Clinical presentation, disease course, and outcome of COVID-19 in hospitalized patients with and without pre-existing cardiac disease: a cohort study across 18 countries

AIMS

Patients with cardiac disease are considered high risk for poor outcomes following hospitalization with COVID-19. The primary aim of this study was to evaluate heterogeneity in associations between various heart disease subtypes and in-hospital mortality.

METHODS AND RESULTS

We used data from the CAPACITY-COVID registry and LEOSS study. Multivariable Poisson regression models were fitted to assess the association between different types of pre-existing heart disease and in-hospital mortality. A total of 16 511 patients with COVID-19 were included (21.1% aged 66-75 years; 40.2% female) and 31.5% had a history of heart disease. Patients with heart disease were older, predominantly male, and often had other comorbid conditions when compared with those without. Mortality was higher in patients with cardiac disease (29.7%; n = 1545 vs. 15.9%; n = 1797). However, following multivariable adjustment, this difference was not significant [adjusted risk ratio (aRR) 1.08, 95% confidence interval (CI) 1.02-1.15; P = 0.12 (corrected for multiple testing)]. Associations with in-hospital mortality by heart disease subtypes differed considerably, with the strongest association for heart failure (aRR 1.19, 95% CI 1.10-1.30; P < 0.018) particularly for severe (New York Heart Association class III/IV) heart failure (aRR 1.41, 95% CI 1.20-1.64; P < 0.018). None of the other heart disease subtypes, including ischaemic heart disease, remained significant after multivariable adjustment. Serious cardiac complications were diagnosed in <1% of patients.

CONCLUSION

Considerable heterogeneity exists in the strength of association between heart disease subtypes and in-hospital mortality. Of all patients with heart disease, those with heart failure are at greatest risk of death when hospitalized with COVID-19. Serious cardiac complications are rare during hospitalization.

Non-invasive assessment of saphenous vein graft patency in asymptomatic patients

The development and progression of atherosclerotic disease in saphenous vein grafts (SVGs) following coronary artery bypass surgery (CABG) are often without symptoms. Four-slice CT is a non-invasive imaging technique reliable for assessing SVG patency. This study utilised CT to assess temporal progression of patency in asymptomatic patients. A four-slice CT scanner was used employing standard techniques. Analysis of the reconstructed images was performed offline by two experienced operators blinded to patient details. The primary aim was vein graft patency. 130 asymptomatic subjects were studied. The mean time from CABG was 7.3 years (range, 15 days to 21 years 9 months; standard deviation (SD), 4.4 years). 294 of the 305 SVGs were suitable for assessment of patency. The overall occlusion rate for assessable grafts was 23.5%. Occlusion rates for grafts <1 year old was 12.5% (2/16), 20.7% (42/203) for grafts 1-10 years old, and 33.3% (25/75) for grafts >10 years old. In conclusion, significant occlusion of SVGs occurs early after CABG in asymptomatic patients. Four-slice CT has the potential for the non-invasive assessment of individuals after surgery.

Guidelines to practice gap in the use of glycoprotein IIb/IIIa inhibitors: from ISAR-REACT to overreact?

Adjunctive use of glycoprotein IIb/IIIa inhibitors (GPI) is associated with favorable outcomes following percutaneous coronary intervention (PCI). Guidelines for use of GPI have been published by various national societies including National Institute of Clinical Excellence (NICE), United Kingdom. The latter has not been updated since publication. The impact of contemporary trials such as ISAR-REACT (which showed no benefit of abciximab and 600 mg of clopidogrel compared with 600 mg of clopidogrel alone, in elective patients) on adherence to NICE guidelines is unknown.

METHODS

We audited use of GPI against NICE guidelines following publication in May 2002. Data were collected from 1,685 patients between September and November in years 2002, 2003, 2004, and 2007.

RESULTS

In 2002 and 2003, only 10.2% and 11.8%, respectively, of patients were noncompliant to NICE guidelines. Over time, there was an increase in patients not given GPI despite meeting NICE criteria. After publication of ISAR-REACT, the comparative figures for noncompliance in 2004 and 2007 were 40.0% and 44.5%. A similar pattern was seen in patients with diabetes; in 2002 and 2003 noncompliance was 16.7% and 11.1%, respectively, and in 2004 and 2007 noncompliance was 38.0% and 44.7%, respectively. Qualitatively, similar findings were recorded in patients with NSTE-ACS. The overall noncompliance to NICE guidelines increased from 11.0% to 42.1% (P < 0.0001) after the ISAR-REACT study.

CONCLUSIONS

We found a decline in compliance to NICE guidelines on GPI usage during PCI. This was likely influenced by contemporary trials demonstrating little or no benefit of GPI in patients undergoing elective PCI who are adequately pretreated with clopidogrel. Our findings suggest the need for a mechanism whereby regular updates to guidelines can be disseminated following new trial evidence.

Atopic optic neuritis

PURPOSE

To report a case of optic neuritis associated with atopic dermatitis, which may represent an optic nerve counterpart of atopic myelitis.

