Journal of the Neurological Sciences, 108 (1992) I-6 Elsevier Science Publishers B.V.
l
JNS 03661
Platelet activity and stroke severity Rajiv Joseph, Enji Han, Chock Tsering, Saul Grunfeld and K.M.A. Welch Laboratory for Experimental Hematology & Stroke, Department of Neurology, Henry Ford Hospital and Health Sciences Center, 2799 IV. Grand Boulevard, Detroit, M! 48202 (USA) (Received 22 March, 1991) (Revised, received 9 July, 1991) (Accepted 19 July, 1991) Key words: Cerebrovascular disease; Platelet; Calcium; Aequorin
Summary Although platelets constitute the major component of a thrombus, its role in determining the clinical severity of thrombotic stroke is unknown. Therefore, we investigated the relationship between platelet ionized calcium ([Ca2+]), a measure of platelet activity and presumably proneness to thrombosis, and clinical stroke severity in 45 consecutively studied acute ischemic stroke patients. Eventhough there was no correlation between the clinical neurological scores and the levels of baseline and activated platelet [Ca2+], stroke was less severe in patients who had been taking aspirin at the time of stroke onset. These results raise several important questions: (a) is the extent of platelet activation a reflection of thrombus volume, (b) does the clinical severity of neurological deficit reflect the causative thrombus volume, and (c) whether the beneficial effect of aspirin in stroke prophylaxis is through its inhibition of platelets alone. Introduction The platelet is intimately involved in the generation of arterial thrombosis, a major cause of ischemic stroke (Constantinides 1967). We have previously shown that platelet [Ca 2+] (Joseph et al. 1989a) and other indices (Joseph et al. 1989b, c) of platelet activation are increased during acute ischemic stroke. Although one would expect the extent of platelet activation to correlate with thrombus volume and stroke severity, to our knowledge there have been no definitive studies to establish a relationship of one with the other (Grotta et al. 1985). Accordingly, we studied the relationship between platelet [Ca2i+ ] as a measure of platelet activity, and the neurological status of acute ischemic stroke patients.
Patients and methods Forty-five consecutive acute ischemic stroke patients admitted to Henry Ford Hospital were studied. The clinical diagnosis of stroke was based on a history of sudden onset of a focal neurological disturbance that
Correspondence to: Dr. Rajiv Joseph, MD, MPhil, Laboratory of Experimental Hematology & Stroke, Department of Neurology, Henry Ford Hospital and Health Sciences Center, 2799 W. Grand Boulevard, Detroit, M! 48202, USA. Tel.: (313) 876-7144.
lasted for more than 24 h. CT excluded hemorrhage in all cases. Most patients were studied within 72 h of stroke onset (Table 1). Clinical evaluation and scoring of stroke severity, and blood for estimation of platelet [Ca~ +] was drawn by the same neurologist (R.J.). At the time of clinical scoring, the status of current medication was known to R.J., but not the results of platelet [Cai2+], as these were done later. In order to obtain a better estimate of stroke severity, three scoring systems were used. The Mathew scale (Mathew 1972) emphasizes motor deficits, Toronto scale (Hachinski, Norris) for higher cortical deficits and Barthel index (Mahoney, Barthel 1965) for overall functional status of the patient. Since clinical stroke severity and measurement of platelet [Ca~+] were carried out independent of each other, testing for correlation between these two parameters was possible. It was thought reasonable to also extend the correlation to the anti-platelet medication status, those taking (aspirin/ibuprofen (Al): n ffi 23) and those not taking anti-platelet agents (no drug (ND): n = 22). The severity of neurological deficit was also compared between these groups. Seventeen of the Al patients were taking aspirin in a dosage of 325 mg daily for 4.2 + 2.1 (SD) years; the remaining 6 patients in the AI sub-group were taking ibuprofen in a dosage of 1167 + 1134 (SD) mg daily for 4.1 _+3.1 (SD) years. Prophylactic aspirin was being taken for the following reasons: primary prevention for myocardial infarction (n ffi 5), arthralgias/arthritis (n = 5), following myocardial infarction (n = 4), and following minor stroke (n =
