In 1993, managing patients with stroke had long remained an elusive and somewhat intimidating task for the neurological world. Previous efforts to treat the condition had produced more frustration than success, leaving clinicians and patients alike in despair for a solution. However, some successes in treating coronary thrombosis during that era rejuvenated researchers’ efforts to crack the code. An international team of researchers had studied a Streptococcus derivative (streptokinase) and others had begun to study a natural substance termed tissue plasminogen activator (tPA) as thrombolytic agents to lyse coronary clots and to treat pulmonary embolism. The adverse event of excessive bleeding found in Australian studies done on streptokinase intervention in patients with stroke prompted researchers to contemplate use of tPA in stroke management.
A group of German, Japanese, and American investigators began to research thrombolysis in acute stroke patients during the mid-1980s.
Dr. Louis Caplan
“What was unique is that patients had a CT scan followed by a catheter angiogram,” said Louis Caplan, MD, a senior member of the division of cerebrovascular disease at Beth Israel Deaconess Medical Center, Boston, professor of neurology at Harvard Medical School, Boston, and founder of the Harvard Stroke Registry at Beth Israel Deaconess Medical Center.
“If they had a blocked vessel, they got the drug, delivered either intravenously or intra-arterially.”
The process involved keeping the catheter open after drug administration to determine whether the vessel had opened or remained occluded. The researchers learned which blocked vessels opened when the drug was given intravenously and which required direct introduction of the drug into the clots.
A group of investigators in the United States funded by the National Institute of Neurological Disease and Stroke then performed a randomized therapeutic trial of intravenous tPA given within 90 minutes and 180 minutes after stroke symptom onset. The study was reported in the New England Journal of Medicine. Soon thereafter, in 1995, the Food and Drug Administration approved the use of tPA following the inclusion and exclusion rules used in the NINDS trial.
After the FDA approved tPA in 1995, stroke management was never the same.
tPA was just one factor in optimizing stroke management
Despite the major therapeutic breakthrough with tPA’s approval, it took the clinics, hospitals, and other acute care systems a while to catch up. “Neurologists and hospitals weren’t ready for acute stroke intervention and proper stroke management in the mid-90s,” Dr. Caplan recalled. “At the time, stroke wasn’t at the forefront of treatment, general neurologists weren’t trained, and there weren’t enough stroke neurologists.”
The preparation and training deficit was further exacerbated by low reimbursement for services. As a result, only about 5% of patients who were eligible for acute stroke management were treated with tPA.
According to Dr. Caplan, during the next 15-20 years, the accumulation of stroke data from MRI and CT vascular imaging clarified further which patients, with what extent of infarction, with which blocked vessels, would be good candidates for treatment.
More patients received interventional treatment using catheters directed into the area of clotting in attempt to remove the blockages. In addition, information regarding intervention at different periods (10-16 hours, up to 24 hours) and conditions (for example, patients with varying degrees of disability, infarct) were tested.
Eventually, hospitals became more attuned to emergency stroke treatment. More neurologists became trained, more stroke centers emerged, and clinicians enjoyed the benefit of technological advancements that allowed them to explore perfusion.