PTCA vs. Thrombolysis Revisited
Source: The GUSTO IIb investigators. A clinical trial comparing primary coronary angioplasty with tissue plasminogen activator for acute myocardial infarction. N Engl J Med 1997;336:1621-1628.
The authors investigated the ongoing controversy regarding the most appropriate acute revascularization therapy used in patients with acute myocardial infarction (AMI)percutaneous transluminal coronary angioplasty (PTCA) vs. thrombolytic therapy with tissue plasminogen activator (TPA). In a substudy of the GUSTO IIb trial, the authors randomly assigned 1138 patients with AMIbased upon the presence of chest pain of less than 12 hours duration and ST segment elevation on the electrocardiogramfrom 57 hospitals to either primary PTCA (565 patients) or accelerated ("front-loaded") TPA (573 patients). The composite end point of the study included death, nonfatal reinfarction, and nonfatal disabling stroke, all occurring within 30 days of the AMI.
Patients in both treatment groups tended to be middle-aged males without hypotension or pulmonary congestion on presentation. Of those patients assigned to primary PTCA therapy, 83% were candidates for such treatment and underwent angioplasty 1.9 hours after ED arrival for a total elapsed time from chest pain onset to therapy of 3.8 hours. Ninety-eight percent of the patients assigned to thrombolytic therapy received TPA 1.2 hours after hospital arrival, with a total elapsed time from symptom onset to thrombolytic agent administration of 3.0 hours. The occurrence of the composite end point was encountered significantly less often in the PTCA group (9.6%) compared to the TPA group (13.7%) at 30 days; no significant difference in composite end-point rate was noted at six months. When the individual components of the composite end point at 30 days were considered separately, the incidence of death (5.7% vs 7%), infarction (4.5% vs 6.5%), and stroke (0.2% vs 0.9%) occurred at statistically similar rates for both treatment groupsPTCA and TPA, respectively.
COMMENT BY WILLIAM J. BRADY, MD
This study suggests that PTCA offers a small-to-moderate, short-term advantage over TPA in the acute treatment of AMI. However, several issues concerning this conclusion warrant further discussion. First, this question has been the focus of numerous other reports and debates. Unfortunately, the reports are somewhat heterogeneous in their construction (e.g., differing therapies, study sites, outcome measures, etc.), making absolute, all-encompassing recommendations impossible and thus providing fuel for further debate. Second, the question of technical expertise should be considered. In this study, the vast majority of physicians performed at least 75 procedures per year; these results may not generalize to smaller-volume centers with less-experienced operators (i.e., less than 50 cases per year). Third, another systems issue regarding time-to-arrival in the catheterization laboratory must be considered. In certain centers, PTCA may not be available, necessitating rapid transfer to another facility; alternatively, in centers with PTCA capability, the catheterization laboratory may not be in operation at the time of the patient’s arrival, particularly a consideration at night and during weekends. Finally, certain patients described as "high-risk" thrombolytic agent candidates (e.g., history of stroke, significant hypertension on presentation, elderly, anterior AMI, pulmonary edema, or cardiogenic shock) may be better served with PTCA.
This article should not be considered the final word on the subject, but it should be considered another step in the continuing exploration of this issue. In acute care medicine, the choice of therapies must be made in light of the individual patient’s presentation, the expertise of the consultant, and the capability of the specific center. This report should not dissuade the clinician from using TPA or other thrombolytic agents in all cases of AMI. In fact, certain patients may be more appropriately served with the rapid administration of TPA in the ED compared to transfer to the catheterization laboratory for PTCA.