Bundle branch block in ST-elevation myocardial infarction: evidence for action.

Several major conceptual advances influence contemporary evaluation and management of patients with a myo-cardial infarction. We now consider myocardial infarction one element in the spectrum of acute coronary syndromes. 1 The term " acute coronary syndromes " is currently used to denote individuals who present without ST-segment elevation on the 12-lead electrocardiogram (unstable an-gina/non-ST-elevation myocardial infarction [NSTEMI]) and with ST-elevation on the 12-lead electrocardiogram (ST-elevation myocardial infarction – STEMI). In 2000, the definition of a myocardial infarction was updated, with a major focus on the use of cardiac specific troponins as the preferred biomarker indicating myocardial necrosis. 2 The introduction of cardiac specific troponins had a greater influence on distinguishing unstable angina from NSTEMI rather than impacting on the diagnosis and management of patients with STEMI. It is also recognized that myocardial infarction is not a fixed process at the time of occlusion of the coronary artery but rather is a dynamic process with a wavefront of necrosis sweeping through the zone of the myocardium at risk. Despite the many promising interventions identified in laboratory studies for modification of infarct size, relatively few have been adopted into routine clinical practice with the exception of timely reperfusion of the infarct related artery. 1 Evidence that drives our thinking about the approach to management of patients with ST-elevation myocardial infarction comes from several sources: randomized controlled trials and registries. We learned from randomized controlled trials that administration of a fibrinolytic is associated with 18% reduction in 35-day mortality compared with placebo. 3 Numerous randomized controlled trials documented the superiority of primary percuta-neous coronary intervention (PCI) over fibrinolysis for reducing mortality in STEMI, provided primary PCI can be performed by a skilled operator, supported by an experienced team, and delivered in a timely fashion. 1 Against the background described above, one must also note the advances in treatment of risk factors for heart disease. This includes more widespread use of sta-tins for lowering cholesterol, more aggressive treatment of hypertension, and greater use of aspirin both in primary prevention and secondary prevention, and public health campaigns to promote cessation of cigarette smoking. 4 Evidence exists in the United States that there is a decline in hospitalizations for acute myocardial infarction. The studies focusing on this epidemiologic observation usually do not distinguish between NSTEMI and STEMI, because the information comes from administrative databases with limited clinical information. The decline in hospitalization rates for acute myocardial …