Short-term effects of early intravenous treatment with a beta-adrenergic blocking agent or a specific bradycardiac agent in patients with acute myocardial infarction receiving thrombolytic therapy

Early intravenous then oral metoprolol in 45,852 patients with acute myocardial infarction: randomised placebo-controlled trial

BACKGROUND

Despite previous randomised trials of early beta-blocker therapy in the emergency treatment of myocardial infarction (MI), uncertainty has persisted about the value of adding it to current standard interventions (eg, aspirin and fibrinolytic therapy), and the balance of potential benefits and hazards is still unclear in high-risk patients.

METHODS

45,852 patients admitted to 1250 hospitals within 24 h of suspected acute MI onset were randomly allocated metoprolol (up to 15 mg intravenous then 200 mg oral daily; n=22,929) or matching placebo (n=22,923). 93% had ST-segment elevation or bundle branch block, and 7% had ST-segment depression. Treatment was to continue until discharge or up to 4 weeks in hospital (mean 15 days in survivors) and 89% completed it. The two prespecified co-primary outcomes were: (1) composite of death, reinfarction, or cardiac arrest; and (2) death from any cause during the scheduled treatment period. Comparisons were by intention to treat, and used the log-rank method. This study is registered with ClinicalTrials.gov, number NCT 00222573.

FINDINGS

Neither of the co-primary outcomes was significantly reduced by allocation to metoprolol. For death, reinfarction, or cardiac arrest, 2166 (9.4%) patients allocated metoprolol had at least one such event compared with 2261 (9.9%) allocated placebo (odds ratio [OR] 0.96, 95% CI 0.90-1.01; p=0.1). For death alone, there were 1774 (7.7%) deaths in the metoprolol group versus 1797 (7.8%) in the placebo group (OR 0.99, 0.92-1.05; p=0.69). Allocation to metoprolol was associated with five fewer people having reinfarction (464 [2.0%] metoprolol vs 568 [2.5%] placebo; OR 0.82, 0.72-0.92; p=0.001) and five fewer having ventricular fibrillation (581 [2.5%] vs 698 [3.0%]; OR 0.83, 0.75-0.93; p=0.001) per 1000 treated. Overall, these reductions were counterbalanced by 11 more per 1000 developing cardiogenic shock (1141 [5.0%] vs 885 [3.9%]; OR 1.30, 1.19-1.41; p<0.00001). This excess of cardiogenic shock was mainly during days 0-1 after admission, whereas the reductions in reinfarction and ventricular fibrillation emerged more gradually. Consequently, the overall effect on death, reinfarction, arrest, or shock was significantly adverse during days 0-1 and significantly beneficial thereafter. There was substantial net hazard in haemodynamically unstable patients, and moderate net benefit in those who were relatively stable (particularly after days 0-1).

INTERPRETATION

The use of early beta-blocker therapy in acute MI reduces the risks of reinfarction and ventricular fibrillation, but increases the risk of cardiogenic shock, especially during the first day or so after admission. Consequently, it might generally be prudent to consider starting beta-blocker therapy in hospital only when the haemodynamic condition after MI has stabilised.

Hospital therapy traditions influence long-term survival in patients with acute myocardial infarction

BACKGROUND

Differences in therapy and outcome among hospitals have been reported, but these studies have seldom used adjustment for differences in patient characteristics. The objective was to investigate the differences in treatment of acute myocardial infarction (AMI) among different hospitals within 1 country and the possible causes and outcomes of these differences.

METHODS

Prospective cohort study using data from the Register of Information and Knowledge about Swedish Heart Intensive care Admissions (RIKS-HIA) on 32,954 consecutive primary admissions of patients with AMI admitted to the intensive coronary care units of 67 Swedish hospitals in 1999-2000. An activity index was calculated for each hospital based on the hospital's ranking regarding proportion of performed examination or given therapy among the AMI patients.

