Atherosclerosis of the ascending aorta is an independent predictor of long-term neurologic events and mortality

Increased S100B in blood after cardiac surgery is a powerful predictor of late mortality

BACKGROUND

Long-term outcome in patients who suffered stroke after undergoing a cardiac operation has been investigated sparingly, but increased long-term mortality has been reported. S100B is a biochemical marker of brain cell ischemia and blood-brain barrier dysfunction. The aim of this investigation was to record the long-term mortality in consecutive patients undergoing cardiac operations and to explore whether increased concentrations of S100B in blood had a predictive value for mortality.

METHODS

Prospectively collected clinical variables, including S100B, in 767 patients who survived more than 30 days after a cardiac operation, were analyzed with actuarial survival analysis and 678 patients were analyzed with Cox multiple regression analysis.

RESULTS

Forty-nine patients (6.4%) were dead at follow-up (range, 18 to 42 months); 11.5% (88 of 767 patients) had elevated S100B 2 days after operation (range, 38 to 42 hours). The probability for death at follow-up was 0.239 if the S100B level was more than 0.3 microg/L, and 0.041 if it was less than 0.3 microg/L. The clinical variables independently associated with mortality were preoperative renal failure, preoperative low left ventricular ejection fraction, emergency operation, severe postoperative central nervous system complication, and elevated S100B values, which turned out to be the most powerful predictor.

CONCLUSIONS

Even slightly elevated S100B values in blood 2 days after cardiac operation imply a bad prognosis for outcome, and especially so in combination with any central nervous system complication.

Effect of blood transfusion on long-term survival after cardiac operation

BACKGROUND

Blood transfusions have been linked to increased morbidity and mortality. Bleeding during and after cardiac operations and the hemodilution effects of cardiopulmonary bypass commonly result in blood transfusions. Because we could not find any studies evaluating the effects of transfusion on long-term survival after cardiac operation, we sought to determine these effects.

METHODS

We studied 1,915 patients who underwent first-time isolated coronary artery bypass operations between July 6, 1994 and December 31, 1997 at our institution. Patients with transfusions were compared with those who had not been transfused. Long-term survival data were obtained from the United States Social Security Death Index. Groups were compared by Cox proportional hazard models, Kaplan-Meier survival plots, and hazard functions.

RESULTS

Six hundred forty-nine of 1,915 study patients (34%) received a transfusion during their hospitalization. Transfused patients were older, smaller, and more likely to be female, and had more comorbidity. Transfused patients also had twice the 5-year mortality (15% vs 7%) of nontransfused patients. After correction for comorbidities and other factors, transfusion was still associated with a 70% increase in mortality (risk ratio = 1.7; 95% confidence interval = 1.4 to 2.0; p = 0.001). By multivariate analysis, transfusion, peripheral vascular disease, chronic obstructive pulmonary disease, New York Heart Association functional class IV, and age were significant predictors of long-term mortality.

CONCLUSIONS

We found that blood transfusions during or after coronary artery bypass operations were associated with increased long-term mortality.

Risk factors for progression of aortic atheroma in stroke and transient ischemic attack patients

BACKGROUND AND PURPOSE

Aortic atheroma is an independent risk factor for stroke and undergoes temporal progression. Clinical and risk factor associations of such progression are unknown. Hyperhomocysteinemia has been linked with atherosclerosis, including that in the cerebral vasculature. This study investigated associations between elevated homocysteine levels and other stroke vascular risk factors and the risk of aortic atheroma progression in patients with cerebrovascular disease.

METHODS

Fifty-seven stroke and 21 transient ischemic attack patients underwent multiplanar transesophageal echocardiograms within 1 month of symptom onset and again at 9 months. Aortic atheroma was graded and stratified by use of existing criteria. Stroke risk factors; use of anticoagulant, antiplatelet, and hypolipidemic drugs; and clinical and etiological subtypes of stroke were recorded and compared in patients stratified for the presence or absence of aortic atheroma progression.