2 3). The indication for ibuprofen treatment in all 6 patients was arthralgias/arthritis. Platelet [Cai2+] was measured in aequorin-loaded gel-filtered washed platelets. The description and validation of this technique has been published elsewhere (Joseph et al. 1989a; Johnson et al. 1985, 1989). Briefly, platelet-rich plasma (PRP) was separated from citrated whole blood by differential centrifugation. PRP was treated with PGEt and the platelets pelleted. The platelet pellet was washed with Hepes-Tyrode buffer and loaded with the photoprotein aequorin using EGTA and ATP. The platelets were then treated with Mg 2+ and filtered through a Sepharose 2B gel column. The aequorin-loaded gel-filtered platelets were collected into Hepes-Tyrode buffer containing 1 mM calcium chloride. The platelet count was adjusted using the same buffer to 1.5 × 10S/mi. The luminescence obtained from 1 ml of the above platelet suspension under the baseline or stimulated state (L) was divided by the luminescence obtained when the same number of platelets were lysed with 1% Triton X-100 (Lmax). Log L/Lm~ x was calculated and used to derive log [Ca~ +] from preconstructed callibration curves for an assumed platelet intracellular [Mg 2+] of 1 raM, as previously described (Joseph et al. 1989a; Joh,-qon et al. 1985, 1989). More recently, as measured by N M R spectroscopy and atomic absorption, the platelet [Mg2+] was 0.05-0.35 mM, substantially lower than that previously assumed (Ware et ai. 1989). If these results are substantiated, then recalibration of the [Ca~ +] curve for aequorin at the lower [Mg2+] should produce lower baseline and activated [Ca 2+] values. This would not, however, influence the relative changes that we obtained (Ware et al. 1989). Thrombin and collagen were the platelet stimulating agents used in this study (Siess 1989). Thrombin of bovine origin (Parke Davis) was applied in final concentrations of 0.5 and 1.0 unit/ml, and native collagen derived from equine tendon (Chrono-Log) in final concentrations of 2 and 4/~g/ml. Correlation between platelet ionized [Ca~ +] and neurological scores and CT infarct size was made using Pearson's correlation coefficient and regression analysis. Student's t-test was used to test for differences in baseline and activated platelet [Ca~ +] in the stroke subgroups.
ResuRs In the 45 patients studied, there was no statistically significant correlation between the level of baseline platelet [Ca~ + ] and the neurological (Mathew, Toronto, and Barthel) scores. This lack of correlation between platelet baseline [Ca~ +] levels and stroke severity was observed, both in patients not taking aspirin/ibuprofen at the time of stroke onset (ND) and in those on these drugs (AI) (Fig. 1). Similar results were obtained with collagen- and thrombin-aetivated platelet [Ca~ + ] measurements. Each [Cai2+] measurement was also regressed on the three clinical scores to test for a combined effect; again no significant relationship was observed. Similiar results were obtained when this relationship was tested separately in the N D and AI subgroups (Fig. 1). The two groups, N D and AI were well matched for age, sex and time from onset of stroke (Table 1). Hypertension, other medication taken within the 14 clays prior to study, echocardiographie, 24 ° cardiac Holter monitor, and carotid ultrasonographic findings also were comparable in both groups (Tables 1 and 2). Patients in the AI group scored better on the Mathew scale, Toronto scale and Barthel index compared to the ND group (Table 3). Baseline, and collagen- and thrombin-induced changes in platelet [Ca~ + ] were also lower in the AI patients, indicating that platelet activity was inhibited in the treated patients (Table 3). The statistical significance for clinical scoring and measurements of platelet [Ca~ +] were maintained when the 17 aspirin treated patients were compared separately to the ND group (Table 4). Although on CT there was a trend towards smaller infarcts being observed ia the AI patients (Table 2), no statistically significant differences were observed in platelet [Cai2+] between patients with large and small infarcts.
