Identification of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) as the rosetting ligand of the malaria parasite P. falciparum

Severe Plasmodium falciparum malaria is characterized by excessive sequestration of infected and uninfected erythrocytes in the microvasculature of the affected organ. Rosetting, the adhesion of P. falciparum-infected erythrocytes to uninfected erythrocytes is a virulent parasite phenotype associated with the occurrence of severe malaria. Here we report on the identification by single-cell reverse transcriptase PCR and cDNA cloning of the adhesive ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1). Rosetting PfEMP1 contains clusters of glycosaminoglycan-binding motifs. A recombinant fusion protein (Duffy binding-like 1-glutathione S transferase; Duffy binding-like-1-GST) was found to adhere directly to normal erythrocytes, disrupt naturally formed rosettes, block rosette reformation, and bind to a heparin-Sepharose matrix. The adhesive interactions could be inhibited with heparan sulfate or enzymes that remove heparan sulfate from the cell surface whereas other enzymes or similar glycosaminoglycans of a like negative charge did not affect the binding. PfEMP1 is suggested to be the rosetting ligand and heparan sulfate, or a heparan sulfate-like molecule, the receptor both for PfEMP1 binding and naturally formed erythrocyte rosettes.

Outcomes in patients treated with ticagrelor or clopidogrel after acute myocardial infarction: experiences from SWEDEHEART registry

AIMS

Ticagrelor reduces ischaemic events and mortality in acute coronary syndrome (ACS) vs. clopidogrel. We wished to study clinical outcomes in a large real-world population post-ACS.

METHODS AND RESULTS

We performed a prospective cohort study in 45 073 ACS patients enrolled into Swedish Web system for Enhancement and Development of Evidence-based care in Heart Disease Evaluated According to Recommended Therapies who were discharged on ticagrelor (N = 11 954) or clopidogrel (N = 33 119) between 1 January 2010 and 31 December 2013. The primary outcome was a composite of all-cause death, re-admission with myocardial infarction (MI) or stroke, secondary outcomes as the individual components of the primary outcome, and re-admission with bleeding. The risk of the primary outcome with ticagrelor vs. clopidogrel was 11.7 vs. 22.3% (adjusted hazard ratio (HR) 0.85 [95% confidence interval: 0.78-0.93]), risk of death 5.8 vs. 12.9% (adjusted HR 0.83 [0.75-0.92]), and risk of MI 6.1 vs. 10.8% (adjusted HR 0.89 [0.78-1.01]) at 24 months. Re-admission with bleeding with ticagrelor vs. clopidogrel occurred in 5.5 vs. 5.2% (adjusted HR 1.20 [1.04-1.40]). In a subset of patients undergoing percutaneous coronary intervention (PCI) on ticagrelor vs. clopidogrel the PCI-related in-hospital bleeding was 3.7 vs. 2.7% (adjusted odds ratio, OR, 1.57 [1.30-1.90]).

CONCLUSION

Ticagrelor vs. clopidogrel post-ACS was associated with a lower risk of death, MI, or stroke, as well as death alone. Risk of bleeding was higher with ticagrelor. These real-world outcomes are consistent with randomized trial results.

Association of Weather With Day-to-Day Incidence of Myocardial Infarction: A SWEDEHEART Nationwide Observational Study

Importance

Whether certain weather conditions modulate the onset of myocardial infarction (MI) is of great interest to clinicians because it could be used to prevent MIs as well as guide allocation of health care resources.

Objective

To determine if weather is associated with day-to-day incidence of MI.

Design, Setting, and Participants

In this prospective, population-based and nationwide setting, daily weather data from the Swedish Meteorological and Hydrological Institute were extracted for all MIs reported to the Swedish nationwide coronary care unit registry, Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART), during 1998 to 2013 and then merged with each MI on date of symptom onset and coronary care unit. All patients admitted to any coronary care unit in Sweden owing to MI were included. A total of 280 873 patients were included, of whom 92 044 were diagnosed as having ST-elevation MI. Weather data were available for 274 029 patients (97.6%), which composed the final study population. Data were analyzed between February 2017 and April 2018.

Exposures

The nationwide daily mean air temperature, minimum air temperature, maximum air temperature, wind velocity, sunshine duration, atmospheric air pressure, air humidity, snow precipitation, rain precipitation, and change in air temperature.

Main Outcomes and Measures

The nationwide daily counts of MI as outcome.

