The outcome of patients with acute myocardial infarction ineligible for thrombolytic therapy. Israeli Thrombolytic Survey Group.

PURPOSE: The aim of this study was to determine the proportion of patients with acute myocardial infarction (AMI) excluded from thrombolytic therapy on a national basis and to evaluate the prognosis of these patients by reasons of ineligibility and according to the alternative therapies that they received during hospitalization. PATIENTS AND METHODS: During a national survey, 1,014 consecutive patients with AMI were hospitalized in all the 25 coronary care units operating in Israel. RESULTS: Three hundred and eighty-three patients (38%) were treated with a thrombolytic agent and included in the GUSTO study. Ineligible patients for GUSTO were treated: (1) without any reperfusion therapy (n = 449), (2) by mechanical revascularization (n = 97), or (3) given 1.5 million units of streptokinase (n = 85) outside of the GUSTO protocol. The inhospital and 1-year post-discharge mortality rates were 6% and 2% in patients included in the GUSTO study; 6% and 5% in those mechanically reperfused; 15% and 10% in those treated with thromoblysis despite ineligibility for the GUSTO trial, and 15% and 13% among patients not treated with any reperfusion therapy. CONCLUSIONS: Ineligibility for thrombolysis among patients with AMI remains high. Patients ineligible for thrombolysis according to the GUSTO criteria, but nevertheless treated with a thrombolytic agent were exposed to an increased risk.

On-site catheterization laboratory and prognosis after acute myocardial infarction. Israeli Thrombolytic Survey Group.

BACKGROUND: Since the introduction of thrombolytic therapy for patients with acute myocardial infarction, the use of coronary angiography has substantially increased. We sought to determine whether the presence of on-site coronary angiographic facilities influenced the utilization of coronary procedures in patients with acute myocardial infarction hospitalized in Israel's coronary care units. METHODS: A prospective survey was conducted in January and February 1992 in the 25 coronary care units operating in Israel, 15 of which had on-site catheterization facilities. Data on demographics, clinical features, thrombolytic therapy, and the type of coronary diagnostic or therapeutic procedures performed during the current in-hospital stay were recorded. Mortality, both in-hospital and 1 year after discharge, was assessed for all patients in the survey. RESULTS: One thousand fourteen consecutive patients with acute myocardial infarction were hospitalized during the survey, 307 (30%) of whom were admitted to 10 coronary care units without and 707 of whom were treated in hospitals with on-site coronary angiography facilities. Demographic and baseline characteristics were similar in both groups. Thrombolytic therapy was provided equally (46%) to patients admitted to hospital with and without catheterization laboratories. Patients admitted to hospitals with these laboratories underwent coronary angiography (26%) and percutaneous transluminal angioplasty and/or coronary artery bypass grafting (12%) in greater numbers than counterparts admitted to hospitals without such laboratories (10% and 5%, respectively). Hospital and cumulative 1-year mortality rates were 11% and 18%, respectively, in patients admitted to hospitals with on-site catheterization facilities vs 10% and 17%, respectively, in the patient group admitted to the other hospitals. Patients receiving thrombolytic therapy had similar hospital mortality rates unrelated to the availability of coronary catheterization laboratories. CONCLUSION: This national survey showed that the availability of invasive coronary facilities led to increased use of diagnostic and therapeutic coronary procedures among patients with acute myocardial infarction. There was no difference in hospital or 1-year mortality rates in patients admitted to hospitals with or without on-site coronary angiographic facilities.

[Restoration of effective artificial cardiac pacing by isoproterenol].

Since the pacing threshold of artificial pacemakers sometimes increases and causes ineffective pacing, emergency restoration of cardiac pacing may occasionally be required. In such situations sympathomimetic agents, such as isoproterenol, increase excitability and lower threshold. A 83-year-old man with acute ineffective pacing and hemodynamic instability is reported. Intravenous administration of isoproterenol restored effective, artificial cardiac pacing.

Malignant arrhythmias in relation to values of serum potassium in patients with acute myocardial infarction.