Discussion Platelet [Ca~ +] is the common pivotal second messenger governing the extent of platelet activation following stimulation with platelet activators such as collagen (Ardlie 1982). Hence, changes in ionized calcium reflect the extent of platelet activation and has been
Fig. l. The relationship between platelet baseline [Ca~+] and neurological scores in acute ischemic stroke patients: (a) platelet calcium vs Mathew (M) score in patients not taking aspirin or ibuprofen at time of stroke onset (ND), a higher M score indicates less severity, (b) platelet calcium vs. Toronto (T) score in ND patients, a lower T score indicates less severity,(c) platelet calcium ,is Barthel (B) index in ND patients, a higher B index indicates less severity,(d) platelet calcium vs M score in acute ischemic stroke patients taking aspirin and/or ibuprofen at the time of stroke onset (AI), (e) platelet calcium vs T score in AI patients, and (f) platelet calcium vs B index in AI patients. There was no correlation observed in any of these analyses. Similar results were seen with collagen- and thrombin-activated platelet Ca2+] levels. ND, n ffi22; AI, n ffi23.
4.00
4.00
b A
3.20
3.20 & 2.40 A
_u m u
A AA A A
A
~
,%
.g_ o
2,40 ,
,~AA &
,.x
o
1.60
1.60
m m
m
0.80
0.80
0.00 2O
0
i
I
40
60
.
,
I
80
100
i
0.00 0.00
140.50
281.00
T O R O N T O SCORE
MATI-EW SCORE
4.00
4.00
,6. ,%
3.20
3.20 ÷
A
A
4-
AA A &
_u
o &
A
2.40
4-
,.6o
0.80
0.80
0
,
,
,
,
,
20
40
60
80
100
++
+41-,(. + 44.+.1.+'1" +
0.00 0
I
i
I
,
I
2O
40
60
80
100
MATHEW SCORE
BARTHEL INDEX
4.00
4.00
3.20
3.20
~
+
"
4-
2.40
_u
~
+
+
u
1.60
0.00
+
4`
++
~
.-I-
1.60
II1
U-
,'.
u ~
**
+
+ 4-
1.60
+:1:
4. 4-
0.80
0.00 O.00
2.40
4` 4-
÷
4`
4` +4-
0.80
140.50 TORONTO SC(DRE
281.00
0
20
40
60
BARTI'-EL INDEX
80
100
used as a index of activation. Using this technique we have shown previously that platelet [Ca~ + ] is increased in patients with acute cerebral infarction (Joseph et al. 1989a) and that aspirin treatment was seen to suppress this increase (Joseph et aL 1988). In this study, by employing platelet [Ca2i+] as an indicator of platelet activation in patients with acute ischemic stroke, we sought for a correlation between the extent of platelet activation and the clinical severity of stroke. The resuits indicate that there is no relationship. However, a definite statement about the role of aspirin in stroke severity is limited by the relatively small number of patients participating in this study. Platelets are the major cellular structure of an arterial thrombus. It has been estimated that at least 50% of an arterial thrombus is composed of platelets (Constantinides 1967; Hovig ctal. 1968; Leung et al. 1983). If one hypothesizes that the volume of thrombus can be reflected by the extent of platelet activation, our study results would indirectly mean that there is no TABLE 1 AGE, SEX, TIME FROM STROKE ONSET AND OTHER MEDICATION TAKEN BY PATIENTS NOT TAKING ASPIRIN AND IBUPROFEN (ND) AND THOSE ON ASPIRIN A N D / O R IBUPROFEN AT THE TIME OF STROKE ONSET (At)
