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Angioplasty prolongs survival in high risk patients with confirmed heart attack

BMJ 2005; 331 doi: https://doi.org/10.1136/bmj.331.7530.0-e (Published 15 December 2005) Cite this as: BMJ 2005;331:0-e

Research question Can angioplasty reduce overall mortality compared with fibrinolysis in patients with heart attack?

Answer Yes. Primary angioplasty reduces overall mortality among patients identified as high risk by the TIMI (thrombolysis in myocardial infarction) score

Why did the authors do the study? Patients with confirmed heart attack who have a percutaneous coronary intervention are less likely to die or have another heart attack or stroke than patients treated with fibrinolytic drugs. But primary angioplasty is not widely available, and it's still unclear whether this invasive treatment reduces all cause mortality. These authors suspected that angioplasty was most likely to be life saving for patients at highest risk of death, and they did this study to find out. They also wanted to know if it was feasible to triage patients on admission using the simple TIMI (thrombolysis in myocardial infarction) score. This score has been shown to identify patients at high risk of death after a heart attack.

What did they do? They reanalysed data from a previous randomised trial comparing fibrinolysis (alteplase) with primary angioplasty in 1527 people with confirmed myocardial infarction. Using the TIMI score, they assigned patients to high risk or low risk subgroups, and compared what happened to them over three years. The TIMI score, which was not available at the time of the original trial, scores patients according to their age (75 years = 3 points; 65-74 years = 2 points), systolic blood pressure (< 100 mm Hg = 3 points), heart rate (> 100 bpm = 2 points), Killip class (class 2-4 = 2 points), weight (< 67 kg = 1 point), anterior ST segment elevation (1 point), time delay between symptoms and treatment (> 4 hours = 1 point), and medical history (angina, diabetes, or hypertension = 1 point). Patients scoring ≥ 5 out of a possible 14 were classified as high risk, the rest as low risk.

What did they find? In the 393 high risk patients, primary angioplasty reduced all cause mortality at three years compared with alteplase (25.3% v 36.2%; hazard ratio 0.66, 95% CI 0.45 to 0.94). That's equivalent to a number needed to treat of nine. Angioplasty did not reduce all cause mortality compared with fibrinolysis in the 1134 low risk patients (8.0% v 5.6%, P = 0.11). Angioplasty looked like a better treatment for high risk patients even when they had to be transferred to get it (mortality 24.6% v 36.8%, P = 0.02, number needed to treat 8). The authors conclude that the TIMI score can identify those heart attack patients for whom primary angioplasty could be life saving.

What does it mean? We already know that primary angioplasty reduces all cause mortality among patients with cardiogenic shock after a heart attack. This study, which is basically a subgroup analysis of a previous randomised trial, extends that benefit to other high risk patients. In hospitals that don't do primary angioplasty, the TIMI score could be a useful tool for identifying patients most likely to benefit from angioplasty, so they can be transferred quickly. The score is simple to calculate, requiring data that are usually readily available on admission.

Acknowledgments

Thune et al. Simple risk stratification at admission to identify patients with reduced mortality from primary angioplasty. Circulation 2005;112: 2017-21

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