Thrombolysis

Despite having been used sporadically for over 40 years, evidence for the effectiveness of thrombolytic therapy in acute ischaemic stroke has only recently become available. A systematic review of the results of 12 of the 14 completed randomised controlled trials in the post-CT era suggests that although thrombolytic therapy (with recombinant tissue plasminogen activator, streptokinase, or urokinase) is associated with about 70 symptomatic (about 50 fatal) intracranial bleeds per 1000 patients treated, its use is associated with perhaps 65 more patients surviving free of dependency at 3-6 months post-stroke (Figure 3.1).90 Even more compelling are the updated analyses of treatment within the first three hours.91 These demonstrate less risk of early intracranial haemorrhage and early death and greater long term net benefit (130 extra patients alive and independent per 1000 treated).

Expt

Ctrl

Peto OR

Weight

Peto OR

Study

n/N

n/N

(95%CI fixed)

%

(95%CI fixed)

Treatment within three hours

ASK 1996

14/41

15/29

2-6

0-49 [0-19,1-28]

ECASS 1995

28/49

25/38

3-2

0-70 [0-29,1-66]

ECASS II 1998

39/81

44/77

6-2

0-70 [0-37,1-30]

MAST-E 1996

19/26

14/21

1-6

1-35 [0-39,4-68]

MAST-I 1995

46/79

69/103

6-6

0-69 [0-38,1-26]

Subtotal (95%CI)

146/276

167/268

20-3

0-70 [0-49,0-99]

Chi-square 1 -61 (df= 4) Z = 2-04

Treatment between three and six hours

ASK 1996

70/133

59/137

10-7

1-47 [0-91,2-36]

ECASS 1995

143/264

160/269

20-6

0-81 [0-57,1-13]

ECASS II 1998

148/328

167/314

25-3

0-72 [0-53,0-99]

MAST-E 1996

105/130

112/133

6-0

0-79 [0-42,1-49]

MAST-I 1995

150/234

131/223

17-1

1-25 [0-86,1-83]

Subtotal (95%CI)

616/1089

629/1076

79-7

0-93 [0-78, 1-10]

Chi-square 9-34 (df = 4) Z = 0-86

Total (95%CI)

762/1365

796/1344

100-0

0-87[0-75, 1 02]

Chi-square 12-99 (df = 9) Z = 1-69

Favours treatment Favours control

Figure 3.1 Results of a systematic review of the randomised trials of thrombolysis administered within six hours of the onset of CT proven ischaemic stroke. The estimate of treatment is expressed as an odds ratio (square, the size of the square indicating the statistical power of the estimate) and its 95% confidence intervals (horizontal bar); the diamond shapes provide estimates of the pooled trial results. An odds ratio of 1 indicates a zero treatment effect, an odds ratio less than 1 indicates treatment better than control, and an odds ratio greater than 1 indicates treatment worse than control. Treatment with thrombolysis within three hours reduced death and dependency at the end of follow up

How practicable the widespread use of thrombolysis will be (particularly for a condition which has not traditionally been thought of as an emergency) remains uncertain, although some units have published impressive figures.92 Recombinant tissue plasminogen activator (r-TPA) is now licensed in the United States and a European licence is likely to be granted in the near future; therefore, it seems reasonable to consider using r-TPA in patients presenting within three hours, and who are similar to the patients included in the trials, provided one has a stroke service which can ensure its safe administration (Box 3.3).

Our view is that further trials are required to establish the balance of risks and benefits in a broader range of patients presenting at different stages, with differing severities and types of ischaemic stroke, different risk factors, and differing scan appearances. Many of the eligibility criteria currently in place are arbitrary and are not based on any reliable evidence. If a larger proportion of patients were eligible for treatment the potential impact on the burden of stroke would be greater and it may then be easier to justify the major changes in the delivery of acute stroke services which are required.

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