ABSTRACT
Although the efficacy of recombinant tissue-type plasminogen activator (rt-PA) in acute myocardial infarction has been demonstrated, little formal dose-ranging information is available. This study examined the use of duteplase, the double-chain rt-PA subsequently used in the Third International Study of Infarct Survival, in a multicenter trial of 267 patients with evolving acute myocardial infarction assigned to receive 1 of 6 weight-adjusted doses. The primary end point was infarct vessel patency after 90 minutes of drug infusion. Patency was defined as Thrombolysis in Myocardial Infarction trial grade 2 or 3 perfusion, and was determined by an independent core laboratory masked to treatment assignment. Patency was present in 48% of patients receiving the lowest dose range and 78% of those receiving the highest, with an association between thrombolytic dose and patency (p = 0.009). The frequency of serious bleeding complications also correlated with the total dose of rt-PA infused (p = 0.003). Bleeding complications were primarily related to instrumentation; blood loss requiring transfusion or otherwise deemed clinically significant occurred in 12% of patients (central nervous system hemorrhage occurred in 1.1%). Thus, higher doses of rt-PA are associated both with increased efficacy and increased risk of serious bleeding complications. Weight-adjusted dosing may provide an optimal risk-benefit ratio for thrombolysis during acute myocardial infarction.
Subject(s)
Myocardial Infarction/drug therapy , Thrombolytic Therapy , Tissue Plasminogen Activator/administration & dosage , Adult , Aged , Dose-Response Relationship, Drug , Female , Hemorrhage/chemically induced , Humans , Male , Middle Aged , Prospective Studies , Recombinant Proteins/administration & dosage , Recombinant Proteins/adverse effects , Tissue Plasminogen Activator/adverse effects , Vascular PatencyABSTRACT
The electrocardiographic diagnosis of uncomplicated hypokalemia rests on ST segment depression, a decrease in T-wave amplitude, prominent U waves and a U-wave to T-wave ratio of greater than 1. The diagnosis is more difficult in a patient receiving digitalis, but the upsloping ST segment of digitalis can be distinguished from that of hypokalemia. The changes of hypokalemia are most apparent in leads V2 and V3.
Subject(s)
Electrocardiography , Hypokalemia/diagnosis , Atrial Fibrillation/complications , Diagnosis, Differential , Digoxin/adverse effects , Humans , Hypokalemia/etiologyABSTRACT
A retrospective analysis of 38 patients undergoing cardiac catheterization with the diagnoses of hypothyroidism and chest pain revealed 23 to be euthyroid while receiving replacement therapy and 15 to be hypothyroid. Cardiac index was significantly reduced (p less than 0.01) in hypothyroid and euthyroid patients with thyroxine values between 4 and 7 micrograms/dl (2.8 +/- 0.7 and 3.0 +/- 0.9 L/min/m2, respectively), compared to euthyroid patients with thyroxine values greater than 7 micrograms/dl with or without coronary artery disease (4.0 +/- 1.2 and 4.0 +/- 0.7 L/min/m2, respectively). Ten hypothyroid patients underwent coronary artery bypass. There were no deaths, and only one patient required prolonged postoperative intubation. With a mean follow-up of 36 months, there have been no myocardial infarctions and one late death, which occurred at 7 years secondary to stroke. We conclude that preoperative thyroid replacement therapy is theoretically dangerous and may not significantly improve hemodynamics until full replacement is achieved. Coronary bypass grafting can be performed safely despite hypothyroidism with excellent early results.