RESULTS

Of the 78, 29 (37%) progressed, 32 (41%) remained unchanged, and 17 (22%) regressed. Progression was most marked at the aortic arch (P=0.005), followed by the ascending segment (P<0.04). In nearly two thirds of the patients in whom aortic atheroma remained unchanged over 9 months, no atheroma was evident on baseline transesophageal echocardiogram. Only homocysteine levels > or =14.0 micromol/L (P=0.02), total anterior cerebral infarct (P=0.02), and large-artery atherosclerosis (P=0.005) significantly correlated with progression.

CONCLUSIONS

Among vascular risk factors, elevated homocysteine levels are associated with aortic atheroma progression. Stroke and transient ischemic attack patients with aortic atheroma should undergo assessment of homocysteine levels, which, if elevated, may be treated with vitamins in an effort to arrest aortic atheroma progression.

Aortic spontaneous echocardiographic contrast and hemostatic markers in patients with nonrheumatic atrial fibrillation

OBJECTIVES

To determine the relationship between spontaneous echocardiographic contrast (SEC) in the descending thoracic aorta and plasma levels of hemostatic markers in patients with nonrheumatic atrial fibrillation (AF).

DESIGN AND SETTINGS

A cross-sectional study at a university hospital.

PATIENTS AND MEASUREMENTS

In 91 consecutive patients (mean +/- SE age, 70 +/- 1 years; 68 men) with nonrheumatic AF who underwent transesophageal echocardiography, plasma levels of markers for platelet activity (platelet factor 4 [PF4] and beta-thromboglobulin [beta-TG]), thrombotic status (thrombin-antithrombin III complex [TAT]), and fibrinolytic status (D-dimer and plasmin-alpha(2)-plasmin inhibitor complex [PIC]) were determined.

RESULTS

Forty-three patients who had aortic SEC (AoSEC) were older (72 years vs 68 years; p < 0.05) and had a higher prevalence of chronic AF (88% vs 52%; p < 0.05) than 48 patients without AoSEC. TAT, PIC, and D-dimer levels were significantly higher in patients with AoSEC than in those without AoSEC, whereas PF4 and beta-TG levels were not different between the two groups. Although the prevalence of cerebral embolism did not differ between the two groups (23% vs 29%), the prevalence of peripheral embolism was higher in patients with AoSEC than in those without AoSEC (10% vs 0%; p < 0.05). Multivariate analysis revealed mitral regurgitation (odds ratio, 7.53; p < 0.02), SEC in the left atrium (odds ratio, 2.14; p < 0.02), and aortic atherosclerosis (odds ratio, 1.87; p < 0.04) emerged as independent predictors of AoSEC.

CONCLUSIONS

Patients with nonrheumatic AF who have AoSEC appear to have enhanced coagulation activity but not platelet activity. Intensive anticoagulation treatment might be required for these patients.

The associations among thoracic aortic atherosclerosis, coronary atherosclerosis and the function of high density lipoprotein

We sought to determine the associations among thoracic aortic atherosclerosis, coronary atherosclerosis and the function of high density lipoprotein (HDL) in a case-control study. The function of HDL can be assessed by the fractional esterification rate of cholesterol in low density lipoprotein (LDL)- and very low density lipoprotein (VLDL)-depleted plasma (FER(HDL)), which reflects a balance of cholesterol uptake by HDL and cholesterol ester (CE) transport in the reverse cholesterol transport (RCT) system in humans. Cases (n=51, age: 64.3+/-8.0 years) and controls (n=51, age: 58.7+/-13.1 years) were defined as subjects with/without angiographically proven coronary artery disease (CAD), respectively and examined for thoracic aortic atherosclerosis (TAA) by transesophageal echocardiography. The severity of TAA was determined by the ratio of average sclerotic areas (ASA) and average sclerotic lengths (ASL). The cases had significantly (P<0.05) higher values of ASA (0.22+/-0.18 vs. 0.10+/-0.11), ASL (0.82+/-0.56 vs. 0.48+/-0.45), ASA/ASL ratio (0.23+/-0.08 vs. 0.17+/-0.09) and FER(HDL) (10.3+/-3.8 vs. 8.3+/-3.5% per hour) and lower HDL-C and apolipoprotein A-I levels than the controls. A receiver operating characteristic (ROC) curve analysis showed that ASA/ASL and FER(HDL) had moderate discriminating ability for CAD and the diagnostic accuracy of ASA/ASL was better than that of FER(HDL) (area under ROC curve: 0.703 and 0.656, respectively). Multivariate logistic regression analysis indicated that ASA/ASL and FER(HDL) were independent indicators for CAD [odds ratio (95% CI): 7.5 (2.4-27), P<0.01 and 4.0 (1.2-15), P<0.05] after adjusting for age, gender and other conventional risk factors, and that a high FER(HDL) value greatly increased the relative risk of CAD associated with a high ASA/ASL. The function of HDL, as assessed by FER(HDL), enhances the ability of TAA to predict CAD.

