Coronary thrombolysis

The contemporary management of acute myocardial infarction

The contemporary management of acute myocardial infarction continues to evolve rapidly. The ultimate goal of therapy is timely, complete, and sustained myocardial reperfusion. There is a powerful time-dependent effect on mortality, and thus the balance between the time and likelihood of maximal reperfusion is crucial in deciding whether to use primary percutaneous balloon angioplasty or thrombolysis as the initial reperfusion strategy. Newer thrombolytic agents allow for equivalent coronary reperfusion compared with the standard accelerated alteplase (tPA) regimen with the advantage of easier dosing regimens. Low molecular weight heparin has been shown to be superior to unfractionated heparin and likely will be the standard of care in the near future. The use of glycoprotein IIb/IIIa inhibitors has been shown to decrease the short- and long-term complication rates in patients with acute coronary syndromes treated medically and with percutaneous coronary interventions; however, the choice of the optimal agent and dosing regimen in various clinical settings remains controversial. Combination therapy with low-dose fibrinolytics, glycoprotein IIb/IIIa inhibitors, and low molecular weight heparin, with or without subsequent early planned percutaneous coronary interventions, may provide the optimal strategy for maximal coronary reperfusion, but the results of large, randomized mortality trials currently underway need to be analyzed. Risk stratification will continue to play a major role in determining which patients should receive a specific therapy. The care of the patient with an acute myocardial infarction will continue to be a challenge requiring the proper selection from the vast pharmaceutic and interventional options available.

Risk stratification in survivors of acute myocardial infarction: routine cardiac catheterization and angiography is a reasonable approach in most patients

Noninvasive risk assessment in survivors of AMI can effectively subdivide patients into groups with differing risk profiles after hospital discharge, but some patients at risk for late death or recurrent AMI may be incorrectly identified; data from cardiac catheterization and angiography provide complementary and generally more powerful prognostic information. Many patients may derive particular benefit from early cardiac catheterization and angiography, including: (1) patients with AMI complicated by recurrent myocardial ischemia, congestive heart failure, and/or complex ventricular arrhythmias; (2) patients with abnormal or inconclusive results of noninvasive testing or those patients unable to perform an exercise test; (3) patients with abnormal left ventricular global systolic function and those with increased left ventricular end-systolic volume; (4) "young" patients (younger than 50 years of age?); (5) older patients (older than 65 to 70 years of age?); (6) patients with non-Q wave AMI; and (7) patients who are receiving thrombolytic therapy. Performance of early cardiac catheterization and angiography in virtually all survivors of AMI, with selective use of appropriate noninvasive tests, may provide a more efficacious means of risk assessment after AMI; if all tests are performed judiciously, the cost of such an approach need not be excessive. A combination of invasive and selected noninvasive tests probably provides optimal information. The risks to the routine performance of diagnostic cardiac catheterization and angiography in all survivors of AMI are: (1) adequate care and attention may not be paid to proper performance of the procedure(s) and to detailed and proper analyses of the data; (2) the need for additional noninvasive testing in selected patients may be ignored; and most importantly, (3) premature or unnecessary revascularization procedures may be performed subsequently. For optimal patient care, the clinician must obtain all necessary data, avoid unnecessary and repetitive tests, know the accuracy of individual tests at his or her own facility, interpret all data in proper context, and then counsel patients objectively about available management strategies. With this approach, all patients who might appropriately benefit from coronary artery revascularization will be correctly identified, and patients who are truly at very low risk (minimal residual coronary artery disease and preserved left ventricular function particularly if associated with a patent infarct-related artery) may be similarly identified and managed appropriately with elimination of unnecessary additional testing and pharmacologic therapy. Finally, whatever approach to risk stratification one chooses for an individual patient, the importance of and the need to correct and/or ameliorate risk factors for coronary artery disease must be recognized and undertaken.

Thrombolytic therapy in acute MI. Weighing the risks and benefits

The underlying cause of acute myocardial infarction can now be effectively treated with thrombolytic agents, thereby increasing myocardial salvage and reducing mortality. Clinicians should always be aware of the risk-to-benefit ratio in treating patients with thrombolytic agents and treat each patient on an individual basis.