METHODS

Clinical examination, MRI, blood investigations.

RESULTS

A 34-year-old man with severe atopic dermatitis developed a steroid-responsive bilateral optic neuritis. Serum IgE was highly elevated, with high titers of mite-specific IgE. Clinical ophthalmological fluctuations paralleled those of atopic dermatitis.

CONCLUSIONS

The clinical features and parallel fluctuations strongly suggest that the patient's optic neuritis was related to atopic dermatitis. This atopic optic neuritis may represent the optic nerve equivalent of atopic myelitis.

Predicting sudden death in patients with mild to moderate chronic heart failure

OBJECTIVES

To explore the relation between non-invasive measures of cardiac function and sudden cardiac death, as well as the development and utility of an index integrating these variables to identify patients at increased risk of this mode of death.

DESIGN

UK-HEART (United Kingdom-heart failure evaluation and assessment of risk trial) was a prospective study conducted between December 1993 and April 2000. The study was specifically designed to identify non-invasive markers of death and mode of death among patients with chronic heart failure.

SETTING

8 UK general hospitals.

MAIN OUTCOME MEASURES

Death and mode of death.

RESULTS

553 patients aged a mean (SD) of 63 (10) years, in New York Heart Association functional class 2.3 (0.02), recruited prospectively. After 2365 patient-years' follow up, 201 patients had died (67 suddenly). Predictors of sudden death were greater cardiothoracic ratio, QRS dispersion, QT dispersion corrected for rate (QTc) across leads V1-V6 on the 12 lead ECG, and the presence of non-sustained ventricular tachycardia. The hazard ratio and 95% confidence intervals (CI) of sudden death for a 10% increase in cardiothoracic ratio was 1.43 (95% CI 1.20 to 1.71), for a 10% increase in QRS dispersion 1.11 (95% CI 1.04 to 1.19), for the presence of non-sustained ventricular tachycardia 2.03 (95% CI 1.27 to 3.25), and for a 10% increase in QTc dispersion across leads V1-V6 1.03 (95% CI 1.00 to 1.07) (all p < 0.04). An index derived from these four factors performed well in identifying patients specifically at increased risk of sudden death.

CONCLUSIONS

Results show that an index derived from three widely available non-invasive investigations has the potential to identify ambulant patients with chronic heart failure at increased risk of sudden death. This predictive tool could be used to target more sophisticated investigations or interventions aimed at preventing sudden death.

[Identification of unstable coronary atherosclerotic plaques]

The mechanisms of atherogenesis are better understood and the detection of atherosclerosis has improved with the different diagnostic methods currently available. However, it is almost impossible at present to differentiate high risk, unstable or vulnerable plaques from quiescent or stable plaques of atherosclerosis. This is a crucial problem given the banality of atherosclerosis on the one hand, and, on the other hand, the serious consequences (acute coronary syndromes, cerebrovascular accidents) of thrombotic occlusion at the site of an atherosclerotic plaque. It has now been established that the composition of the plaque is more important than the degree of stenosis, a fundamental concept in the risk of plaque rupture, precipitating the cascade of reactions leading to uncontrolled thrombosis. Consequently, new imaging techniques should address the problem of analysing the composition of atheromatous plaques. Endovascular ultrasonography, fast CT, angioscopy, nuclear imaging techniques and MRI are so many promising tools. However, non-invasive techniques should be distinguished from invasive ones. In all probability, it will be the former which will turn out to be the most useful diagnostic aid in pauci or asymptomatic patients. This article reviews the different imaging techniques under evaluation for the identification of risk of plaque rupture.

Cardiac gated breath-hold black blood MRI of the coronary artery wall: an in vivo and ex vivo comparison

BACKGROUND

High resolution magnetic resonance (MR) imaging of the coronary artery wall in vivo has been limited by the cardiac and respiratory motion, flow artifacts as well as the relatively small size of the coronary arteries. We sought to validate in vivo black blood MR imaging of the coronary artery wall using a double inversion recovery fast spin echo MR imaging sequence with limited breath-holding and cardiac gating for suppression of motion artifacts by comparison with ex vivo MR imaging.

METHODS

Yorkshire albino swine (n = 6) were used in this study and coronary lesions were induced with balloon angioplasty. Four weeks after balloon injury of the coronary arteries MR imaging of the coronary artery lesions was performed. High resolution in vivo and ex vivo images of the coronary artery wall and lesions were obtained using a double inversion recovery fast spin echo sequence in a 1.5 T MR system. There was a statistically significant agreement (p < 0.0001) between measurements of vessel wall area (r = 0.87, slope = 0.87) and maximal wall thickness (r = 0.84, slope = 0.88) from in vivo and ex vivo MR images of the coronary arteries. The mean differences between in vivo and ex vivo measurements were 0.56 +/- 1.98 mm2 for vessel wall area and 0.02 +/- 0.36 mm for maximal wall thickness.

