Broad anti-pathogen potential of DEAD box RNA helicase eIF4A-targeting rocaglates

Inhibition of eukaryotic initiation factor 4A has been proposed as a strategy to fight pathogens. Rocaglates exhibit the highest specificities among eIF4A inhibitors, but their anti-pathogenic potential has not been comprehensively assessed across eukaryotes. In silico analysis of the substitution patterns of six eIF4A1 aa residues critical to rocaglate binding, uncovered 35 variants. Molecular docking of eIF4A:RNA:rocaglate complexes, and in vitro thermal shift assays with select recombinantly expressed eIF4A variants, revealed that sensitivity correlated with low inferred binding energies and high melting temperature shifts. In vitro testing with silvestrol validated predicted resistance in Caenorhabditis elegans and Leishmania amazonensis and predicted sensitivity in Aedes sp., Schistosoma mansoni, Trypanosoma brucei, Plasmodium falciparum, and Toxoplasma gondii. Our analysis further revealed the possibility of targeting important insect, plant, animal, and human pathogens with rocaglates. Finally, our findings might help design novel synthetic rocaglate derivatives or alternative eIF4A inhibitors to fight pathogens.

Effects of medical therapy, transcatheter intervention, and surgery on outcomes of patients with functional mitral regurgitation: a systematic review and network meta-analysis

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Ching-Hui Sia was supported by the National University of Singapore Yong Loo Lin School of Medicine's Junior Academic Fellowship Scheme.

Background

Functional mitral regurgitation (FMR) is the most common valvular heart disease worldwide. Despite recent major trials, the relative efficacy between medical therapy, transcatheter intervention, and surgery for the treatment of FMR remains poorly understood.

Purpose

We performed a systematic review and network meta-analysis of all published randomised controlled trials (RCTs) and observational studies to compare the efficacy between medical therapy, transcatheter intervention, and surgery on the clinical outcomes of patients with FMR.

Methods

Four electronic databases (PubMed, EMBASE, SCOPUS, and the Cochrane Library) were searched from inception to March 13, 2022, for studies reporting clinical outcomes in patients with FMR and comparing the efficacy between either medical therapy, transcatheter intervention, or surgery. Frequentist network meta-analysis models were utilised to summarise the studies. This study was registered in the International Prospective Register of Systematic Reviews.

Results

10 articles were included in the analysis, comprising a combined cohort of 1,981 patients. Network meta-analysis demonstrated that compared to medical therapy, transcatheter intervention achieved a lower relative risk in the composites of all-cause mortality (risk ratio [RR]: 0.43; 95% confidence interval [CI] 0.22-0.82) and mitral regurgitation (MR) severity grade ≥3+ (RR: 0.06; 95% CI 0.01-0.42). Compared to surgery, transcatheter intervention achieved a lower relative risk in the composites of cardiovascular death (RR: 0.36; 95% CI 0.17-0.75) and MR severity grade ≥3+ (RR: 0.25; 95% CI 0.09-0.70) and higher relative risk in the composite of heart failure hospitalisation (RR: 2.94; 95% CI 1.26-6.82). Compared to medical therapy, surgery achieved a higher relative risk in the composite of cardiovascular death (RR: 2.54; 95% CI 1.18-5.47) and lower relative risks in the composites of all-cause mortality (RR: 0.56; 95% CI 0.34-0.91) and heart failure hospitalisation (RR: 0.28; 95% CI 0.13-0.61).

Conclusion

Medical therapy, transcatheter intervention, and surgery in patients with FMR displayed differing effects on the various clinical outcomes. Further head-to-head trials are required to better understand the optimal treatment modality in this population.

Sex-based comparisons of clinical characteristics and outcomes of patients with embolic stroke of undetermined source with implantable loop recorders

Funding Acknowledgements

Type of funding sources: None.

Introduction

Embolic strokes of undetermined source (ESUS) constitute a significant proportion of all ischemic strokes, but sex-based comparisons of clinical characteristics and outcomes of ESUS patients have not been well explored. As such, we aimed to examine how sex influences outcomes of ESUS patients.

Methods

Retrospective cohort study performed on consecutive ESUS patients with an implanted ILR between December 2013 to September 2021. We obtained information on the patients’ characteristics, treatments, and outcomes from the electronic medical records. Cox regression was used to investigate whether sex was independently associated with outcomes.

Results

There were 176 patients included in this study. The mean duration of follow-up was 1254 ± 724 days. Mean age was 60.8 ± 12.0 and 47 (26.7%) of patients were female. On univariable Cox regression analysis for subsequent atrial fibrillation (AF) on implantable loop recorder (ILR), patients with subsequent AF on ILR were more likely to be female (HR 2.19, 95% CI 1.04–4.63, p = 0.040), older (HR 1.07, 95% CI 1.03–1.12, p = 0.001), have a lower glomerular filtration rate (eGFR) (HR 0.98, 95% CI 0.97– 0.99, p = 0.004), and have previous percutaneous coronary intervention (PCI) (HR 2.60, 95% CI 1.05–6.46, p = 0.039). On multivariable Cox regression, after adjustment for age, eGFR and previous PCI status, female sex remained independently associated with the development of subsequent AF on ILR. Female sex was not associated with other outcomes including mortality, subsequent acute myocardial infarction, stroke/transient ischemic attack and heart failure.

Conclusions

In this cohort of ESUS patients with ILR implantation, female sex was independently associated with a higher risk of development of AF on ILR. However, female sex was not a predictor of mortality, subsequent acute myocardial infarction, stroke/transient ischemic attack and heart failure.

Association of left atrial ejection fraction and cardiovascular outcomes in Asian patients with hypertrophic cardiomyopathy

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): National University of Singapore Yong Loo Lin School of Medicine's Junior Academic Fellowship Scheme

Background

The optimal method of risk stratification of hyp­ertrophic cardiomyopathy (HCM) patients, especially in the Asian population, is unknown. Left atrial ejection fraction (LAEF) is an emerging risk marker for cardiovascular outcomes. This study aimed to investigate whether LAEF was associated with cardiovascular outcomes in Asian patients with HCM.

Methods

This was a retrospective cohort study performed in a tertiary academic centre involving 291 consecutive patients diagnosed with HCM between 2010 and 2017. We collected the relevant clinical characteristics of these patients and retrospectively analysed the index transthoracic echocardiograms for novel left atrial indices including LAEF. We obtained the maximum (LAVmax) and minimum left atrial volumes (LAVmin) using the biplane method of disks in apical 4- and 2-chamber views. LAEF was derived by dividing the difference between LAVmax and LAVmin by LAVmax. We assessed the patients for outcomes of (1) heart failure requiring admission, and (2) a composite of adverse outcomes including all-cause mortality, ventricular tachycardia / ventricular fibrillation (VT/VF) events, appropriate device therapy if an implantable cardioverter defibrillator (ICD) was implanted, stroke and heart failure hospitalization.

Results

The patients had a mean age of 59.0 ± 16.7 years-old at diagnosis and had a male preponderance (71.2%). The most common comorbidities were hypertension, diabetes mellitus and ischemic heart disease. On univariable logistic regression analysis, maximum and minimum left atrial volume index (LAVI) as well as LAEF showed a significant association with heart failure and the predefined composite outcome. On Cox regression analysis adjusting for variables of age, sex, left ventricular ejection fraction (LVEF), left ventricular maximal wall thickness >30mm, significant left ventricular outflow tract (LVOT) gradient of > 30mmHg and more than moderate mitral regurgitation, maximum and minimum LAVI as well as LAEF retained an association with heart failure admission but only minimum LAVI and LAEF were associated with the composite outcome [(OR 0.019, 95% CI 0.02-0.230, p=0.002), (OR 0.226, 95% CI 0.053-0.960, p=0.044), (OR 1.030, 95% CI 1.016-1.045, p<0.001), and (OR 1.016, 95% CI 1.005-1.026, p=0.004) respectively].

Conclusion

LAEF was an independently associated with congestive heart failure as well as a composite of adverse outcomes in Asian patients with HCM.

Abnormal left atrial strain is associated with eventual diagnosis of atrial fibrillation in patients with embolic stroke of undetermined source

Funding Acknowledgements

Type of funding sources: None.

Background

Patients with embolic stroke of undetermined source (ESUS) have no immediate attributable cause despite initial evaluation. Occult paroxysmal atrial fibrillation (pAF) diagnosed on prolonged electrocardiographic monitoring may be subsequently found in 20% of patients initially classified as ESUS [1]. Anatomic and functional alterations of left atrium (LA) are known to predict pAF in the general population [2]. Recent studies have suggested that LA dysfunction is linked to the risk of development of pAF in stroke patients and may precede LA enlargement [1]. LA strain analysis may be helpful to predict the development of pAF as it can detect subclinical functional impairment [2]. The aim of this study was to analyse whether LA strain can be a marker for the development of new-onset AF in patients with ESUS and sinus rhythm.

Methods

Our single-centre observational cohort study examined 157 patients hospitalised for ESUS in our tertiary hospital between October 2014 and October 2017 who underwent AF monitoring with an implantable loop recorder (ILR). These patients were followed up for occurrence of new-onset pAF and recurrence of ischaemic stroke. All patients underwent transthoracic echocardiography (TTE) during index hospitalisation as part of the workup for ESUS. Echocardiographic images were obtained and analysed post-hoc for two-dimensional (2D) speckle tracing deformation parameters. These LA strain parameters were analysed against the primary outcome of AF detection and secondary outcome of recurrent ischaemic stroke.

