Early ablation of newly diagnosed paroxysmal atrial fibrillation (NEWPaAF) versus newly diagnosed persistent atrial fibrillation (NEWPeAF): Comparison of patient populations and ablation outcomes

INTRODUCTION

Little is known about very early atrial fibrillation (AF) ablation after first AF detection.

METHODS

We evaluated patients with AF ablation <4 months from newly diagnosed paroxysmal AF (NEWPaAF) and newly diagnosed persistent AF (NEWPeAF). We compared the two patient populations and compared ablation outcomes to those undergoing later ablation.

RESULTS

Ablation was done <4 months from AF diagnosis in 353 patients (135 = paroxysmal, 218 = persistent). Early ablation outcome was best for NEWPaAF versus NEWPeAF for initial (p = 0.030) but not final (p = 0.102) ablation. Despite recent AF diagnosis in both groups, they were clinically quite different. NEWPaAF patients were younger (64.3 ± 13.0 vs. 67.3 ± 10.9, p = 0.0020), failed fewer drugs (0.39 vs. 0.60, p = 0.007), had smaller LA size (4.12 ± 0.58 vs. 4.48 ± 0.59 cm, p < 0.0001), lower BMI (28.8 ± 5.0 vs. 30.3 ± 6.0, p = 0.016), and less CAD (3.7% vs. 11.5%, p = 0.007), cardiomyopathies (2.2% vs. 22.9%, p = 0.0001), hypertension (46.7% vs. 67.4%, p < 0.0001), diabetes (8.1% vs. 17.4%, p = 0.011) and sleep apnea (20.0% vs. 30.3%, p = 0.031). For NEWPaAF, early ablation AF-free outcome was no better than later ablation (p = 0.314). For NEWPeAF, AF-free outcomes were better for early ablation than later ablation (p < 0.0001). Delaying ablation allowed more strokes/TIAs in both AF types (paroxysmal p = 0.014, persistent p < 0.0001).

CONCLUSIONS

Patients presenting for early ablation after newly diagnosed persistent AF have more pre-existing comorbidities and worse initial ablation outcomes than patients with NEWPaAF. For NEWPaAF, there was no advantage to early ablation, as long as the AF remained paroxysmal. For NEWPeAF, early ablation gave better outcomes than later ablation and they should undergo early ablation. For both AF types, waiting was associated with more neurologic events, suggesting all patients should consider earlier ablation.

Identification of supraventricular tachycardia mechanisms with surface electrocardiograms using a convolutional neural network

Background

It remains difficult to definitively distinguish supraventricular tachycardia (SVT) mechanisms using a 12-lead electrocardiogram (ECG) alone. Machine learning may identify visually imperceptible changes on 12-lead ECGs and may improve ability to determine SVT mechanisms.

Objective

We sought to develop a convolutional neural network (CNN) that identifies the SVT mechanism according to the gold standard of SVT ablation and to compare CNN performance against experienced electrophysiologists among patients with atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), and atrial tachycardia (AT).

Methods

All patients with 12-lead surface ECG during sinus rhythm and SVT and had successful SVT ablation from 2013 to 2020 were included. A CNN was trained using data from 1505 surface ECGs that were split into 1287 training and 218 test ECG datasets. We compared the CNN performance against independent adjudication by 2 experienced cardiac electrophysiologists on the test dataset.

Results

Our dataset comprised 1505 ECGs (368 AVNRT, 304 AVRT, 95 AT, and 738 sinus rhythm) from 725 patients. The CNN areas under the receiver-operating characteristic curve for AVNRT, AVRT, and AT were 0.909, 0.867, and 0.817, respectively. When fixing the specificity of the CNN to the electrophysiologist adjudicators' specificity, the CNN identified all SVT classes with higher sensitivity: (1) AVNRT (91.7% vs 65.9%), (2) AVRT (78.4% vs 63.6%), and (3) AT (61.5% vs 50.0%).

Conclusion

A CNN can be trained to differentiate SVT mechanisms from surface 12-lead ECGs with high overall performance, achieving similar performance to experienced electrophysiologists at fixed specificities.

Very long term outcomes of atrial fibrillation ablation

BACKGROUND

Little is known about the very long term durability of atrial fibrillation (AF) ablation.

OBJECTIVE

The purpose of this study was to evaluate very long term AF ablation outcomes.

