Causes of cardiovascular and noncardiovascular death in the ISCHEMIA trial.

BACKGROUND: The International Study of Comparative Health Effectiveness with Medical and Invasive Approaches trial demonstrated no overall difference in the composite primary endpoint and the secondary endpoints of cardiovascular (CV) death/myocardial infarction or all-cause mortality between an initial invasive or conservative strategy among participants with chronic coronary disease and moderate or severe myocardial ischemia. Detailed cause-specific death analyses have not been reported. METHODS: We compared overall and cause-specific death rates by treatment group using Cox models with adjustment for pre-specified baseline covariates. Cause of death was adjudicated by an independent Clinical Events Committee as CV, non-CV, and undetermined. We evaluated the association of risk factors and treatment strategy with cause of death. RESULTS: Four-year cumulative incidence rates for CV death were similar between invasive and conservative strategies (2.6% vs 3.0%; hazard ratio [HR] 0.98; 95% CI [0.70-1.38]), but non-CV death rates were higher in the invasive strategy (3.3% vs 2.1%; HR 1.45 [1.00-2.09]). Overall, 13% of deaths were attributed to undetermined causes (38/289). Fewer undetermined deaths (0.6% vs 1.3%; HR 0.48 [0.24-0.95]) and more malignancy deaths (2.0% vs 0.8%; HR 2.11 [1.23-3.60]) occurred in the invasive strategy than in the conservative strategy. CONCLUSIONS: In International Study of Comparative Health Effectiveness with Medical and Invasive Approaches, all-cause and CV death rates were similar between treatment strategies. The observation of fewer undetermined deaths and more malignancy deaths in the invasive strategy remains unexplained. These findings should be interpreted with caution in the context of prior studies and the overall trial results.

Prognostic value of plasma von Willebrand factor and soluble P-selectin as indices of endothelial damage and platelet activation in 994 patients with nonvalvular atrial fibrillation.

BACKGROUND: Abnormal plasma markers of a prothrombotic state have been described in atrial fibrillation (AF), but no such marker has yet been shown to reliably predict future stroke or cardiovascular outcome in AF. We hypothesized that raised plasma levels of von Willebrand factor (vWf, an index of endothelial damage/dysfunction) and/or soluble P-selectin (sP-sel, an index of platelet activation) might predict vascular events in AF. METHODS AND RESULTS: We measured vWf and sP-sel levels by ELISA in 994 participants receiving aspirin in the Stroke Prevention in Atrial Fibrillation III trial, at study entry or after 3 months, and related these indices to the subsequent incidence of stroke and vascular events. Plasma vWf levels were a significant predictor of both stroke (P=0.03) and vascular events (P<0.001), with the greatest risk for those with the highest levels of vWf. After adjustment for other clinical predictors, the relationship between vWf and stroke became nonsignificant, but vWf remained an independent predictor of vascular events (relative risk, 1.2 [95% CI, 1.0-1.4] per 20 IU/dL increase in vWf; P=0.02). No significant relationships were found between sP-sel levels and outcome. CONCLUSIONS: Among patients with AF who received aspirin, raised levels of vWf (endothelial damage/dysfunction) were predictive of stroke and vascular events, but raised sP-sel levels (platelet activation) were not associated with increased cardiovascular risk. Endothelial damage/dysfunction (or vWf itself) may play an important role in the mechanisms behind stroke and cardiovascular outcome among aspirin-treated AF patients and might represent a target for novel therapies or an adjunctive aid to risk stratification in AF.

Plasma von Willebrand factor and soluble p-selectin as indices of endothelial damage and platelet activation in 1321 patients with nonvalvular atrial fibrillation: relationship to stroke risk factors.

BACKGROUND: Epidemiological studies have identified clinical and echocardiographic factors associated with increased stroke risk in atrial fibrillation (AF), but mechanisms linking these factors to stroke in AF are incompletely understood. We hypothesized that stroke risk factors may be associated with increased endothelial damage/dysfunction and platelet activation among patients with AF. METHODS AND RESULTS: We measured plasma levels of von Willebrand factor (vWF, a marker of endothelial damage/dysfunction) and soluble P-selectin (sP-sel, a marker of platelet activation) by ELISA in 1321 participants in the Stroke Prevention in Atrial Fibrillation (SPAF) III study and related these indices to the presence of stroke risk factors and cardiovascular disease. Age (P<0.001), prior cerebral ischemia (P<0.01), recent heart failure (P<0.001), diabetes (P<0.001), and body mass index (P<0.001) were independently associated with increased vWF (r(2) adjusted=9%). Independent associates of increased sP-sel were diabetes (P=0.01), peripheral vascular disease (P<0.001), and current smoking (P=0.01), whereas prior cerebral ischemia (P=0.002) and female sex (P<0.001) were associated with reduced sP-sel (r(2) adjusted=4%). Using prospectively validated stroke risk stratification criteria, we observed a significant stepwise increase in vWF from low- to moderate- to high-risk groups (r(2) adjusted=3%, P<0.001), whereas sP-sel remained constant (P= 0.24). CONCLUSIONS: Four recognized risk factors for stroke in AF (advancing age, prior cerebral ischemia, recent heart failure, and diabetes) were independently associated with raised plasma vWF (or endothelial damage/dysfunction), whereas only 1 (diabetes) was associated with increased sP-sel (platelet activation). Further longitudinal studies are now needed to confirm relationships between endothelial damage/dysfunction, platelet activation, and stroke in AF.

