Unique Swedish registry study may change treatment for heart attacks

Aspiration of blood clots from the coronary artery of the heart in cases of acute myocardial infarction does not save more lives than simple treatment with balloon expansion. This is the finding of a unique new Scandinavian study being presented today at the European Cardiology Conference in Amsterdam. The findings are also being published in the New England Journal of Medicine.

- Our results call into question the benefit of suctioning off blood clots as a routine. The findings of the study will probably have an immediate effect on clinical practice and international guidelines, says lead author Ole Fröbert, a professor at the Department of Cardiology, Örebro University Hospital.

The study was coordinated by Uppsala Clinical Research Center (UCR), which is an entity within Uppsala University and Uppsala County Council. The study comprises 7200 patients and is the first study of aspiration of blood clots in acute myocardial infarction that is large enough to draw meaningful conclusions about mortality and morbidity. It is also the largest randomised study of a treatment technique for acute myocardial infarction ever undertaken. The study is unique, and Sweden’s well-organised medical care system with national quality registries has been a precondition for its implementation.

- Thanks to our public registries the study was with highest imaginable quality at a marginal cost compared with a conventional clinical research study. This type of study opens up the possibility of evaluating established forms of treatment that are important to patients but lack commercial interest and can help Sweden regain its role as world leader in clinical investigations, says Stefan James, director and initiator of the study and a specialist consultant physician and associate professor at UCR.

The study was carried out in collaboration with all hospitals in Sweden. Half of the patients received only balloon (stent) treatment and the other half underwent aspiration treatment, to suction off a blood clot prior to balloon treatment.

The results show that mortality 30 days after the operation did not differ between the groups. Nor was there any difference between the two groups regarding for example the risk of a new heart attack, stroke, or complications stemming from treatment. Nor did high-risk groups such as smokers, patients with diabetes, or patients with large blood clots evince any benefits from the treatment. International guidelines currently recommend that patients with acute myocardial infarction should be treated with removal of blood clots by aspiration, and it has been regarded as especially effective in patients with large blood clots. However, later research has shown that suctioning off a blood clot can entail risks of stroke or blood clots, for example.

- Our results show that suctioning blood clots is free of risk, but that patients don’t benefit from it, says Stefan James.

Reference: Fröbert, Lagerqvist et al, Thrombus Aspiration during ST- Elevation Myocardial Infarction - A Multicenter, Prospective, Registry-Based Randomized Clinical Trial, New England Journal of Medicine.

For more information, please contact Stefan James, associate professor of cardiology, Uppsala Clinical Research Center (UCR), mobile: +46 (0)705-94 44 04, e-mail: Stefan.james@ucr.uu.se or Ole Fröbert, professor of cardiology at Örebro University Hospital, mobile: +46(0)730-89 54 13, e-mail: Ole.frobert@orebroll.se

FACTS

About acute myocardial infarction:

Acute myocardial infarction is caused by a blood clot blocking the flow of blood to one of the heart’s coronary arteries, which immediately leads to part of the heart ceasing to function owing to lack of oxygen. This in turn can lead to cardiac arrest or permanent damage to the heart. Acute myocardial infarction is treated with drugs to dissolve blood clots and stent expansion of the blocked artery by inserting a thin plastic tube up to the heart via the wrist or groin. The artery is then often reinforced with a thin metal tube to keep it open. Before expanding the artery a thin plastic tube can be used to suction off the blood clots blocking the artery. The purpose of this is to remove the clot so it will not be fragmented by the stent.

About Swedeheart and TASTE:

Swedeheart is a national quality registry run by physicians and nurses with the support of the Swedish Associations of Local Authorities and Regions. Participation is voluntary, and all patients have the opportunity to refuse to participate in national registries. The registry is in operation at all hospitals in the country, and all patients undergoing stent expansion of acute myocardial infarction are included. Swedeheart’s purpose is to improve medical care by registering background factors, morbidity, blood samples, and treatments administered. Economic and practical means to do this are provided by medical care principals. Data registered in Swedeheart is disidentified from civic registration numbers and used to monitor the quality of care and for research. In the TASTE (Thrombus Aspiration in ST-Elevation Myocardial Infarction in Scandinavia) study, physicians, following approval from the ethical review board, asked patients with acute myocardial infarction to participate in the study, where treatment with or without aspiration of blood clots was randomly assigned.

Uppsala Clinical Research Center, UCR, is one of Sweden’s and the world’s leading centres for clinical research. UCR is organised as an independent entity within Uppsala University and Uppsala County Council.  UCR has more than 100 employees working in various sections such as clinical treatment trials, national quality registries, statistics and epidemiology, the biomarker laboratory, and Uppsala Biobank.