METHODS

We followed 5200 patients undergoing 7145 ablation procedures. We evaluated outcomes after single and multiple ablation procedures for paroxysmal (PAF; 33.6%), persistent (PeAF; 56.4%), and long-standing (LsAF; 9.9%) AF. We compared 3 ablation eras by initial ablation catheter: early (101 patients) using solid big tip (SBT) catheters (October 2003 to December 2005), intermediate (2143 patients) using open irrigated tip (OIT) catheters (December 2005 to August 2016), and contemporary (2956 patients) using contact force (CF) catheters (March 2014 to December 2021).

RESULTS

AF freedom at 5, 10, and 15 years was as follows: initial ablation: PAF 67.8%, 56.3%, 47.6%; PeAF 46.6%, 35.6%, 26.5%; and LsAF 30.4%, 18.0%, 3.4%; final ablation: PAF 80.3%, 72.6%, 62.5%; PeAF 60.1%, 50.2%, 42.5%; and LsAF 43.4%, 32.0%, 20.6%. For PAF and PeAF, CF ablation procedures were better than OIT ablation procedures (P < .0001) and both were better than SBT ablation procedures (P < .001). LsAF had no outcome improvement over the eras. The 8-year success rate after final ablation for CF, OIT, and SBT catheter eras was as follows: PAF 79.1%, 71.8%, 60.0%; PeAF 55.9%, 50.7%, 38.0%; and LsAF 42.7%, 36.2%, 31.8%. Highest AF recurrence was in the first 2 years, with a 2- to 15-year recurrence of 2%/yr. Success predictors after initial and final ablation procedures were younger age, smaller left atrium, shorter AF duration, male sex, less persistent AF, lower CHA₂DS₂-VASc score, fewer drugs failed, and more recent catheter era.

CONCLUSION

After year 2, there is 2%/yr recurrence rate for all AF types. Ablation success is best in the CF catheter era, intermediate in the OIT era, and worst in the SBT era. Over the ablation eras, outcomes improved for PAF and PeAF but not for LsAF. We should follow patients indefinitely after ablation. We need an understanding of how to better ablate more persistent AF.

Log-Spectral Matching GAN: PPG-based Atrial Fibrillation Detection can be Enhanced by GAN-based Data Augmentation with Integration of Spectral Loss

Photoplethysmography (PPG) is a ubiquitous physiological measurement that detects beat-to-beat pulsatile blood volume changes and hence has a potential for monitoring cardiovascular conditions, particularly in ambulatory settings. A PPG dataset that is created for a particular use case is often imbalanced, due to a low prevalence of the pathological condition it targets to predict and the paroxysmal nature of the condition as well. To tackle this problem, we propose log-spectral matching GAN (LSM-GAN), a generative model that can be used as a data augmentation technique to alleviate the class imbalance in a PPG dataset to train a classifier. LSM-GAN utilizes a novel generator that generates a synthetic signal without a up-sampling process of input white noises, as well as adds the mismatch between real and synthetic signals in frequency domain to the conventional adversarial loss. In this study, experiments are designed focusing on examining how the influence of LSM-GAN as a data augmentation technique on one specific classification task - atrial fibrillation (AF) detection using PPG. We show that by taking spectral information into consideration, LSM-GAN as a data augmentation solution can generate more realistic PPG signals.

Long-Term Electrocardiographic and Echocardiographic Progression of Arrhythmogenic Right Ventricular Cardiomyopathy and Their Correlation With Ventricular Tachyarrhythmias

BACKGROUND

Prior studies of structural and electrocardiographic changes in arrhythmogenic right ventricular (RV) cardiomyopathy and their role in predicting ventricular arrhythmias (ventricular tachycardia) have shown conflicting results.

METHODS

We reviewed 405 ECGs, 315 transthoracic echocardiographies, and 441 implantable cardioverter defibrillator interrogations in 64 arrhythmogenic RV cardiomyopathy patients (56% men, mean age [SD], 44.2 [14.6] years) over a mean follow-up of 10 (range, 2.3-19) years. Generalized estimating equations were used to identify the association between ECG abnormalities, clinical variables, and transthoracic echocardiographic measurements (>mild degree of tricuspid regurgitation, RV outflow tract diameter in parasternal long axis and short axis, RV end-diastolic area, fractional area change).