Results

A total of 157 ESUS patients, with a mean age of 61.0 (±11.6) years, were followed up for a median duration of 3.5 (interquartile range 3.29) years. ILR monitoring detected AF in 27 patients (17.2%). 27 patients developed recurrent ischaemic strokes. Of the 27 patients with newly diagnosed AF on ILR, 24 (88.9%) were commenced on oral anticoagulation; the remaining 3 patients were not on anticoagulation due to high bleeding risk and frailty.

Patients who had newly diagnosed AF had more impaired left atrial reservoir strain (LASr; 23.5% ± 10.3%, P = 0.042) and left atrial conduit strain (LAScd; -10.5% ± 5.3%, P = 0.003) compared with patients who remained in sinus rhythm. Multivariable logistic regression analysis adjusting for age, sex, hypertension, hyperlipidaemia, diabetes mellitus and left ventricular ejection fraction (LVEF) showed that LAScd was associated with occult AF (adjusted odds ratio [aOR] = 1.110, 95% CI, 1.019-1.209, P = 0.017) and the composite outcome of AF and recurrent ischaemic stroke (OR = 1.069, 95% CI, 1.014-1.138, P = 0.038). Abnormal LAScd was significantly associated with occult AF even when stratified by normal LA volume index (LAVI) (OR = 2.672, 95% CI, 1.035-8.548, P = 0.048) and high LAVI (OR = 1.713, 95% CI, 1.023-2.869, P = 0.041).

Conclusion

Impaired left atrial strain was associated with occult AF detection in patients with ESUS undergoing ILR monitoring.

Natural history of functional mitral regurgitation: a systematic review and individual patient data meta-analysis

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Ching-Hui Sia was supported by the National University of Singapore Yong Loo Lin School of Medicine's Junior Academic Fellowship Scheme.

Background

Functional mitral regurgitation (FMR) precipitates a vicious cycle of left ventricular volume overload and remodelling, leading to perpetual worsening of FMR and left ventricular dysfunction, with a resultant poor prognosis. However, there is a lack of conclusive data on the natural progression of FMR in patients who do not undergo valvular intervention.

Purpose

We performed a one-stage meta-analysis on reconstructed individual patient data (IPD) to elucidate the natural history of FMR.

Methods

Four databases (PubMed, Embase, Scopus, Cochrane) were searched for randomised controlled trials or cohorts, published from inception to March 13, 2022, reporting clinical outcomes in patients with FMR not receiving valvular intervention. IPD meta-analysis, as the gold standard approach for evidence synthesis, was performed with reconstructed IPD obtained from the survival curves reported in the included studies. Pooled survival estimates were derived. Quality assessment of included studies was conducted using the Cochrane risk-of-bias tool and Newcastle Ottawa Scale. This study was registered on the International Prospective Register of Systematic Reviews.

Results

A total of five studies were included, comprising a total cohort of 691 patients with FMR who did not undergo valvular intervention. The mean age of the cohort was 72.4 years (95% CI 67.6 to 77.1) and the proportion of males was 61.1% (95% CI 43.8 to 76.0). All-cause mortality was analysed over a follow-up duration of five years, while hospitalisation for heart failure, cardiovascular death, and the composite of all-cause mortality and hospitalisation for heart failure were analysed over a follow-up duration of three years. The probability of survival of patients with FMR without intervention was 79.4% (95% CI 76.2 to 82.3), 50.9% (95% CI 46.6 to 55.1), and 39.6% (95% CI 33.1 to 46.0) at one, three, and five years respectively. The probability of survival free from the composite of all-cause mortality and hospitalisation for heart failure was 51.3% (95% CI 46.8 to 55.6) and 12.0% (95% CI 8.9 to 15.7) at one year and three years respectively. The probability of survival free from hospitalisation for heart failure was 58.3% (95% CI 54.0 to 62.3) and 19.7% (95% CI 16.0 to 23.7) at one and three years respectively. The probability of survival free from cardiovascular death was 75.4% (95% CI 68.9 to 80.8) and 45.6% (95% CI 29.1 to 60.7) at one and three years respectively. All included studies were of low to moderate risk of bias.

Conclusion

FMR in the absence of valvular intervention is associated with poor survival and cardiovascular outcomes. Further research should focus on the role of interventions to mitigate its poor prognosis.

Characteristics and outcomes of aortic stenosis patients with and without stroke

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Sia CH was supported by the National University of Singapore Yong Loo Lin School of Medicine’s Junior Academic Faculty Scheme

Background

Aortic stenosis (AS) is related to several atherosclerosis risk factors and is associated with an increased risk of ischaemic stroke. Some reports suggest that aortic valve calcification may predispose to embolic stroke although this is not well-studied. The literature is also sparse regarding individual stroke subtypes and predictors of stroke in AS.

Purpose

We aimed to 1) Describe rates of ischaemic stroke in AS including specific stroke subtypes; 2) Compare clinical and echocardiographic characteristics of patients with AS who subsequently developed ischaemic stroke versus those who did not, and 3) Identify independent variables associated with subsequent stroke in AS.

Methods

Patients with AS were recruited from an echocardiography database from September 2011 to December 2015 at a single tertiary centre. The primary study endpoint was acute ischaemic stroke. Clinical characteristics and echocardiographic parameters were compared between patients who suffered a stroke after AS diagnosis and those who did not. Multivariable Cox regression analysis was used to identify factors associated with subsequent stroke.

Results

A total of 703 patients with AS were studied, with a median follow-up duration of 3.0 (IQR 0.5, 5.0) years. Twenty-two patients (3.1%) developed stroke following AS diagnosis (large vessel, 18.2%; cardioembolic, 50.0%; small vessel, 18.2%; other determined ischaemic stroke, 13.6%). These patients had a greater prevalence of previous stroke or transient ischaemic attack (TIA) (50.0%) compared to patients who did not develop subsequent stroke (20.9%), p<0.001. Patients with AS who developed subsequent stroke also more commonly had atrial fibrillation at the time of indexed echocardiography (40.0%) compared to their counterparts who did not develop stroke (13.5%), p=0.004 (Table 1). Other cardiovascular risk factors and traditional echocardiographic parameters of AS severity were similar between the 2 groups. Degenerative calcified aortic valve was not associated with the development of all types of ischaemic stroke or cardioembolic stroke. AS severity was also not associated with development of stroke. Multivariable Cox regression analysis found previous stroke or TIA (HR 8.00, 95% CI 2.70–23.58, p<0.001) and atrial fibrillation at time of echocardiography (HR 8.81, 95% CI 1.34–10.80, p=0.012) to be independent predictors of subsequent stroke in AS. The key findings of our study are summarised in Figure 1.

Conclusions

Cardioembolic stroke is the most common stroke subtype in patients with AS. Previous history of stroke or TIA and atrial fibrillation at time of diagnostic echocardiography are independent predictors of subsequent stroke in AS. Calcified aortic valve was not found to be a risk factor for all types of ischaemic stroke or cardioembolic stroke.

Real-world comparison of intracoronary imaging and fractional flow reserve measurements on outcomes of semi-urgent and elective percutaneous coronary intervention in a multi-ethnic asian population

Funding Acknowledgements

Type of funding sources: None.

Background

Intracoronary imaging and fractional flow reserve measurements (FFR) are helpful in optimisation of percutaneous coronary intervention (PCI) for patients with stable coronary artery disease, but their comparative efficacy is not well described. Furthermore, few studies involve Asian patients in a real-world context.

Purpose

This study aims to compare the use of intracoronary imaging and fractional flow reserve measurements on the outcomes of semi-urgent and elective PCI in a multi-ethnic Asian population.

Methods

This was a retrospective database study of patients who underwent semi-urgent and elective PCI from 1st Jan 2014 to 31st Dec 2015 at a tertiary academic centre. The patients were split into 2 groups – imaging-guided (IG) consisting of intravascular ultrasound guided PCI or optical coherence tomography guided PCI and physiology-guided (PG) which included FFR-guided PCI. Patients who underwent both IG PCI and PG PCI were excluded. Incidence rates of major adverse cardiovascular events (MACE) (Subsequent myocardial infarction, congestive cardiac failure, all-cause mortality) and major adverse cardiovascular and cerebrovascular events (MACCE) (Subsequent myocardial infarction, congestive cardiac failure, stroke or transient ischemic attack and all-cause mortality) were compared between the two groups. One-to-one propensity score matching (PSM) was performed to control for potential bias.

Results

Of 1,732 patients studied, the median age was 61.0 years (IQR 53.0 to 68.0) and 336 were female (19.4%). There were 266 patients (15.4%) in IG and 186 (10.7%) in PG. The patients were followed up for 33 ±37 months. A total of 133 pairs were matched. In the unmatched cohort, there was no statistical difference between the IG and PG group in the incidence of MACE (24.2% vs 15.5%, p= 0.099) and MACCE (26.6% vs 17.7%, p= 0.112). Baseline and procedural characteristics were balanced between the IG and PG groups. In the matched cohort, the incidence rates of MACE (11.3% vs 7.5%, p= 0.383) and MACCE (15.8% vs 12.8%, p=0.596) did not differ significantly between the two groups.

Conclusion

In a real-world multi-ethnic Asian registry of semi-urgent and elective PCI patients, there was no difference in outcomes whether patients underwent the use of intracoronary imaging or fractional flow reserve measurements during PCI.

