A new study from Scandanavia may influence the treatment of acute myocardial infarction. But it also may end up having a much bigger impact on the entire field of medicine by pointing the way to an entirely new way of performing randomized clinical trials rapidly and inexpensively. One expert said the trial design may represent “a new paradigm,” and for once the use of the p-word may actually be appropriate.
Thrombus aspiration for ST-segment elevation myocardial infarction (STEMI) has been kicking around for a long time, but its utility has never been definitively evaluated. The procedure uses a dedicated catheter to suck the clot out of the vessel prior to stent implantation. In an accompanying editorial, Robert Byrne and Adnan Kastrati write that thrombus extraction “is an intuitively attractive strategy and one that is simple to carry out.”
The Scandanavian study has its origins in an earlier study, TAPAS, which found an unexpected benefit on mortality at one year for thrombus aspiration, though the trial was not designed to assess mortality. On the basis of TAPAS, thrombus aspiration was given a level IIA endorsement in both European and U.S. guidelines.
TASTE (Thrombus Aspiration in ST-Elevation Myocardial Infarction in Scandinavia) was presented at the European Society of Cardiology meeting in Amsterdam and published simultaneously in the New England Journal of Medicine. The investigator-initiated randomized trial was performed as part of the Swedish Coronary Angiography and Angioplasty Registry (SCAAR), which in this case included 1 center each in Iceland and Denmark. After obtaining consent, patients were randomized through “an online randomization module within the SCAAR database.”
A total of 7244 STEMI patients were randomized, representing a striking 60% of all STEMI patients referred for PCI in Sweden and Iceland during the study period. All-cause mortality at 30 days was not significantly different between the two groups:
- 2.8% in the thrombus aspiration group versus 3% of the PCI-only group (hazard ratio 0.94, CI 0.72-1.22, p=0.63)
A similar result was observed in the per-protocol analysis.
There were no significant differences in the rate of rehospitalization due to reinfarction, stent thrombosis, target-lesion revascularization, target-vessel revascularization, neurological complications, or other clinical outcomes, though there were trends in favor of thrombus aspiration in hospitalization for MI and stent thrombosis. The results were consistent across all major subgroups.
In their editorial, Byrne and Kastrati hold out hope that thrombus aspiration may turn out to be beneficial. They predict that “many interventional cardiologists will continue to perform thrombus aspiration for now,” based on hints of efficacy and the lack of any safety issues found in the trial.
Furthermore, they write, 30-day followup may not be long enough to detect a benefit, since the benefit in the TAPAS trial only emerged at 1 year. They urge the TASTE investigators to report the 12-month findings of their trial, and note that another large-scale randomized trial is nearing completion. “For now,” however, “the hope that this simple, easy-to-use, intuitively attractive technology could save the lives of patients presenting with myocardial infarction remains an unmet aspiration.”
A New Paradigm?
But the sweetest part of TASTE may be that the investigators were able to conduct a rapid and low-cost trial utilizing a new model, “a registry-based randomized clinical trial,” by incorporating the trial within the already existing framework of SCAAR: “The data were monitored and adjudicated as part of the regular registry validation; we did not perform separate, dedicated monitoring and adjudication of the data for the TASTE trial.”
In an accompanying Perspective, Michael Lauer and Ralph D’Agostino, Sr. ask whether randomized registry trials may be “the next disruptive technology in clinical research.” Current trials are expensive and “too complex and difficult to apply.” The usual alternative, traditional observational studies utilizing registries, “lack the rigor of randomization.”
TASTE, they write, represents “a new paradigm… that can potentially release us from the circular (and expensive) trap of the randomized-versus-registry debate.”
“The TASTE investigators designed a large-scale trial to answer an important clinical question and carried it out at remarkably low cost by building on the platform of an already-existing high-quality observational registry. With this clever design, which leveraged clinical information that was already being gathered for the registry and for other preexisting databases, the investigators were able to quickly identify potential participants, to enroll thousands of patients in little time…, to avoid filling out long case-report forms, to obtain accurate follow-up with minimal effort, and to report their findings, all for less than the amount of a typical modular R01 grant…”