RESULTS

After adjustment for 24 background characteristics, there were few significant deviations among hospitals in the proportion treated with acute reperfusion, antiplatelets, beta-blockers, or angiotensin-converting enzyme (ACE) inhibitors. However, 3- to 10-fold differences existed among hospitals in the proportion of patients treated with intravenous beta-blockers, intravenous nitroglycerin, intravenous or subcutaneous anticoagulants, and lipid-lowering medication, and even larger discrepancies in echocardiography and revascularization within 14 days. There was a strong (r = 0.69, P < .001) correlation between hospital activity index between the years and a correlation between the hospital's activity index and 1-year mortality (r = -0.30, P = .014). There was no correlation between hospital size and activity index.

CONCLUSIONS

Even after adjustment for differences in patient characteristics, there are differences between the hospital treatment cultures for patients with AMI that persists over time. Concerning everywhere-available treatment options, the treatment activity is independent of the size of the center. A more active treatment tradition is associated with a lower short- and long-term mortality in AMI patients.

Benefits of inpatient initiation of beta-blockers

Clinical trials have demonstrated that beta-blockers effectively reduce mortality in patients after a myocardial infarction (MI) and in patients with chronic heart failure. Treatment guidelines recommend that all patients after MI without a contraindication receive early beta-blocker treatment. Initiation of beta-blockers also should be considered for stable patients who are hospitalized with heart failure. Despite well-documented benefits, however, beta-blockers are still underused. Barriers that cause reluctance by physicians to initiate therapy include the traditional belief that beta-blockers are contraindicated in patients with left ventricular dysfunction, complexity of management, perceived risk of adverse events, and potential for short-term clinical deterioration. Intervention programs promoting beta-blockers for inpatients have increased their use at discharge and after long-term follow-up. Because of pharmacologic differences, agent selection is also critical. Agents must have proven clinical efficacy, an established dose-titration regimen, and desirable pharmacokinetic properties. Increasing the use of these life-saving agents has the potential for substantial clinical impact.

Impact of intravenous Beta-Blockade before primary angioplasty on survival in patients undergoing mechanical reperfusion therapy for acute myocardial infarction

OBJECTIVES

We sought to examine the effect of intravenous beta-blockers administered before primary percutaneous coronary intervention (PCI) on survival and myocardial recovery after acute myocardial infarction (AMI).

BACKGROUND

Studies of primary PCI but not thrombolysis have suggested that beta-blocker administration before reperfusion may enhance survival. Whether oral beta-blocker use before admission modulates this effect is unknown.

METHODS

The Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial randomized 2082 AMI patients to either stenting or balloon angioplasty, each +/- abciximab. In accordance with the protocol, intravenous beta-blockers were administered before PCI in the absence of contraindications.

RESULTS

A total of 1136 patients (54.5%, BB+ group) received beta-blockers before PCI, whereas 946 (45.5%, BB- group) did not. The 30-day mortality was significantly lower in the BB+ group than in the BB- group (1.5% vs. 2.8%, p = 0.03), an effect entirely limited to patients who had not been receiving beta-blockers before admission (1.2% vs. 2.9%, p = 0.007). In contrast, no survival benefit with pre-procedural beta-blockers was observed in patients receiving beta-blockers at home (3.3% vs. 1.9%, respectively, p = 0.47). By multivariate analysis, pre-procedural beta-blocker use was an independent predictor of lower 30-day mortality among patients without previous beta-blocker therapy (relative risk = 0.38 [95% confidence interval 0.17 to 0.87], p = 0.02). The improvement in left ventricular ejection fraction from baseline to seven months was also greater after intravenous beta-blockers (3.8% vs. 1.3%, p = 0.01), an effect limited to patients not receiving oral beta-blockers before admission.

CONCLUSIONS

In patients with AMI undergoing primary PCI, myocardial recovery is enhanced and 30-day mortality is reduced with pre-procedural intravenous beta-blockade, effects confined to patients untreated with oral beta-blocker medication before admission.