Results

In 274 029 patients, mean (SD) age was 71.7 (12) years. Incidence of MI increased with lower air temperature, lower atmospheric air pressure, higher wind velocity, and shorter sunshine duration. The most pronounced association was observed for air temperature, where a 1-SD increase in air temperature (7.4°C) was associated with a 2.8% reduction in risk of MI (unadjusted incidence ratio, 0.972; 95% CI, 0.967-0.977; P <.001). Results were consistent for non-ST-elevation MI as well as ST-elevation MI and across a large range of subgroups and health care regions.

Conclusions and Relevance

In this large, nationwide study, low air temperature, low atmospheric air pressure, high wind velocity, and shorter sunshine duration were associated with risk of MI with the most evident association observed for air temperature.

Beyond fitness tracking: The use of consumer-grade wearable data from normal volunteers in cardiovascular and lipidomics research

The use of consumer-grade wearables for purposes beyond fitness tracking has not been comprehensively explored. We generated and analyzed multidimensional data from 233 normal volunteers, integrating wearable data, lifestyle questionnaires, cardiac imaging, sphingolipid profiling, and multiple clinical-grade cardiovascular and metabolic disease markers. We show that subjects can be stratified into distinct clusters based on daily activity patterns and that these clusters are marked by distinct demographic and behavioral patterns. While resting heart rates (RHRs) performed better than step counts in being associated with cardiovascular and metabolic disease markers, step counts identified relationships between physical activity and cardiac remodeling, suggesting that wearable data may play a role in reducing overdiagnosis of cardiac hypertrophy or dilatation in active individuals. Wearable-derived activity levels can be used to identify known and novel activity-modulated sphingolipids that are in turn associated with insulin sensitivity. Our findings demonstrate the potential for wearables in biomedical research and personalized health.

Contemporary use of ticagrelor in patients with acute coronary syndrome: insights from Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART)

AIMS

The platelet inhibitor ticagrelor is strongly recommended during 12 months post-acute coronary syndrome (ACS) in European guidelines. We analysed clinical characteristics of patients given ticagrelor for ACS in the real world.

METHODS AND RESULTS

We studied the use of ticagrelor in patients admitted for ACS in Sweden between 1 January 2012 and 31 December 2013 who were enrolled in the Swedish Web system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies (SWEDEHEART). Clinical characteristics were investigated for patients prescribed ticagrelor at discharge as well as for patients undergoing percutaneous coronary intervention who were prescribed ticagrelor. Independent factors associated with selecting ticagrelor were analysed in logistic regression. We found that 44.0% (n = 12 601) out of a total of 28 639 patients had been prescribed ticagrelor at discharge. After adjusting for age and sex, prior cardiovascular disease was less common in patients discharged on ticagrelor (myocardial infarction, ischaemic stroke, and peripheral vascular disease; P for all <0.001). The risk of death as predicted by GRACE score and the risk of major bleeding as predicted by CRUSADE score were both lower in ticagrelor-treated patients vs. others (median 99 vs. 126 and median 23 vs. 25, respectively; P for both < 0.001). The intended treatment duration at discharge was 12 months in 82.5% of patients and <12 months in 9.3%.

CONCLUSION

Ticagrelor is preferentially being used in patients at lower risk. A minority of patients are recommended ticagrelor during <12 months.

Digital phenotyping by consumer wearables identifies sleep-associated markers of cardiovascular disease risk and biological aging

Sleep is associated with various health outcomes. Despite their growing adoption, the potential for consumer wearables to contribute sleep metrics to sleep-related biomedical research remains largely uncharacterized. Here we analyzed sleep tracking data, along with questionnaire responses and multi-modal phenotypic data generated from 482 normal volunteers. First, we compared wearable-derived and self-reported sleep metrics, particularly total sleep time (TST) and sleep efficiency (SE). We then identified demographic, socioeconomic and lifestyle factors associated with wearable-derived TST; they included age, gender, occupation and alcohol consumption. Multi-modal phenotypic data analysis showed that wearable-derived TST and SE were associated with cardiovascular disease risk markers such as body mass index and waist circumference, whereas self-reported measures were not. Using wearable-derived TST, we showed that insufficient sleep was associated with premature telomere attrition. Our study highlights the potential for sleep metrics from consumer wearables to provide novel insights into data generated from population cohort studies.

Particulate air pollution on cardiovascular mortality in the tropics: impact on the elderly

BACKGROUND

Air pollution has a significant health impact. Most data originate from temperate regions. We aim to study the health impact of air pollution, particularly among the elderly, in a tropical region.

METHODS

A daily time-series analysis was performed to estimate excess risk (ER) of various air pollutants on daily death counts amongst the general population in Singapore from 2001 to 2013. Air pollutants included particulate matters smaller than 10 μm, and 2.5 μm (PM₁₀, PM_2.5), carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃) and sulphur dioxide (SO₂). The studied outcomes were non-accidental and cardiovascular mortality. Single-day lag and distributed lag models were studied and adjusted for confounders.