Age (years) (mean 4. SD) Sex(M:F) Time from stroke onset (days, mean+SD)
ND (n = 22)
A! (n = 23)
65 4-13 14:8
65 4-10 13:10
2.94. 2.1
2,8+ 1.6
Risk factors
Hypertension Diabetes mellitus Smoking
12 1 6
16 6 4
Antithrombotic therapy Aspirin lbuptofen Dipyridamole Warfarin Heparin (IV)
0 0 0 2 6
17 6 3 0 4
Antihypertensive therapy Calcium channel blockers Beta-blockers ACE-inhibitors CIonidine Alpha-methyl dopa Thiazide/frusemide
2 0 3 i 0 4
3 6 2 I 1 7
Cardiac therapy Nitroglycerin Digoxin Theophylline
1 1 3
4 2 2
Antidiahetic therapy Insulin Oral hypoglycemics
1 1
1 2
TABLE 2 FINDINGS ON HEAD CT, ECHOCARDIOGRAPHY, 24° CARDIAC HOLTER MONITOR AND CAROTID ULTRASONOGRAPHY IN ND AND AI PATIENTS The results of these investigations were reasonably comparable in the two groups. Acute ischemic stroke patients ND Computed tomography (n) Large infarcts "Cortical" Small infarcts "Lacunes" Negative Echocardiography (n) Normal Left ventricular hypertrophy Left ventrieular hypokinesia Left atrial enlargement Valvular insufficiency Thrombus Prosthetic valve 24° Cardiac Holter (n) Normal sinus rhythum Pacemaker rhythum Minimum heart rate ( 4. SD) Maximum heart rate ( + SD) Carotid dopplers (n) Stenosis (right side) < 10% 11-30% 31-60% 61-100% Stenosis (left side) < 10% I! -30% 31-6{)% 61-100% Plaque (right side) Abr..ent Mild-moderate Severe (calcific) Plaque (left side) Absent Mild-moderate Severe (calcific)
AI
22 9(41%)
23 5 (22%)
8 (36%)
13 (57%)
5 (23%) 20 4 10 6 1 4 0 0 17 17 0 57+!1 174-18 11
5 (22%) 17 3 10 4 1 2 0 1 20 19 1 55d- 12 109+ 16 15
4 5 1 1
6 6 3 0
5 3 2 I
6 5 4 0
1 6 4
2 5 8
2 3 6
3 6 6
relationship between the clinical severity of stroke and thrombus size. Whatever the real underlying explanation, this absence of relationship between platelet ionized calcium and stroke severity is not totally unexpected because of several other factors that could influence the extent of neurological deficit. One obvious determinant is the location of the thrombotic occlusion. An infarct in the brainstem is likely to cause far more deficit than would a similar sized infarct in the prefrontal lobe. Other factors that could influence the clinical picture include the extent of collateral circulation and the degree of arterial narrowing. However, all these factors being equal, one would still
TABLE 3 NEUROLOGICAL STATUS AND PLATELET [Ca2+l IN ND AND AI PATIENTS Neurological scores were better, and platelet baseline and stimulated [Cal2+ ] levels were lower in the AI patients. A higher Mathew score and Barthel index, and a lower Toronto score indicates less severe neurological deficit. Calcium concentrations in ~M. All values are mean + SD.
