Predictive indexes for atherosclerotic risk are imperfect, suggesting that there are predictive factors not commonly considered. Such a factor may be the white blood cell (WBC) count. Epidemiologic studies have shown correlations between the WBC count and the risk of myocardial infarction and stroke. The risk of acute myocardial infarction is approximately four times as great in persons with WBC counts high in the normal range (greater than 9000/microL [9 X 10(9)/L]) as in persons with WBC counts low in the normal range (less than 6000/microL [6 X 10(9)/L]); only 50% to 65% of the excess risk of the high-count individuals is explainable by tobacco smoking (which covaries with WBC count). A high WBC count also predicts greater risk of reinfarction and of in-hospital death. Less rigorously studied, the constitutional neutropenia of Yemenite Jews appears to afford protection against atherosclerotic disease. Among WBC types, the strongest epidemiologic association has been with the neutrophil count. Such a predictive value of WBC count is plausible and satisfying, because WBCs make a major contribution to the rheologic properties of blood; alter adhesive properties under stress--including the stress of ischemia, enhancing their rheologic importance; and participate in endothelial injury, both acutely and chronically, by adhering to endothelium and damaging it with toxic oxygen compounds and proteolytic enzymes. Techniques newly developed or under development may allow us to refine the predictive value of the WBC count by combining it with measures of cell activation and/or activatability.

Hyperfibrinogenemia is an independent risk factor for cardiovascular events in stroke survivors. Intervention trials with fibrinogen lowering measures may be warranted.

Twenty-three patients suffering from type II, non-insulin-dependent diabetes were compared with matched controls. Suspensions with standardized white and red cell counts were filtered in a novel device capable of discriminating filter occlusion and cell transit time. Results confirm previous studies indicating that red cell deformability is impaired in diabetes. According to our findings, this may be caused by a slight overall loss of red cell fluidity together with the existence of a subpopulation of more markedly rigid erythrocytes. Furthermore, we demonstrate that white cell filterability is reduced in type II diabetes. This could be due to decreased white cell deformability, increased white cell adhesion, or both. Analysis of diabetic subgroups indicates that the white cell rheology is impaired to a greater extent in patients taking oral antidiabetic drugs than in patients controlled by diet alone. Altered white cell rheology could help to explain the pathological blood cell filterability frequently reported in diabetes. More important, impaired white cell rheology might significantly contribute to microcirculatory flow abnormalities jeopardizing O2 exchange in the terminal vascular bed.

Forty-two stable patients with claudication were assigned to two groups. Group I (n 22) was submitted to regular, standardized treadmill exercise for 2 months. During this time the maximal and pain-free walking distances increased significantly (more than 100%

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.