Reconstructed meta-analysis of percutaneous coronary intervention versus coronary artery bypass grafting for left main disease

Background

Randomized controlled trials (RCTs) comparing percutaneous coronary intervention (PCI) with drug-eluting stents and coronary artery bypass grafting (CABG) for patients with left main coronary artery disease (LMCAD) have reported conflicting results.

Objectives

We performed a systematic review from inception to 23 May 2021 and one-stage reconstructed individual-patient data meta-analysis (IPDMA) that included 10-year mortality outcomes.

Methods

The primary outcome was 10-year all-cause mortality. Secondary outcomes included myocardial infarction (MI), stroke and unplanned revascularization at 5 years. We did IPDMA using published Kaplan-Meier curves to provide individual data points in coordinates and numbers at risk were used to increase the calibration accuracy of the reconstructed data. Shared frailty model or, when proportionality assumptions were not met, a restricted mean survival time model were fitted to compare outcomes between treatment groups.

Results

Of 583 articles retrieved, 5 RCTs were included. A total of 4595 patients from these 5 RCTs were randomly assigned to PCI (N=2297) or CABG (N=2298). The cumulative 10-year all-cause mortality after PCI and CABG was 12.0% versus 10.6% respectively (HR 1.093, 95% CI: 0.925–1.292; p=0.296). PCI conferred similar time-to-MI (RMST ratio 1.006, 95% CI: 0.992–1.021, p=0.391) and stroke (RMST ratio 1.005, 95% CI: 0.998–1.013, p=0.133) at 5 years. Unplanned revascularization was more frequent following PCI compared with CABG (HR 1.807, 95% CI: 1.524–2.144, p<0.001) at 5 years.

Conclusion

This meta-analysis using reconstructed participant-level time-to-event data showed no statistically significant difference in cumulative 10-year all-cause mortality between PCI versus CABG in the treatment of LMCAD.

Funding Acknowledgement

Type of funding sources: None.

Higher long-term mortality in patients with concomitant acute coronary syndrome and aortic stenosis

Background

Aortic stenosis (AS) and acute coronary syndrome (ACS) share similar cardiovascular risk factors, and their concomitant presentation is increasing in incidence with the aging population. Yet literature regarding the prognosis of patients with concomitant ACS and AS remains scarce.

Methods

This retrospective cohort study examined consecutive patients presenting with ACS (ST-segment elevation myocardial infarction [STEMI] and non-STEMI [NSTEMI]) and concomitant AS between 1 January 2011 and 31 March 2021 in a tertiary hospital. The cohort was divided into mild, moderate and severe AS based on index echocardiogram. The primary outcome was all-cause mortality. Kaplan-Meier curves were constructed to compare all-cause mortality among the three groups of patients, based on ACS type and left ventricular ejection fraction (LVEF). Multivariable Cox regression was performed to identify independent predictors of all-cause mortality.

Results

Of a total of 563 patients, 264 had mild (46.9%), 193 moderate (34.3%) and 106 severe AS (18.8%). The mean follow-up duration was 2.5 (± 2.4) years. Majority of patients (72.5%) presented with NSTEMI. Patients with moderate and severe AS had higher rates of all-cause mortality compared to those with mild AS (49.7% vs. 51.4% vs. 35.6% respectively, p=0.002). Concomitant moderate (HR 1.439, 95% CI 1.012–2.048, p=0.043) and severe AS (HR 1.844, 95% CI 1.159–2.933, p=0.010) were independent predictors of all-cause mortality after adjusting for age, gender, LVEF, ACS type, chronic kidney disease, diabetes, hypertension, coronary artery bypass grafting and aortic valve replacement as a time-dependent variable. The Kaplan-Meier curves demonstrated excess mortality in moderate and severe AS, compared to the mild AS group (p<0.001), with similar survival trends observed in the STEMI and the NSTEMI groups, as well as those with preserved LVEF.

Conclusion

Regardless of the ACS presentation type, long-term excess mortality in those with concomitant moderate or severe AS was observed. The adverse prognosis typically observed in patients with concomitant severe AS, in the setting of ACS, extends to patients with moderate AS.

Funding Acknowledgement

Type of funding sources: None.

Association of body mass index with long-term outcomes after elective and semi-urgent percutaneous coronary intervention

Background

While obesity is associated with cardiovascular mortality and morbidity, patients with higher body mass index (BMI) may have better outcomes post-percutaneous coronary intervention (PCI). This “obesity paradox” is controversial and needs clarification.

Purpose

We aimed to investigate the relationship between BMI and outcomes post-PCI in an Asian cohort.

Methods

A retrospective cohort study was performed on consecutive patients who underwent semi-urgent PCI for non-ST elevation myocardial infraction or unstable angina, and elective PCI for stable angina from January 2014 to December 2015 in a tertiary centre. Patients were underweight (BMI <18.5), normal weight (BMI 18.5–22.9), overweight (BMI 23–24.9), pre-obese (BMI 25–29.9) or obese (BMI ≥30), according to the WHO Asian classification. The primary endpoint was all-cause mortality. The secondary outcomes were subsequent events of stroke or transient ischemic attack, myocardial infarction (MI) and congestive cardiac failure (CCF).

Results

1,610 patients were followed up for 3.71 (±0.97) years, 19.7% were female and mean age was 62.1 years (Table 1). BMI showed a U-shaped relationship with the incidence of death (p<0.001), MI (p=0.005), and CCF (p<0.001) (Figure 1A), which was also shown on Kaplan Meier analysis (Figures 1B-E). With reference to normal weight patients on multivariable Cox analysis, overweight (adjusted HR 0.64, 95% CI 0.42–0.97) and pre-obese (adjusted HR 0.55, 95% CI 0.38–0.80) patients had lower mortality. Underweight patients had higher risk (adjusted HR 2.12, 95% CI 1.01–4.46), while pre-obese patients had lower risk of MI (adjusted HR 0.56, 95% CI 0.34–0.92) compared to normal weight patients. Underweight and obese patients had higher risk of CCF (underweight: adjusted HR 3.05, 95% CI 1.45–6.42; obese: adjusted HR 1.86, 95% CI 1.03–3.35) compared to normal weight patients.

Conclusion

Patients at the lower and upper extremes of BMI demonstrated higher risk of mortality, MI and CCF post-PCI.

Funding Acknowledgement

Type of funding sources: None.

Clinical characteristics, echocardiographic features and long-term outcomes of patients with ischaemic versus non-ischaemic left ventricular thrombus

Background

Left ventricular thrombus (LVT) may develop in patients following myocardial infarction (MI), as well as in ischaemic and non-ischaemic cardiomyopathies, and may result in acute ischaemic stroke. Smaller studies comparing LVT associated with ischaemic and non-ischaemic aetiologies only reported 1-year outcomes or focused on specific subpopulations. We aimed to compare the clinical and echocardiographic characteristics and longer-term outcomes in a large population of patients with ischaemic versus non-ischaemic LVT.

Methods

This was a retrospective study of 552 consecutive patients with echocardiographically-identified LVT from March 2011 to January 2021 at a tertiary centre. Ischaemic LVT included LVT associated with MI and ischaemic cardiomyopathy. Non-ischaemic LVT included cases without evidence of ischaemia. Echocardiographic images were interpreted by trained cardiologists. We studied thrombus resolution as well as 5-year rates of ischaemic stroke and all-cause mortality.

Results

Of the 552 patients, mean age was 59.9 years and 84.4% were male. 492 patients had ischaemic LVT and 60 patients had non-ischaemic LVT. Ischaemic LVT was associated with older age (60.4 versus 55.3 years), male sex (86.8% versus 65.0%), smoking (49.2% versus 25.0%) and hyperlipidaemia (54.3% versus 28.3%). Left ventricular ejection fraction (LVEF) was lower in non-ischaemic LVT (28.9% versus 31.9%). LVEF ≤35% was associated with increased mortality in ischaemic LVT (HR 2.11, 95% CI 1.32–3.38). Rates of thrombus resolution, stroke and all-cause mortality were similar in the 2 groups. Anticoagulation was associated with a lower risk of stroke in ischaemic LVT (HR 0.32, 95% CI 0.16–0.66) and lower mortality in both ischaemic (HR 0.44, 95% CI 0.26–0.72) and non-ischaemic LVT (HR 0.14, 95% CI 0.03–0.61).

Conclusion

Patients with ischaemic LVT were more often older, male, smokers and had cardiovascular co-morbidities compared to those with non-ischaemic LVT. Thrombus resolution, stroke and all-cause mortality rates were similar in both groups. Anticoagulation was associated with lower mortality but this needs to be investigated in future prospective studies.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): CHS was supported by the National University of Singapore Yong Loo Lin School of Medicine's Junior Academic Faculty Scheme

Prognostically distinct phenotypes of metabolic health beyond obesity in aortic stenosis

Background

Whilst current evidence are in favour of metabolic health and non-obesity in the reduction of incident cardiovascular disease, little is known regarding the prognosis across the metabolic phenotypes once cardiovascular disease occurs. This study examined the prognosis of patients with significant aortic stenosis (AS) based on the presence of metabolic health and obesity.

Methods

This retrospective cohort on consecutive patients presenting with moderate-to-severe AS to a tertiary hospital between 2010 and 2015. Patients were allocated into 4 groups based on obesity and metabolic health: metabolically healthy obese (MHO), metabolically healthy non-obese (MHNO), metabolically unhealthy obese (MUO) and metabolically unhealthy non-obese (MUNO). Metabolic health was defined in accordance to Program Adult Treatment Panel III criteria. The primary outcome was all-cause mortality. Cox regression examined independent associations between mortality and metabolic phenotypes, adjusting for aortic valve area, ejection fraction, age, sex, chronic kidney disease and AVR as a time-dependent covariate.