RESULTS

In single-day lag models, a 10 μg/m³ increase in particulate matter was associated with significant increases in non-accidental (PM₁₀ ER: 0.627%; 95% confidence interval (CI): 0.260-0.995% and PM_2.5 ER: 0.660%; 95% CI: 0.204-1.118%) and cardiovascular mortality (PM₁₀ ER: 0.897; 95% CI: 0.283-1.516 and PM_2.5 ER: 0.883%; 95% CI: 0.121-1.621%). This was significant in the elderly ≥ 65 years but not in those < 65 years and were seen in the acute phase of lag 0-5 days. Effects by other pollutants were minimal. For cardiovascular mortality, the effects turned protective at a cumulative lag of 30 days in the elderly and could due to "harvesting".

CONCLUSIONS

These first contemporary population-based data from an equatorial country with tropical climate show that exposure to particulate air pollution was significantly associated with non-accidental mortality and cardiovascular mortality, especially in the elderly.

Predisposing factors and consequences of elevated biomarker levels in long-distance runners aged >or=55 years

Cardiac biomarkers play an important role in the diagnosis of cardiovascular disease. Elevated levels can be seen in the context of strenuous exercise. We studied this phenomenon in senior endurance runners. We included 185 participants (61.1 +/- 5 years; 29% women) at a 30-km cross-country race who were self-reportedly in excellent health. Before and after the race, the creatinine, N-terminal pro-brain natriuretic peptide (NT-proBNP), and troponin T were analyzed, and participation in the number of previous races and the race duration were recorded. NT-proBNP increased from 53 ng/L (interquartile range 31 to 89) to 121 ng/L (interquartile range 79 to 184) and troponin T from undetectable to 0.01 microg/L (interquartile range 0.01 to 0.04). The independent predictors of a large NT-proBNP increase were (1) greater levels present at baseline, (2) a greater increase in creatinine (both p <0.001), (3) older age (p = 0.01), and (4) a longer race duration (p <0.05). Troponin T elevation was independently predicted by (1) older age (p = 0.01), (2) a greater increase in creatinine, and (3) participation in fewer previous races (both p <0.05). Of the 15 runners with an elevated (>194 ng/L) baseline NT-proBNP level (8.1% of 185), 4 were found to have serious cardiovascular disease (2.2% of whole sample). Of these 4 patients, 1 died from sudden cardiac death within months after the race. In conclusion, biomarker elevation occurs commonly in senior runners. A high baseline NT-proBNP is predictive of a large release during exercise, suggesting that the factors that control the at rest levels also determine its release with exertion. Troponin T elevation was seen in less-experienced participants. A small group of very ill runners were identified by NT-proBNP analysis.

Outcomes in patients treated with ticagrelor versus clopidogrel after acute myocardial infarction stratified by renal function

OBJECTIVES

We aimed to analyse outcomes of ticagrelor and clopidogrel stratified by estimated glomerular filtration rate (eGFR) in a large unselected cohort of patients with acute myocardial infarction (MI).

METHODS

We used follow-up data in MI survivors discharged on ticagrelor or clopidogrel enrolled in the Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies registry. The association between ticagrelor versus clopidogrel and the primary composite outcome of death, MI or stroke and the secondary outcome rehospitalisation with bleeding diagnosis at 1 year, was studied using adjusted Cox proportional hazards models, stratifying after eGFR levels.

RESULTS

In total, 45 206 patients with MI discharged on clopidogrel (n=33 472) or ticagrelor (n=11 734) were included. The unadjusted 1-year event rate for the composite endpoint of death, MI or stroke was 7.0%, 18.0% and 48.0% for ticagrelor treatment and 11.0%, 33.0% and 64.0% for clopidogrel treatment in patients with eGFR_>60 (n=33 668), eGFR_30-60 (n=9803) and eGFR_<30 (n=1735), respectively. After adjustment, ticagrelor as compared with clopidogrel was associated with a lower 1-year risk of the composite outcome (eGFR_>60: HR 0.87, 95% CI 0.76 to 99, eGFR_30-60: 0.82 (0.70 to 0.97), eGFR_<30: 0.95 (0.69 to 1.29), P for interaction=0.55) and a higher risk of bleeding (eGFR_>60: HR 1.10, 95% CI 0.90 to 1.35, eGFR_30-60: 1.13 (0.84 to 1.51), eGFR_<30: 1.79 (1.00 to 3.21), P for interaction=0.30) across the eGFR strata.