RESULTS

There was a 4.65 (95% CI, 0.51%-8.8%) increase in RV end-diastolic area, a 3.75 (95% CI, 1.17%-6.34%) decrease in fractional area change, and 1.9 (95% CI, 1.3-2.8) higher odds (odds ratio) of RV wall motion abnormality with every 5-year increase in age after patients' first transthoracic echocardiography. >Mild tricuspid regurgitation was an independent predictor of RV enlargement and dysfunction (hazard ratio of >10% drop in fractional area change from baseline [95% CI], 3.51 [1.77-6.95] and hazard ratio of >10% increase in RV end-diastolic area from baseline [95% CI], 4.90 [2.52-9.52]). Patients with implantable cardioverter defibrillator were more likely to develop >mild tricuspid regurgitation and larger structural and functional disease progression. More pronounced increase in RV end-diastolic area was translated into higher rates of any ventricular tachycardia. Inferior T-wave inversions and sum of R waves (mm) in V1 to V3 were predictors of RV enlargement and dysfunction with the former also predicting risk of any ventricular tachycardia.

CONCLUSIONS

Arrhythmogenic RV cardiomyopathy is a progressive disease. Tricuspid regurgitation is an independent predictor of structural disease progression, which may be exacerbated by use of a transvenous implantable cardioverter defibrillator lead.

Effect of preload reducing therapy on right ventricular size and function in patients with arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of sudden cardiac death in young people and athletes. To date, no treatment has proven to slow the progression of the disease. Preload reducing agents such as nitrates and diuretics have shown promising results in preventing training-induced development of ARVC in a murine model.

OBJECTIVE

The purpose of this study was to describe our experience with preload reducing therapy in patients with ARVC and symptomatic right ventricular (RV) dysfunction.

METHODS

We performed retrospective chart review of prospectively collected registry data and included 20 patients with definite ARVC who had serial echocardiographic measurements and an implantable cardioverter-defibrillator. Six of the 20 patients with RV end-diastolic area (RVEDA) above median (>25 cm²) and New York Heart Association functional class II-IV symptoms were successfully treated with long-term isosorbide dinitrate 5-40 mg tid (at maximum tolerated dose) and hydrochlorothiazide-spironolactone 25-25 mg daily. The main outcomes of interest were RVEDA, RV fractional area change (FAC), and RV outflow tract measurements. Generalized estimating equations with repeated measures were used to identify the association between preload reducing agents and echocardiographic structural progression.

RESULTS

Patients who received preload reducing agents (n = 6) were older and had larger RVs with lower FAC at baseline. However, treatment with preload reducing agents was associated with less RVEDA enlargement during mean 3.3 (range 1-6.7) years of treatment in multivariate analysis (% change in RVEDA associated with treatment -7.71; 95% confidence interval -13.29 to -2.13; P = .007).

CONCLUSION

Preload reducing agents show promising results in slowing RV enlargement in patients with ARVC and show possible disease-modifying potential.

Long-Term Outcome of Patients With Idiopathic Ventricular Fibrillation: A Meta-Analysis

BACKGROUND

The long-term outcome of the patients with idiopathic ventricular fibrillation (IVF) is not well known.

METHODS AND RESULTS

Relevant studies published through May 21, 2014 were searched and identified in the MEDLINE, PsycINFO, Cochrane Library, CINAHL, and EMBASE databases and a hand search of article references was also performed. Random-effect models were used for pooling proportions of mortality and recurrent events. Twenty-three studies were included with a total of 639 patients (449 males) with a mean age ranging from 33 to 51 years. Eighty percent of patients had received ICD implantation. Over an average of 5.3 years follow-up, 167 patients (31%) experienced a recurrence of ventricular arrhythmic events (proportion, 0.29 [95% CI 0.21-0.38]). Moreover, 17 patients (3.1%) died among all studies (proportion, 0.01 [95% CI 0.00-0.04]). No association was found between the induction of sustained ventricular tachycardia or ventricular fibrillation at baseline electrophysiological study and risk of recurrent ventricular arrhythmias (risk difference: 0.12 [95% CI, 0.08-0.32]).

CONCLUSIONS

In patients with IVF, this meta-analysis revealed an estimated recurrent event rate of 31% and a pooled mortality rate of 3.1% during an average of 5 years follow-up. The results of baseline electrophysiological studies are not predictive of future ventricular arrhythmias.

Contribution of Major Lifestyle Risk Factors for Incident Heart Failure in Older Adults: The Cardiovascular Health Study

OBJECTIVES

The goal of this study was to determine the relative contribution of major lifestyle factors on the development of heart failure (HF) in older adults.

BACKGROUND

HF incurs high morbidity, mortality, and health care costs among adults ≥65 years of age, which is the most rapidly growing segment of the U.S.