Results

Of 727 patients, the majority (51.6%) were MUNO, followed by MUO (32.7%), MHNO (11.4%), and MHO (4.3%). MHNO had the highest mortality (43.0%), followed by the MUNO (37.5%), MUO (30.0%) and MHO (6.9%) groups (p=0.001). Compared to MHNO, MHO (HR 0.159, 95% CI 0.038–0.668, p=0.012) and MUO (HR 0.614, 95% CI 0.403–0.937, p=0.024) were independently associated with lower all-cause mortality rates, after adjusting for confounders. In obese patients, metabolic health had favourable survival compared to metabolically unhealthy (p=0.015), but this protective impact of metabolic health was not observed in overweight or normal weight individuals. Obesity had favourable survival compared to overweight and normal weight, in both metabolically health (p=0.002) and unhealthy (p=0.007) patients,

Conclusion

MHO patients with AS have the most favourable prognosis whilst the seemingly healthy MHNO group had the worst survival. There should be a paradigm shift towards prioritising metabolic health rather than weight reduction in patients with significant AS.

Funding Acknowledgement

Type of funding sources: None.

Streptomyces sp. AC04842: Genomic Insights and Functional Expression of Its Latex Clearing Protein Genes (lcp1 and lcp2) When Cultivated With Natural and Vulcanized Rubber as the Sole Carbon Source

Rubber-degrading Actinobacteria have been discovered and investigated since 1985. Only recently, through the advancement of genomic sequencing and molecular techniques, genes and pathways involved in rubber degradation are being revealed; however, the complete degradation pathway remains unknown. Streptomyces sp. AC04842 (JCM 34241) was discovered by screening at a Culture Collection Centre in Sarawak for Actinomycetes forming a clear zone on natural rubber latex agar. Streptomyces is a dominant and well-studied soil bacterium playing an important role in soil ecology including carbon recycling and biodegradation. Streptomyces sp. AC04842 draft genome revealed the presence of 2 putative latex clearing protein (lcp) genes on its chromosome and is closely related to Streptomyces cellulosae. Under the Streptomyces genus, there are a total of 64 putative lcp genes deposited in the GenBank and UniProt database. Only 1 lcp gene from Streptomyces sp. K30 has been characterized. Unlike Streptomyces sp. K30 which contained 1 lcp gene on its chromosome, Streptomyces sp. AC04842 contained 2 lcp genes on its chromosome. Streptomyces sp. AC04842 lcp1 and lcp2 amino acid sequences showed 46.13 and 69.11%, respectively, similarity to lcp sequences of Streptomyces sp. K30. Most rubber degrading strains were known to harbor only 1 lcp gene, and only recently, 2–3 lcp homologs have been reported. Several studies have shown that lcp-homolog expression increased in the presence of rubber. To study the expression of lcp1 and lcp2 genes for Streptomyces sp. AC04842, the strain was incubated in different types of rubber as the sole carbon source. In general, the lcp1 gene was highly expressed, while the lcp2 gene expression was upregulated in the presence of vulcanized rubber. Mixtures of natural and vulcanized rubber did not further increase the expression of both lcp genes compared with the presence of a specific rubber type. In this study, we paved the way to the exploration of lcp homologs and their function in degrading different types of rubber.

Rubber Degrading Strains: Microtetraspora and Dactylosporangium

Rubber composed of highly unsaturated hydrocarbons, modified through addition of chemicals and vulcanization are widely used to date. However, the usage of rubber, faces many obstacles. These elastomeric materials are difficult to be re-used and recovered, leading to high post-consumer waste and vast environmental problems. Tyres, the major rubber waste source can take up to 80 years to naturally degrade. Experiments show that the latex clearing proteins (Lcp) found in Actinobacteria were reportedly critical for the initial oxidative cleavage of poly(cis-1,4-isoprene), the major polymeric unit of rubber. Although, more than 100 rubber degrading strains have been reported, only 8 Lcp proteins isolated from Nocardia (3), Gordonia (2), Streptomyces (1), Rhodococcus (1), and Solimonas (1) have been purified and biochemically characterized. Previous studies on rubber degrading strains and Lcp enzymes, implied that they are distinct. Following this, we aim to discover additional rubber degrading strains by randomly screening 940 Actinobacterial strains isolated from various locations in Sarawak on natural rubber (NR) latex agar. A total of 18 strains from 5 genera produced clearing zones on NR latex agar, and genes encoding Lcp were identified. We report here lcp genes from Microtetraspora sp. AC03309 (lcp1 and lcp2) and Dactylosporangium sp. AC04546 (lcp1, lcp2, lcp3), together with the predicted genes related to rubber degradation. In silico analysis suggested that Microtetraspora sp. AC03309 is a distinct species closely related to Microtetraspora glauca while Dactylosporangium sp. AC04546 is a species closely related to Dactylosporangium sucinum. Genome-based characterization allowed the establishment of the strains taxonomic position and provided insights into their metabolic potential especially in biodegradation of rubber. Morphological changes and the spectrophotometric detection of aldehyde and keto groups indicated the degradation of the original material in rubber samples incubated with the strains. This confirms the strains’ ability to utilize different rubber materials (fresh latex, NR product and vulcanized rubber) as the sole carbon source. Both strains exhibited different levels of biodegradation ability. Findings on tyre utilization capability by Dactylosporangium sp. AC04546 is of interest. The final aim is to find sustainable rubber treatment methods to treat rubber wastes.

Inhibition Effect of Extract of Psychotria viridiflora Stem on α-Amylase and α-Glucosidase and Its Application in Lowering the Digestibility of Noodles

A collection of tropical medicinal plants from East Malaysia's rainforests are used by indigenous tribes for their curative properties. Despite their purported healing properties, these forest plant species are largely unexplored and hence remain virtually unknown to the outside world. In this study, antidiabetic properties of Psychotria viridiflora, a plant used to treat diabetes by a local community in Sarawak, Malaysia were investigated. Ethyl acetate (EA) extract of P. viridiflora stem was found to exhibit high starch hydrolase inhibition activity with an IC₅₀ value of 15.4 ± 2.1 μg/ml against porcine α-amylase and an IC₅₀ value of 32.4 ± 3.7 μg/ml against rat intestinal α-glucosidase. A complex mixture of A-type oligomeric proanthocyanidins containing (epi)fisetinidol, (epi)afzelechin, (epi)guibourtinidol, and (epi)catechin were found. These compounds may be responsible for the starch hydrolase inhibition activity. Ethyl acetate (EA) extract of P. viridiflora stem was incorporated into wheat and rice flour to reformulate noodles with slow digestibility and was assessed under in vitro simulated gastrointestinal conditions. A dose-dependent effect on digestibility was observed for both noodles upon incorporation of 1-6% (w/w) of EA extract, with noodles containing 6% (w/w) extract exhibiting the greatest reduction in digestibility. As compared to rice noodles containing 6% extract (31.16% inhibition), wheat noodles with the same extract concentration had a smaller decline in digestibility (27.25% inhibition) after 180 min. Overall, our findings highlight the potential of P. viridiflora in the prevention of postprandial hyperglycaemia.

ACTINOMYCETES ISOLATED FROM WETLAND AND HILL PADDY DURING THE WARM AND COOL SEASONS IN SARAWAK, EAST MALAYSIA

As part of the Natural Product Discovery programme at Sarawak Biodiversity Centre (SBC), our study targeted isolation and evaluation of actinomycetes diversity from paddy rice fields. Samples from two types of paddy farming system practiced in Sarawak, wet land and hill paddy, were collected and processed leading to the selection of 578 strains distributed among 24 genera and 10 families. Analysis using phylogenetic clustering indicated a total of 159 taxonomic units (TU). The taxonomic position and the ranking of the TU allowed their classification in 4 novel species, 61 putative novel species and 94 known species or species of uncertain position. The high genus diversity and percentage of novel or putative novel species demonstrate the biodiversity potential of Sarawak ecosystems, even in man-managed ecosystems.

P263 Characterisation of patients with acute myocardial infarction complicated by left ventricular thrombus

Funding Acknowledgements

None

Background/Introduction

Left ventricular (LV) thrombus is a widely recognized complication of acute myocardial infarction (AMI).  Limited data are available from South East Asian patients with this post-infarction complication nor on whether patients with non-ST segment elevation myocardial infarction (NSTEMI) or STEMI with associated LV thrombosis exhibit differing clinical characteristics and/or outcomes. Left Ventricular Ejection Fraction (LVEF) ≤ 40% is a recognized predictor of LV thrombus formation, but there is limited data on LV thrombus patients with EF > 40% or in NSTEMI patients.

Purpose

This study aims to investigate and compare the clinical characteristics, treatment and outcomes of post-AMI patients with LV thrombus formation, with a particular emphasis on those with EF ≤ 40% and in NSTEMI patients. 

Methods

Among 5829 consecutive echocardiogram results containing the keyword "thrombus" from August 2006 to September 2017, we identified 289 post-AMI patients with acute LV thrombus formation. Demographics, treatment and outcome measures were analysed.

