Background: The recommended treatment for non-ST-elevation acute coronary syndrome in patients with moderate to high risk of coronary artery disease is early invasive therapy, with revascularization if indicated. Most of the evidence supporting this strategy was provided by two large clinical trials that showed improved survival, fewer myocardial infarctions and coronary symptoms, and better quality of life 24 months after invasive treatment. One subsequent study confirmed these results. Another subsequent study comparing early with delayed invasive treatment failed to show an advantage with early intervention. Lagerqvist and colleagues studied the longer-term benefit of early intervention by calculating the five-year follow-up status of participants in one of the original trials (FRISC-II [FRagmin and Fast Revascularisation during InStability in Coronary artery disease]).

The Study: The original FRISC-II trial included 2,457 patients who presented to 58 Scandinavian hospitals with unstable coronary disease. Patients randomly assigned to invasive treatment received angiography and prompt (within seven days) revascularization if stenosis of 70 percent or more was demonstrated in an artery that supplied a substantial area of myocardium. Patients in the noninvasive group received angiography only if they had refractory or recurrent symptoms despite maximal medical therapy. Both groups received standard medical therapy as indicated.

Results: Five-year follow-up data (May 2006) were available for 2,434 patients (99 percent). Overall, statistically significant differences remained between the groups in myocardial infarction, death, or both (see accompanying table). The difference between the groups in mortality was not statistically significant at the two-year follow-up compared with the five-year follow-up results. When analyzed by age, patients who were younger than 70 years at randomization had lower mortality at five years in the invasive group compared with the noninvasive group (5.6 versus 7.0 percent). Intervention strategies appeared to benefit high-risk patients more than those with fewer risk factors (e.g., diabetes, previous myocardial infarction, raised troponin concentration, hypertension). At five years, 21.2 percent of medium- to high-risk patients in the invasive group reached the combined end point of death or myocardial infarction compared with 28.1 percent of medium- to high-risk patients in the noninvasive group. The corresponding figures for mortality were 10.5 and 12.0 percent. More than one half of patients in the noninvasive group underwent a revascularization procedure during the five years of follow-up.

Conclusion: The authors conclude that early invasive treatment of non-ST-elevation acute coronary syndrome is associated with sustained benefit in survival and myocardial infarction, especially in patients at moderate to high risk. The benefit was demonstrated at five years in men, nonsmokers, and patients with two or more risk factors. The optimal treatment strategy in low-risk and other patients is not yet clear.