CONCLUSIONS

Treatment with ticagrelor as compared with clopidogrel in patients with MI was associated with lower risk for the composite of death, MI or stroke and a higher bleeding risk across all strata of eGFR. Of caution, bleeding events were more abundant in patients with eGFR_<30.

Air pollution in relation to very short-term risk of ST-segment elevation myocardial infarction: Case-crossover analysis of SWEDEHEART

OBJECTIVE

Studies have related air pollution to myocardial infarction (MI) events over days or weeks, with few data on very short-term risks. We studied risk of ST-segment elevation MI (STEMI) within hours of exposure to air pollution while adjusting for weather.

METHODS

We performed a case-crossover study of STEMI cases in Stockholm, Sweden (Jan 2000-June 2014) based on SWEDEHEART. Exposures during hazard periods up to 24 h prior to admission were compared to bidirectionally sampled control periods. Risks attributable to sulphur dioxide (SO₂), nitrogen dioxide (NO₂), ozone and particulate pollutants (PM_2.5, PM₁₀) were studied in conditional logistic regression models for interquartile range increments.

RESULTS

Risk of STEMI (n = 14,601) was associated with NO₂ (strongest at 15-h lag) and with PM_2.5 (strongest at 20-h lag), in single-pollutant models adjusting for air temperature and humidity (NO₂: odds ratio (OR; 95% confidence interval) 1.065 (1.031-1.101); PM_2.5: 1.026 (1.001-1.054)). After adjusting models for atmospheric pressure (significantly associated with STEMI risk at 14-24-h lags), NO₂ remained highly statistically significant (1.057 (1.022-1.094)) but not PM_2.5 (1.024 (0.997-1.052)). No associations were seen for SO₂, ozone or PM₁₀.

CONCLUSION

Risk of STEMI rises within hours of exposure to air pollutants, with strongest impact of NO₂. These findings are complementary to earlier reports which have not acknowledged widely the importance of very short-term fluctuations in air pollution.

Transesophageal echocardiography measurements of aortic annulus diameter using biplane mode in patients undergoing transcatheter aortic valve implantation

BACKGROUND

Aortic stenosis (AS) is a relevant common valve disorder. Severe AS and symptoms and/or left ventricular dysfunction (EF <50%) have the indication for aortic valve replacement (AVR). Majority of the patients with AS are elderly often with co-morbidities and generally have high preoperative risk. Transcatheter aortic valve implantation (TAVI) is offered in this group. Four different sizes of Corevalve prosthesis are available. Correct measurement of aortic size prior to TAVI is of great important to choose the right prosthesis size to avoid among others paravalvular leak or prosthesis patient mismatch.Aim of the study is to assess the aortic annulus diameter in patients undergoing TAVI by biplane (BP) mode using transesophageal echocardiography (TEE) and compare it to two-dimensional (2D) transthoracic echocardiography (TTE) and 2DTEE using three-dimensional (3D) TEE as reference method.

METHODS

The study population consisted of 50 patients retrospectively (24 men and 26 women, mean age 85±8 years of age) who all had undergone echocardiography examination prior to TAVI.

RESULTS

The mean aortic annulus diameter was 20.4±2.2 mm with TTE, 22.3±2.5 mm with 2DTEE, 22.9±1.9 mm with BP-mode and 23.1±1.9 mm with 3DTEE. TTE underestimated the mean aortic annulus diameter in comparison to transesophageal imaging modalities (p<0.001). Using 3DTEE, 2% of patients were unsuitable for TAVI due to a too-small AoA (n=1). This figure was similar with BP (4%, n=2; p=1.00) but considerably larger with 2DTTE (36%, n=18; p < 0.001) and 2DTEE (12%, n=6; p=0.06). There was a strong correlation between BP-mode and 3DTEE for assessment of aortic annulus diameter (r-value 0.88) with small mean difference (-0.2±0.9 mm) whereas the other modalities showed larger 95% confidence interval and modest correlation (2DTTE vs. 3DTEE, -6.3 to 0.9 mm, r=0.64 and 2DTEE vs. 3DTEE, -4.8 to 3.2 mm, r=0.61).

CONCLUSION

A multi-dimensional method is preferred to assess aortic annulus diameter in TAVI patients since there is risk of underestimation using single plane. Biplane mode is the method of choice in view of speedy post-processing with no need for expensive dedicated software. Lastly, single plane methods lead to misclassification of patients as unsuitable for TAVI. This may be of major clinical importance.