CONCLUSIONS

Using breathholding and cardiac gating, it is possible to perform high resolution MR imaging of the coronary artery wall in vivo with good suppression of motion artifacts with a double inversion recovery fast spin echo black blood imaging sequence.

Atherosclerotic aortic component quantification by noninvasive magnetic resonance imaging: an in vivo study in rabbits

OBJECTIVES

We sought to demonstrate the ability that noninvasive in vivo magnetic resonance imaging (MRI) has to quantify the different components within atherosclerotic plaque.

BACKGROUND

Atherosclerotic plaque composition plays a critical role in both lesion stability and subsequent thrombogenicity. Noninvasive MRI is a promising tool for the characterization of plaque composition.

METHOD

Thoracic and abdominal aortic atherosclerotic lesions were induced in rabbits (n = 5). Nine months later, MRI was performed in a 1.5T system. Fast spin-echo sequences (proton density-weighted and T2-weighted [T2W] images) were obtained (in-plane resolution: 350 x 350 microns, slice thickness: 3 mm). Magnetic resonance images were correlated with matched histopathological sections (n = 108).

RESULTS

A significant correlation (p < 0.001) was observed for mean wall thickness and vessel wall area between MRI and histopathology (r = 0.87 and r = 0.85, respectively). The correlation was also present on subanalysis of the thoracic and upper part of the abdominal aorta, susceptible to respiratory motion artifacts. There was a significant correlation for plaque composition (p < 0.05) between MRI and histopathology for the analysis of lipidic (low signal on T2W, r = 0.81) and fibrous (high signal on T2W, r = 0.86) areas with Oil Red O staining. T2-weighted images showed greater contrast than proton density-weighted between these different components of the plaques as assessed by signal intensity ratio analysis with the mean difference in signal ratios of 0.47 (S.E. 0.012, adjusted for clustering of observations within lesions) being significantly different from 0 (t1 = 39.1, p = 0.016).

CONCLUSIONS

In vivo noninvasive high resolution MRI accurately quantifies fibrotic and lipidic components of atherosclerosis in this model. This may permit the serial analysis of therapeutic strategies on atherosclerotic plaque stabilization.

Combination thrombolytic therapy and percutaneous coronary intervention: the future for revascularisation for acute myocardial infarction?

It seems theoretically sound to consider rescue percutaneous coronary intervention (PCI) in patients with failed thrombolysis. However, randomised controlled data in this setting are limited. In this brief review we will present those trials analysing the role of rescue PCI in patients with acute myocardial infarction and failed thrombolysis, and consider appropriate management strategies in this setting.

Magnesium for atrial fibrillation after coronary artery bypass graft surgery: its role in aetiology and prevention

OBJECTIVE

To summarise the potential consequences of atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG) and the relationship of the arrhythmia with serum magnesium concentration ([Mg]) and to review the trials of magnesium supplementation as prophylaxis against post-CABG AF.

DATA SOURCES

Abstracts, articles and published reviews on AF after CABG and magnesium prophylaxis.

SUMMARY OF REVIEW

AF after CABG occurs in 20-40% of patients. It may cause haemodynamic compromise, stroke, prolongation of hospital stay and an increased use of resources. Effective prophylaxis offers the enticing prospect of reductions in morbidity, hospital stay and resource utilisation. There is circumstantial evidence suggesting that hypomagnesaemia may predispose to cardiac arrhythmias. Serum [Mg] falls after CABG due to haemodilution and beta-adrenergic mediated mechanisms. Several studies have reported an association between hypomagnesaemia and post-CABG AF, but a causal relationship has not been established. Trials have demonstrated that magnesium (Mg) replacement can attenuate the perioperative fall in serum [Mg], but have failed to show efficacy of Mg therapy in AF prevention after CABG. The perioperative changes in serum [Mg] do not seem to reflect changes in intracellular magnesium, including within the atria.

CONCLUSIONS

AF after CABG is common and a drain on resources through its association with increased morbidity and hospital stay. Previous studies investigating the relationship between serum [Mg] and AF after CABG have produced inconsistent results. The current evidence from randomised, placebo-controlled trials does not support the use of Mg therapy to prevent AF after CABG and strengthens the likelihood of any association between post-CABG AF and hypomagnesaemia being a passive one. That Mg appears ineffective as prophylaxis for postoperative AF may partly be due to limitations in trial methodology, but most probably reflects the poor correlation between serum total [Mg] and intracellular magnesium, specifically the intra-atrial magnesium content.

Ventricular dilation after anterior ST-elevation myocardial infarction in the thrombolytic era

BACKGROUND

The aim of this work was to study changes in end-diastolic volume 6 months after Q-wave and non-Q-wave anterior ST-elevation myocardial infarction by echocardiography. Ventricular dilation after anterior Q-wave myocardial infarction is well-recognized. However, there is a dearth of information about the natural history of ventricular volumes after non-Q-wave myocardial infarction.