Neurological status Matthew scale Toronto scale Barthel index
ND (n = 22)
A! (n = 23)
P value
66 58 53
83 18 78
< 0.005 < 0.005 < 0.01
+27 +_54 +-40
+_10 + 17 + 24
Platelet ionized [Ca 2+ ] Baseline [Ca 2 + ] 2.23 +- 0.47
1.78 +_ 0.41
< 0.005
Collagen induction 4 ~tg/ml 2/~g/ml
3.79+_ 1 . 3 1 3.32+ 1.21
2A0+- 0.87 2.11 +- 0.73
< 0.0005 < 0.0005
Thrombin induction 1.0unit/ml 0.5anit/ml
4,80+ 1,69 4.15+ 1.34
3.38+- 1.18 3.05+ 1 . 1 1
l
JNS 03661
Platelet activity and stroke severity Rajiv Joseph, Enji Han, Chock Tsering, Saul Grunfeld and K.M.A. Welch Laboratory for Experimental Hematology & Stroke, Department of Neurology, Henry Ford Hospital and Health Sciences Center, 2799 IV. Grand Boulevard, Detroit, M! 48202 (USA) (Received 22 March, 1991) (Revised, received 9 July, 1991) (Accepted 19 July, 1991) Key words: Cerebrovascular disease; Platelet; Calcium; Aequorin
Summary Although platelets constitute the major component of a thrombus, its role in determining the clinical severity of thrombotic stroke is unknown. Therefore, we investigated the relationship between platelet ionized calcium ([Ca2+]), a measure of platelet activity and presumably proneness to thrombosis, and clinical stroke severity in 45 consecutively studied acute ischemic stroke patients. Eventhough there was no correlation between the clinical neurological scores and the levels of baseline and activated platelet [Ca2+], stroke was less severe in patients who had been taking aspirin at the time of stroke onset. These results raise several important questions: (a) is the extent of platelet activation a reflection of thrombus volume, (b) does the clinical severity of neurological deficit reflect the causative thrombus volume, and (c) whether the beneficial effect of aspirin in stroke prophylaxis is through its inhibition of platelets alone. Introduction The platelet is intimately involved in the generation of arterial thrombosis, a major cause of ischemic stroke (Constantinides 1967). We have previously shown that platelet [Ca 2+] (Joseph et al. 1989a) and other indices (Joseph et al. 1989b, c) of platelet activation are increased during acute ischemic stroke. Although one would expect the extent of platelet activation to correlate with thrombus volume and stroke severity, to our knowledge there have been no definitive studies to establish a relationship of one with the other (Grotta et al. 1985). Accordingly, we studied the relationship between platelet [Ca2i+ ] as a measure of platelet activity, and the neurological status of acute ischemic stroke patients.
Patients and methods Forty-five consecutive acute ischemic stroke patients admitted to Henry Ford Hospital were studied. The clinical diagnosis of stroke was based on a history of sudden onset of a focal neurological disturbance that
Correspondence to: Dr. Rajiv Joseph, MD, MPhil, Laboratory of Experimental Hematology & Stroke, Department of Neurology, Henry Ford Hospital and Health Sciences Center, 2799 W. Grand Boulevard, Detroit, M! 48202, USA. Tel.: (313) 876-7144.
lasted for more than 24 h. CT excluded hemorrhage in all cases. Most patients were studied within 72 h of stroke onset (Table 1). Clinical evaluation and scoring of stroke severity, and blood for estimation of platelet [Ca~ +] was drawn by the same neurologist (R.J.). At the time of clinical scoring, the status of current medication was known to R.J., but not the results of platelet [Cai2+], as these were done later. In order to obtain a better estimate of stroke severity, three scoring systems were used. The Mathew scale (Mathew 1972) emphasizes motor deficits, Toronto scale (Hachinski, Norris) for higher cortical deficits and Barthel index (Mahoney, Barthel 1965) for overall functional status of the patient. Since clinical stroke severity and measurement of platelet [Ca~+] were carried out independent of each other, testing for correlation between these two parameters was possible. It was thought reasonable to also extend the correlation to the anti-platelet medication status, those taking (aspirin/ibuprofen (Al): n ffi 23) and those not taking anti-platelet agents (no drug (ND): n = 22). The severity of neurological deficit was also compared between these groups. Seventeen of the Al patients were taking aspirin in a dosage of 325 mg daily for 4.2 + 2.1 (SD) years; the remaining 6 patients in the AI sub-group were taking ibuprofen in a dosage of 1167 + 1134 (SD) mg daily for 4.1 _+3.1 (SD) years. Prophylactic aspirin was being taken for the following reasons: primary prevention for myocardial infarction (n ffi 5), arthralgias/arthritis (n = 5), following myocardial infarction (n = 4), and following minor stroke (n =
