Primary PTCA reduces short-term mortality but PTCA after thrombolysis shows no benefit in acute MI
ACP J Club. 1995 July-Aug;123:8. doi:10.7326/ACPJC-1995-123-1-008
Michels KB, Yusuf S. Does PTCA in acute myocardial infarction affect mortality and reinfarction rates? A quantitative overview (meta-analysis) of the randomized clinical trials. Circulation. 1995 Jan 15;91:476-85.
To assess the effect of percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (MI) on mortality and reinfarction rates.
Studies were identified through a literature search using MEDLINE and Index Medicus; extensive hand searching using cross-references from original articles and reviews; and screening of abstracts from the major cardiology meetings between 1984 and 1994 (Scientific Sessions of the American Heart Association, the American College of Cardiology, and the European Society of Cardiology). Principal authors of identified studies were also contacted to determine whether any published or unpublished trials had been missed.
Studies were selected if they were randomized trials of PTCA in the treatment of acute MI. The end points of interest were mortality within 6 weeks of MI, mortality 1 year after MI, nonfatal reinfarction within 6 weeks of MI, and nonfatal reinfarction up to 1 year after MI.
Data on the study design, the number of patients actually receiving PTCA, and the 6-week and 52-week outcomes (survival and recurrence-free survival) were extracted. Extracted data were sent to the principal investigators of each study for a review of accuracy. Data were combined across studies using the method described by Mantel and Haenszel.
26 trials were identified and 23 met the selection criteria. Primary PTCA was evaluated in 7 of the trials; PTCA after thrombolysis was studied in the other 16, for a total of 8496 patients. In the 7 trials comparing primary PTCA with thrombolytic therapy, short-term mortality (6-week) was reduced in the PTCA group (odds ratio [OR], 0.56; 95% CI, 0.33 to 0.94),and a reduction also occurred in the combined outcome of short-term mortality and nonfatal reinfarction (OR, 0.53; CI, 0.35 to 0.80). Long-term data were not available from enough patients to provide reliable estimates beyond 6 weeks. In trials that compared thrombolysis and PTCA with thrombolytic therapy alone, no significant difference existed in short-term or long-term (52-week) mortality. Lower mortality was observed between 6 and 52 weeks and appeared to be particularly marked in trials in which PTCA was used as a routine strategy (OR 0.58, CI 0.39 to 0.87).
Among patients with acute myocardial infarction, 6-week mortality is lower in those receiving primary percutaneous transluminal angioplasty than in those receiving thrombolytic therapy; however, the long-term benefit will remain unclear until larger studies are done. The addition of angioplasty to thrombolytic therapy does not result in improved clinical outcomes compared with the use of thrombolytic therapy alone.
Source of funding: Not stated.
For article reprint: Dr. S. Yusuf, 252 McMaster-HGH Clinic, Hamilton General Hospital, 237 Barton Street East, Hamilton, Ontario L8L 2X2. FAX 905-521-1166.
Hartzler and colleagues (1) first described using PTCA in acute MI without preceding thrombolytic therapy: the "direct" approach, or primary angioplasty. Since then, several small trials have suggested that primary angioplasty may provide a survival advantage for patients with acute MI. This meta-analysis by Michels and Yusuf shows that primary angioplasty results in a statistically significant and clinically substantial reduction in mortality at 6 weeks with little effect on mortality at 1 year. Another meta-analysis examining 5 of the same primary angioplasty trials found a similar reduction in mortality (OR, 0.57; 95% CI, 0.48 to 0.68) (2).
How do we integrate these results into our clinical practice? It is clear that adding angioplasty to thrombolytic therapy does not improve clinical outcomes, with the possible exception of rescue angioplasty of occluded vessels in patients with failed thrombolysis. Despite the early superiority of primary angioplasty, we do not have evidence to show that this benefit is prolonged. Angioplasty also has numerous drawbacks. Only a limited number of facilities are available; trained staff must be on call around the clock; the inherent delay in assembling the angioplasty team can be substantial; not all patients who present with acute MI are candidates for angioplasty; and the cost of angioplasty may be higher than that of intravenous thrombolytic therapy. Angioplasty, however, may provide a superior alternative to thrombolytic therapy in patients for whom the risks of thrombolytic therapy are increased (uncontrolled hypertension, recent major surgery or trauma, bleeding diathesis, or recent cerebrovascular accident). Also, a review of earlier series examining direct angioplasty suggested that patients in cardiogenic shock and patients with a history of previous bypass surgery may have better outcomes with angioplasty (3). Additional randomized controlled trials are needed to further investigate these patient subsets and to determine the long-term effectiveness of primary angioplasty.
Mark H. Eckman, MD
Tufts University School of Medicine Boston, Massachusetts