A Pilot Study of a New Thrombolytic Agent for Acute Ischemic Stroke in Taiwan Within A Five-Hour Window

Stroke and Thrombolysis in Developing Countries

Summary of review

The epidemiology of stroke is well investigated in the developed world; however, in the developing world stroke is less well documented. Most of the available stroke data from these countries are hospital-based. Stroke thrombolysis is currently used in few developing countries like Brazil, Argentina, Senegal, Iran, Pakistan, China, Thailand, and India. The two main barriers for implementation of thrombolysis therapy in developing countries are the high cost of tissue plasminogen activator and lack of proper infrastructure. Most of the centers with the infrastructure to deliver thrombolysis for stroke are predominantly private sector, and only available in urban areas.

Conclusion

Until a more cost-effective thrombolytic agent and the proper infrastructure for widespread use of thrombolysis therapy are available, developing nations should focus on primary and secondary stroke prevention strategies and the establishment of stroke units wherever possible. Such multi-faceted approaches will be more cost-effective for developing countries than the use of thrombolysis.

Different doses of recombinant tissue-type plasminogen activator for acute stroke in Chinese patients

BACKGROUND AND PURPOSE

The relationship between the dose of recombinant tissue-type plasminogen activator (r-tPA) and its safety/efficacy for ischemic stroke has not been well evaluated in the East Asian population. We assessed the safety/efficacy of different doses of r-tPA for acute ischemic stroke in Chinese patients.

METHODS

A total of 1004 eligible patients were classified according to the dose of r-tPA received for managing acute ischemic stroke: 0.9 mg/kg (n=422), 0.8 mg/kg (n=202), 0.7 mg/kg (n=199), and 0.6 mg/kg (n=181). The safety outcome was symptomatic intracerebral hemorrhage and death within 3 months. The efficacy outcome was good functional outcome (modified Rankin Scale ≤1) at 3 months.

RESULTS

There was a significant trend for symptomatic intracerebral hemorrhage with age (P=0.002). With multivariate logistic regression analysis, a dose of 0.9 mg/kg was a predictor of symptomatic intracerebral hemorrhage (P=0.0109), and a dose ≤0.65 mg/kg was a predictor of good functional outcome (P=0.0369). In patients aged 71 to 80 years, there was a significant trend of increasing symptomatic intracerebral hemorrhage (P=0.0130) and less good functional outcome (P=0.0179) with increasing doses of r-tPA. There was also a trend of increasing mortality (P=0.0971) at 3 months in these patients.

CONCLUSIONS

These results did not support the dose of 0.9 mg/kg of r-tPA being optimal for all patients in the East Asian population. In elderly patients (71-80 years), a lower dose of 0.6 mg/kg is associated with a better outcome. Confirmation of the results through randomized trial is required.

Improving reperfusion therapy for acute ischaemic stroke

BACKGROUND

The first generation of clinical reperfusion treatment, intravenous (IV) fibrinolysis with tissue plasminogen activator (tPA), was a transformative breakthrough in stroke care, but is far from ideal.

OBJECTIVES

TO survey emerging strategies to increase the efficacy and safety of cerebral reperfusion therapy.

METHODS

Narrative review.

RESULTS AND CONCLUSIONS

Innovative IV pharmacologic reperfusion strategies include: extending IV tPA use to patients with mild deficits; developing novel fibrinolytic agents (tenecteplase, desmetolplase, plasmin); using ultrasound to enhance enzymatic fibrinolysis; combination clot lysis therapies (fibrinolytics with GPIIb/IIIa agents or direct thrombin inhibitors); co-administration of MMP-9 inhibitors to deter haemorrhagic transformation; and prehospital neuroprotection to support threatened tissues until reperfusion. Endovascular recanalisation strategies are rapidly evolving, and include intra-arterial fibrinolysis, mechanical clot retrieval, suction thrombectomy, and primary stenting. Combined approaches appear especially promising, using IV fibrinolysis to rapidly initiate reperfusion, mechanical endovascular treatment to debulk large, proximal thrombi, and intra-arterial (IA) fibrinolysis to clear residual distal thrombus elements and emboli.