Diltiazem in acute myocardial infarction treated with thrombolytic agents: a randomised placebo-controlled trial. Incomplete Infarction Trial of European Research Collaborators Evaluating Prognosis post-Thrombolysis (INTERCEPT)

BACKGROUND

Diltiazem reduces non-fatal reinfarction and refractory ischaemia after non-Q-wave myocardial infarction, an acute coronary syndrome similar to the incomplete infarction that occurs after successful reperfusion. We postulated that this agent would reduce cardiac events in patients after acute myocardial infarction treated initially with thrombolytic agents-a clinical application previously unexplored with heart-rate-lowering calcium antagonists.

METHODS

A prospective, randomised, double-blind, sequential trial was done in 874 patients with acute myocardial infarction, but without congestive heart failure, who first received thrombolytic agents. Patients received either 300 mg oral diltiazem once daily, or placebo, initiated within 36-96 h of infarct onset, and given for up to 6 months. The trial primary endpoint was the cumulative first event rate of cardiac death, non-fatal reinfarction, or refractory ischaemia. Additional prespecified endpoints included several composites of non-fatal cardiac events (non-fatal reinfarction combined with refractory ischaemia, all recurrent ischaemia, or the need for myocardial revascularisation). The diagnosis of ischaemia, whether refractory or recurrent, and the need for myocardial revascularisation, was always based on objective electrocardiographical evidence of ischaemia, either at rest or on exertion.

RESULTS

For the trial primary endpoint, 131 events occurred in the 444 placebo patients and 97 events in the 430 diltiazem patients (hazard ratio 0.79; 95% CI, 0.61-1.02; p=0.07). For non-fatal cardiac events, diltiazem treatment was associated with a relative decrease (0.76; 0.58-1.00) in the combined event rate of non-fatal reinfarction and refractory ischaemia. There was a similar decrease in the composite non-fatal endpoints of non-fatal reinfarction combined with all recurrent ischaemia (0.80; 0.64-1.00) and non-fatal reinfarction combined with the need for myocardial revascularisation (0.67; 0.46-0.96). The need for myocardial revascularisation alone was significantly reduced by 42% (0.61; 0.39-0.96). No major safety issues were encountered.

CONCLUSIONS

Diltiazem did not reduce the cumulative occurrence of cardiac death, non-fatal reinfarction, or refractory ischaemia during a 6-month follow-up, but did reduce all composite endpoints of non-fatal cardiac events, especially the need for myocardial revascularisation.

Intracranial hemorrhage rates and effect of immediate beta-blocker use in patients with acute myocardial infarction treated with tissue plasminogen activator. Participants in the National Registry of Myocardial Infarction-2

In acute myocardial infarction (AMI), immediate beta-blocker therapy reduces the incidence of reinfarction and recurrent chest pain in patients receiving tissue plasminogen activator (t-PA). Data from the Thrombolysis in Myocardial Infarction (TIMI)-2 trial also raises the possibility that such therapy may reduce the rate of intracranial hemorrhage (ICH). We reviewed data obtained from 60,329 patients treated with t-PA who were enrolled in the National Registry of Myocardial Infarction 2. Of the 60,329 in the study cohort, 23,749 patients (39.4%) were treated with immediate beta-blocker therapy and 542 patients (0.9%) developed an ICH. In a multivariate model that included all covariates known to be associated with the development of ICH, immediate beta-blocker therapy was associated with a 31% reduction in the ICH rate (odds ratio 0.69, 95% confidence intervals 0.57 to 0.84). Thus, in the present study, the use of immediate beta-blocker therapy in patients with AMI treated with t-PA was associated with a significant reduction in ICH. This finding supports the observations made in the TIMI 2 trial and serves to reinforce the recommendations made by the American College of Cardiology/American Heart Association task force that immediate beta-blocker therapy should be administered to all patients with AMI who do not have contraindications to this therapy.

Atenolol use and clinical outcomes after thrombolysis for acute myocardial infarction: the GUSTO-I experience. Global Utilization of Streptokinase and TPA (alteplase) for Occluded Coronary Arteries

OBJECTIVES

We assessed the use and effects of acute intravenous and later oral atenolol treatment in a prospectively planned post hoc analysis of the GUSTO-I dataset.

BACKGROUND

Early intravenous beta blockade is generally recommended after myocardial infarction, especially for patients with tachycardia and/or hypertension and those without heart failure.