The relationship between levels of potassium in the serum and the development of malignant arrhythmias was examined in a retrospective study involving 1011 patients presenting with acute myocardial infarction. Thirteen percent of the overall patients studied had significant hypokalemia (k less than 3.5 mmol/liter). The average initial level of potassium in patients who developed malignant arrhythmias was (4.10 mmol/liter) significantly lower (P less than 0.01) than those patients who did not develop such arrhythmias (4.19 mmol/liter). To determine whether the level of potassium was, in itself, the primary cause of malignant arrhythmias following myocardial infarction, a subgroup analysis of factors influencing these levels was performed. It was determined that diabetics have a higher level of potassium than nondiabetics (4.2 mmol/liter versus 4.11 mmol/liter - P = 0.01) and a lower incidence of malignant arrhythmias (50.5% versus 63.5% - P = 0.002). No correlation was found between treatment with either digitalis or diuretics and malignant arrhythmias. Size and location of infarcted areas was found to have a direct relationship with development of arrhythmias. Size and location of infarctions, however, were not found to be related to levels of potassium in the serum. Our findings support and clarify earlier suggestions establishing the levels of potassium in the serum as an important causative factor, together with size and location of infarctions, in the development of malignant arrhythmias.

[External cardiac pacing in a mobile intensive cardiac care unit].

External cardiac pacing has recently been reintroduced as an effective method in emergency cardiac stimulation. We report for the first time the results of external cardiac pacing in a mobile intensive cardiac care unit. In 9 of 10 patients treated during the first 3 months of 1990, effective pacing was achieved. We conclude that external cardiac pacing is a rapid, safe and effective means of temporary pacing during emergency treatment, before admission to hospital.

Repeat infusion of recombinant tissue-type plasminogen activator in patients with acute myocardial infarction and early recurrent myocardial ischemia.

When conventional treatment of patients with early clinical reinfarction after thrombolytic therapy fails, mechanical revascularization may be attempted. An alternative strategy, repeat thrombolytic infusions, is reported. Fifty-two patients with acute myocardial infarction were treated with one or two additional thrombolytic infusions of recombinant tissue-type plasminogen activator (rt-PA) because of nonsustained ischemia after initial treatment with rt-PA or streptokinase. Thirty-five patients received the second infusion within 1 h of the first; 13 patients received the second infusion 1 to 72 h after the first and 4 patients received it later during their hospitalization. Bleeding complications occurred in 10 patients (19%); however, most of these were minor (no intracranial bleeding) and only 2 patients required blood transfusion. In 14 patients in whom the decrease in fibrinogen and plasminogen levels was measured after the first and second infusions, this decrease was only 25% and 63%, respectively--only slightly higher than the 22% and 53% decreases measured in 63 patients who had only one rt-PA infusion. In 44 patients (85%), the acute ischemia resolved completely within 1 h after initiation of the second infusion. In 23 patients (44%), pain and ST segment elevation did not recur and invasive coronary intervention was avoided. Thus, repeat rt-PA infusions can stabilize a substantial number of patients with acute reinfarction and, even when relief is temporary, repeat rt-PA infusions can minimize myocardial damage while patients await mechanical revascularization.

Continuous rt-PA infusion as a salvage strategy to maintain patency of the infarct artery; safety of high cumulative dose and subsequent emergency coronary artery angioplasty and bypass surgery.

Acute re-occlusion of an infarct artery reperfusion attained by thrombolytic therapy may be treated by emergency coronary angioplasty or bypass surgery. Repeated infusion of a thrombolytic agent is an additional treatment strategy. Three patients with reinfarctions that occurred very early after successful reperfusion were treated with continuous infusion of recombinant tissue-type plasminogen activator (rt-PA). These patients received a rt-PA dose of 300-360 mg while they awaited emergency mechanical revascularization procedures. Two patients had coronary angioplasty immediately after receiving repeated infusions of rt-PA and one underwent coronary bypass surgery while receiving a third rt-PA infusion. There were no bleeding complications in the 2 patients who underwent coronary angioplasty, and no excessive bleeding in the patient who received coronary bypass surgery. Thus, repeated continuous rt-PA infusions can be used to maintain the patency of recurrently occluding infarct arteries until definitive mechanical revascularization can be performed.