METHODS

We prospectively investigated separate and combined associations of lifestyle risk factors with incident HF (1,380 cases) over 21.5 years among 4,490 men and women in the Cardiovascular Health Study, which is a community-based cohort of older adults. Lifestyle factors included 4 dietary patterns (Alternative Healthy Eating Index, Dietary Approaches to Stop Hypertension, an American Heart Association 2020 dietary goals score, and a Biologic pattern, which was constructed using previous knowledge of cardiovascular disease dietary risk factors), 4 physical activity metrics (exercise intensity, walking pace, energy expended in leisure activity, and walking distance), alcohol intake, smoking, and obesity.

RESULTS

No dietary pattern was associated with developing HF (p > 0.05). Walking pace and leisure activity were associated with a 26% and 22% lower risk of HF, respectively (pace >3 mph vs. <2 mph; hazard ratio [HR]: 0.74; 95% confidence interval [CI]: 0.63 to 0.86; leisure activity ≥845 kcal/week vs. <845 kcal/week; HR: 0.78; 95% CI: 0.69 to 0.87). Modest alcohol intake, maintaining a body mass index <30 kg/m(2), and not smoking were also independently associated with a lower risk of HF. Participants with ≥4 healthy lifestyle factors had a 45% (HR: 0.55; 95% CI: 0.42 to 0.74) lower risk of HF. Heterogeneity by age, sex, cardiovascular disease, hypertension medication use, and diabetes was not observed.

CONCLUSIONS

Among older U.S. adults, physical activity, modest alcohol intake, avoiding obesity, and not smoking, but not dietary patterns, were associated with a lower risk of HF.

Association between atrial fibrillation and silent cerebral infarctions: a systematic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is a common cause of stroke. Silent cerebral infarctions (SCIs) are known to occur in the presence and absence of AF, but the association between these disorders has not been well-defined.

PURPOSE

To estimate the association between AF and SCIs and the prevalence of SCIs in stroke-free patients with AF.

DATA SOURCES

Searches of MEDLINE, PsycINFO, Cochrane Library, CINAHL, and EMBASE from inception to 8 May 2014 without language restrictions and manual screening of article references.

STUDY SELECTION

Observational studies involving adults with AF and no clinical history of stroke or prosthetic valves who reported SCIs.

DATA EXTRACTION

Study characteristics and study quality were assessed in duplicate.

DATA SYNTHESIS

Eleven studies including 5317 patients with mean ages from 50.0 to 83.6 years reported on the association between AF and SCIs. Autopsy studies were heterogeneous and low-quality; therefore, they were excluded from the meta-analysis of the risk estimates. When computed tomography (CT) and magnetic resonance imaging (MRI) studies were combined, AF was associated with SCIs in patients with no history of symptomatic stroke (odds ratio, 2.62 [95% CI, 1.81 to 3.80]; I(2) = 32.12%; P for heterogeneity = 0.118). This association was independent of AF type (paroxysmal vs. persistent). The results were not altered significantly when the analysis was restricted to studies that met at least 70% of the maximum possible quality score (odds ratio, 3.06 [CI, 2.24 to 4.19]). Seventeen studies reported the prevalence of SCIs. The overall prevalence of SCI lesions on MRI and CT among patients with AF was 40% and 22%, respectively.

LIMITATION

Most studies were cross-sectional, and autopsy studies were heterogeneous and not sufficiently sensitive to detect small lesions.

CONCLUSION

Atrial fibrillation is associated with more than a 2-fold increase in the odds for SCI.

PRIMARY FUNDING SOURCE

Deane Institute for Integrative Research in Atrial Fibrillation and Stroke, Massachusetts General Hospital.

Dietary macronutrients, genetic variation, and progression of coronary atherosclerosis among women

BACKGROUND

Previous studies observed the surprising finding that saturated fat was inversely associated with atherosclerosis progression in postmenopausal women, whereas polyunsaturated fat (PUFA) and carbohydrates were positively associated. Whether certain genes modify the association of diet with atherosclerotic progression is unknown.

METHODS

Using Haplotype-tagging single nucleotide polymorphisms, we evaluated gene-diet interactions with 3 preselected genes involved in fatty acid and carbohydrate metabolism: sterol regulatory element binding protein-1 (SREBP1), insulin-induced gene-1 (INSIG1), and SREBP cleavage-activating protein (SCAP). Diet was assessed at baseline. Quantitative coronary angiography was performed at baseline and after a mean of follow-up of 3.09 years in 2,227 coronary segments in 234 postmenopausal women.