METHODS

One hundred ninety patients receiving thrombolytic therapy after anterior ST-elevation myocardial infarction were studied. All patients had 2D echocardiograms and 12-lead electrocardiograms recorded within 24 hours of symptoms and at 3, 42, and 180 days later. In addition, a further electrocardiogram was recorded on day 7 to assess patients for the presence of Q waves. Peak creatine kinase over the first 3 days of admission was recorded. End-diastolic volume index was the study end point.

RESULTS

Peak creatine kinase was strongly associated with ventricular dilation in both groups (P <.001). Mean end-diastolic volume in the Q-wave group increased significantly from day 1 to 6 months (P <.05) but did not alter after non-Q-wave infarction. However, when patients were selected on predefined criteria for significant change in ventricular dilation (>10 mL/m(2)), then 35% of those with and 15% of those without Q waves fell into this category. Within this group, the increase in end-diastolic volume followed a similar pattern, with the maximum percentage increase occurring between day 1 and 6 weeks.

CONCLUSIONS

In the postthrombolytic group of anterior ST-elevation myocardial infarction, a minority of patients without Q-wave development also undergo significant ventricular dilation.

Acute antithrombotic effect of a front-loaded regimen of clopidogrel in patients with atherosclerosis on aspirin

There is a need for a rapid antithrombotic effect after the administration of antiplatelet drugs in the setting of acute coronary syndromes and percutaneous interventions. Clopidogrel, a new thienopyridine derivative, is an efficient antiplatelet agent. However, the standard regimen of clopidogrel (75 mg/d) requires 2 to 3 days before significant antithrombotic effects. Patients with stable arterial disease on chronic aspirin therapy (n=20) were treated with clopidogrel either with a front-loaded regimen, 300 mg the first day and 75 mg/d the next 7 days, or with a standard regimen, 75 mg/d for 8 days. Blood thrombogenicity was assessed by quantification of platelet-thrombus formation in an ex vivo perfusion chamber, by ADP-induced platelet aggregation, and by ADP-induced fibrinogen binding. At 2 hours, mean total thrombus area with the standard regimen was not significantly reduced. In contrast, at 2 hours, the mean total thrombus area with the front-loaded regimen was significantly decreased by 23.1+/-8.5% versus baseline (P<0.05). ADP-induced platelet aggregation (with 5 and 10 micromol/L) was also significantly (P<0.05) reduced with the front-loaded regimen at 2 hours, with the mean platelet aggregation being 82.2+/-4.4% and 81.8+/-4.5%, respectively, versus baseline. Similarly, flow cytometry demonstrated a significant decrease (P<0. 05) in the ADP-induced fibrinogen binding (with 0.12 and 0.6 micromol/L) at 2 hours in this front-loaded regimen group (36.1+/-2. 0% and 53.2+/-9.3%). With the standard regimen, platelet activity was not significantly reduced at 2 hours. Our data suggest that a front-loaded regimen of clopidogrel added to aspirin achieves a significant antithrombotic effect at 2 hours in patients with known atherosclerotic disease on chronic aspirin therapy. This provides a rationale for using front-loaded clopidogrel in combination with aspirin in percutaneous coronary interventions.

Thrombolysis and adjunctive therapies in acute myocardial infarction

Thrombolysis and percutaneous transluminal angioplasty represent the cornerstone of the pharmacologic treatment of and the interventional approach to patients with myocardial infarction (MI). They are very effective. However, they are hampered by some critical limitations. Therefore, alternatives to standard thrombolytic therapy have been developed. Platelet glycoprotein (GP) IIb/IIIa blockade is under investigation and seems very attractive. This review will focus on the use of GP IIb/IIIa antagonists and thrombin inhibitors as adjunctive therapies to the thrombolytic treatment of patients with acute MI.

Noninvasive in vivo magnetic resonance imaging of experimental coronary artery lesions in a porcine model

BACKGROUND

The ability to characterize and quantify coronary artery atherosclerotic lesions accurately, reproducibly, and noninvasively may allow the stratification of risk for future acute coronary syndromes and help direct therapeutic management. MRI has been shown to accurately characterize and quantify atherosclerosis; however, because of the combination of cardiac and respiratory motion artifacts, nonlinear course, and relatively small size of the coronary arteries, these techniques have not been able to be translated to the coronary system in vivo.

METHODS AND RESULTS

Coronary lesions were induced in Yorkshire albino swine (n=6) with balloon angioplasty, and 4 weeks later MRI of the coronary artery lesions was performed. High-resolution in vivo images of the coronary artery wall and lesions were obtained with a double-inversion-recovery fast-spin-echo sequence in a 1.5-T MR system. There was good agreement between measurements of vessel wall thickness and area from MR images of the coronary arteries and the matched histopathology sections (n=43). The mean difference (MRI minus histopathology +/- SD) for mean wall thickness was 0.26+/-0.18 mm, and for vessel wall area, 5.65+/-3.51 mm(2). MRI was also able to visualize intralesion hematoma (sensitivity 82%, specificity 84%).

CONCLUSIONS

Using a clinical MR system, we were able to image coronary artery lesions in vivo in an experimental porcine model. Further studies are needed to assess the ability of MRI to characterize coronary atherosclerotic lesions in vivo.

