E. Gurfinkel et al., IMPORTANCE OF THROMBOSIS AND THROMBOLYSIS IN SILENT ISCHEMIA - COMPARISON OF PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION AND UNSTABLE ANGINA, British Heart Journal, 71(2), 1994, pp. 151-155
Objective-To investigate whether plaque rupture and thrombosis have a
role in silent ischaemia as well as in unstable angina. Design-Prospec
tive analysis of the results of haemostatic diagnostic tests at the mo
ment of developing silent ischaemia at rest. Setting-Coronary care uni
t. Patients-22 patients with acute myocardial infarction, 12 patients
with symptomatic angina (unstable angina), and 10 normal volunteers (c
ontrol group). Interventions-Continuous cardiac monitoring detected 15
asymptomatic episodes (silent ischaemia) in 6 patients with unstable
angina. Blood samples were obtained at admission and when an asymptoma
tic alteration was detected and 10 minutes later. Main outcome measure
s-Comparisons of concentrations of tissue plasminogen activator, uroki
nase type plasminogen activator, tissue plasminogen activator inhibito
r-1, cross-linked fibrin degradation products, von Willebrand factor,
and thrombin-antithrombin III complexes in patients and controls at ad
mission; same comparisons in patients with silent ischaemia at the sta
rt of an episode and 10 minutes later. Results-Tissue plasminogen acti
vator concentrations were raised at admission in patients with acute m
yocardial infarction (mean (SD) 14.2 (6) ng/ml) and in patients with u
nstable angina (10.1 (2.5) ng/ml) in comparison with controls (5.1 (2.
7) ng/ml, p < 0.01 and < 0.05 respectively). There was no differences
between the two groups of patients, however. Similar results were obse
rved at the start of a silent ischaemic episode (9.8 (1.9) ng/ml) and
10 minutes later (10.5 (2.9) ng/ml) compared with controls (p < 0.05).
Tissue plasminogen activator inhibitor-1 concentrations were raised i
n patients with acute myocardial infarction (45.1 (15) ng/ml) compared
with volunteers (20.6 (16) ng/ml, p < 0.01). In patients with silent
ischaemia tissue plasminogen activator inhibitor-1 concentrations were
slightly but not significantly increased. Concentrations of cross-lin
ked fibrin degradation products (D dimer) increased during unstable an
gina (2150 (350) ng/ml) and silent ischaemia (2270 (450) ng/ml) compar
ed with the concentrations in volunteers (340 (80) ng/ml) and patients
with acute myocardial infarction (310 (120) ng/ml; p < 0.01). Conclus
ions-The results suggest that thrombosis mediates the pathophysiologic
al mechanisms of silent ischaemia and unstable angina.