Patients admitted for unstable angina or non-ST-segment-elevation myocardial infarction have better outcomes if they undergo early invasive treatment rather than conservative treatment, according to an article published in the Cochrane Database of Systematic Reviews (Issue 3, 2006).

“Available evidence suggests that an early invasive strategy is superior to a conservative strategy,” said lead author Michel Hoenig, MD. “However, we are far from having as solid an answer as we need given the prevalence and costs associated with treating this disease.”

The reviewers examined five major randomized clinical trials that compared an early invasive approach to a conservative approach in patients with this acute coronary syndrome, evaluating rates for recurrent infarction and mortality both in-hospital and long term. They also looked at differences in rates of intractable angina and rehospitalization during the first 6 to 12 months after the initial event.
The early invasive approach was superior to the conservative approach for all outcomes.

In the early invasive approach, patients undergo angiography and patients with significant obstruction are treated with angioplasty and stenting. Some patients require bypass surgery rather than a percutaneous coronary intervention.

In the conservative approach, patients are treated with medication. Only those whose symptoms persist or worsen or who have evidence of arterial stenosis on noninvasive tests undergo invasive procedures. Supporters maintain that once patients have been stabilized with medical therapy, noninvasive tests can be used to identify high-risk patients who would be most likely to benefit from invasive treatment.

Among study participants, patients in the early invasive group were about one third less likely to have uncontrolled chest pain or to be rehospitalized 6 to 12 months after hospitalization.

Based on the two trials with the longest follow-up, patients in the early invasive group also had a 25 percent lower risk of death or second myocardial infarction two to five years after the initial event.

However, patients randomized to early invasive treatment had a two-fold increased risk of procedure-related myocardial infarction and an increased risk of bleeding during the initial hospitalization.

According to William Boden, MD, chief of cardiology at Buffalo General Hospital, this finding underscores the importance of factoring in an individual patient’s level of risk when considering whether to proceed with invasive treatment: “Common to all of the trials is this hazard of increased death or heart attack within the first seven days or so of a catheter-based procedure. This is why I think it’s important to risk-stratify patients, because the early hazard would be magnified in the low-risk patient and would be mitigated to a degree in the high-risk patient.”

The reviewers came to a similar conclusion when they looked at which patients were most likely to benefit from the early invasive approach. In two of the studies, only patients who were considered at high risk based on ECG findings or lab test results had a reduced risk of death or myocardial infarction with the early invasive approach.