High resolution ex vivo magnetic resonance imaging of in situ coronary and aortic atherosclerotic plaque in a porcine model

Atherosclerotic plaque composition is central to the pathogenesis of plaque disruption and acute thrombosis. Thus, there is a need for accurate imaging and characterization of atherosclerotic lesions. Even though there is no ideal animal model of atherosclerosis, the porcine model is considered to most closely resemble human atherosclerosis. We report the feasibility of MR imaging and characterizing of atherosclerotic lesions from in situ coronary arteries and aortas in an ex vivo setting and validate this with histopathology. Coronary and aortic atherosclerosis was induced in Yucatan mini-swine (n=4) by a combination of atherogenic diet (6 months) and balloon injury. All coronary arteries were imaged ex vivo on the intact heart, preserving the curvature of their course. The aorta also underwent MR imaging. The MR images were correlated with the matched histopathology sections for both the coronary arteries (n=54) and the aortas (n=43). MR imaging accurately characterized complex atherosclerotic lesions, including calcified, lipid rich, fibrocellular and hemorrhagic regions. Mean wall thickness for the coronary arteries (r=0.94, slope: 0.81) and aortas (r=0.94, slope: 0.81) as well as aortic plaque area (r=0.97, slope: 0.90) was accurately determined by MR imaging (P<0.0001). Coronary artery MR imaging is not limited by the curvature of the coronary arteries in the heart. MR imaging accurately quantifies and characterizes coronary and aortic atherosclerotic lesions, including the vessel wall, in this experimental porcine model of complex atherosclerosis. This model may be useful for future study of MR imaging of atherosclerosis in vivo.

The role of plaque rupture and thrombosis in coronary artery disease

Atherosclerosis and its thrombotic complications are the major cause of morbidity and mortality in the industrialized world. The progression of atherosclerotic plaques in the coronary circulation is dependent on several risk factors. It is now clear that plaque composition is a major determinant of the risk of subsequent plaque rupture and superimposed thrombosis. The vulnerability of plaques to rupture is further determined by extrinsic triggering factors. Following rupture, the fatty core of the plaque and its high content of tissue factor provide a powerful substrate for the activation of the coagulation cascade. Plaque rupture can be clinically silent or cause symptoms of ischaemia depending on thrombus burden and the degree of vessel occlusion. In addition, plaque rupture and subsequent healing is recognized to be a major cause of further rapid plaque progression. This review looks at the mechanisms underlying the development and progression of atherosclerotic plaques, factors leading to plaque rupture and subsequent thrombosis and their clinical consequences. Finally, we speculate on targets for future research.

Atrial fibrillation after coronary artery bypass surgery: a model for preoperative risk stratification

BACKGROUND

Atrial fibrillation (AF) occurs in 20% to 40% of patients after CABG. Identification of patients vulnerable for arrhythmia will allow targeting of those most likely to benefit from prophylactic therapy. The aim of the present study was to evaluate accuracy of a prospectively defined signal-averaged P-wave duration (SAPD) cutoff and additional preoperative characteristics for the prediction of AF after CABG.

METHODS AND RESULTS

Patients undergoing elective isolated CABG were recruited to the present prospective study. SAPD was recorded in all patients. Filtered signals from 3 orthogonal leads were combined in a vector analysis, and total SAPD was measured preoperatively. Postoperative in-hospital AF occurred in 92 (28.2%) of 326 patients. Patients who developed AF were older (65.9 versus 61.7 years of age; P<0.0005) and had longer SAPD (158 versus 145 ms; P<0.0005) than non-AF patients. Incidence of AF increased in patients > or =75 years of age and increased progressively throughout the range of SAPD. Stepwise logistic regression analysis of preoperative variables identified that SAPD >155 ms (odds ratio, 5.37; 95% CI, 3.10 to 9.30; P<0.0005), advanced age (odds ratio, 1. 53; 95% CI, 1.26 to 1.86 per 5-year increase in age; P<0.0005), and male sex (odds ratio, 2.88; 95% CI, 1.30 to 6.40; P<0.01) independently predicted AF. Prospectively defined SAPD >155 ms predicted AF with positive and negative predictive accuracy of 49% and 84%, respectively.

CONCLUSIONS

A combination of prolonged SAPD, advanced age, and male sex identifies patients at high risk for development of AF after CABG.