Arterial vasodilatory and ventricular diastolic reserves determine the stroke volume response to exercise in elderly female hypertensive patients

Elderly female hypertensives with arterial stiffening constitute a majority of patients with heart failure with preserved ejection fraction (HFpEF), a condition characterized by inability to increase cardiac stroke volume (SV) with physical exercise. As SV is determined by the interaction between the left ventricle (LV) and its load, we wished to study the role of arterial hemodynamics for exertional SV reserve in patients at high risk of HFpEF. Twenty-one elderly (67 ± 9 yr) female hypertensive patients were studied at rest and during supine bicycle stress using echocardiography including pulsed-wave Doppler to record flow in the LV outflow tract and arterial tonometry for central arterial pressure waveforms. Arterial compliance was estimated based on an exponential relationship between pressure and volume. The ratio of aortic pressure-to-flow in early systole was used to derive characteristic impedance, which was subsequently subtracted from total resistance (mean arterial pressure/cardiac output) to yield systemic vascular resistance (SVR). It was found that patients with depressed SV reserve (NoRes; reserve <15%; n = 10) showed decreased arterial compliance during exercise, while patients with SV reserve ≥15% (Res; n = 11) showed increased compliance. Exercise produced parallel increases in LV end-diastolic volume and arterial volume in Res patients while NoRes patients exhibited a lesser decrease in SVR and a drop in effective arterial volume. Poor SV reserve in elderly female hypertensives is due to simultaneous failure of LV preload and arterial vasodilatory reserves. Abnormal arterial function contributes to a high risk of HFpEF in these patients.

Defining a 'frequent admitter' phenotype among patients with repeat heart failure admissions

AIMS

We aimed to identify a 'frequent admitter' phenotype among patients admitted for acute decompensated heart failure (HF).

METHODS AND RESULTS

We studied 10 363 patients in a population-based prospective HF registry (2008-2012), segregated into clusters based on their 3-year HF readmission frequency trajectories. Using receiver-operating characteristic analysis, we identified the index year readmission frequency threshold that most accurately predicts HF admission frequency clusters. Two clusters of HF patients were identified: a high frequency cluster (90.9%, mean 2.35 ± 3.68 admissions/year) and a low frequency cluster (9.1%, mean 0.50 ± 0.81 admission/year). An index year threshold of two admissions was optimal for distinguishing between clusters. Based on this threshold, 'frequent admitters', defined as patients with ≥ 2 HF admissions in the index year (n = 2587), were of younger age (68 ± 13 vs 69 ± 13 years), more often male (58% vs. 54%), smokers (38.4% vs. 34.4%) and had lower left ventricular ejection fraction (37 ± 17 vs. 41 ± 17%) compared to 'non-frequent admitters' (< 2 HF admissions in the index year; n = 7776) (all P < 0.001). Despite similar rates of advanced care utilization, frequent admitters had longer length of stay (median 4.3 vs. 4.0 days), higher annual inpatient costs (€ 7015 vs. € 2967) and higher all-cause mortality at 3 years compared to the non-frequent admitters (adjusted odds ratio 2.33, 95% confidence interval 2.11-2.58; P < 0.001).

CONCLUSION

'Frequent admitters' have distinct clinical characteristics and worse outcomes compared to non-frequent admitters. This study may provide a means of anticipating the HF readmission burden and thereby aid in healthcare resource distribution relative to the HF admission frequency phenotype.

Harnessing technology and molecular analysis to understand the development of cardiovascular diseases in Asia: a prospective cohort study (SingHEART)

Background

Cardiovascular disease (CVD) imposes much mortality and morbidity worldwide. The use of “deep learning”, advancements in genomics, metabolomics, proteomics and devices like wearables have the potential to unearth new insights in the field of cardiology. Currently, in Asia, there are no studies that combine the use of conventional clinical information with these advanced technologies. We aim to harness these new technologies to understand the development of cardiovascular disease in Asia.

Methods

Singapore is a multi-ethnic country in Asia with well-represented diverse ethnicities including Chinese, Malays and Indians. The SingHEART study is the first technology driven multi-ethnic prospective population-based study of healthy Asians. Healthy male and female subjects aged 21–69 years old without any prior cardiovascular disease or diabetes mellitus will be recruited from the general population. All subjects are consented to undergo a detailed on-line questionnaire, basic blood investigations, resting and continuous electrocardiogram and blood pressure monitoring, activity and sleep tracking, calcium score, cardiac magnetic resonance imaging, whole genome sequencing and lipidomic analysis. Outcomes studied will include mortality and cause of mortality, myocardial infarction, stroke, malignancy, heart failure, and the development of co-morbidities.