Results

Cardiovascular risk factors such as dyslipidaemia (54.0%) and hypertension (50.5%) were commonly present in post-AMI patients with LV thrombus. Mean LVEF was 33.0 ± 10.4%. The majority (68.0%) of patients received triple therapy and 59.5% achieved thrombus resolution. NSTEMI patients had greater number of co-morbidities including heart failure (p < 0.01), documented history of  ischaemic heart disease preceding the AMI leading to thrombus formation (p < 0.01) and lower LVEF (28.3 ± 9.3% vs. 34.8 ± 10.3% , p < 0.01) compared with STEMI cases. On multivariate analysis, having a lower EF was a significant independent predictor of stroke (HR 0.96, 95% CI 0.93-1.00, p = 0.03) and all-cause mortality (HR 0.95, 95% CI 0.92-0.99, p < 0.01). The categories of STEMI and NSTEMI did not predict thrombus resolution, stroke events or all-cause mortality after adjustment.

Conclusion(s)

  Post-AMI LV thrombus patients with NSTEMI and STEMI differed in terms of their co-morbidities in their demographics and co-morbidities but it was a lower EF that was associated with an increased risk of stroke and all-cause mortality. Further studies on this topic are required.

P910An Asian perspective on left ventricular outflow tract cut-offs and the resulting discrepancy in severity grading of aortic stenosis

Objectives

Inconsistencies in grading of aortic stenosis (AS) severity have been reported based on measurement of left ventricular outflow tract diameter (LVOTd), but this remains to be studied in an Asian population. We investigated consistency of grading AS severity at various LVOTd, and subsequently postulated alternative cut-offs for more consistent grading of AS severity.

Methods

350 consecutive patients with index echocardiographic diagnosis of severe AS were divided them into three groups based on LVOTd: “small” (<20mm), “average” (20–22mm), “large” (>22mm). In each group, the consistency of flow-dependent (transaortic mean pressure gradient (MG)) and flow-independent parameters (AVA) were used for classification of AS severity.

Results

Of 350 patients, 51.7% had small LVOTd, while 30.8% and 17.5% had average and large LVOTd respectively. Consistent grading by LVOTd based on AVA and MG, was seen in 33.7% of patients with small, 47.6% with average, 57.7% with large LVOTd. When the hypothetical AVA cut-off of 0.9cm2 was used, consistent grading improved to 38.0% in small, 56.5% in average and 70% in large LVOTd. At an AVA cut-off of 0.8cm2, there was further incremental improvement in the small LVOTd group to 54.1% (p<0.05).

Table 1. Consistent grading by LVOTd based on current guidelines Small LVOTd (<20mm, n=181) Average LVOTd (20–22mm, n=108) Large LVOTd (>22mm, n=61) Consistent grading AVA < cut-off MG >40 Consistency (%) Consistent grading AVA < cut-off MG >40 Consistency (%) Consistent grading AVA < cut-off MG >40 Consistency (%) n=61 33.7 n=51 47.6 n=35 57.7 n=69 38 n=61 56.5 n=43 70* n=98 54.1*+ n=70 65.1* n=43 70.8* *p-value <0.05 when compared with AVA cut-off 0.8cm2 for each LVOTd category; +p-value <0.05 when compared with AVA cut-off 0.9cm2 for each LVOTd category.

Figure 1

Conclusion

Current severe AS guidelines are most consistent with those in the large LVOTd group. However, the majority of the study's Asian population is in the small LVOTd group, which is the group most susceptible to discrepancy in AS grading. Improved consistency in echocardiographic grading may be attained with a lower AVA cut-off in this Asian cohort.

P3366Increased left ventricular remodelling index in paradoxical low-flow severe aortic stenosis with preserved left ventricular ejection fraction compared to normal-flow

Background

Left Ventricular Remodelling Index (LVRI) has been demonstrated to be able to reliably discriminate between an athlete's heart and pathological LV remodelling. Patients with paradoxical low-flow severe aortic stenosis (LF AS) despite preserved left ventricular ejection fraction (LVEF) are a distinct group from normal-flow (NF) with poorer prognosis, more concentric hypertrophy and smaller LV cavities.

Purpose

We compared LVRI in LF compared to NF AS and examined clinical outcomes.

Methods

We studied consecutive patients with index echocardiographic diagnosis of severe AS (aortic valve area<1cm2) with preserved LVEF (>50%). LVRI was determined by the ratio of LV mass to the end-diastolic volume.

Results

Of the 450 patients studied, 149 (33.1%) were LF. There were no significant differences in baseline clinical profile of patients between LF and NF. LVRI was significantly higher in patients with LF compared to NF (2.27±0.68 vs 1.85±0.53 g/ml, p<0.001). Patients with high LVRI (>1.56 g/ml) had poorer clinical outcomes in terms of mortality (log-rank 9.18, p=0.002) and admissions for cardiac failure (log-rank 7.61, p=0.006).

Low-flow (n=149) Normal-flow (n=301) Mean difference/Odds Ratio (95% CI) p-value Age (years) 73.5 (±12.8) 71.0 (±13.1) 2.5 (−0.1 to 5.1) 0.053 Body Mass Index (g/m2) 24.6 (±5.6) 24.7 (±5.3) −0.1 (−1.2 to 1.1) 0.877 Gender (male) 49 (32.9%) 125 (41.5%) 0.7 (0.5 to 1.1) 0.076 Hypertension 100 (67.1%) 195 (64.8%) 1.1 (0.7 to 1.7) 0.624 Diabetes 57 (38.3%) 100 (33.2%) 1.2 (0.8 to 1.9) 0.295 Hyperlipidaemia 79 (53.0%) 147 (49.0%) 1.2 (0.8 to 1.7) 0.425 End-diastolic volume (ml) 72.3 (±18.9) 112.6 (±26.3) −40.2 (−44.9 to −35.5) <0.001 Left ventricular ejection fraction (%) 66.0 (±7.9) 67.4 (±7.1) −1.4 (−2.9 to 0.2) 0.077 Left ventricular mass index (g/m2) 99.7 (±33.0) 126.8 (±37.4) −27.2 (−34.8 to −19.6) <0.001 Transaortic mean pressure gradient (mmHg) 32.2 (±17.4) 37.1 (±19.9) −4.9 (−8.6 to −1.1) 0.011 Aortic valve area (cm2) 0.78 (±0.16) 0.79 (±0.17) 0.1 (−0.2 to 0.1) 0.635 Stroke volume index (ml/m2) 28.6 (±5.6) 46.9 (±9.8) −18.3 (−20.0 to −16.6) <0.001 Left ventricular remodelling index (LVRI, g/ml) 2.27 (±0.68) 1.85 (±0.53) 0.42 (0.31 to 0.54) <0.001

LVRI in LF versus NF AS

Conclusion

Pathological LV remodelling as evidenced by increased LVRI was more common in LF compared to NF AS. Patients with increased LVRI also had worse clinical outcomes.

Acknowledgement/Funding

None

Luteipulveratus halotolerans sp. nov., an actinobacterium (Dermacoccaceae) from forest soil

The taxonomic position of an actinobacterium strain, C296001T, isolated from a soil sample collected in Sarawak, Malaysia, was established using a polyphasic approach. Phylogenetically, strain C296001T was closely associated with the genus Luteipulveratus and formed a distinct monophyletic clade with the only described species, Luteipulveratus mongoliensis NBRC 105296T. The 16S rRNA gene sequence similarity between strain C296001T and L. mongoliensis was 98.7 %. DNA–DNA hybridization results showed that the relatedness of strain C296001T to L. mongoliensis was only 21.5 %. The DNA G+C content of strain C296001T was 71.7 mol%. Using a PacBio RS II system, whole genome sequences for strains C296001T and NBRC 105296T were obtained. The genome sizes of 4.5 Mbp and 5.4 Mbp determined were similar to those of other members of the family Dermacoccaceae. The cell-wall peptidoglycan contained lysine, alanine, aspartic acid, glutamic acid and serine, representing the peptidoglycan type A4α l-Lys-l-Ser-d-Asp. The major menaquinones were MK-8(H4), MK-8 and MK-8(H2). Phosphatidylglycerol, phosphatidylinositol, diphosphatidylglycerol and phosphoglycolipid were the polar lipids, while the whole-cell sugars were glucose, fucose and lesser amounts of ribose and galactose. The major fatty acids were iso-C16 : 0, anteiso-C17 : 0, iso-C16 : 1 H, anteiso-C17 : 1ω9c, iso-C18 : 0 and 10-methyl C17 : 0. Chemotaxonomic analyses showed that C296001T had typical characteristics of members of the genus Luteipulveratus, with the main differences occurring in phenotypic characteristics. On the basis of the phenotypic and chemotaxonomic evidence, it is proposed that strain C296001T be classified as a representative of a novel species in the genus Luteipulveratus, for which the name Luteipulveratus halotolerans sp. nov. is recommended. The type strain is C296001T ( = ATCC TSD-4T = JCM 30660T).

Flemingin-Type Prenylated Chalcones from the Sarawak Rainforest Plant Desmodium congestum

In an ongoing program to identify new anti-infective leads, an extract derived from whole plant material of Desmodium congestum collected in the Sarawak rainforest was found to have anti-MRSA activity. Bioassay-guided isolation led to the isolation of two new prenylated chalcones, 5'-O-methyl-3-hydroxyflemingin A (1) and 5'-O-methylflemingin C (2), which were closely related to the flemingins previously isolated from various Flemingia species. Chalcones 1 and 2, which were determined to be 4:6 enantiomeric mixtures by chiral HPLC, exhibited moderate activity against a panel of Gram-positive bacteria and were also cytotoxic to the HEK293 human embryonic kidney cell line.