Relationship of interleukin-6 and C-reactive protein to the prothrombotic state in chronic atrial fibrillation.

OBJECTIVES: We sought to test the hypothesis that there is a relationship between inflammation and the prothrombotic state in atrial fibrillation (AF). BACKGROUND: Atrial fibrillation is associated with a prothrombotic or hypercoagulable state, which may contribute to an increased risk of stroke and thromboembolism. Inflammation may be involved in the pathogenesis of AF, but the role of inflammation in the pathophysiology of the prothrombotic state of AF has not been studied in detail, despite evidence of a link between inflammation and arterial atherothrombotic disorders. METHODS: We measured plasma indexes of inflammation (C-reactive protein [CRP] and interleukin-6 [IL-6]) and the prothrombotic state, including markers of platelet activation (soluble P-selectin), endothelial damage/dysfunction (von Willebrand factor), the coagulation cascade (tissue factor [TF], fibrinogen), and indexes of blood rheology (plasma viscosity, plasma fibrinogen, and hematocrit) in 106 patients with chronic AF and 41 healthy control subjects included in a cross-sectional analysis. RESULTS: Compared with controls, AF patients had higher levels of IL-6 (p = 0.034), CRP (p = 0.003), TF (p = 0.019), and plasma viscosity (p = 0.045). Plasma IL-6 levels were higher among AF patients at "high" risk of stroke (p = 0.003). After adjusting for potential confounding clinical variables (e.g., vascular disease), AF remained significantly associated with a raised logarithmic transformation (log) of TF (p = 0.04), but the relationships between AF and log IL-6, log CRP, and plasma viscosity became nonsignificant. Among AF patients, log TF (p < 0.001) and high stroke risk (p = 0.003) were independent associates of log IL-6 (adjusted r(2) = 0.443), whereas log fibrinogen (p < 0.001) and plasma viscosity (p = 0.04) were independent associates of log CRP (adjusted r(2) = 0.259). CONCLUSIONS: Increased plasma IL-6, CRP, and plasma viscosity support the case for the existence of an inflammatory state among "typical" populations with chronic AF. These indexes of inflammation are related to indexes of the prothrombotic state and may be related to the clinical variables of the patients (underlying vascular disease and co-morbidities), rather than simply to the presence of AF itself.

Atrial fibrillation and the prothrombotic state in the elderly: the Rotterdam Study.

BACKGROUND AND PURPOSE: Atrial fibrillation (AF) is a major cause of stroke among the elderly. Evidence for a prothrombotic state in AF is controversial, and there is a lack of studies among the elderly. We studied the relationships between AF and 3 prothrombotic plasma markers-von Willebrand factor (vWf; a marker of endothelial damage/dysfunction), soluble P-selectin (sP-sel; a marker of platelet activation), and fibrinogen-in a matched case-control study nested within a large community-based study of an elderly population. METHODS: We identified 162 elderly participants (mean+/-SD age, 78+/-8 years; 51% male) in the Rotterdam Study with documented AF and matched each case by age and sex to 2 population controls. vWf and sP-sel were measured by enzyme-linked immunosorbent assay; fibrinogen was measured with the Clauss method. We used conditional logistic regression analysis to assess the relationships between the markers and AF, adjusting for potential confounders. RESULTS: There were no significant relationships between either fibrinogen (P=0.8) or sP-sel (P=0.6) and AF. However, a positive linear relationship between vWf level and presence of AF remained significant after adjustment for potential confounders among women (odds ratio [OR], 1.17; 95% CI, 1.02 to 1.34) per 10-IU/dL increase in vWf but not among men (OR, 1.06; 95% CI, 0.96 to 1.17). CONCLUSIONS: We observed a positive relationship between AF and plasma vWf (or endothelial damage/dysfunction) in our elderly population, which was most apparent among women. Fibrinogen and sP-sel levels were unrelated to AF. The prothrombotic state of AF may be subject to sex differences, but longitudinal studies are needed to determine the relationship between these plasma markers and stroke risk.

Is the hypercoagulable state in atrial fibrillation mediated by vascular endothelial growth factor?