2 3). The indication for ibuprofen treatment in all 6 patients was arthralgias/arthritis. Platelet [Cai2+] was measured in aequorin-loaded gel-filtered washed platelets. The description and validation of this technique has been published elsewhere (Joseph et al. 1989a; Johnson et al. 1985, 1989). Briefly, platelet-rich plasma (PRP) was separated from citrated whole blood by differential centrifugation. PRP was treated with PGEt and the platelets pelleted. The platelet pellet was washed with Hepes-Tyrode buffer and loaded with the photoprotein aequorin using EGTA and ATP. The platelets were then treated with Mg 2+ and filtered through a Sepharose 2B gel column. The aequorin-loaded gel-filtered platelets were collected into Hepes-Tyrode buffer containing 1 mM calcium chloride. The platelet count was adjusted using the same buffer to 1.5 × 10S/mi. The luminescence obtained from 1 ml of the above platelet suspension under the baseline or stimulated state (L) was divided by the luminescence obtained when the same number of platelets were lysed with 1% Triton X-100 (Lmax). Log L/Lm~ x was calculated and used to derive log [Ca~ +] from preconstructed callibration curves for an assumed platelet intracellular [Mg 2+] of 1 raM, as previously described (Joseph et al. 1989a; Joh,-qon et al. 1985, 1989). More recently, as measured by N M R spectroscopy and atomic absorption, the platelet [Mg2+] was 0.05-0.35 mM, substantially lower than that previously assumed (Ware et ai. 1989). If these results are substantiated, then recalibration of the [Ca~ +] curve for aequorin at the lower [Mg2+] should produce lower baseline and activated [Ca 2+] values. This would not, however, influence the relative changes that we obtained (Ware et al. 1989). Thrombin and collagen were the platelet stimulating agents used in this study (Siess 1989). Thrombin of bovine origin (Parke Davis) was applied in final concentrations of 0.5 and 1.0 unit/ml, and native collagen derived from equine tendon (Chrono-Log) in final concentrations of 2 and 4/~g/ml. Correlation between platelet ionized [Ca~ +] and neurological scores and CT infarct size was made using Pearson's correlation coefficient and regression analysis. Student's t-test was used to test for differences in baseline and activated platelet [Ca~ +] in the stroke subgroups.
ResuRs In the 45 patients studied, there was no statistically significant correlation between the level of baseline platelet [Ca~ + ] and the neurological (Mathew, Toronto, and Barthel) scores. This lack of correlation between platelet baseline [Ca~ +] levels and stroke severity was observed, both in patients not taking aspirin/ibuprofen at the time of stroke onset (ND) and in those on these drugs (AI) (Fig. 1). Similar results were obtained with collagen- and thrombin-aetivated platelet [Ca~ + ] measurements. Each [Cai2+] measurement was also regressed on the three clinical scores to test for a combined effect; again no significant relationship was observed. Similiar results were obtained when this relationship was tested separately in the N D and AI subgroups (Fig. 1). The two groups, N D and AI were well matched for age, sex and time from onset of stroke (Table 1). Hypertension, other medication taken within the 14 clays prior to study, echocardiographie, 24 ° cardiac Holter monitor, and carotid ultrasonographic findings also were comparable in both groups (Tables 1 and 2). Patients in the AI group scored better on the Mathew scale, Toronto scale and Barthel index compared to the ND group (Table 3). Baseline, and collagen- and thrombin-induced changes in platelet [Ca~ + ] were also lower in the AI patients, indicating that platelet activity was inhibited in the treated patients (Table 3). The statistical significance for clinical scoring and measurements of platelet [Ca~ +] were maintained when the 17 aspirin treated patients were compared separately to the ND group (Table 4). Although on CT there was a trend towards smaller infarcts being observed ia the AI patients (Table 2), no statistically significant differences were observed in platelet [Cai2+] between patients with large and small infarcts.
