715-2 A Prospective, Randomized Trial Evaluating the Prophylactic Use of Balloon Pumping in High Risk Myocardial Infarction Patients: PAMI-2

Myocardial infarction (MI) patients with advanced age, multivessel disease or ventricular dysfunction continue to have a poor prognosis despite reperfusion therapy. Furthermore, the majority of deaths from MI occur within the first 48 hours, thus risk stratification and therapeutic interventions ideally should occur acutely. The PAMI-2 study has prospectively evaluated the hypotheses that 1) emergency catheterization with primary PTCA may allow acute risk stratification and 2) clinical outcome, ventricular function and infarct vessel patency will be improved by balloon pumping in patients identified to be high risk. MI patients who presented 0–12 hrs underwent emergency catheterization and PTCA and were stratified as high risk if one of the following was present: age>70 yrs, vein graft occlusion, 3 vessel disease, ejection fraction <45%, suboptimal PTCA result or if malignant arrhythmias persisted post PTCA. High risk patients were randomized to receive or not receive an intra aortic balloon pump (IABP) for 48 hrs. Catheterization was repeated at day 7 to determine infarct vessel patency and improvement in ventricular function. At 6 weeks a rest and exercise radionuclide ventriculogram was performed. To date, 320 patients have been enrolled, 175 of which have complete data available for analysis. The reasons for high risk status include: advanced age 38%, poor LV function 55%, 3 vessel disease 37%, vein graft occlusion 6%, suboptimal PTCA 9%, and arrhythmias 5%. Despite the high risk status, in-hospital outcomes have been favorable: death 2.9%, recurrent MI 5.8%, stroke 1.2%, angiographic reocclusion 5.8%, heart failure 19.1% and combined events 26.6%. Thus “high risk” patients treated with primary PTCA±balloon pumping appear to have a good prognosis. Whether the improved outcome is due to balloon pump support or simply due to aggressive mechanical revascularization will be determined in the entire cohort by March 1995

A Prospective, Randomized Evaluation of Prophylactic Intraaortic Balloon Counterpulsation in High Risk Patients With Acute Myocardial Infarction Treated With Primary Angioplasty fn1fn1Funding for this study was provided in part by unrestricted grants from Advanced Cardiovascular Systems, Inc., Santa Clara, California; Mallinkrodt Medical, Inc., Saint Louis, Missouri; Datascope Corporation, Montvale, New Jersey; St. Jude Medical, Chelmsford, Massachusetts; and Siemens Corporation, Iselin, New Jersey.

AbstractObjectives. A large, international, multicenter, prospective, randomized trial was performed to determine the role of prophylactic intraaortic balloon pump (IABP) counterpulsation after primary percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI).Background. Previous studies have suggested that routine IABP use after primary PTCA reduces infarct-related artery reocclusion, augments myocardial recovery and improves clinical outcomes.Methods. Cardiac catheterization was performed in 1,100 patients within 12 h of onset of AMI at 34 clinical centers. Clinical and angiographic variables were used to stratify patients undergoing primary PTCA into high and low risk groups. High risk patients were then randomized to 36 to 48 h of IABP (n = 211) or traditional care (n = 226). The study had 80% power to detect a reduction in the primary end point from 30% to 20%.Results. There was no significant difference in the predefined primary combined end point of death, reinfarction, infarct-related artery reocclusion, stroke or new-onset heart failure or sustained hypotension in patients treated with an IABP versus those treated conservatively (28.9% vs. 29.2%, p = 0.95). The IABP strategy conferred modest benefits in reduction of recurrent ischemia (13.3% vs. 19.6%, p = 0.08) and subsequent unscheduled repeat catheterization (7.6% vs. 13.3%, p = 0.05) but did not reduce the rate of infarct-related artery reocclusion (6.7% vs. 5.5%, p = 0.64), reinfarction (6.2% vs. 8.0%, p = 0.46) or mortality (4.3% vs. 3.1%) and was associated with a higher incidence of stroke (2.4% vs. 0%, p = 0.03). IABP use did not result in enhanced myocardial recovery as assessed by paired admission to predischarge and 6-week rest and exercise left ventricular ejection fraction.Conclusions. In contrast to previous studies, a prophylactic IABP strategy after primary PTCA in hemodynamically stable high risk patients with AMI does not decrease the rates of infarct-related artery reocclusion or reinfarction, promote myocardial recovery or improve overall clinical outcome.(J Am Coll Cardiol 1997;29:1459–67