BACKGROUND AND PURPOSE: Tissue factor (TF; an initiator of coagulation) and vascular endothelial growth factor (VEGF; a marker of angiogenesis) are involved in the hypercoagulable state associated with malignancy. We investigated their roles in chronic atrial fibrillation (AF), a condition also associated with increased risk of stroke and thromboembolism, as well as a prothrombotic or hypercoagulable state. METHODS: We studied 25 patients with AF (20 men; mean+/-SD age, 62+/-13 years) who were compared with 2 control groups in sinus rhythm: 30 healthy control subjects (17 men; mean age, 60+/-9 years) and 35 patient control subjects with coronary artery disease (CAD; 27 men; mean age, 60+/-12 years). Plasma levels of TF, VEGF, and the VEGF receptor sFlt-1 were measured by enzyme-linked immunosorbent assay. RESULTS: VEGF, sFlt-1, and TF were significantly different between the 3 groups, with abnormal levels in AF and CAD patients compared with control subjects (P<0.001, P=0.022, and P=0.008, respectively). Among the AF patients, TF levels were significantly correlated with VEGF (Spearman's r=0.65, P<0.001) and sFlt (r=0.54, P=0.006) levels. Only TF and VEGF levels were significantly correlated in CAD patients (r=0.39, P=0.02). There were no significant correlations among the healthy control subjects. CONCLUSIONS: Patients with chronic AF have high TF levels, in keeping with the prothrombotic state associated with this arrhythmia. The relationships between TF and VEGF and its receptor sFlt-1 in AF suggest a possible role for VEGF in the hypercoagulable state found in AF, as seen in malignancy and atherosclerosis.

Prognostic significance of raised plasma levels of interleukin-6 and C-reactive protein in atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is a risk factor for stroke and death. Inflammation has been associated with AF, but the prognostic significance of inflammatory mediators, such as interleukin-6 (IL-6) and C-reactive protein (CRP), among patients with AF is unknown. We hypothesized that increased plasma levels of IL-6 and CRP, as indexes of an inflammatory state, would be associated with an increased risk of stroke and death among patients with AF. METHODS: We undertook a pilot study to determine dates of stroke or death occurring among 77 AF cases, with stored plasma samples having initially been obtained during attendance at our specialist AF clinic between 1993 and 1995. Plasma IL-6 and CRP were measured by ELISA and a high-sensitivity latex particle turbidimetric assay, respectively. RESULTS: Patients were followed up for a median duration of 2305 days (interquartile range, 1692 to 2592) [equivalent to 6.3 (4.6 to 7.1) years]. During this period, there were 8 (10%) strokes, 22 (29%) deaths, and 28 (36%) patients who had stroke or death. Prior stroke and high (above median) IL-6 levels were independent predictors of stroke. Age was the only independent predictor of death. High (above median) IL-6 levels remained a significant predictor of stroke or death, even after adjustment for age (hazard ratio, 2.91; 95% CI, 1.20 to 6.51; P =.007), and was the only independent predictor of stroke or death. Trends toward increased risk with high plasma CRP did not reach statistical significance (P =.06 for stroke or death). CONCLUSIONS: In this pilot study, high plasma IL-6 levels were an independent predictor of stroke and the composite end point of stroke or death, suggesting that inflammation in AF may predict a poor prognosis.

Ethnicity in relation to atrial fibrillation and stroke (the West Birmingham Stroke Project).

To test the hypothesis that ethnic differences may exist in the epidemiology of atrial fibrillation (AF) and other cardiovascular conditions among patients admitted to the hospital with nonhemorrhagic stroke, we reviewed registry data over a 2-year period of 832 consecutive patients admitted with nonhemorrhagic stroke to our hospital, which serves a multiethnic population. Indo-Asians and Afro-Caribbeans with acute (nonhemorrhagic) stroke had a lower prevalence of AF, despite a greater prevalence of diabetes and hypertension, than whites. AF was an independent predictor of increased mortality after stroke in our multiethnic population as a whole, but AF appears to be a less prominent factor in stroke among Indo-Asians and Afro-Caribbeans than in whites.

Comparison of outcomes of patients with symptomatic peripheral artery disease with and without atrial fibrillation (the West Birmingham Atrial Fibrillation Project).

In a multiethnic cohort of 388 patients admitted with symptomatic peripheral artery disease, atrial fibrillation was associated with emergency admission and increased mortality. Despite a greater prevalence of hypertension and diabetes in Afro-Caribbeans and diabetes in Indo-Asians, no significant differences were found in atrial fibrillation prevalence or mortality among different ethnic groups. Patients with symptomatic peripheral artery disease and atrial fibrillation should be regarded as "high risk" and managed with optimal medical therapy, including appropriate thromboprophylaxis and close follow-up.

Predictive value of indexes of inflammation and hypercoagulability on success of cardioversion of persistent atrial fibrillation.

