Primary Angioplasty vs. "Front-Loaded" TPA
Source: GUSTO II b angioplasty substudy investigator. N Engl J Med 1997;336:1621-1628.
Prior randomized trials using varied thrombolytic regimens have suggested improved flow rates and short-term event rates with angioplasty. However, concerns that such results may not be applicable to broader clinical practice have been raised. Additionally, the possibility exists that a lytic regimen, if superior to other regimens, might narrow the gap with angioplasty. In an international trial, the GUSTO II b investigators randomized 1138 patients who presented within 12 hours with an ST elevation myocardial infarction to either PTCA or "front-loaded," weight-adjusted TPA. The primary end point was a composite of death, nonfatal reinfarction, and nonfatal disabling stroke. The incidence of one or more of the end points in patients treated with PTCA was 9.6% compared with 13.7% in the TPA-treated cohort (odds ratio, 0.67; P = 0.033), with the largest number of end points being reinfarction. At six months, there was no significant difference in the incidence of the end points (14.1% vs 16.1%, respectively).
Comment by William Strauss, MD
This trial confirms the relative superiority of PTCA compared to lytic therapy noted in smaller randomized trials. Indeed, the number of patients in this trial is essentially identical to the sum total of the prior trials. However, the magnitude of the benefit was far less impressive, either because the lytic regimen was truly superior to prior regimens or due to the selected nature of participant facilities in the prior trials and the small size of the studies. The latter explanation is supported by the fact that the number of lives saved in the prior trials was greater than noted compared to placebo (i.e., no reperfusion therapy). This study's results also paralleled the findings of a meta-analysis of the earlier trials,1 which similarly noted an early superiority with PTCA (30-45 days), that no longer held true in the long term. Four years ago, I was impressed with the editorial accompanying the publication of three of the more important of the above earlier studies.2 At that time, it was noted that although PTCA appeared to have some advantages, "only 18% of the hospitals in the United States have the capability of performing angioplasty, and even fewer can do it on an emergency basis." The same is almost certain still today. The authors of the current study note that the approach to the re-establishment of perfusion for the patient with an acute myocardial infarction is continuing to evolve, with stenting and potent antiplatelet adjunctive agents on the horizon. However, for now we must remind ourselves that the primary need remains reperfusion therapy, in the most timely fashion possible. Yes, if an experienced interventional cardiologist and lab is available, PTCA may have some small to moderate short-term benefits and certainly should be considered for the severely hypertensive patient or patient with antecedent cerebrovascular disease. However, lengthy delay to arrange for transfer for PTCA may more than wipe out any potential advantage and belies the proven benefits.
1. Michels KB, Yusef S. Circulation 1995;91:476-485.
2. Lange RA, Hillis LD. N Engl J Med 1993;328:726-728.
Dr. Strauss is Director of Preventive Cardiology, Department of Veteran Affairs Medical Center, West Roxbury, MA.