Early Magnesium Treatment After Aneurysmal Subarachnoid Hemorrhage: Individual Patient Data Meta-Analysis

BACKGROUND AND PURPOSE

Delayed cerebral ischemia (DCI) is an important cause of poor outcome after aneurysmal subarachnoid hemorrhage (SAH). Trials of magnesium treatment starting <4 days after symptom onset found no effect on poor outcome or DCI in SAH. Earlier installment of treatment might be more effective, but individual trials had not enough power for such a subanalysis. We performed an individual patient data meta-analysis to study whether magnesium is effective when given within different time frames within 24 hours after the SAH.

METHODS

Patients were divided into categories according to the delay between symptom onset and start of the study medication: <6, 6 to 12, 12 to 24, and >24 hours. We calculated adjusted risk ratios with corresponding 95% confidence intervals for magnesium versus placebo treatment for poor outcome and DCI.

RESULTS

We included 5 trials totaling 1981 patients; 83 patients started treatment<6 hours. For poor outcome, the adjusted risk ratios of magnesium treatment for start <6 hours were 1.44 (95% confidence interval, 0.83-2.51); for 6 to 12 hours 1.03 (0.65-1.63), for 12 to 24 hours 0.84 (0.65-1.09), and for >24 hours 1.06 (0.87-1.31), and for DCI, <6 hours 1.76 (0.68-4.58), for 6 to 12 hours 2.09 (0.99-4.39), for 12 to 24 hours 0.80 (0.56-1.16), and for >24 hours 1.08 (0.88-1.32).

CONCLUSIONS

This meta-analysis suggests no beneficial effect of magnesium treatment on poor outcome or DCI when started early after SAH onset. Although the number of patients was small and a beneficial effect cannot be definitively excluded, we found no justification for a new trial with early magnesium treatment after SAH.

Intra-arterial thrombolysis in acute ischaemic stroke

Several thrombolytic agents for the treatment of acute ischaemic stroke have been examined; however, to date, only the i.v. administration of recombinant tissue plasminogen activator is licensed in Australia. Although no trials directly comparing intra-arterial and i.v. delivery of thrombolytics exist, intra-arterial thrombolysis has several potential advantages, including angiographic assessment of the thrombus and the site of occlusion and collateral circulation, improved recanalization, and delivery of higher local concentrations of thrombolytic agents and extending the therapeutic time window for treatment. We conducted a retrospective audit of our experience with the use of intra-arterial urokinase to treat acute ischaemic stroke at an Australian tertiary-care hospital between June 1993 and June 2003. We examined time from stroke onset to assessment, computerized tomography scan, cerebral angiography and thrombolysis, anatomical classification of intra-arterial thrombus, rates of symptomatic intracerebral haemorrhage, and clinical outcome at 3 months. We believe that in carefully selected individuals in appropriate centres of expertise, intra-arterial thrombolytic therapy holds great promise.

Use of computed tomography pulmonary angiography in the diagnosis of pulmonary embolismin patients with an intermediate probability ventilation/perfusion scan

BACKGROUND

Computed tomography pulmonary -angiography (CTPA) plays an increasingly important role in the diagnosis of pulmonary embolism (PE). Although accurate in the detection of large PE, its accuracy in other patient groups is yet to be defined.

AIM

To compare CTPA with pulmonary angiography as a second-line investigation in patients with a ventilation/perfusion (VQ) scan indicating an intermediate probability of PE.

METHODS

We recruited 25 patients over a 17-month period. Subjects were eligible if they: (i). had clinically suspected PE, (ii). had a VQ scan indicating an intermediate probability of PE and (iii). were referred for pulmonary angiography. Subjects underwent CTPA within 36 h of the VQ scan. CTPA was interpreted without knowledge of the results of the pulmonary angiogram by two of the authors.

RESULTS

PE was prevalent (i.e. embolus detected at pulmonary angiography) in seven of 25 subjects (28%). The sensitivity of CTPA was 57% and the specificity was 94%.

CONCLUSIONS

In the setting of intermediate-probability VQ scanning, CTPA may be used to clarify the diagnosis of PE. However, a negative CTPA cannot -definitely exclude PE. Conventional pulmonary angiography may be necessary to determine the presence of PE if CTPA is negative.