The aim of the present study was to investigate whether success or failure of direct-current cardioversion in patients with persistent atrial fibrillation may be related to indexes of inflammation (as indicated by C-reactive protein and interleukin-6, platelet activation [soluble P-selectin levels], endothelial damage/dysfunction [von Willebrand factor], coagulation cascade [tissue factor and fibrinogen], and rheology [plasma viscosity and hematocrit]). We found that C-reactive protein levels are a predictor of initial cardioversion success, although they failed to predict long-term outcome. Although inflammation may be associated with "permanence" of atrial fibrillation, indexes of platelet activation, endothelial damage/dysfunction, or coagulation showed no relation to the immediate and long-term (2-month) cardioversion outcome.

Relation of interleukin-6, C-reactive protein, and the prothrombotic state to transesophageal echocardiographic findings in atrial fibrillation.

Atrial fibrillation (AF) is a major cause of morbidity and mortality from stroke due to thromboembolism from the fibrillating left atrium, including its appendage. We hypothesized that indexes of inflammation (as indicated by C-reactive protein and interleukin-6) and indexes of the prothrombotic state in AF that represent platelet activation (soluble P-selectin levels), endothelial damage or dysfunction (von Willebrand factor), coagulation (tissue factor and fibrinogen), and hemorrheology (plasma viscosity and hematocrit) would be related to the presence of thromboembolic predictors on transesophageal echocardiography in patients with long-term AF. To test this hypothesis, we recruited 37 patients with long-term AF who were receiving warfarin therapy with an international normalized ratio of > or =2.0 for > or =3 weeks before transesophageal echocardiography. Twenty-two patients had dense spontaneous echo contrast (SEC) visible in the left atrium or left atrial appendage, 10 had complex atheromatous plaque in the descending aorta, 11 had peak left atrial appendage velocities < or =0.2 m/s, and 3 had thrombus visible in the left atrial appendage. Twenty-eight patients had > or =1 transesophageal echocardiographic (TEE) risk factor for thromboembolism. Plasma levels of C-reactive protein (p = 0.03) and soluble P-selectin (p = 0.04) and hematocrit (p = 0.004) were higher among patients with AF with dense SEC than among those without. No significant associations were found for other TEE risk factors. Hematocrit was the only variable significantly associated with the presence of > or =1 TEE risk factor among patients with AF (p = 0.007) and the only independent associate of dense SEC after multivariate analysis (relative risk 1.4, 95% confidence interval 1.1 to 1.6) per 1% increase in hematocrit (p = 0.003, r(2) = 0.22). Although hematocrit was the only independent associate of dense SEC and > or =1 TEE risk factor, significant associations between dense SEC and the 2 indexes, C-reactive protein and soluble P-selectin, may indicate that mechanisms other than stasis are present with dense SEC. These observations support an "inflammatory hypothesis" in the pathogenesis of SEC that may have implications for thrombogenesis in AF.

Interleukin-6, tissue factor and von Willebrand factor in acute decompensated heart failure: relationship to treatment and prognosis.

Arterial thrombotic and thromboembolic complications are increased in congestive heart failure (CHF), and are a particular problem in acute decompensated heart failure, which carries a poor prognosis. As interleukin-6 (IL-6) has been shown to induce the potent procoagulant tissue factor (TF) in experimental models, we hypothesized that the pro-inflammatory IL-6 may be one mechanism contributing to thrombosis in heart failure, mediated via endothelial expression of TF on activated/damaged cells [indicated by plasma von Willebrand factor (vWF)]. Seventy-seven patients (67% men, New York Heart Association class III-IV, 87%) with acute CHF were recruited, and were compared with 53 chronic stable CHF patients in sinus rhythm (66% men, New York Heart Association class III-IV, 2%) and 37 healthy controls (68% men). Acute CHF patients in sinus rhythm had elevated baseline levels of IL-6 (P < 0.0001), TF (P = 0.041) and vWF (P < 0.0001) (all measured by enzyme-linked immunosorbent assay) compared with both chronic CHF and healthy control groups. A correlation exists in acute CHF between baseline TF and IL-6 (Spearman r = 0.64, P < 0.0001). After 3 months treatment, with control or alleviation of heart failure symptoms in 40 patients, there was a fall in levels of IL-6 (P < 0.0001) and vWF (P < 0.0001), but levels still remained significantly higher than healthy controls. Patients who died at 6 months follow-up also had higher baseline levels of IL-6 (P = 0.008), TF (P = 0.037) and vWF (P = 0.039) when compared with those who remained alive. Elevated IL-6 may contribute to the thrombotic and thromboembolic complications in acute heart failure, in a process mediated via increased TF and vWF. Improvement of symptoms and plasma markers after treatment of acute CHF and prediction of prognosis by the markers may be useful in the clinical setting.