METHODS

Besides one of four thrombolytic strategies, patients without hypotension, bradycardia or signs of heart failure were to receive atenolol 5 mg intravenously as soon as possible, another 5 mg intravenously 10 min later and 50 to 100 mg orally daily during hospitalization. We compared the 30-day mortality of patients given no atenolol (n=10,073), any atenolol (n=30,771), any intravenous atenolol (n=18,200), only oral atenolol (n=12,545) and both intravenous and oral drug (n=16,406), after controlling for baseline differences and for early deaths (before oral atenolol could be given).

RESULTS

Patients given any atenolol had a lower baseline risk than those not given atenolol. Adjusted 30-day mortality was significantly lower in atenolol-treated patients, but patients treated with intravenous and oral atenolol treatment vs. oral treatment alone were more likely to die (odds ratio, 1.3; 95% confidence interval, 1.0 to 1.5; p=0.02). Subgroups had similar rates of stroke, intracranial hemorrhage and reinfarction, but intravenous atenolol use was associated with more heart failure, shock, recurrent ischemia and pacemaker use than oral atenolol use.

CONCLUSIONS

Although atenolol appears to improve outcomes after thrombolysis for myocardial infarction, early intravenous atenolol seems of limited value. The best approach for most patients may be to begin oral atenolol once stable.

Zatebradine inhibits tachycardia induced by bronchodilators without affecting respiratory resistance in dogs

Bronchodilators used for bronchial asthma reduce respiratory resistance but also increase heart rate to some extent. It is often difficult to use such bronchodilators with elderly patients and patients with heart disease. The object of our study was to investigate whether a specific bradycardic agent, zatebradine, inhibited the heart rate increased by bronchodilators without affecting respiratory resistance. We evaluated the effects of zatebradine on the increases in heart rate and inhibition of the respiratory resistance in response to the bronchodilators, isoproterenol, procaterol (a beta 2-adrenoceptor agonist), 6-(3-dimethylaminopropionyl)-forskolin, NKH 477 (an adenylyl cyclase activator) and aminophylline in the anesthetized and artificially ventilated dog. When zatebradine in doses of 0.05-1.5 mg/kg i.v. decreased heart rate without affecting arterial blood pressure, it dose dependently attenuated the increase in heart rate in response to isoproterenol, procaterol, NKH 477 and aminophylline but did not affect the inhibition by these substances of the increase in respiratory resistance induced by histamine. Propranolol (0.01-0.3 mg/kg i.v.) dose dependently inhibited not only the increase in heart rate but also the inhibition of the respiratory resistance induced by isoproterenol and procaterol. The present results indicate that zatebradine selectively inhibits the increase in heart rate in response to cyclic AMP-dependent bronchodilators without affecting their bronchodilator effects in anesthetized dogs and suggest that zatebradine may be a useful drug for prevention of the tachycardia induced by bronchodilators used for patients with bronchial asthma.

Effects of the administration of captopril, metoprolol and of the captopril-metoprolol combination as adjuvant therapy during thrombolysis in acute myocardial infarction

The aim of the study was to verify, during thrombolysis in patients with anterior acute myocardial infarction, the safety and effects of beta-blockers or ACE-inhibitors and their combination in the short and long term. One-hundred sixty-six patients hospitalized within 4 h from the onset of the symptoms (first episode), eligible for thrombolysis, Killip class I-II, were randomized (single blind) into four groups. Group A (42 patients) received 6.25 mg captopril (orally) 15 min before thrombolysis and metoprolol (i.v.) not later than 1 h, and orally afterwards. Group B (42 patients) received 6.25 mg captopril 15 min before thrombolysis. Group C (37 patients) received metoprolol not later than 1 h. Group D (45 patients) received thrombolysis only. Later (day 3), groups C and D also received captopril. We checked ventricular arrhythmias (first 2h) from thrombolysis, creatine kinase peak, creatine kinase peak normalization time, late ventricular arrhythmias at Holter test pre-discharge (Lown's class > 2). At follow-up (mean 30.5 +/- 2 months), mortality was evaluated for reinfarction and ventricular failure. Age and sex were similar.