Stroke after cardiac surgery: short- and long-term outcomes

BACKGROUND

Stroke remains a devastating complication of cardiac surgery, but stroke prevention remains elusive. Evaluation of early and long-term clinical outcomes and brain-imaging findings may provide insight into stroke prognosis, etiology, and prevention.

METHODS

Five thousand nine hundred seventy-one cardiac surgery patients were prospectively studied for clinical evidence of stroke. Stroke and nonstroke patients were compared by early outcomes. Data collected for stroke patients included brain imaging results, long-term functional status, and survival. Outcome predictors were then determined.

RESULTS

Stroke was diagnosed in 214 (3.6%) patients. Brain imaging demonstrated acute infarction in 72%; embolic in 83%, and watershed in 24%. Survival for stroke patients was 67% at 1 year and 47% at 5 years. Independent predictors of survival were cerebral infarct type, creatinine elevation, cardiopulmonary bypass time, preoperative intensive care days, postoperative awakening time, and postoperative intensive care days. Long-term disability was moderate to severe in 69%.

CONCLUSIONS

Stroke after cardiac surgery has profound repercussions that are independently related to infarct type and clinical factors. These data are essential for clinical decision making and prognosis determination.

Postoperative renal insufficiency

The poor clinical outcomes associated with postoperative HARI necessitate increased vigilance for HARI detection and intervention to minimize the progression to dialysis dependency. Patient survival significantly worsens if HARI requires the initiation of dialysis. Postoperative changes, including intravascular volume expansion, SIRS, and reduced lean body mass, frequently confound the detection of HARI. Serum creatinine levels frequently do not reflect the decreased renal function because creatinine production rate is decreased with reduced lean body mass, and the serum creatinine concentration is reduced by increased intravascular volume expansion and increased volume of distribution associated with anasarca. Additional indices of renal function must be used postoperatively, including urine output, net volume status, urinalysis with microscopic examination of the spun pellet, and corrected estimations of creatinine clearance. Few therapeutic interventions currently exist to reverse HARI other than optimization of renal perfusion and limitation of nephrotoxin exposure. Dialysis remains a cornerstone of maintenance therapy for refractory and severe HARI. Selection of dialysis modality continues to be based on modality availability and patient stability.

Cardiac Causes of Stroke

At least 20% of all ischemic strokes are cardioembolic. Cardiac conditions that cause cerebral embolism are classified as major or minor depending on whether the causal link has or has not been fully established between the underlying cardiac condition and the stroke. Atrial fibrillation, acute myocardial infarction, valvular heart disease, infective endocarditis, nonbacterial thrombotic endocarditis, and atrial myxoma are the main cardiac causes of cerebral embolism. Patent foramen ovale, atrial septal aneurysm, mitral valve prolapse, mitral annular calcification, calcific aortic stenosis, and mitral valve strands are cardiac conditions with a potential causal link to cerebral embolism, but until now, either they have been found to be poor predictors of recurrent stroke or their risk of recurrent stroke is unknown. The management of patients with a stroke of cardiac source is twofold: 1) treatment of the acute phase of stroke and 2) prophylactic treatment of recurrent thromboembolism. When possible, primary prevention of cerebral embolism should be recommended, particularly in cardiac conditions with known high risk of stroke (eg, atrial fibrillation, mitral stenosis, or presence of mechanical prosthetic heart valves).