Discussion

An initial target of 2500 patients has been set. From October 2015 to May 2017, an initial 683 subjects have been recruited and have completed the initial work-up the SingHEART project is the first contemporary population-based study in Asia that will include whole genome sequencing and deep phenotyping: including advanced imaging and wearable data, to better understand the development of cardiovascular disease across different ethnic groups in Asia.

Impact of aortic root size on left ventricular afterload and stroke volume

PURPOSE

The left ventricle (LV) ejects blood into the proximal aorta. Age and hypertension are associated with stiffening and dilation of the aortic root, typically viewed as indicative of adverse remodeling. Based on analytical considerations, we hypothesized that a larger aortic root should be associated with lower global afterload (effective arterial elastance, EA) and larger stroke volume (SV). Moreover, as antihypertensive drugs differ in their effect on central blood pressure, we examined the role of antihypertensive drugs for the relation between aortic root size and afterload.

METHODS

We studied a large group of patients (n = 1250; 61 ± 12 years; 78 % males; 64 % hypertensives) from a single-center registry with known or suspected coronary artery disease. Aortic root size was measured by echocardiography as the diameter of the tubular portion of the ascending aorta. LV outflow tract Doppler was used to record SV.

RESULTS

In the population as a whole, after adjusting for key covariates in separate regression models, aortic root size was an independent determinant of both SV and EA. This association was found to be heterogeneous and stronger in patients taking a calcium channel blocker (CCB; 10.6 % of entire population; aortic root size accounted for 8 % of the explained variance of EA).

CONCLUSION

Larger aortic root size is an independent determinant of EA and SV. This association was heterogeneous and stronger in patients on CCB therapy.

The impact of arterial load on left ventricular performance: an invasive haemodynamic study in severe mitral stenosis

KEY POINTS

A hallmark of mitral stenosis (MS) is the markedly altered left ventricular (LV) loading. As most of the methods used to determine LV performance in MS patients are influenced by loading conditions, previous studies have shown conflicting results. The present study calculated LV elastance, which is a robust method to quantify LV function. We demonstrate that LV loading in MS patients is elevated but normalizes after valve repair and might be a result of reflex pathways. Additionally, we show that the LV in MS is less compliant than normal due to a combination of right ventricular loading and the valvular disease itself. Immediately after valve dilatation the increase in blood inflow into the LV results in even greater LV stiffness. Our findings enrich our understanding of heart function in MS patients and provide a simple reproducible way of assessing LV performance in MS.

ABSTRACT

Left ventricular (LV) function in rheumatic mitral stenosis (MS) remains an issue of controversy, due to load dependency of previously employed assessment methods. We investigated LV performance in MS employing relatively load-independent indices robust to the altered loading state. We studied 106 subjects (32 ± 8 years, 72% female) with severe MS (0.8 ± 0.2 cm(2) ) and 40 age-matched controls. MS subjects underwent simultaneous bi-ventricular catheterization and transthoracic echocardiography (TTE) before and immediately after percutaneous transvenous mitral commisurotomy (PTMC). Sphygmomanometric brachial artery pressures and TTE recordings were simultaneously acquired in controls. Single-beat LV elastance (Ees ) was employed for LV contractility measurements. Effective arterial elastance (Ea ) and LV diastolic stiffness were measured. MS patients demonstrated significantly elevated afterload (Ea : 3.0 ± 1.3 vs. 1.5 ± 0.3 mmHg ml(-1) ; P < 0.001) and LV contractility (Ees : 4.1 ± 1.6 vs. 2.4 ± 0.5 mmHg ml(-1) ; P < 0.001) as compared to controls, with higher Ea in subjects with smaller mitral valve area (≤ 0.8 cm(2) ) and pronounced subvalvular fusion. Stroke volume (49 ± 16 to 57 ± 17 ml; P < 0.001) and indexed LV end-diastolic volume (LVEDVindex : 57 ± 16 to 64 ± 16 ml m(-2) ; P < 0.001) increased following PTMC while Ees and Ea returned to more normal levels. Elevated LV stiffness was demonstrated at baseline and increased further following PTMC. Our findings provide evidence of elevated LV contractility, increased arterial load and increased diastolic stiffness in severe MS. Following PTMC, both LV contractility and afterload tend to normalize.

