previously observed in the left ventricle, with potentially clinically significant impairment in right ventricular systolic function.

Dynamic release and clearance of circulating microparticles during cardiac stress

RATIONALE

Microparticles are cell-derived membrane vesicles, relevant to a range of biological responses and known to be elevated in cardiovascular disease.

OBJECTIVE

To investigate microparticle release during cardiac stress and how this response differs in those with vascular disease.

METHODS AND RESULTS

We measured a comprehensive panel of circulating cell-derived microparticles by a standardized flow cytometric protocol in 119 patients referred for stress echocardiography. Procoagulant, platelet, erythrocyte, and endothelial but not leukocyte, granulocyte, or monocyte-derived microparticles were elevated immediately after a standardized dobutamine stress echocardiogram and decreased after 1 hour. Twenty-five patients developed stress-induced wall motion abnormalities suggestive of myocardial ischemia. They had similar baseline microparticle levels to those who did not develop ischemia, but, interestingly, their microparticle levels did not change during stress. Furthermore, no stress-induced increase was observed in those without inducible ischemia but with a history of vascular disease. Fourteen patients subsequently underwent coronary angiography. A microparticle rise during stress echocardiography had occurred only in those with normal coronary arteries.

CONCLUSIONS

Procoagulant, platelet, erythrocyte, and endothelial microparticles are released during cardiac stress and then clear from the circulation during the next hour. This stress-induced rise seems to be a normal physiological response that is diminished in those with vascular disease.

Preterm heart in adult life: cardiovascular magnetic resonance reveals distinct differences in left ventricular mass, geometry, and function

BACKGROUND

Preterm birth leads to an early switch from fetal to postnatal circulation before completion of left ventricular in utero development. In animal studies, this results in an adversely remodeled left ventricle. We determined whether preterm birth is associated with a distinct left ventricular structure and function in humans.

METHODS AND RESULTS

A total of 234 individuals 20 to 39 years of age underwent cardiovascular magnetic resonance. One hundred two had been followed prospectively since preterm birth (gestational age=30.3±2.5 week; birth weight=1.3±0.3 kg), and 132 were born at term to uncomplicated pregnancies. Longitudinal and short-axis cine images were used to quantify left ventricular mass, 3-dimensional geometric variation by creation of a unique computational cardiac atlas, and myocardial function. We then determined whether perinatal factors modify these left ventricular parameters. Individuals born preterm had increased left ventricular mass (66.5±10.9 versus 55.4±11.4 g/m(2); P<0.001) with greater prematurity associated with greater mass (r = -0.22, P=0.03). Preterm-born individuals had short left ventricles with small internal diameters and a displaced apex. Ejection fraction was preserved (P>0.99), but both longitudinal systolic (peak strain, strain rate, and velocity, P<0.001) and diastolic (peak strain rate and velocity, P<0.001) function and rotational (apical and basal peak systolic rotation rate, P =0.05 and P =0.006; net twist angle, P=0.02) movement were significantly reduced. A diagnosis of preeclampsia during the pregnancy was associated with further reductions in longitudinal peak systolic strain in the offspring (P=0.02, n=29).

CONCLUSIONS

Individuals born preterm have increased left ventricular mass in adult life. Furthermore, they exhibit a unique 3-dimensional left ventricular geometry and significant reductions in systolic and diastolic functional parameters.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01487824.

Antenatal glucocorticoid exposure and long-term alterations in aortic function and glucose metabolism

OBJECTIVE

Animal studies have demonstrated long-term effects of in utero glucocortcoid exposure on vascular development and glucose metabolism. We hypothesized that there would be a similar impact in humans.

METHODS

One hundred and two young adults born preterm aged 23 to 28 years, with prospective data collection from birth, and 95 adults born term after uncomplicated pregnancies underwent cardiovascular MRI. We compared cardiac and aortic structure and function, as well as cardiovascular risk profile, in a nested case-control study of 16 participants exposed to antenatal steroids and 32 who were not, but with otherwise similar perinatal care. Outcomes were compared with normal ranges in those born term.

RESULTS

Adults whose mothers had received antenatal steroids had decreased ascending aortic distensibility (9.88 ± 3.21 vs 13.62 ± 3.88 mm Hg(-1) × 10(3), P = .002) and increased aortic arch pulse wave velocity (5.45 ± 1.41 vs 4.47 ± 0.91 m/s, P = .006). The increase in stiffness was equivalent to that of term adults a decade older. Those who had in utero exposure to antenatal steroids also had significant differences in homeostatic model assessments for β-cell function (P = .010), but in multiple regression analysis this did not explain the impact of steroids on aortic function.

CONCLUSIONS

Antenatal glucocorticoid exposure in preterm infants is associated with increased aortic arch stiffness and altered glucose metabolism in early adulthood.

