Fibrinogen and viscosity as risk factors for subsequent cardiovascular events in stroke survivors.

OBJECTIVE: To investigate whether abnormalities in blood viscosity predict a poor prognosis for subsequent cardiovascular events in stroke survivors. DESIGN: Nested case-control study among a cohort of survivors of a first stroke, followed for an average of 2 years. Patients with a second stroke, myocardial infarction, or cardiovascular death were matched with patients who did not have such events (control patients). SETTING: Buchberg-Klinik, Bad Tölz, Germany, a specialized center for stroke rehabilitation. PATIENTS: A total of 625 consecutive patients. Twenty-one patients (3.5%) were lost to follow-up. Sixty pairs were matched. MEASUREMENTS: Native and hematocrit-standardized blood viscosity at three shear rates, hematocrit, plasma viscosity, fibrinogen, erythrocyte sedimentation rate, total leukocyte count, and the matching variables. RESULTS: Eighty-five patients had a second stroke, myocardial infarction, or died due to a cardiovascular event. Patients with re-events had higher blood viscosity and fibrinogen levels than the control patients. In the 60 matched pairs, the mean of the paired differences between patients with re-events and control patients was 5.03 mPa.s (95% CI, 1.262 to 8.941; P = 0.01) for native blood viscosity at shear rate 0.7 s-1, for plasma viscosity, 0.044 mPa.s (CI, 0.006 to 0.083; P greater than 0.02), and for fibrinogen, 0.056 g/L (CI, 0.010 to 0.101; P greater than 0.02). Odds ratios were significantly increased only for plasma viscosity (odds ratio, 2.86; CI, 1.06 to 8.43) and fibrinogen (odds ratio, 3.67; CI, 1.31 to 11.69). CONCLUSIONS: Hyperfibrinogenemia is an independent risk factor for cardiovascular events in stroke survivors. Intervention trials with fibrinogen lowering measures may be warranted.

Can rheologic variables be of prognostic relevance in arteriosclerotic diseases?

The hypothesis that blood rheology is of prognostic value in patients with arteriosclerotic diseases was tested in a prospective study of 843 patients at a rehabilitation clinic. They were tested for blood serum and plasma viscosity, hematocrit, fibrinogen, red cell aggregation and deformability, erythrocyte sedimentation rate, white cell count, cholesterol, and triglycerides. End points were defined as a second stroke or myocardial infarction or cardiovascular death within two years of the initial examination. Patients suffering such end points as compared with matched pairs (n = 74; matching criteria: identical manifestation of arteriosclerosis, identical sex and similar age and risk factors) had significantly higher native blood viscosity (p = 0.002), red cell aggregation (p = 0.01), serum viscosity (p = 0.01), fibrinogen (p = 0.02), and cholesterol (p = 0.01). It is concluded that rheologic factors are associated with the prognosis in patients with arteriosclerotic diseases.

Impaired blood rheology: a risk factor after stroke?

The hypothesis that blood rheology is of prognostic value in stroke patients was tested in a prospective study. A total of 523 patients in the rehabilitation phase of stroke (outside the acute phase reaction after stroke) were tested for blood, serum and plasma viscosity, haematocrit, fibrinogen, red cell aggregation and deformability, ESR, white cell count, cholesterol and triglycerides. Endpoints were defined as a second stroke (lethal or not) within 2 years after the initial examination. Patients suffering such endpoints exhibit elevated blood viscosity, red cell aggregation, plasma and serum viscosity, fibrinogen and cholesterol levels, compared to patients without endpoints. It is concluded that rheological factors are associated with the prognosis after a first stroke.

[Hyperviscosity. An independent risk factor after a survived stroke]. / Hyperviskosität. Ein unabhängiger Risikofaktor nach überlebtem Schlaganfall.

Several lines of evidence indicate that pathologic blood flow properties lead to a deterioration in the prognosis of patients with arteriosclerotic diseases, especially after a stroke. We tested this hypothesis in a prospective study including 625 patients with a first stroke that dated back less than five years (7.4 +/- 11.3 months, mean +/- sd). Investigated parameters were native and hematocrit standardized blood viscosity (at shear rates 0.7 s-1, 2.4 s-1 and 95.5 s-1) and its most important determinants (i.e. hematocrit, plasma viscosity, fibrinogen), erythrocyte sedimentation rate, leukocytes, cholesterol, triglycerides, blood pressure and BMI. For smoking patients were scored into four groups. Two years after these investigations a follow up was performed (response rate 96.3%). 71 patients with study endpoint (second stroke, heart attack or death due to the underlying cardiovascular disease) were identified. In 65 cases matching of a patient with and a patient without endpoint was possible. Criteria for matching were: cholesterol, triglycerides, diabetes, BMI, gender, age blood pressure, smoking, time interval between first stroke and rheologic measurements and concomitant diseases. Native blood viscosity was significantly higher in patients with endpoint (p less than 0.01) as compared to patients without (37.4 +/- 12.5 mPas vs 32.1 +/- 8.9 mPas at a shear rate of 0.7 s-1). All other variables did not differ significantly between both groups. It is concluded that in patients, who have survived a first stroke, high blood viscosity is a risk factor, independent from the accepted ones.

Does blood rheology revert to normal after myocardial infarction?

After myocardial infarction there is an acute deterioration of the flow properties of blood. The present study was designed to test whether the abnormality persists. Blood and plasma viscosity, red cell aggregation and deformability, haematocrit, erythrocyte sedimentation rate, white cell count, cholesterol, and triglycerides were measured in 51 patients who had had a myocardial infarction 5.4 (mean) years before. Results in patients and controls were compared and matched pairs with identical cardiovascular risk factors were also selected. Blood viscosity and red cell aggregation were increased and red cell deformability was decreased in the 51 patients. The abnormalities were independent of the interval since infarction and persisted for years. The rheological abnormalities present after myocardial infarction are at least partly independent of the acute event and acute phase reactions. They contribute to the reduced perfusion of the microcirculation of the heart.