RESULTS

Global effects of each gene and gene-diet interactions for different fats, total fat, and carbohydrate were evaluated. Global tests revealed no main effects between SCAP, INSIG1, and SREBP1 haplotypes and progression of atherosclerosis (P = .87, P = .58, and P = .44). After correction for 5 nutrients evaluated (Bonferroni-corrected 2-tailed α = .01), no significant gene-nutrient interactions were seen, except for a borderline global interaction between SREBP1 and PUFA intake (P interaction = .013). This interaction was specific to the G-C haplotype (frequency 35%) and was driven by n-6 rather than n-3 PUFA (P for interaction < .0001). The interaction was robust to estimated isocaloric replacement of PUFA with any other nutrient. Per each 5% energy from n-6 PUFA, a 0.21-mm greater decline in mean minimal coronary artery diameter was seen among women per each copy of the second most frequent haplotype of SREBP1.

CONCLUSIONS

We observed an interaction between SREBP1 and PUFA consumption that might explain the positive association of PUFA with atherosclerosis progression in this cohort.

Abstract T P161: Atrial Fibrillation is Associated With Increased Risk of Silent Cerebral Infarction: A Systematic Review and Meta-analysis

Background: Several studies report an association between atrial fibrillation (AF) and silent cerebral infarcts (SCIs), but no meta-analysis has been done to provide a pooled estimate.

Methods: We searched 5 electronic databases -MEDLINE, PsycINFO, Cochrane Library, CINAHL, and EMBASE- and manually screened bibliographies of pertinent articles. The main outcome of interest was evidence of brain infarcts on imaging or autopsy with no attributable clinical symptoms. Only peer-reviewed prospective and non-prospective studies of patients with no clinical history of stroke or prosthetic valves were included. Random effects meta-analyses using the DerSimonian and Laird method were performed. A sensitivity analysis was carried out restricted to studies which reported adjusted risk estimates. To examine the proportionate excess risk of SCIs associated with AF, we estimated the population-attributable risk (PAR) for each study and reported the pooled PAR.

Results: Of 964 retrieved abstracts, 12 were included (Image). A total of 8461 patients (786 with AF and 7675 without AF) were included in the analysis. 366 (46.56%) patients with AF and 1633 (21.28%) patients without AF had SCIs. AF was significantly associated with SCIs in patients with no clinical stroke history (odds ratio (OR) [95% confidence interval (CI)] = 2.11[1.23, 3.61], I2=80.9%). Pooled PAR [95%CI] was 0.16[0.09, 0.23]. Removing one study at a time did not change the significance of the results or the heterogeneity. The result of the analysis restricted to studies with adjusted ORs remained similar (OR [95% CI] = 2.58 [1.30, 5.14], I2= 73.1%). Among the studies with adjusted ORs, only one included lesions of< 3mm in their definition of SCIs. Removing this study from the secondary analysis eliminated the heterogeneity without changing the results substantially.

Conclusions: AF is associated with a more than twofold increase in the odds of SCI. Similar to clinical stroke, about 16% of SCIs are attributable to AF.

Cognitive impairment associated with atrial fibrillation: a meta-analysis

BACKGROUND

Atrial fibrillation (AF) has been linked with an increased risk for cognitive impairment and dementia.

PURPOSE

To complete a meta-analysis of studies examining the association between AF and cognitive impairment.

DATA SOURCES

Search of MEDLINE, PsycINFO, Cochrane Library, CINAHL, and EMBASE databases and hand search of article references.

STUDY SELECTION

Prospective and nonprospective studies reporting adjusted risk estimates for the association between AF and cognitive impairment.

DATA EXTRACTION

Two abstracters independently extracted data on study characteristics, risk estimates, methods of AF and outcome ascertainment, and methodological quality.

DATA SYNTHESIS

Twenty-one studies were included in the meta-analysis. Atrial fibrillation was significantly associated with a higher risk for cognitive impairment in patients with first-ever or recurrent stroke (relative risk [RR], 2.70 [95% CI, 1.82 to 4.00]) and in a broader population including patients with or without a history of stroke (RR, 1.40 [CI, 1.19 to 1.64]). The association in the latter group remained significant independent proof of clinical stroke history (RR, 1.34 [CI, 1.13 to 1.58]). However, there was significant heterogeneity among studies of the broader population (I2 = 69.4%). Limiting the analysis to prospective studies yielded similar results (RR, 1.36 [CI, 1.12 to 1.65]). Restricting the analysis to studies of dementia eliminated the significant heterogeneity (P = 0.137) but did not alter the pooled estimate substantially (RR, 1.38 [CI, 1.22 to 1.56]).