Impact of tachycardia and sympathetic stimulation by cold pressor test on cardiac diastology and arterial function in elderly females

Abnormal vascular-ventricular coupling has been suggested to contribute to heart failure with preserved ejection fraction in elderly females. Failure to increase stroke volume (SV) during exercise occurs in parallel with dynamic changes in arterial physiology leading to increased afterload. Such adverse vascular reactivity during stress may reflect either sympathoexcitation or be due to tachycardia. We hypothesized that afterload elevation induces SV failure by transiently attenuating left ventricular relaxation, a phenomenon described in animal research. The respective roles of tachycardia and sympathoexcitation were investigated in n = 28 elderly females (70 ± 4 yr) carrying permanent pacemakers. At rest, during atrial tachycardia pacing (ATP; 100 min(-1)) and during cold pressor test (hand immersed in ice water), we performed Doppler echocardiography (maximal untwist rate analyzed by speckle tracking imaging of rotational mechanics) and arterial tonometry (arterial stiffness estimated as augmentation index). Estimation of arterial compliance was based on an exponential relationship between arterial pressure and volume. We found that ATP produced central hypovolemia and a reduction in SV which was larger in patients with stiffer arteries (higher augmentation index). There was an associated adverse response of arterial compliance and vascular resistance during ATP and cold pressor test, causing an overall increase in afterload, but nonetheless enhanced maximal rate of untwist and no evidence of afterload-dependent failure of relaxation. In conclusion, tachycardia and cold provocation in elderly females produces greater vascular reactivity and SV failure in the presence of arterial stiffening, but SV failure does not arise secondary to afterload-dependent attenuation of relaxation.

Building a Longitudinal National Integrated Cardiovascular Database - Lessons Learnt From SingCLOUD

Background: Real world data on clinical outcomes and quality of care for patients with coronary artery disease (CAD) are fragmented. We describe the rationale and design of the Singapore Cardiovascular Longitudinal Outcomes Database (SingCLOUD).

Methods and Results: We designed a health data grid to integrate clinical, administrative, laboratory, procedural, prescription and financial data from all public-funded hospitals and primary care clinics, which provide 80% of health care in Singapore. Here, we explain our approach to harmonize real-world data from diverse electronic medical and non-medical platforms to develop a robust and longitudinal dataset. We present pilot data on patients with myocardial infarction (MI) treated with percutaneous coronary intervention (PCI) between 2012 and 2014. The initial data set had 53,395 patients. Of these, 35,203 had CAD confirmed on coronary angiography, of whom 21,521 had PCI. Eventually, limiting to 2012–2014, 3,819 patients had MI with PCI, while 5,989 had MI. Compared with the quality improvement registry, Singapore Cardiac Data Bank, which had 189 fields for analysis, the SingCLOUD platform generated an additional 313 additional data fields, and was able to identify an additional 250 heart failure events, 664 major adverse cardiovascular events at 2 years, and low-density lipoprotein levels to 1 year for 3,747 patients.

Conclusions: By integrating multiple incongruent data sources, SINGCLOUD enables in-depth analysis of real-world cardiovascular “big data”.

Diastolic function and its association with diabetes, hypertension and age in an outpatient population with normal stress echocardiography findings

Background

Diastolic dysfunction can be caused by hypertension or diabetes mellitus, and it is also often found with increasing age. In a given patient, the cause of diastolic dysfunction is therefore not always obvious. We sought to study the interplay of these risk factors for diastolic dysfunction in an outpatient population with a low likelihood of ischemic heart disease.

Methods

Consecutive patients referred for stress echocardiography were included retrospectively. Exclusion criteria included pathological stress response, atrial arrhythmia, left ventricular ejection fraction < 55%, and more than mild valvular disease. Standard diastolic parameters were recorded in all patients. In a subset of patients, mechanistic analysis of early filling was performed using the parameterized diastolic filling (PDF) method.

Results

We included 726 patients (median [interquartile range] age 56 (44–65) years, 57% male). The prevalence of diabetes and hypertension was 43 and 49%, respectively. In multiple linear regression modeling, the presence of diabetes, hypertension, sex and increasing age explained a moderate amount of the variance in e’ velocities, E/A ratio and E/e’ (R² = 0.31–0.48, p < 0.001), and a low amount of the variance in left atrial volume index (LAVI) and the PDF parameters (n = 446, R² = 0.05–0.17, p < 0.001). Sex was only related to LAVI and E/e’ for the conventional parameters (beta − 0.94, p = 0.04, and beta − 0.91, p < 0.001, respectively).

Conclusions

Diabetes, hypertension, increasing age, and to a lesser extent sex, explain a moderate amount of the variance in conventional diastolic parameters related to myocardial tissue velocities and E/A ratio in a healthy outpatient population. The effect of these risk factors was substantially less pronounced on left atrial volume index and the PDF parameters.