In vivo dynamic real-time monitoring and quantification of platelet-thrombus formation: use of a local isotope detector

Current methods for monitoring thrombosis and thrombus growth are invasive and provide only single-time-point data. Animal models rely mainly on flow changes as a surrogate of thrombus formation. Our aim was to validate a unique potentially noninvasive system to detect and quantify dynamic thrombus formation in vivo by using a porcine model of carotid artery injury. Thrombus growth was monitored by deposition of autologous (111)In-labeled platelet activity over the injured artery by use of miniaturized gamma detectors and Doppler blood flow. Counts were recorded at 2-minute intervals for 2 hours. The technique was validated by comparing standard antithrombotic agents against controls. Platelet recruitment was detected before significant change in flow. Thrombus formation, calculated as the area under the curve (platelets x minutes x 10(6)), was greatest for control animals (11.7+/-1.28), followed by animals treated with aspirin (6.13+/-0.91, P<0.05), heparin (2.45+/-0.34, P<0.05), and hirudin (0.2+/-0.01, P<0.01 compared with heparin). The rate of platelet deposition was assessed as the slope of the curve in the first 30 minutes (platelets x 10(6) per minute) for the following treatment groups of animals: control, 3.53+/-0.34; aspirin, 1.67+/-0. 34 (P<0.01); heparin, 1.55+/-0.3 (P<0.01); and hirudin, 0.25+/-0.03 (P<0.001). There was no statistical difference between heparin and aspirin treatments. Change in flow was assessed as reduction from baseline: control, >99+/-0.34%; aspirin, 39+/-9.1%; heparin, 36+/-12. 5%; and hirudin, 17+/-5.4%. There was no statistical difference between the aspirin- and heparin-treated groups. Morphometric analysis revealed >99+/-0.63% occlusion of the luminal area with thrombus for the control group, 43+/-14.3% for the aspirin-treated group, 30+/-5.6% for the heparin-treated group, and <10+/-1.8% for the hirudin-treated group. Assessment of platelet-thrombus formation with this technique was more sensitive than change in flow in determining antithrombotic efficacy, and thrombus formation was detected earlier. This study validates a new quantitative, sensitive, potentially noninvasive, portable, in vivo monitoring of dynamic thrombus growth, which appears applicable to phase II studies in humans.

Serial in vivo MRI documents arterial remodeling in experimental atherosclerosis

BACKGROUND

Arterial remodeling in response to atherosclerosis may be outward (positive) or inward (negative) and is an important mechanism in the clinical manifestations of atherosclerosis and restenosis after percutaneous coronary interventions. Postmortem and intravascular ultrasound studies of arterial remodeling do not allow serial and noninvasive data to be obtained. In a rabbit model of atherosclerosis, we sought to validate MRI as a new tool for documentation of arterial remodeling.

METHODS AND RESULTS

Watanabe heritable hyperlipidemic rabbits underwent serial MRI at baseline and 6 months after aortic balloon denudation. The lumen area had a small but significant (P=0.006) increase, from 4.36+/-0.16 to 4. 89+/-0.12 mm(2). There was a large, significant (P<0.0001) increase in the outer wall area, from 7.96+/-0.19 to 10.46+/-0.19 mm(2). The vessel wall area (a marker of atherosclerotic burden) increased significantly (P<0.0001), from 3.61+/-0.07 to 5.57+/-0.09 mm(2). Thus, the increase in atherosclerotic burden over time was completely accounted for by positive arterial remodeling. The subgroup used for histopathological validation confirmed a significant (P<0.0001) agreement between histopathology and MRI for assessment of all 3 parameters.

CONCLUSIONS

MRI can provide serial and noninvasive data about the arterial wall, allowing assessment of arterial remodeling in this rabbit model. Thus, MRI appears to be a useful tool for the investigation of arterial remodeling both in native atherosclerosis and after percutaneous coronary intervention.

The heparin management test: a new device for monitoring anticoagulation during coronary intervention

Whole blood coagulation analysers are widely used during percutaneous coronary interventions. The precise degree of anticoagulation in patients is important in this setting. The aim of this investigation was to compare the results obtained with ACT (Hemochron) and HMT, the Heparin Management Test (TAS) in patients undergoing percutaneous coronary interventions. Patients (n = 100) were enrolled prospectively. Each patient received 10,000 units of heparin. At the end of the procedure, the mean ACT was 284+/-31 seconds and the mean HMT was 292+/-33 seconds. The correlation between the two methods was highly significant (r = 0.64, p<0.001). The HMT correlates well with ACT values in patients undergoing percutaneous coronary interventions. Its use in the management of these patients should be considered.

Histopathology and pathogenesis of plaque instability and thrombus formation

Our knowledge of the pathogenesis of plaque instability has undergone profound changes in recent years. Research in this field has been driven by the fact that atherosclerosis and its thrombotic complications continue to be the major cause of mortality and morbidity throughout the industrialized world. The different types of atherosclerotic lesions, mechanisms of atherosclerotic progression, plaque vulnerability and rupture are now better understood. This has led to evolution of therapeutic strategies designed to stabilize atherosclerotic plaque and to reduce progression. Further-more, knowledge of mechanisms leading to thrombosis after plaque rupture have led to the development of antithrombotic strategies to prevent and reduce complications arising from such an event. This review will describe the histopathology and pathogenesis leading to plaque instability, the factors associated with subsequent rupture and assess the role of thrombosis in the progression of atherosclerotic disease. We will focus on current therapeutic strategies to identify and reduce vulnerable plaques and speculate on future areas for research.