A nucleotide signature for identification of Aglaia stellatopilosa Pannell

Members of the genus Aglaia have been reported to contain bioactive phytochemicals. The genus, belonging to the Meliaceae family, is represented by at least 120 known species of woody trees or shrubs in the tropical rain forest. As some of these species are very similar in their morphology, taxonomic identification can be difficult. A reliable and definitive molecular method which can identify Aglaia to the level of the species will hence be useful in comparing the content of specific bioactive compounds between the species of this genus. Here, we report the analysis of DNA sequences in the internal transcribed spacer (ITS) of the nuclear ribosomal DNA and the observation of a unique nucleotide signature in the ITS that can be used for the identification of Aglaia stellatopilosa. The nucleotide signature consists of nine bases over the length of the ITS sequence (654 bp). This uniqueness was validated in 37 samples identified as Aglaia stellatopilosa by an expert taxonomist, whereas the nucleotide signature was lacking in a selection of other Aglaia species and non-Aglaia genera. This finding suggests that molecular typing could be utilized in the identification of Aglaia stellatopilosa.

Photodynamic activity of plant extracts from Sarawak, Borneo

Photodynamic therapy (PDT) is a medical treatment that involves the irradiation of an administered photosensitizing drug with light of a particular wavelength to activate the photosensitizer to kill abnormal cells. To date, only a small number of photosensitizers have been clinically approved for PDT, and researchers continue to look for new molecules that have more desirable properties for clinical applications. Natural products have long been important sources of pharmaceuticals, and there is a great potential for discovery of novel chemotypes from under-explored biodiversities in the world. The objective of this study is to mine the terrestrial plants in Sarawak, Borneo Island, for new photosensitizers for PDT. In a screening program from 2004 to 2008, we prepared and studied 2,400 extracts from 888 plants for their photosensitizing activities. This report details the bioprospecting process, preparation and testing of extracts, analysis of the active samples, fractionation of four samples, and isolation and characterization of photosensitizers.

Identification of traditional medicinal plant extracts with novel anti-influenza activity

The emergence of drug resistant variants of the influenza virus has led to a need to identify novel and effective antiviral agents. As an alternative to synthetic drugs, the consolidation of empirical knowledge with ethnopharmacological evidence of medicinal plants offers a novel platform for the development of antiviral drugs. The aim of this study was to identify plant extracts with proven activity against the influenza virus. Extracts of fifty medicinal plants, originating from the tropical rainforests of Borneo used as herbal medicines by traditional healers to treat flu-like symptoms, were tested against the H1N1 and H3N1 subtypes of the virus. In the initial phase, in vitro micro-inhibition assays along with cytotoxicity screening were performed on MDCK cells. Most plant extracts were found to be minimally cytotoxic, indicating that the compounds linked to an ethnomedical framework were relatively innocuous, and eleven crude extracts exhibited viral inhibition against both the strains. All extracts inhibited the enzymatic activity of viral neuraminidase and four extracts were also shown to act through the hemagglutination inhibition (HI) pathway. Moreover, the samples that acted through both HI and neuraminidase inhibition (NI) evidenced more than 90% reduction in virus adsorption and penetration, thereby indicating potent action in the early stages of viral replication. Concurrent studies involving Receptor Destroying Enzyme treatments of HI extracts indicated the presence of sialic acid-like component(s) that could be responsible for hemagglutination inhibition. The manifestation of both modes of viral inhibition in a single extract suggests that there may be a synergistic effect implicating more than one active component. Overall, our results provide substantive support for the use of Borneo traditional plants as promising sources of novel anti-influenza drug candidates. Furthermore, the pathways involving inhibition of hemagglutination could be a solution to the global occurrence of viral strains resistant to neuraminidase drugs.

'Office-hour' ambulatory blood pressure monitoring is sufficient for blood pressure diagnosis

We conducted this study to determine whether 'office hour', defined as time period from 0800 to 1800 hours, ambulatory blood pressure monitoring (ABPM) predicts daytime ('waking-hour') and 24-h ABPM results, and to examine the impact of sleep disturbance on ABPM and nocturnal dip. Eighty-four patients (mean age 49+/-18 years, 47 males) were studied. Systolic, diastolic and mean 4-, 6-, 8-, 'office-hour' as well as 'waking-hour' blood pressures (BPs) were obtained from 24-h ABPM readings. Of these, no statistical differences were found between 8-h and 'office-hour' systolic, diastolic and mean BPs compared to 'waking-hour' values. There was complete concordance between 'office-hour' and 'waking-hour' ABPM diagnosis based on British Hypertension Society definitions. Sleep disturbance was found in 22 patients (26%). Although nocturnal dip was not significantly different in either sleep-disturbed or non-disturbed patients, patients who reported sleep disturbance had significantly higher proportion of borderline/abnormal BP diagnosis compared to non-sleep-disturbed counterpart during both 'waking hour' and night time. In patients without sleep disturbance, there was complete concordance between 'office-hour', 'waking-hour' and 24-h ABPM diagnosis based on British Hypertension Society definitions. 'Office-hour' ABPM is predictive of 'waking-hour' and 24-h ambulatory BP readings. Sleep disturbance is common in patients undergoing the test, and significantly raises the BP readings. We therefore propose 'office-hour' ABPM as an accurate, reliable and comfortable method of continual non-invasive BP monitoring, and omitting routine night time BP monitoring.

High-sensitivity C-reactive protein is predictive of medium-term cardiac outcome in high-risk Asian patients presenting with chest pain syndrome without myocardial infarction

INTRODUCTION

High-sensitivity C-reactive protein (hs-CRP) has been shown to be predictive of cardiac events but data among Asians is comparatively few. We evaluated the role of hs-CRP in the prediction of adverse cardiac outcome in a cohort of high-risk patients presenting with chest pain syndrome without myocardial infarction (MI).

MATERIALS AND METHODS

Three hundred and forty-seven patients were prospectively recruited over an 18-month period and patients with MI as documented by serial electrocardiogram abnormalities, and creatinine kinase or troponin elevation were excluded. Mean follow-up duration was 901 +/- 306 days. Kaplan-Meier and Cox proportional hazards modelling were used to evaluate outcome and determine association with predictor variables.

RESULTS

The composite primary endpoint of cardiac mortality, non-fatal MI, cardiac failure or coronary revascularisation procedure (coronary artery bypass grafting or angioplasty) unrelated to the index admission was reached in 37 patients. History of previous MI (P = 0.002), presence of at least 1 coronary artery with > or =50% stenosis (P = 0.028) and elevated hs-CRP levels were associated with an adverse cardiac outcome (P = 0.001 for CRP in the upper quartile, and 0.002 for CRP > or = 1mg/L, respectively). None of the traditional cardiovascular risk factors (hypertension, diabetes mellitus, dyslipidaemia, significant family history, smoking, male gender and increased age) was predictive. Multivariate modelling showed elevated hs-CRP to confer the highest risk for an adverse cardiac outcome (P <0.001).

CONCLUSION

Hs-CRP is useful in further stratifying high-risk multi-ethnic patients presenting with chest pain despite no evidence of MI. Close follow-up and aggressive management of these patients may be warranted.

The impact of diabetes mellitus on the prognostic value of a normal dobutamine stress echocardiogram in patients with intermediate to high cardiovascular risk

INTRODUCTION

There is currently limited data on the prognostic value of a normal dobutamine stress echocardiogram (DSE) in patients with intermediate to high cardiovascular risk. The impact of diabetes mellitus, recently recognised as a cardiovascular risk-equivalent, has not been previously evaluated. This study aims to determine the prognostic value of a normal DSE in these patients.

METHODS

The study population includes all patients with two cardiovascular risk factors or diabetes mellitus and a normal DSE (baseline and peak stress) with three months follow-up. A total of 122 patients (47 females, 75 males; mean age 59.6 years) were recruited. Impact of diabetes mellitus on subsequent cardiovascular events was determined.

RESULTS

Diabetes mellitus was present in 32.8 percent, hypertension in 72.1 percent, smoking in 27.0 percent, family history of premature coronary artery disease in 15.6 percent, and hypercholesterolemia in 66.4 percent. On follow-up until 6.4 years (mean 4.1 years), there were four myocardial infarctions (0.8 percent per patient/year) and five revascularisation procedures (1.0 percent per patient/year). The majority of adverse events occurred among patients with diabetes mellitus (three out of four myocardial infarctions; four out of five revascularisations). Diabetes mellitus independently predicted subsequent cardiac events on both univariate and multivariate analyses (p value is equal to 0.015 and 0.011, respectively). Presence of diabetes mellitus also conferred a worse outcome on survival analysis (p value is equivalent to 0.0046).

CONCLUSION

The presence of diabetes mellitus adversely affects clinical outcome despite a normal DSE. Patients without diabetes mellitus, but with intermediate to high cardiovascular risk, and a normal DSE have a better medium term outcome.

