If the recovery of blood flow after a stroke is delayed, long-term damage may occur. In addition, the probability of successful treatment is reduced by 6%. Delays in restoring blood flow after stroke are apparently associated with significantly reduced chances of good long-term outcomes. In addition, a longer time interval reduces the chances of successful catheter-based intrarterial lysis therapy.
The importance of time in the clinical trial.
Time is an important indicator of the clinical outcome that can be achieved and the likelihood of successful treatment in patients who have suffered a stroke. In one study, they examined the influence of time from stroke onset to treatment initiation and successful reperfusion (restoration of blood flow to the brain) on the clinical effects of intra-arterial therapy (IAT). IAT involves inserting a catheter into an artery and moving it to the point of blockage. Once there, thrombolytic drugs are administered and/or a mechanical reopening of the artery is performed. In both cases, the clot is ideally removed, blood flow to the brain tissue is restored and its destruction is prevented. The randomized clinical trial compared the outcome of an IAT (usually performed by a stent retriever) with the outcome of patients who did not receive an IAT. A total of 500 patients were involved in the study, of whom 233 ultimately underwent intervention. Time to treatment initiation was defined as the time from onset of stroke symptoms to inguinal puncture (TOG) for catheter placement in the groin. Time from onset to reperfusion was defined as the time (TOR) required to reopen the blockage or terminate the procedure in cases where reperfusion could not be achieved. All patients also received guideline-based treatment of an ischemic insult. This included intravenous administration of fibrolytic agents if indicated.
A 1-hour delay before reperfusion reduced the probability of success by 6%.
Among the 500 patients, the median duration of TOG was 260 minutes (4 hours, 20 minutes), whereas the median duration of TOR was 340 minutes (5 hours, 40 minutes). Of the 233 patients who underwent surgery, 17 (7.3%) did not reach the treatment room. In 25 patients (10.7%), treatment was initiated within 3 hours of stroke onset, in 96 patients (41.2%), treatment was initiated between 3 and 4.5 hours after stroke onset, whereas in 95 patients (40.8%), treatment could be initiated more than 4.5 hours after onset. 19 patients (8.2%) required more than six hours before treatment. In analyzing their data, the authors found a clear correlation between baseline terms and treatment effect. However, no statistically significant relationship was found between TOG and the effect of the intervention. The authors conclude that each hour of delay until successful reperfusion reduces the chance of a good clinical outcome by 6%. The study underscores the critical importance of IAT as early as possible in patients with acute ischemic stroke. The absolute treatment effect of an IAT and its decrease over time is much greater than that of intravenous therapy. However, the most important finding for scientists is that patients with acute ischemic stroke need immediate diagnosis to initiate appropriate treatment. In case of arterial occlusion, intra-arterial treatment should be performed as soon as possible.