Discussion Platelet [Ca~ +] is the common pivotal second messenger governing the extent of platelet activation following stimulation with platelet activators such as collagen (Ardlie 1982). Hence, changes in ionized calcium reflect the extent of platelet activation and has been
Fig. l. The relationship between platelet baseline [Ca~+] and neurological scores in acute ischemic stroke patients: (a) platelet calcium vs Mathew (M) score in patients not taking aspirin or ibuprofen at time of stroke onset (ND), a higher M score indicates less severity, (b) platelet calcium vs. Toronto (T) score in ND patients, a lower T score indicates less severity,(c) platelet calcium ,is Barthel (B) index in ND patients, a higher B index indicates less severity,(d) platelet calcium vs M score in acute ischemic stroke patients taking aspirin and/or ibuprofen at the time of stroke onset (AI), (e) platelet calcium vs T score in AI patients, and (f) platelet calcium vs B index in AI patients. There was no correlation observed in any of these analyses. Similar results were seen with collagen- and thrombin-activated platelet Ca2+] levels. ND, n ffi22; AI, n ffi23.
4.00
4.00
b A
3.20
3.20 & 2.40 A
_u m u
A AA A A
A
~
,%
.g_ o
2,40 ,
,~AA &
,.x
o
1.60
1.60
m m
m
0.80
0.80
0.00 2O
0
i
I
40
60
.
,
I
80
100
i
0.00 0.00
140.50
281.00
T O R O N T O SCORE
MATI-EW SCORE
4.00
4.00
,6. ,%
3.20
3.20 ÷
A
A
4-
AA A &
_u
o &
A
2.40
4-
,.6o
0.80
0.80
0
,
,
,
,
,
20
40
60
80
100
++
+41-,(. + 44.+.1.+'1" +
0.00 0
I
i
I
,
I
2O
40
60
80
100
MATHEW SCORE
BARTHEL INDEX
4.00
4.00
3.20
3.20
~
+
"
4-
2.40
_u
~
+
+
u
1.60
0.00
+
4`
++
~
.-I-
1.60
II1
U-
,'.
u ~
**
+
+ 4-
1.60
+:1:
4. 4-
0.80
0.00 O.00
2.40
4` 4-
÷
4`
4` +4-
0.80
140.50 TORONTO SC(DRE
281.00
0
20
40
60
BARTI'-EL INDEX
80
100
used as a index of activation. Using this technique we have shown previously that platelet [Ca~ + ] is increased in patients with acute cerebral infarction (Joseph et al. 1989a) and that aspirin treatment was seen to suppress this increase (Joseph et aL 1988). In this study, by employing platelet [Ca2i+] as an indicator of platelet activation in patients with acute ischemic stroke, we sought for a correlation between the extent of platelet activation and the clinical severity of stroke. The resuits indicate that there is no relationship. However, a definite statement about the role of aspirin in stroke severity is limited by the relatively small number of patients participating in this study. Platelets are the major cellular structure of an arterial thrombus. It has been estimated that at least 50% of an arterial thrombus is composed of platelets (Constantinides 1967; Hovig ctal. 1968; Leung et al. 1983). If one hypothesizes that the volume of thrombus can be reflected by the extent of platelet activation, our study results would indirectly mean that there is no TABLE 1 AGE, SEX, TIME FROM STROKE ONSET AND OTHER MEDICATION TAKEN BY PATIENTS NOT TAKING ASPIRIN AND IBUPROFEN (ND) AND THOSE ON ASPIRIN A N D / O R IBUPROFEN AT THE TIME OF STROKE ONSET (At)