V(D)J rearrangement in Nijmegen breakage syndrome

Repair of DNA double-strand breaks is essential for maintenance of genomic stability, and is specifically required for rearrangement of immunoglobulin (Ig) and T cell receptor (TCR) loci during development of the immune system. Abnormalities in these repair processes also contribute to oncogenic chromosomal rearrangements that underlie many lymphoid malignancies. Nijmegen breakage syndrome (NBS) is a rare autosomal recessive condition characterized by immunodeficiency, radiation sensitivity, and increased predisposition to lymphoid cancers bearing oncogenic Ig and TCR locus translocations. NBS patients fail to produce nibrin, a protein required for the nuclear localization and function of a DNA repair complex that includes Mre11 and Rad50. Mre11 has biochemical properties that suggest a potential role in V(D)J recombination. We studied V(D)J recombination in NBS cells in vitro and in vivo, using cell lines and peripheral blood leukocyte DNA from NBS patients. We found that NBS cells were competent to rejoin signal substrates with normal efficiency and high fidelity. Coding substrates were similarly rejoined efficiently, and coding end structures appeared normal. In B cells from NBS patients, the spectrums of IgH CDR3 regions were diverse and normally distributed. Moreover, the lengths and composition of Igkappa VJ joins and IgH VDJ joins derived from NBS and normal subjects were indistinguishable. Our data indicate that nibrin plays no essential role in V(D)J recombination and is not required for the generation of an apparently diverse B cell repertoire.

Identification, characterization, and mapping of a mouse homolog of the gene mutated in Nijmegen breakage syndrome

The rare autosomal recessive disorder Nijmegen breakage syndrome (NBS) results from mutations in the NBS1 gene on human chromosome 8q21. A mouse homolog of the NBS1 gene was isolated and its nucleotide sequence determined. Somatic cell hybrid analysis and fluorescence in situ hybridization were used to map this gene, Nbn, to mouse chromosome band 4A. Northern blotting revealed comparable levels of Nbn transcripts in most tissues in the mouse. However, transcripts were elevated 10-20 fold in the testes, consistent with a possible role for the product of the Nbn gene in meiotic recombination.

Retroviral expression of the NBS1 gene in cultured Nijmegen breakage syndrome cells restores normal radiation sensitivity and nuclear focus formation

The majority of cases of the autosomal recessive disorder Nijmegen breakage syndrome (NBS) are associated with null mutations in the NBS1 gene, which encodes a 95 kDa protein, nibrin. Cell lines established from NBS patients fail to express nibrin and display hypersensitivity to ionizing radiation and dysregulation of the nuclear localization of two key proteins involved in DNA repair, Mre11 and Rad50. Conclusive proof that mutations in the NBS1 gene are responsible for NBS requires that re-expression of normal nibrin in NBS cells complements these phenotypes. In the current study, retroviral expression vectors containing a normal copy of the NBS1 gene or a mutated form derived from a NBS patient were introduced into a well- characterized NBS cell line. Introduction of a normal copy of the NBS1 gene, but not the mutant form, resulted in robust expression of nibrin that displayed correct nuclear localization. Expression of nibrin also restored the ability of nibrin, Mre11 and Rad50 to complex and to redistribute within the nucleus in response to ionizing radiation. Radiation sensitivity of NBS cells expressing wild-type nibrin was restored to normal levels. Hence, introduction of the NBS1 gene can correct the phenotypes observed in NBS cells.

Clinical characteristics and outcome in postinfarction pseudoaneurysm

The clinical characteristics and outcome in 22 patients with postinfarction pseudoaneurysm were studied. The medium-term outcome was poor (median follow-up 3.6 years), but cardiac rupture was uncommon in patients treated conservatively.

Spontaneous aortic laceration causing flail aortic valve and acute aortic regurgitation

Spontaneous laceration of the aorta is an unusual cause of flail aortic valve. We report a case of acute aortic regurgitation caused by flail aortic valve as a result of spontaneous laceration of the ascending aorta. The role of transesophageal echocardiography in the diagnosis of this condition is discussed.

Prognostic value of a Doppler index combining systolic and diastolic performance in idiopathic-dilated cardiomyopathy

This study sought to investigate, in patients with idiopathic-dilated cardiomyopathy, the clinical and prognostic value of a Doppler-derived index of myocardial function that combines systolic and diastolic time intervals of the left heart cycle. The Doppler index was measured in 75 patients (aged 61 +/- 13 years; 45 men and 30 women) in sinus rhythm and 75 age- and sex-matched controls. Ejection time was measured from the left ventricular outflow Doppler signal. The sum of isovolumic times was obtained by subtracting the ejection time from the interval between cessation and onset of mitral inflow measured from the mitral inflow velocity profile. The index was the sum of isovolumic times divided by ejection time. The values of the Doppler index in patients with idiopathic-dilated cardiomyopathy (0.85 +/- 0.32) were significantly higher than values in controls (0.37 +/- 0.08, p < 0.001). During follow-up of 5 years, 1 patient underwent cardiac transplantation and 36 patients died, 29 of cardiac, 5 of noncardiac, and 2 of unknown causes. Univariate analysis demonstrated that the Doppler index (chi-square = 18.3, p < 0.001), ejection fraction (chi-square = 15.2, p <0.001), symptom status (chi-square = 9.2, p = 0.002), and mitral deceleration time (chi-square = 5.2, p = 0.02) were significant predictors of outcome. However, multivariate stepwise analysis of these variables showed that the Doppler index (chi-square = 10.7, p = 0.001) and ejection fraction (chi-square = 6.7, p = 0.01) were the most significant independent predictors of outcome. The Doppler index reflects disease severity and has incremental prognostic value in dilated cardiomyopathy. Ease of use, nongeometric dependency, excellent separation of clinical groups, and a strong relation to outcome enhance its appeal.

Mechanisms of hemolysis after mitral valve repair: assessment by serial echocardiography

OBJECTIVES

We sought to determine, using serial echocardiography, the hydrodynamic mechanisms involved in the occurrence of hemolysis after mitral valve repair.

BACKGROUND

Recently, fluid dynamic simulation models have identified distinct patterns of mitral regurgitant flow disturbances in patients with mitral prosthetic hemolysis that were associated with high shear stress and may therefore produce clinical hemolysis. Rapid acceleration, fragmentation, and collision jets were associated with high shear stress and hemolysis whereas slow deceleration and free jets were not.

METHODS

We reviewed serial echocardiographic studies of 13 consecutive patients with hemolytic anemia after mitral valve repair who were referred for mitral reoperation between January 1985 and December 1996 (group 1). Thirteen patients undergoing reoperation for mitral regurgitation after mitral valve repair but without hemolysis served as controls (group 2).

RESULTS

The mitral regurgitant jet was central in origin in 12 group 1 patients and 9 group 2 patients (Fisher exact test, p= 0.3). The other patients had para-ring regurgitation. Group 1 patients had collision (n=11), rapid acceleration (n=2) or fragmentation (n=1) jets whereas group 2 patients had slow deceleration (n=11) or free jets (n=2) (Fisher exact test, p < 0.0001). One patient with hemolysis had both collision and rapid acceleration jets. The "culprit" jet could be identified on the postbypass transesophageal echocardiography (TEE) study in only 1 patient at the time of initial mitral repair. Twelve group 1 patients underwent reoperation, with subsequent resolution of hemolysis in all patients. At reoperation, the initial repair was found to be intact in 8 (67%) patients.

CONCLUSION

Distinct patterns of flow disturbance associated with high shear stress were identified by color Doppler imaging in patients with hemolysis after mitral valve repair. The majority (92%) of these color flow disturbances were not present during intraoperative postbypass TEE study after initial mitral repair and subsequently developed in the early postoperative period.

Value of a Doppler-derived index combining systolic and diastolic time intervals in predicting outcome in primary pulmonary hypertension

Primary pulmonary hypertension is characterized by elevated pulmonary arterial pressure and vascular resistance, frequently producing right heart failure and death. Therefore, the Doppler right ventricular (RV) index, which is a measure of global RV function, could be a useful predictor of outcome in primary pulmonary hypertension. The Doppler RV index, defined as the sum of isovolumic contraction time and isovolumic relaxation time divided by ejection time, was retrospectively measured in 53 patients (38 women, aged 45 +/- 14 years) with primary pulmonary hypertension. Ejection time was measured from the pulmonary outflow velocity signal. The sum of isovolumic contraction time and isovolumic relaxation time was obtained by subtracting ejection time from the duration of tricuspid regurgitation. The Doppler RV index tended to be elevated (median 0.83) compared with normal ranges. Normal Doppler RV index was 0.28 +/- 0.04. After a mean follow-up duration of 2.9 years, 4 patients underwent lung transplantation and 30 patients died; the cause was cardiac in 28, noncardiac in 1, and uncertain in 1. Univariately, the Doppler RV index (chi-square 20.7, p <0.0001), severity of tricuspid regurgitation (chi-square 8.2, p = 0.004), treatment with calcium blockers (chi-square 6.6, p = 0.01), heart rate (chi-square 5.1, p = 0.02), and symptom status (chi-square 4.9, p = 0.03) were associated with adverse outcome (cardiac deaths and lung transplantation). However, only the Doppler RV index and treatment with calcium blockers were independent predictors within the multivariate model. Our results indicate that the Doppler RV index is a useful predictor of adverse outcome in patients with primary pulmonary hypertension.

Clinical profile and outcome in 52 patients with cardiac pseudoaneurysm

BACKGROUND

Cardiac pseudoaneurysm, a contained cardiac rupture, predisposes patients to further rupture. However, knowledge of the clinical profile and natural history of this cardiac complication is limited.

OBJECTIVE

To study the clinical features and outcomes of patients with cardiac pseudoaneurysm.

DESIGN

Retrospective analysis of patients with cardiac pseudoaneurysm seen between January 1980 and September 1996.

SETTING

Mayo Clinic in Rochester, Minnesota; Scottsdale, Arizona; and Jacksonville, Florida.