Atheromas of the thoracic aorta: clinical and therapeutic update

Atherosclerotic lesions of the thoracic aorta have recently been recognized as an important cause of stroke and peripheral embolization, which may result in severe neurologic damage as well as multiorgan failure and death. Their prevalence is approximately 27% in patients with previous embolic events. Transesophageal echocardiography is the modality of choice for the diagnosis of these atheromas, although computed tomography, magnetic resonance imaging and intraoperative epiaortic ultrasound are complementary. Two clinical syndromes account for the embolic phenomena, atheroemboli and, more commonly, thromboemboli. In addition to such superimposed thrombi, plaque thickness (especially > or =4 mm) also correlates with embolic risk. This risk is high, with 12% of patients having a recurrent stroke within approximately one year, and up to 33% of patients having a stroke or peripheral embolus. In addition, aortic atheromas (as seen with intraoperative transesophageal echocardiography and intraoperative epiaortic ultrasound) are an important cause of stroke during heart surgery requiring cardiopulmonary bypass. Such strokes occur during approximately 12% of cardiac operations employing cardiopulmonary bypass when aortic arch atheromas are seen with transesophageal echocardiography (six times the general intraoperative stroke rate). Although anticoagulant strategies have been reported with encouraging results in nonrandomized studies, prospective, randomized data must be developed before an effective and safe treatment strategy can be determined. This review details the current state of knowledge in this area, including the clinical and pathologic evidence that thoracic aortic atherosclerosis is an important embolic source, data which guide current therapy and future directions for clinical investigation.

Atrial fibrillation and thromboembolism: a decade of progress in stroke prevention

Atrial fibrillation is associated with a sixfold increased risk for stroke. More than a dozen published randomized trials of anticoagulants or antiplatelet agents for stroke prevention provide solid evidence on which to base antithrombotic prophylaxis. Adjusted-dose warfarin reduces risk for stroke by about 60% compared with placebo, aspirin reduces this risk (primarily for nondisabling stroke) by about 20% compared with placebo, and warfarin reduces it by about 40% compared with aspirin. Warfarin provides maximal protection against stroke at international normalized ratios of 2.0 to 3.0. Risk stratification of patients with atrial fibrillation identifies those who potentially benefit most or least from anticoagulation; this is important because a substantial percentage of patients with atrial fibrillation have relatively low rates of stroke if they are given aspirin. Many elderly patients with recurrent intermittent atrial fibrillation experience high rates of stroke and benefit from anticoagulation. The value of precordial or transesophageal echocardiography in addition to clinical risk stratifiers for stratifying stroke risk is controversial. Altered hemostasis favoring thrombosis may contribute to formation of atrial appendage thrombus, but these conditions remain ill defined. The past decade has brought unprecedented progress toward understanding thromboembolism in patients with atrial fibrillation and has changed the clinical perspective of a prevalent cardiac arrhythmia into an important opportunity for stroke prevention. Making the most of this promise calls for appreciation of the epidemiology of atrial fibrillation and the concept of risk specificity in the face of diverse therapeutic options.

Neurological complications of cardiac surgery: the need for new paradigms in prevention and treatment

Neurological injury is a devastating complication of cardiac surgery that results in a longer duration of hospitalization, increased costs, and increased likelihood of death. Such injury can affect any level of the central nervous system, and its manifestations are broad, ranging from neurocognitive dysfunction to frank stroke. Many variables have been found to be indicative or risk for perioperative neurological injury, but the predictive models are more useful for stroke risk than for neurocognitive dysfunction. Strategies aimed at reducing neurological injury during cardiac surgery have focused, for the most part, on the technical aspects of cardiopulmonary bypass. The concomitant performance of carotid endarterectomy and cardiac surgery continues to be controversial, although the management of patients with symptomatic carotid stenosis is better defined. Cerebral embolism, including atheroembolism from the ascending aorta, has an important role in the pathogenesis of neurological injury of all types. Epiaortic ultrasound imaging of the aorta is a sensitive technique for the identification of atherosclerosis of the ascending aorta at the time of surgery, which can allow it to be avoided and therefore reduce the risk for atheroembolism. Results of laboratory investigations have provided insight into the mechanisms of ischemic neuronal injury and a basis for the development of neuroprotective drugs. Neuroprotection may best be accomplished during cardiac surgery because, in contrast to nonsurgical situations, potential agents can be administered before the neurological insult occurs. Reducing the incidence of perioperative stroke will require a multidisciplinary approach that includes novel diagnostic and therapeutic strategies.