高リスク患者はACSに対する積極的な治療の恩恵を被る

A more aggressive treatment approach to patients with non-ST elevation acute coronary syndrome (ACS) leads to better long-term outcomes than more conservative care, according to research presented at the American College of Cardiology's 59th annual scientific session.

The FIR Trial Collaboration is the first meta-analysis of all relevant studies containing five-year data. The lead investigators from each of the studies (FRISC-II, RITA-3 and ICTUS) collaboratively analyzed the individual patient data to determine the long-term outcomes of using either a more aggressive routine invasive (RI) strategy - consisting of early coronary angiography for every patient followed by revascularization, if indicated - or a more conservative selective invasive (SI) strategy-consisting of standard medical treatment and coronary angiography only for specific cases-in patients with severe symptoms or signs of ischemia.

At the five-year mark, patients receiving the RI strategy had lower incidences of cardiovascular death and non-fatal myocardial infarction. Specifically, 14.7 percent of the 2,721 patients randomized to the RI group experienced either cardiovascular death or non-fatal myocardial infarction, compared with 17.9 percent of the 2,746 patients in the SI group. The most marked treatment effect was seen for non-fatal myocardial infarction alone, which occurred in 10 percent of the RI cohort and 12.9 percent of the SI cohort, but the researchers also saw both a lower number of cardiovascular deaths alone and a lower number of deaths from any cause in the RI group.

"The reason why we need this combined 'meta-analysis' of all the trials, and based on individual patient data, is that there is inconsistency in the findings of the individual studies," said Dr. Keith A. Fox, the British Heart Foundation Professor of Cardiology at the Centre for Cardiovascular Science at the University of Edinburgh, United Kingdom, and the study's lead researcher. "It is only with this combined analysis that we can get a conclusive result. The study has demonstrated that there is a clear impact on reduced CV death and myocardial infarction."

In addition to discovering that an RI strategy produced better long-term results than a SI strategy, the team also uncovered an unexpected finding: not all patients benefited equally. Those in the highest risk group - based on a number of variables including age, diabetes, and previous myocardial infarction, among others - benefitted the most from undergoing the RI strategy. The researchers note that risk can be estimated at the bedside using a simple scale based upon the patient's characteristics (age, diabetes, ECG signs of ischemia, hypertension, prior myocardial infarction and Body Mass Index).

While Fox notes that this finding highlights a common paradox in medical treatment - that the majority of patients who receive interventions are low risk - he adds that the study lends support to the idea of systematically risk-stratifying patients in order to determine who should receive an intervention.

"If patients are high risk and without contraindication but they are not going for an invasive strategy, we need to ask 'why,'" Fox said.

The need for risk stratification is supported by guidelines including the American College of Cardiology/American Heart Association Guidelines.

The meta-analysis was conducted using resources from each of the host institutions for their respective studies. The original studies were supported as disclosed in the original publications.

This study is simultaneously published in the Journal of the American College of Cardiology and online.