RESULTS

Early ventricular arrhythmias: Group A, five cases; Group B, five cases; Group C, 15 cases; Group D, 16 cases. Creatine kinase peak: Group A, 1875 +/- 220 U/l; Group B, 1566 +/- 168 U/l; Group C, 2274 +/- 212 U/l; Group D 2103 +/- 232 U/l. Creatine kinase peak normalization time: Group A, 57.7 +/- 3 h; Group B, 58.1 +/- 3 h; Group C, 72.7 +/- 3 h; Group D, 69.5 +/- 2 h (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of oral pretreatment with metoprolol on left ventricular wall motion, infarct size, hemodynamics, and regional myocardial blood flow in anesthetized dogs during thrombotic coronary artery occlusion and reperfusion

OBJECTIVES

To study the effects of oral pretreatment with metoprolol over 3 days on hemodynamics, left ventricular function, regional myocardial blood flow, and infarct size in an anesthetized dog model of thrombotic occlusion of the anterior descending coronary artery treated with thrombolysis.

METHODS

Ten dogs received 200 mg metoprolol (Selozok) orally and 8 dogs received placebo for 3 days twice daily and 1 hour before the experiment. Under general anesthesia, thrombotic occlusion was provoked by the copper-coil technique. Intracardiac pressures and their derivatives, cardiac output (thermodilution method), regional coronary blood flow (microspheres), global and regional left ventricular function (ventriculography), and infarct size (triphenyltetrazolium staining) were measured. Measurements were performed during control, after 60 minutes of occlusion, and after 30 and 90 minutes of reperfusion. Thrombolysis was performed in all dogs 60 minutes after occlusion by intravenous infusion of 10 micrograms/kg/min of rt-PA for 30 minutes.

RESULTS

During control cardiac output was lower, total peripheral resistance higher, and Tau and the left ventricular isovolumic relaxation time greater in the metoprolol group. During occlusion and after reperfusion, there were no significant hemodynamic differences between both groups. Blood flow to the area at risk and circumflex territory during occlusion were, respectively, 12.8 +/- 5.80 ml/100 g/min versus 9.65 +/- 8.35 ml/100 g/min (p > 0.05) and 42.58 +/- 7.86 ml/100 g/min versus 61.52 +/- 20.43 ml/100 g/min (p = 0.01) in the metoprolol- and placebo-treated dogs. The ratios of flow area at risk/circumflex territories in the epicardial, midmyocardial, and endocardial layers were, respectively, 0.44 +/- 0.20, 0.19 +/- 0.09, and 0.20 +/- 0.13 in the metoprolol- versus 0.24 +/- 0.16, 0.08 +/- 0.06, and 0.06 +/- 0.07 (p > or = 0.04) in the placebo-treated dogs. The ratio of flow endocardium/epicardium was higher (p > or = 0.02) in the active treatment group during the control period, both in the area at risk and circumflex territory; this was also the case in the circumflex territory at the end of the experiment (p = 0.003). Thirty minutes after occlusion, blood flow to the three layers of the area at risk rose to 2-3 times control values in both groups; a significant increase above control values also occurred in the circumflex territory. After 90 minutes reperfusion, blood flow to both territories was similar in both groups but was comparable to the control; however, in necrotic tissue of the subendocardial layer of both groups, flow fell below control values (p < 0.05). End-systolic volume rose from 21.2 +/- 7.4 ml to 36.1 +/- 11.5 ml (p < 0.05), end-diastolic volume remained constant (46.0 +/- 13.8 vs. 47.9 +/- 12.1 ml; p > 0.05), and ejection fraction fell from 53.9 +/- 8.3% to 25.8 +/- 10.2% (p < 0.05) at the end of the experiment in the metoprolol group. Respective figures for the placebo group were 19.4 +/- 7.9 versus 27.9 +/- 10.9 (p < 0.05), 38.5 +/- 13.0 versus 42.1 +/- 11.0 (p > 0.05), and 50.6 +/- 5.7 versus 35.5 +/- 11.7 (p < 0.05). Fractional shortening of the chords analyzed was similar in both groups during the control period; it fell significantly at the end of the experiment in three chords of the metoprolol group and in five chords of the placebo group. The apical chord in the placebo, but not in the metoprolol, dogs was dyskinetic: fractional shortening was -0.86 +/- 9.7 versus 7.5 +/- 13.5% (p > 0.05). The area at risk was 41.6 +/- 10.6 cm2 in metoprolol- and 40.5 +/- 7.2 cm2 in placebo-treated dogs (p > 0.05); the infarct size, expressed as a percentage of the area at risk, was 29.0 +/- 22.5% and 45.3 +/- 23.6% (p = 0.02), respectively.