A new strategy of total arterial revascularization

We report a new strategy of total arterial revascularization based on bilateral internal thoracic arteries (ITAs) and a radial artery (RA). The technique employs a graft extension of the proximal third of the right internal thoracic artery (RITA) with the RA, in combination with the T-graft technique, by which the lower two-thirds of the free RITA is anastomosed to the side of the left internal thoracic artery (LITA).

The role of signal averaged P wave duration and serum magnesium as a combined predictor of atrial fibrillation after elective coronary artery bypass surgery

OBJECTIVE

To investigate the role of low serum magnesium as a trigger for atrial fibrillation in patients with a substrate for the arrhythmia (assessed by signal averaged P wave duration).

DESIGN

A case-control study.

SETTING

A regional referral cardiac centre.

PATIENTS AND INTERVENTIONS

105 consecutive patients undergoing elective coronary artery bypass surgery had signal averaged P wave recordings before operation. Serum electrolytes were analysed preoperatively and on days 1, 2, and 5 after surgery.

MAIN OUTCOME MEASURES

Any episode of electrocardiographically recorded atrial fibrillation was taken as a study end point.

RESULTS

Of 102 patients discharged, 27 (26%) had documented episodes of atrial fibrillation at a mean of 2.7 days after surgery. A combination of P wave duration > 155 ms and serum magnesium on the first postoperative day of < 0.7 mmol/l had a sensitivity of 75% and specificity of 80% for predicting atrial fibrillation. Duration of hospital stay (7.9 v 6.8 days) was longer in the atrial fibrillation group (P < 0.01). Stepwise regression showed age, serum magnesium < 0.7 mmol/l on the first postoperative day (both P < 0.001), angiotensin converting enzyme inhibitor withdrawal (P < 0.02), and signal averaged P wave duration (P = 0.04) to be independent predictors.

CONCLUSIONS

The combination of signal averaged P wave duration and low serum magnesium on the first postoperative day identified the majority of patients with atrial fibrillation after coronary artery bypass surgery. Early identification and pharmacological treatment for selected patients may reduce the incidence of postoperative atrial fibrillation.

Longitudinal analysis of soluble intercellular adhesion molecule 1 in retinal vasculitis patients

Increased levels of soluble intercellular adhesion molecule 1 (sICAM-1) in serum have been demonstrated in several human disease conditions. We have previously shown, in a point-prevalence study, a positive correlation between sICAM-1 levels and disease relapse in patients with idiopathic retinal vasculitis. We now report a longitudinal study over 1 year in which sICAM-1 levels were compared with clinical disease status in order to determine this relationship further. Serum samples from 11 patients with idiopathic retinal vasculitis were tested for the presence of sICAM-1 by enzyme linked immunosorbent assay. Eight control subjects were also tested. Five out of 11 patients presented with relapse and had raised sICAM-1 levels compared with quiescent periods of their disease. Five out of 11 patients showed no relapse over 1 year and also no increase in sICAM-1 levels. One patient showed increased levels of sICAM-1, but no clinical signs of relapse. These results indicate that sICAM-1 is associated with disease activity in retinal vasculitis patients and could indicate dysfunction of the blood-retina barrier.

Thrombophilic factors in ischaemic and non-ischaemic idiopathic retinal vasculitis

Two common causes of visual loss in idiopathic retinal vasculitis (RV) are retinal ischaemia and cystoid macular oedema. This study investigated whether thrombophilic factors are more prevalent in patients with ischaemic RV than non-ischaemic RV. Twenty patients with RV (10 ischaemic, 10 non-ischaemic) were prospectively recruited before starting systemic immunosuppression. Twenty-one different haemostatic parameters were tested. Seventeen patients had at least one haemostatic abnormality. Three patients had low Protein S, one had low Protein C. Three patients had positive anticardiolipin antibody titres, 1 had poor fibrinolytic activity, 3 had raised fibrinogen levels. Ten patients had raised lipoprotein (a) levels. Fibrinogen levels were higher in the smokers (p = 0.02). Although all von Willebrand's factor levels were within the normal range, they were higher in the ischaemic group (p = 0.008), in which smoking was more prevalent. This study has shown a high prevalence of thrombophilic abnormalities in RV patients, and implicates smoking in the aetiology of ischaemic RV.

Nitrates in myocardial infarction: influence on infarct size, reperfusion, and ventricular remodelling

OBJECTIVE

To assess the possible benefits of intravenous isosorbide dinitrate in acute myocardial infarction and oral isosorbide mononitrate in subacute myocardial infarction.

METHODS

316 patients presenting with acute myocardial infarction were entered into double blind placebo controlled clinical trials assessing infarct size by enzyme release, ventricular size and function by echocardiography, reperfusion by continuous 12 lead ST segment monitoring and late potentials by high resolution electrocardiography.