LIMITATIONS

There is an inherent bias because of confounding variables in observational studies. There was significant heterogeneity among included studies.

CONCLUSION

Evidence suggests that AF is associated with a higher risk for cognitive impairment and dementia, with or without a history of clinical stroke. Further studies are required to elucidate the association between AF and subtypes of dementia as well as the cause of cognitive impairment.

Extraluminal atherosclerosis: an under-recognised finding in human aortocoronary venous bypass grafts

BACKGROUND

Coronary artery bypass grafting (CABG) is commonly compromised by graft atherosclerosis. Histopathologic studies confirm various forms of atherosclerosis, including positively remodelled lesions in native coronary arteries but there are no histopathologic reports of extraluminal atherosclerosis in vein grafts.

METHODS

We prospectively investigated the histopathologic presence and pattern of extraluminal atherosclerosis in human old vein grafts in a two-year interval among patients undergoing redo-CABG at three university hospitals in Tehran. We separately documented clinical and angiographic findings.

RESULTS

We evaluated 100 segments from 20 human old vein grafts obtained during the redo CABG. All but four segments demonstrated some degrees of luminal narrowing. Luminal atherosclerotic plaques were detectable in 61 segments. We detected extraluminal atheroscleoris in seven segments. Mean vessel wall thickness was greater in segments containing extraluminal plaques (1.41±0.26 mm versus 0.91±0.04 mm, P=0.008). Angiographic findings had a modest correlation with presence or absence of luminal atheromatous lesions (Spearman's rho: 0.331, P=0.007). Angiographic degree of stenosis could not predict the presence of positively remodelled atherosclerotic plaques (Spearman's rho: -2.21, P=0.073).

CONCLUSION

Previous studies suggested positive remodelling in vein grafts. Out study provides histopathologic evidence on extraluminal atherosclerosis in human aortocoronary vein grafts.

Estimating the global and regional burden of suboptimal nutrition on chronic disease: methods and inputs to the analysis

BACKGROUND/OBJECTIVES

Global burdens of cardiovascular disease (CVD), diabetes and cancer are on the rise. Little quantitative data are available on the global impact of diet on these conditions. The objective of this study was to develop systematic and comparable methods to quantitatively assess the impact of suboptimal dietary habits on CVD, diabetes and cancer burdens globally and in 21 world regions.

SUBJECTS/METHODS

Using a comparative risk assessment framework, we developed methods to establish for selected dietary risk factors the effect sizes of probable or convincing causal diet-disease relationships, the alternative minimum-risk exposure distributions and the exposure distributions. These inputs, together with disease-specific mortality rates, allow computation of the numbers of events attributable to each dietary factor.

RESULTS

Using World Health Organization and similar evidence criteria for convincing/probable causal effects, we identified 14 potential diet-disease relationships. Effect sizes and ranges of uncertainty will be derived from systematic reviews and meta-analyses of trials or high-quality observational studies. Alternative minimum-risk distributions were identified based on amounts corresponding to the lowest disease rates in populations. Optimal and alternative definitions for each exposure were established based on the data used to quantify harmful or protective effects. We developed methods for identifying and obtaining data from nationally representative surveys. A ranking scale was developed to assess survey quality and validity of dietary assessment methods. Multi-level hierarchical models will be developed to impute missing data.

CONCLUSIONS

These new methods will allow, for the first time, assessment of the global impact of specific dietary factors on chronic disease mortality. Such global assessment is not only possible but is also imperative for priority setting and policy making.

Pathophysiology of aortocoronary saphenous vein bypass graft disease

Aortocoronary saphenous vein bypass grafting relieves anginal pain in patients with coronary artery disease. However, its effectiveness is limited due to graft failure; the 10-year patency rate is 50%-60%. Early, 1-year and late graft failure may be due to thrombosis, fibrointimal hyperplasia and atherosclerosis, respectively. There is general agreement that vein graft atherosclerosis differs from arterial lesions in terms of temporal and histological changes. Vein graft atherosclerosis is more rapid, with diffuse concentric changes and a less noticeable fibrous cap, making venous plaques more vulnerable to rupture and subsequent thrombus formation. Despite progress in understanding the pathophysiology, some aspects of vein graft atherosclerosis need to be clarified. This review focuses on the pathophysiologic aspects of this widespread, costly and disabling disease, with emphasis on late graft occlusion and distinctions between arterial and venous atherosclerosis in terms of histology, pathophysiology and risk factors.