PATIENTS

52 patients with pseudoaneurysm.

RESULTS

Pseudoaneurysm was discovered incidentally in 25 asymptomatic patients (48%). Four patients (8%) presented acutely (3 with acute myocardial infarction and 1 with cardiac tamponade). Other clinical presentations were congestive heart failure in 8 patients (15%), chest pain in 7 (13%), syncope or arrhythmia in 5 (10%), and systemic embolism in 3 (6%). Initial diagnostic tests were echocardiography in 32 patients, cardiac catheterization in 12, magnetic resonance imaging in 4, and computed tomography in 2. Diagnosis was made intraoperatively in two patients. Pseudoaneurysm occurred after cardiac surgery in 30 patients (58%) and after myocardial infarction in 22 (42%). Location of the pseudoaneurysm was primarily related to its cause: Pseudoaneurysm was located in the inferior or posterolateral wall in 18 of 22 patients (82%) after myocardial infarction, in the right ventricular outflow tract in 13 of 15 patients (87%) after congenital heart surgery, in the posterior subannular region of the mitral valve in 4 of 4 patients (100%) after mitral valve replacement, and in the subaortic region in 3 of 3 (100%) after aortic valve replacement. Forty-two patients (81%) had surgical repair (surgical mortality rate, 7%). Ten patients (19%) did not have surgery. Nineteen patients died after a median survival of 2.3 years (range, 3 days to 8.2 years): Eight died of noncardiac cause, 5 of congestive heart failure, 4 of acute myocardial infarction, and 2 of cardiac arrhythmia (ventricular tachycardia). No further cardiac ruptures were documented.

CONCLUSIONS

A substantial number of patients with pseudoaneurysm are asymptomatic. Although surgical repair is the treatment of choice, conservative management in selected patients with increased surgical risk seems reasonable because no deaths were caused by further rupture.

Hypertrophic cardiomyopathy with obstruction: important diagnostic clue provided by the direction of the mitral regurgitation jet

We present an unusual case of hypertrophic cardiomyopathy complicated by mitral regurgitation resulting from chordal rupture with flail posterior mitral leaflet. The diagnosis was suggested by the presence of an anteriorly directed mitral regurgitation jet on transthoracic color flow imaging, in addition to the typical posterolateral-lateral jet caused by systolic anterior mitral motion. The flail posterior leaflet was confirmed by transesophageal echocardiography, and the patient underwent mitral valve repair in addition to myectomy. This combination of hypertrophic cardiomyopathy and flail mitral leaflet usually requires surgical intervention, and prompt diagnosis is important. The presence of an anteriorly directed mitral regurgitant jet should always raise suspicion of posterior mitral leaflet abnormality.

Retained left atrial catheter: an unusual cardiac source of embolism identified by transesophageal echocardiography

Embolic events have become a major indication for transesophageal echocardiography. We report three patients with cerebrovascular accident who were discovered to have retained left atrial catheter as a cardiac source of embolism. These radiolucent catheters, placed during previous cardiac surgery, were used for perioperative left atrial monitoring. Fracture of the catheter occurred during percutaneous removal after surgery. Subsequent identification was established by transesophageal echocardiography, which demonstrated a characteristic appearance of the catheter remnant within the left atrium. All patients underwent reoperation to remove the retained catheter and have had no recurrent embolic events. Although uncommon, retained catheter in the left atrium is an important potential source of systemic embolism. The diagnosis can be easily made with transesophageal echocardiography and should prompt surgical extraction of the catheter.

A case of unusual electrocardiographic presentation of right ventricular myocardial infarction

This is a case of an unusual electrocardiographic manifestation of a patient with right ventricular (RV) myocardial infarction occurring in association with left ventricular inferoposterior myocardial infarction. There was massive ST-segment elevation in the precordial leads resembling that of an anterior myocardial infarct in addition to the ST-segment elevation seen normally in right ventricular leads. Two-dimensional echocardiography confirmed right ventricular hypokinesia and coronary angiography revealed single-vessel coronary artery disease involving the right coronary artery. It served to remind us that the presence of diffuse and massive ST-segment elevation in the precordial leads in a patient with inferior myocardial infarction may indicate simultaneous RV infarction and warrants further confirmatory tests.

Electrocardiographic abnormalities in right ventricular infarction associated with right bundle branch block

An 80-year-old woman with pre-existing complete right bundle branch block presented with severe chest pain. The 12-lead electrocardiogram, together with right-sided chest leads, showed complete right bundle branch block and ST segment elevation in leads II, III, aVF, V5, V6 and V4R to V6R. These electrocardiographic abnormalities indicate acute 'Q wave' inferolateral and right ventricular infarction coexisting with right bundle branch block.

Dobutamine stress echocardiography in the elderly Asian patients

Dobutamine stress echocardiography (DSE) is an established non-invasive technique for the evaluation of coronary artery disease (CAD). It has been shown to be both safe and accurate. However, its utility and safety in the elderly, in particular, elderly Asian patients has not been studied. Between September 1992 and December 1994, we performed a total of 75 consecutive DSE studies in patients over the age of 65. Of these, 50 (67%) were females. Forty-nine patients had hypertension, 26 had diabetes mellitus, 10 were smokers, 5 had a recent or previous myocardial infarction and another 4 had a history of heart failure. Indications for DSE were, inability to perform the standard treadmill exercise test (40 patients), an abnormal resting electrocardiogram (ECG) (14 patients), a prior false positive or inconclusive treadmill test, risk stratification post myocardial infarction (4 patients) or preoperative cardiac evaluation (23 patients). The test was terminated in the majority of patients following attainment of the target heart rate. Atropine stimulation was required in 61 (81%) patients. Chest pain was provoked in 11 patients. No death or myocardial infarction occurred. Minor non-cardiac symptoms occurred in another 6 patients but this did not necessitate termination of the procedure. Three patients had transient hypotension, none of which was symptomatic. Arrhythmia occurred in 23 patients but the majority were isolated atrial or ventricular premature beats (20); 1 patient had atrial fibrillation and another developed transient junctional rhythm. Only one patient developed ventricular tachycardia but this was not haemodynamically significant and terminated easily with an intravenous dose of lignocaine. A conclusive result could be obtained in 72 (96%) patients. We concluded that DSE could be performed and interpreted in the majority of elderly Asian patients studied. Despite supplemental atropine, an aggressive dosing protocol and the inclusion of patients with a myocardial scar or history of heart failure, adverse effects were rare and often did not require any specific therapy.

Clinical and echocardiographic features of mitral valve prolapse patients in a local population

Mitral valve prolapse (MVP) is a commonly diagnosed condition with varied clinical presentations but local data is lacking. In our study, we reviewed 98 patients (54 males, 44 females) with echocardiographic mitral valve prolapse diagnosed between 1991 and 1993 to study the clinical profile and echocardiographic features of patients with this condition in our local population. The mean and median age at presentation/detection were 42 years and 38 years respectively. The majority of the patients were asymptomatic (59%); the rest presented with palpitations (21%), congestive heart failure (4%) and infective endocarditis (5%). On clinical examination, 64 patients had mitral regurgitation (13 patients had both mitral regurgitation murmur and a systolic click), while one or more systolic clicks were heard in another 32 patients. Six patients also had associated Marfan syndrome. 2D echo revealed isolated anterior and posterior leaflet involvement in 55 and 19 patients respectively. Another 24 patients had involvement of both leaflets. Mitral regurgitation was detected on colour Doppler study in 78 patients. Nine patients had associated tricuspid valve prolapse. Of the 98 patients, 8 patients developed flail mitral valve. Four were detected at presentation/diagnosis, while the other 4 were diagnosed incidentally on routine follow-up 2D echo. Of these 8 patients, one developed cardiac failure. The patients had been on follow-up for a mean period of 9 months. During this period, mitral regurgitation progressed in 3 patients resulting in valve surgery. Only 20 patients had arrhythmias detected on ambulatory ECG monitoring, most of them were frequent atrial and ventricular premature beats. No patient was found to have haemodynamically significant arrhythmia. In summary, most patients with MVP had anterior mitral valve leaflet prolapse and mitral regurgitation. Although most patients with MVP are asymptomatic or have minor symptoms, it is associated with significant morbidity.

Dobutamine stress echocardiography: angiographic correlates

We started a dobutamine stress echocardiography (DSE) programme in September 1992. Until January 1994, we had performed 300 such procedures. Of these patients, 81 underwent cardiac catheterisation within 6 months of DSE without a cardiac event in the interim. Eleven DSEs were performed to assess myocardial viability and another 6 were inconclusive for myocardial ischaemia. The remaining 64 were correlated with the angiographic data to determine the utility of this technique in our institution. The mean age of the cohort was 57 years. Thirty-six patients were referred for DSE in the workup for chest pain, either anginiform (22) or atypical (14). Fourteen patients had a recent (6) or remote (8) myocardial infarction. Thirteen patients were asymptomatic. Significant obstructive coronary artery disease (CAD) was identified in 36 patients of whom 17 and 19 had single and multivessel disease respectively. The sensitivity of DSE in the entire cohort was 89% and the specificity 82%. Positive and negative predictive values of DSE were 86% and 85% respectively. Although the numbers involved were small, sensitivity figures for single and multivessel disease were 94% and 84% respectively. Of the patients with single vessel CAD, prediction of the artery involved by presumed territorial supply was accurate in 81%. DSE is a highly accurate tool for evaluating CAD, identifying both the patient with CAD and the location of disease.