RESULTS

301 patients, of whom 292 (97%) received thrombolytic treatment, were randomised on admission to intravenous isosorbide dinitrate or placebo. Overall, there was no significant effect of treatment on infarct size, ST segment resolution, ventricular remodelling, or late potentials at day 3. A trend was observed towards a reduction in infarct size in patients with non-Q wave infarction treated with isosorbide dinitrate. Heterogeneity of nitrate effect was observed in relation to the degree of ST segment elevation on presentation with a clear benefit of isosorbide dinitrate in patients with moderate ST segment elevation (472 U/l v 704 U/l, P = 0.003) and a trend towards a deleterious effect in patients with marked ST segment elevation (1152 U/l v 1058 U/l, P = 0.2). ST segment re-elevation was more common among patients receiving nitrate treatment than in those assigned to placebo (29 v 16, P < 0.05). Some 160 patients underwent a further randomisation to sustained release isosorbide mononitrate or placebo on day 3. Echocardiographic volumes after 6 weeks of treatment were similar in the two groups.

CONCLUSIONS

No benefit was observed with administration of nitrates in the treatment groups as a whole for either acute or subacute infarction. There was, however, evidence of heterogeneity of effect in the different subgroups of acute infarction, and the possibility that nitrates may have differing actions in different groups of patients should be considered.

Adhesion molecule expression on circulating lymphocytes and monocytes in patients with isolated idiopathic retinal vasculitis

Idiopathic retinal vasculitis (RV) is a disease of unknown aetiology in which immune responses are involved in the pathogenesis of disease. T cells are thought to be important in this disease and there is evidence of peripheral T cell activation in a significant proportion of patients. The authors examined the expression of the leukocyte adhesion molecules (LeuCAMs) CD11a and CD18 on the peripheral T cells and monocytes of 11 patients with active idiopathic retinal vasculitis compared with 11 age, sex and race matched controls. Although the percentage of T cells expressing HLA DR was increased in the patient group the percentage of cells expressing CD11a and CD18 and the density, expressed as mean fluorescence intensity (MFI) were no different in the two groups. The expression of CD11a and CD18 on peripheral blood monocytes was also not found to be different between patients and controls. Adhesion between leukocytes and endothelial cells is essential for emigration of leukocytes and their accumulation in disease. Our findings suggest that any upregulation of leukocyte adhesion molecules occurring as part of this process is taking place in response to locally produced cytokines.

Soluble intercellular adhesion molecule-1 (sICAM-1) as a marker of disease relapse in idiopathic uveoretinitis

This study reports the results of a point prevalence study of markers of endothelial dysfunction in the serum of patients with idiopathic uveoretinitis. sICAM-1, soluble endothelial leucocyte adhesion molecule (sELAM), anti-endothelial cell antibodies (AECA) and von Willebrand factor (vWF) levels were measured in 32 patients with isolated idiopathic uveoretinitis and seven with uveitis in association with systemic disease, using commercial and in-house ELISAs. Raised levels of AECA were found in 31% of patients with isolated uveitis, vWF in 28%, sELAM in 15.6% and sICAM-1 in 31%. Further analysis revealed that raised sICAM-1 levels were closely associated with recent relapse of disease (P = 0.00003). Patients with accompanying systemic disease were found to have a similar prevalence of these serum abnormalities to those with isolated ocular disease. In conclusion, vascular endothelial dysfunction may contribute to pathogenesis in uveoretinitis, and in particular sICAM-1 may prove a marker of disease relapse in this condition.

Late potentials and ventricular enlargement after myocardial infarction. A new role for high-resolution electrocardiography?

BACKGROUND

Arrhythmias are common in patients who have developed ventricular enlargement after myocardial infarction.

METHODS AND RESULTS

A prospective study was undertaken to assess the relation between ventricular dilatation and the development of late potentials after myocardial infarction. Echocardiograms and signal-averaged ECGs were recorded on days 1,3,7, and 42 in 52 patients with a first anterior myocardial infarction. Twenty-nine percent of patients were late potential-positive on their initial signal-averaged ECG recorded on the day of admission. The incidence of late potentials rose during the next week to a peak of 42% at day 7, declining to 13% by day 42. The presence of late potentials on the day of admission was associated with an increase in end-diastolic volume index of 16.1 +/- 6.0 mL/m2 (mean +/- SEM), compared with a decreased of 4.7 +/- 2.7 mL/m2 among late potential-negative patients (P < .006). Qualitatively similar results were evident for late potentials on day 3 and day 7. By contrast, there was no association between late potentials on day 42 and ventricular dilatation. Marked dynamic changes in late potentials were evident during the first week. Patients with persistent late potentials (n = 9) on all three recordings in the first week showed a marked increase in end-diastolic volume index of 21.3 +/- 8.1 mL/m2 (P < .005 in comparison with patients who were persistently negative [n = 20]). Patients demonstrating dynamic positivity (n = 15) not present on all three recordings in the first week showed no significant increase in end-diastolic volume index.

CONCLUSION

It is concluded that late potentials during the first week after infarction are associated with subsequent ventricular dilatation. These early-phase late potentials may be a manifestation of cell slippage. They arise before gross topographical enlargement and may serve as a predictor of ventricular dilatation.