Myocardial infarction and heart failure—a dangerous intersection☆

Despite the distinctly different diagnostic criteria for myocardial infarction and heart failure, these clinical entities are often intertwined. Indeed, a history of prior myocardial infarction increases the risk of heart failure, and, importantly, manifestations of heart failure during a myocardial infarction greatly increase mortality risk during the acute as well as chronic phases of myocardial infarction. These statements are so entrenched that the reliability of any data set not demonstrating these relations would be seriously questioned. In this issue of The American Journal of Medicine, Hellerman and colleagues from the Mayo Clinic have compiled a useful summation of the published literature on the incidence of heart failure during myocardial infarction and prognosis (1). Despite their acknowledged limitations, the consistency of information regarding the multifold risk of death in those who have heart failure during myocardial infarction is impressive. This meta-analysis illustrates well the important differences between population-based and consecutive admission studies and randomized clinical trials. Populationbased and registry populations are more representative of clinical practice than are clinical trials. The younger age of the subjects in clinical trials and the greater likelihood of their being male reflect the disproportionately lower inclusion of elderly women in such trials. The process of screening and consenting tends to exclude the less independent sections of our population. Even though investigators may attempt to enroll subjects that are more representative, mundane issues, such as transportation for follow-up visits or a clinician’s assessment of relative frailty, even subconsciously, select for healthier patients in clinical trials. Of interest, despite the difference in absolute mortality rates reported in population-based and clinical trial publications, the relative increase in the risk of death for patients developing signs or symptoms of heart failure during myocardial infarction was similar. Two recent publications from major registries, the National Registry of Myocardial Infarction and the Global Registry of Acute Coronary Events, continue to underscore the strong negative effects of developing heart failure during myocardial infarction on survival and hospital discharge (2,3). As the current meta-analysis and the above registries indicate, mortality is greatest in those who manifest acute failure. However, clinicians should be mindful that preinfarct patient characteristics such as lipid levels, smoking, hypertension, and diabetes continue to affect prognosis adversely following infarction. In survivors of myocardial infarction, the knowledge of whether the infarct was complicated by acute heart failure, the degree of left ventricular dysfunction, and the extent of coronary disease or ischemic burden are important in premyocardial infarction risk assessment (4). The trends for improving survival following myocardial infarction have been impressive during the last two decades (5). In some respects, intense revascularization efforts and use of effective agents such as aspirin, betablockers, angiotensin-converting enzyme (ACE) inhibitors, and statins have contributed to the larger numbers of survivors now at risk of postinfarct events. With the Multicenter Automatic Defibrillator Implantation Trial II demonstrating reductions in sudden death in patients with coronary artery disease and depressed left ventricular ejection fraction (6), we can anticipate further increases in the number of myocardial infarction survivors at risk of heart failure. Similarly, in the more chronic phases after infarction, the development of signs and symptoms indicates a markedly increased risk of death. The approximately 15% of patients in the Survival And Ventricular Enlargement (SAVE) trial who required hospitalization for the management of heart failure during 3.5 years of follow-up had a sixfold higher mortality than did those who did not have heart failure (7). In fact, more minor manifestations of heart failure not requiring hospitalization but prompting initiation or augmentation of digitalis or diuretic therapy for the management of heart failure without hospitalization were associated with a fourfold increased risk of death compared with the rest of the SAVE subjects (8). Identifying and quantifying the magnitude of this problematic intersection of heart failure and myocardial infarction is only the beginning of a strategy to improve outcomes. The best way to avoid heart failure complicating or following a myocardial infarction is to avoid the infarct in the first place. The importance of primary preAm J Med. 2002;113:341–343. From the Cardiovascular Division, Brigham and Women’s Hospital, Boston, Massachusetts 02115. Dr. Pfeffer has received honoraria or educational or research grants from, or has served as a consultant for, Astra Zeneca, Aventis, BristolMyers Squibb, Novartis, and Pfizer. Requests for reprints should be addressed to Marc A. Pfeffer, MD, PhD, Cardiovascular Division, Brigham and Women’s Hospital, 75 Francis Street, Boston, Massachusetts 02115, or mpfeffer@rics.bwh. harvard.edu. Manuscript submitted April 22, 2002.