Intravenous rt-PA versus endovascular therapy for acute ischemic stroke

The influence of baseline stroke severity on outcome makes comparisons between nonrandomized studies of intravenous and intra-arterial (IA) therapy problematic. Using pooled data from the placebo arms of randomized trials in acute ischemic stroke, we derived predictive functions for outcome. We then compared the outcomes from published trials to these functions. Net benefit was calculated by comparison of the individual study with the predicted outcome based on the therapeutic time window. Similar net benefit for IA therapy and intravenous therapy was found at 3 hours and 6 hours; a slight advantage for IA therapy was mitigated by an increase in mortality at 6 hours and by publication bias. No net benefit for IA therapy was shown in the time window greater than 6 hours. Conclusive evidence for the superiority of either therapy awaits prospective randomized trials.

Outcomes of thrombolytic therapy for acute ischemic stroke in Chinese patients: the Taiwan Thrombolytic Therapy for Acute Ischemic Stroke (TTT-AIS) study

BACKGROUND AND PURPOSE

The safety and efficacy of alteplase for ischemic stroke has not been examined in Chinese patients. We assessed the safety and efficacy of alteplase for acute ischemic stroke in daily clinical practice in Taiwan.

METHODS

A prospective, multicenter, observational study was conducted in Taiwan from December 2004 to July 2008. Eligible patients (241) receiving alteplase were recruited and divided into 2 groups: standard dose (0.90 + or - 0.02 mg/kg, n=125) and lower dose (0.72 + or - 0.07 mg/kg, n=116). Primary outcome measures were safety: symptomatic intracerebral hemorrhage and death within 3 months. The secondary outcome measure was efficacy a modified Rankin scale of 0 to 2 after 3 months.

RESULTS

The standard-dose group had higher rates of symptomatic intracerebral hemorrhage using National Institute of Neurological Diseases and Stroke, European Cooperative Acute Stroke Study, and Safe Implementation of Thrombolysis in Stroke-Monitoring Study definitions (10.4% versus 5.2%, 8.0% versus 2.6%, and 5.6% versus 1.7%, respectively) and mortality within 3 months (12.8% versus 6.9%), twice that of the lower-dose group. This pattern was more prominent in older patients. Significantly higher rates of symptomatic intracerebral hemorrhage per European Cooperative Acute Stroke Study (15.4% versus 3.3%, P=0.0257) and mortality (21.1% versus 5.0%, P=0.0099) and significantly lower independence rate (32.6% versus 53.6%, P=0.0311) were observed among patients > or = 70 years old receiving the standard dose than those receiving the lower dose.

CONCLUSIONS

This study suggests that the standard dose of 0.9 mg/kg alteplase may not be optimal for treating aged Chinese patients. However, the dose of recombinant tissue plasminogen activator for ischemic stroke in Chinese patients should be based on more broad and convincing evidences and randomized trials of lower versus higher doses are needed.

[Thrombolysis for ischemic stroke: an update]

Even 10 years after the approval of thrombolysis this life-saving and disability reducing therapy is still underused. Important reasons for that are very strict inclusion criteria such as the early and narrow time-window, fear of bleeding complications and doubts regarding the effectiveness. An intensive and constant effort is required to educate the public that stroke is a treatable emergency. In addition to the medical reasons, economic considerations in a context of decreasing resources emphasize the importance of effective stroke treatment. The results of numerous recent studies such as the European register SITS-MOST help to strengthen the confidence in thrombolysis. In addition the development and advancement of new imaging tools such as multiparametric MRI and advanced CT-techniques will improve patient selection and may enable us to extend the time-window for treatment. Intraarterial thrombolysis, "bridging" methods and new devices for intravascular intervention are the subjects of intensive ongoing research. Even though no randomized trials are available intraarterial thrombolysis is the treatment of choice for acute basilar occlusion, but if this intervention is not available an intravenous approach may be an equal alternative.