From gene to epigene-based therapies targeting the vascular endothelium

Vascular endothelial dysfunction is a key biological process underlying the development of cardiovascular disease and therefore of potential importance as a target for gene-based therapy. Modification of nitric oxide bioavailability through gene therapy is possible in animal studies and of clinical relevance because of the central role for nitric oxide in vascular homeostasis. However, most clinical trials have so far focused on endothelial-related pathways, in particular, vascular endothelial growth factor, to induce angiogenesis, with variable results. The slow progress of the development of gene-therapy targeted at the endothelium relates to a range of complexities of design of therapy including mode of gene delivery. This is usually achieved through the use of viral or non-viral vectors but the best physical and vector methods for delivery of complimentary DNA to the vascular endothelium remains under investigation. More recently there has been emerging interest into other genome-based methods to alter vascular phenotype, in particular, gene-based modification of endothelial progenitor cell function and whether gene function might be modifiable through induced epigenetic changes.

Prevention of vascular dysfunction after preeclampsia: a potential long-term outcome measure and an emerging goal for treatment

Preeclampsia is increasingly being recognised as more than an isolated disease of pregnancy. In particular, preeclampsia has emerged as an independent risk factor for maternal cardiovascular disease and has recently been recognised as a risk factor for cardiovascular disease in children exposed in utero. Preeclampsia and cardiovascular disease may share important pathophysiological and molecular mechanisms and further investigation into these is likely to offer insight into the origins of both conditions. This paper considers the links between cardiovascular disease and preeclampsia and the implication of these findings for refinement of the management of patients whose care is complicated by preeclampsia.

Characterization of c-Ki-ras and N-ras oncogenes in aflatoxin B1-induced rat liver tumors

c-Ki-ras and N-ras oncogenes have been characterized in aflatoxin B1-induced hepatocellular carcinomas. Detection of different protooncogene and oncogene sequences and estimation of their frequency distribution were accomplished by polymerase chain reaction, cloning, and plaque screening methods. Two c-Ki-ras oncogene sequences were identified in DNA from liver tumors that contained nucleotide changes absent in DNA from livers of untreated control rats. Sequence changes involving G.C to T.A or G.C to A.T nucleotide substitutions in codon 12 were scored in three of eight tumor-bearing animals. Distributions of c-Ki-ras sequences in tumors and normal liver DNA indicated that the observed nucleotide changes were consistent with those expected to result from direct mutagenesis of the germ-line protooncogene by aflatoxin B1. N-ras oncogene sequences were identified in DNA from two of eight tumors. Three N-ras gene regions were identified, one of which was shown to be associated with an oncogene containing a putative activating amino acid residing at codon 13. All three N-ras sequences, including the region detected in N-ras oncogenes, were present at similar frequencies in DNA samples from control livers as well as liver tumors. The presence of a potential germ-line oncogene may be related to the sensitivity of the Fischer rat strain to liver carcinogenesis by aflatoxin B1 and other chemical carcinogens.

Creation of a test plasmid for detecting G-C-to-T-A transversions by changing serine to arginine in the active site of beta-lactamase

Oligonucleotide-directed mutagenesis of the beta-lactamase gene, bla, on pBR322 was used to change the codon for the active-site serine 70, AGC, to CGC, coding for arginine. Escherichia coli cells carrying the mutant plasmid, pGD104, were sensitive to ampicillin, indicating that the arginine-containing enzyme is inactive. We characterized the reversion of the mutant bla gene by a number of mutagens and in different genetic backgrounds and demonstrated that full ampicillin resistance can be restored only by a G-C-to-T-A transversion occurring at the first base of the codon. Thus, reversion of the mutant bla gene is diagnostic for G-C-to-T-A transversions, and bacteria carrying pGD104 can be used as test strains to detect the occurrence of this mutation.

Loss of an apurinic/apyrimidinic site endonuclease increases the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine to Escherichia coli

xthA- Escherichia coli, which are missing a major cellular apurinic/apyrimidinic (AP) endonuclease, are 5- to 10-fold more sensitive than xthA+ bacteria to mutagenesis by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) under conditions that induce the "adaptive response." The xthA(-)-dependent mutations are also dependent on SOS mutagenic processing and consist of both transversion and transition base substitutions. When MNNG-adapted xthA- bacteria are challenged with a high dose of MNNG, more xthA(-)-dependent SOS-dependent mutations are induced, and transversions are enhanced relative to transitions. The mutations induced by challenge are eliminated in xthA- alkA- bacteria, which are also deficient for 3-methyladenine glycosylase II activity. These data are consistent with the hypothesis that AP sites, at least some of which are produced by glycosylase activity, are mutagenic intermediates following cellular DNA alkylation.