Age (years) (mean 4. SD) Sex(M:F) Time from stroke onset (days, mean+SD)
ND (n = 22)
A! (n = 23)
65 4-13 14:8
65 4-10 13:10
2.94. 2.1
2,8+ 1.6
Risk factors
Hypertension Diabetes mellitus Smoking
12 1 6
16 6 4
Antithrombotic therapy Aspirin lbuptofen Dipyridamole Warfarin Heparin (IV)
0 0 0 2 6
17 6 3 0 4
Antihypertensive therapy Calcium channel blockers Beta-blockers ACE-inhibitors CIonidine Alpha-methyl dopa Thiazide/frusemide
2 0 3 i 0 4
3 6 2 I 1 7
Cardiac therapy Nitroglycerin Digoxin Theophylline
1 1 3
4 2 2
Antidiahetic therapy Insulin Oral hypoglycemics
1 1
1 2
TABLE 2 FINDINGS ON HEAD CT, ECHOCARDIOGRAPHY, 24° CARDIAC HOLTER MONITOR AND CAROTID ULTRASONOGRAPHY IN ND AND AI PATIENTS The results of these investigations were reasonably comparable in the two groups. Acute ischemic stroke patients ND Computed tomography (n) Large infarcts "Cortical" Small infarcts "Lacunes" Negative Echocardiography (n) Normal Left ventricular hypertrophy Left ventrieular hypokinesia Left atrial enlargement Valvular insufficiency Thrombus Prosthetic valve 24° Cardiac Holter (n) Normal sinus rhythum Pacemaker rhythum Minimum heart rate ( 4. SD) Maximum heart rate ( + SD) Carotid dopplers (n) Stenosis (right side) < 10% 11-30% 31-60% 61-100% Stenosis (left side) < 10% I! -30% 31-6{)% 61-100% Plaque (right side) Abr..ent Mild-moderate Severe (calcific) Plaque (left side) Absent Mild-moderate Severe (calcific)
AI
22 9(41%)
23 5 (22%)
8 (36%)
13 (57%)
5 (23%) 20 4 10 6 1 4 0 0 17 17 0 57+!1 174-18 11
5 (22%) 17 3 10 4 1 2 0 1 20 19 1 55d- 12 109+ 16 15
4 5 1 1
6 6 3 0
5 3 2 I
6 5 4 0
1 6 4
2 5 8
2 3 6
3 6 6
relationship between the clinical severity of stroke and thrombus size. Whatever the real underlying explanation, this absence of relationship between platelet ionized calcium and stroke severity is not totally unexpected because of several other factors that could influence the extent of neurological deficit. One obvious determinant is the location of the thrombotic occlusion. An infarct in the brainstem is likely to cause far more deficit than would a similar sized infarct in the prefrontal lobe. Other factors that could influence the clinical picture include the extent of collateral circulation and the degree of arterial narrowing. However, all these factors being equal, one would still
TABLE 3 NEUROLOGICAL STATUS AND PLATELET [Ca2+l IN ND AND AI PATIENTS Neurological scores were better, and platelet baseline and stimulated [Cal2+ ] levels were lower in the AI patients. A higher Mathew score and Barthel index, and a lower Toronto score indicates less severe neurological deficit. Calcium concentrations in ~M. All values are mean + SD.
Neurological status Matthew scale Toronto scale Barthel index
ND (n = 22)
A! (n = 23)
P value
66 58 53
83 18 78
< 0.005 < 0.005 < 0.01
+27 +_54 +-40
+_10 + 17 + 24
Platelet ionized [Ca 2+ ] Baseline [Ca 2 + ] 2.23 +- 0.47
1.78 +_ 0.41
< 0.005
Collagen induction 4 ~tg/ml 2/~g/ml
3.79+_ 1 . 3 1 3.32+ 1.21
2A0+- 0.87 2.11 +- 0.73
< 0.0005 < 0.0005
Thrombin induction 1.0unit/ml 0.5anit/ml
4,80+ 1,69 4.15+ 1.34
3.38+- 1.18 3.05+ 1 . 1 1