E/e' in relation to outcomes in ST-elevation myocardial infarction

BACKGROUND

Myocardial infarction (MI) is a high-risk condition especially when filling pressure is raised, and earlier reports have suggested that E/e' is associated with poor outcome. However, whether E/e' predicts risk better than LVEF, which is the current standard of practice, is not known. We investigated this question in the largest and most rigorous study of MI patients so far.

METHODS AND RESULTS

We studied 660 patients with ST-elevation MI (STEMI) treated with primary percutaneous coronary intervention and related E/e' to short-term mortality (in-hospital death), as well as long-term events at 2 years comprising (a) a composite of MI, stroke, heart failure, and death, and (b) death alone. Short-term models were adjusted for age, sex, and LVEF. Long-term models were adjusted for age, sex, diabetes, revascularization procedure, history of MI, hypertension, renal function, drugs on discharge, and LVEF. Elevated E/e'> 15 indicated higher risk of short-term events (n = 19:7.0% (95% confidence interval 3.4-10.8%) vs. 1.0% (0.3 - 2.3%); adjusted odds ratio 3.7 (1.3-10.5)). While elevated E/e' was also associated with long-term outcomes (n = 103 composite events: 15.9% (11.9% - 21.4%) vs 6.8% (5.2% - 8.7%), P < .001; n = 38 death events: 6.0% (3.9% - 9.5%) vs 2.0% (1.3% - 3.2%), P = .001), E/e' was rendered nonsignificant for long-term outcomes by multivariable adjustment (p = ns for both). LVEF, on the contrary, was a highly significant predictor in the adjusted long-term model.

CONCLUSION

E/e' is associated with poor outcome in STEMI, but LVEF is a stronger predictor of long-term risk.

Allometric Relationships for Cardiac Size and Longitudinal Function in Healthy Chinese Adults - Normal Ranges and Clinical Correlates

BACKGROUND

Cardiac size measurements require indexing to body size. Allometric indexing has been investigated in Caucasian populations but a range of different values for the so-called allometric power exponent (b) have been proposed, with uncertainty as to whether allometry offers clinical utility above body surface area (BSA)-based indexing. We derived optimal values for b in normal echocardiograms and validated them externally in cardiac patients.

METHODS AND RESULTS

Values for b were derived in healthy adult Chinese males (n=1,541), with optimal b for left ventricular mass (LVM) of 1.66 (95% confidence interval 1.41-1.92). LV hypertrophy (LVH) defined as indexed LVM >75 g/m^1.66 was associated with adverse outcomes in an external validation cohort (n=738) of patients with acute coronary syndrome (odds ratio for reinfarction: 2.4 (1.1-5.4)). In contrast, LVH defined by BSA-based indexing or allometry using exponent 2.7 exhibited no significant association with outcomes (P=NS for both). Cardiac longitudinal function also varied with body size: septal and RV free wall s', TAPSE and lateral e' all scaled allometrically (b=0.3-0.9).

CONCLUSIONS

An optimal b of 1.66 for LVM in healthy Chinese was found to validate well, with superior clinical utility both to that of BSA-based indexing and to b=2.7. The effect of allometric indexing of cardiac function requires further study.

Characterization and evaluation of NGF antisense oligonucleotides: inhibition of NGF synthesis in transfected COS cells

We present a system for the assessment of the inhibiting capacity of antisense oligonucleotides. The aim of this study was to identify an oligonucleotide that can inhibit chicken nerve growth factor (NGF) synthesis. Five antisense chicken NGF phosphorothioate oligonucleotides, AS1-5, were designed and were tested for their capacity to inhibit NGF expression in COS cells. COS cells that transiently expressed chicken NGF were treated with the oligonucleotides, and NGF expression was analyzed using a bioassay and Western blotting for NGF protein. Two oligonucleotides, AS 1 and AS 5, were more capable than the others of inhibiting expression compared with nonsense oligonucleotide, and they targeted the translational initiation and stop sites. The chicken NGF is expressed at a high level from an adenovirus major late promoter, and AS 1 was capable of inhibiting more than 80% of the NGF expression as determined using the bioassay and Western blotting. Expression of another member of the NGF gene family, neurotrophin-4, was not affected by treatment of the antisense oligonucleotides. A 10-fold lower concentration of the AS 1 oligonucleotide could be used to inhibit NGF synthesis if the cellular uptake was facilitated using lipofectin compared with addition of oligonucleotide directly to the culture medium. The amount of oligonucleotide taken up by the cells was similar in the lipofectin-treated cells as in the cells treated by a 10-fold higher concentration of medium-supplemented nucleotide. This system based on COS cells can facilitate evaluation of the capacity of inhibiting antisense oligonucleotides, particularly targeting those genes in which endogenous products are present in low levels and are difficult to analyze.