CONCLUSIONS

Oral pretreatment with metoprolol limited infarct size and improved regional left ventricular function, probably due to its negative chronotropic and inotropic effects, and also due to an enhancement of collateral flow fr

Early intravenous administration of metoprolol enhances myocardial salvage by thrombolysis with recombinant tissue-type plasminogen activator after thrombotic coronary artery occlusion in the dog by improvement of the collateral blood flow to the area at risk

OBJECTIVES

We studied the effects of beta 1-adrenergic blockade preceding thrombolysis on hemodynamic variables, myocardial blood flow and infarct size in a canine model of thrombotic occlusion of the left anterior descending coronary artery.

BACKGROUND

Previous work suggested a reduction in infarct size and improvement in left ventricular function by intravenous beta-blockade preceding thrombolysis.

METHODS

Experiments were conducted in 34 anesthetized dogs; 17 received 0.975 mg/kg body weight of metoprolol intravenously starting 15 min after occlusion, and thrombolysis was initiated 60 min after occlusion. Seventeen dogs received saline solution followed by thrombolysis. Coronary blood flow was measured by radioactive microspheres, infarct size by a dye method, hemodynamic variables by catheter-tipped pressure transducers and cardiac output by the thermodilution method.

RESULTS

Infarct size in metoprolol- and placebo-treated dogs was 23.62 +/- 18.04% and 41.50 +/- 16.03% of area at risk, respectively (p < 0.01). Before occlusion, myocardial blood flow and hemodynamic variables were similar. Sixty minutes after occlusion, cardiac output (1.94 +/- 0.41 vs. 2.32 +/- 0.68 liters/min, p < 0.01) was lower in the metoprolol-treated dogs. Collateral flow to the area at risk (17.27 +/- 7.44 vs. 10.25 +/- 5.33) and to its epicardial (21.68 +/- 8.04 vs. 11.5 +/- 6.10), midmyocardial (14.30 +/- 8.63 vs. 7.35 +/- 4.94) and endocardial (13.18 +/- 8.21 vs. 6.26 +/- 5.34 cm3/min per 100 g) layers was higher (p < or = 0.05) in the metoprolol-treated dogs. The ratio of epicardial flow area at risk/circumflex territory was inversely correlated to infarct size (r = -0.69, p < 0.01). After 5 min of occlusion, collateral flow was comparable in the five dogs of each group; over the next 55 min it remained constant in the metoprolol group but decreased in the placebo dogs.

CONCLUSIONS

Intravenous metoprolol, administered before thrombolysis, enhances infarct size limitation, partly by improvement of collateral flow to area at risk.

Significance of arrhythmias during the first 24 hours of acute myocardial infarction treated with alteplase and effect of early administration of a beta-blocker or a bradycardiac agent on their incidence

BACKGROUND

Although early intravenous beta-blocker therapy during acute myocardial infarction (AMI) reduces the incidence of fatal arrhythmias in patients not treated with thrombolytic agents, its antiarrhythmic effect in thrombolysed patients remains controversial. We investigated prospectively the arrhythmia incidence in 244 patients with AMI receiving alteplase and a double-blind randomized adjunctive therapy with intravenous atenolol, alinidine, or placebo. Moreover, the characteristics and prognostic significance of early arrhythmias and their relation with infarct size and coronary patency were evaluated.

METHODS AND RESULTS

All patients underwent 24-hour Holter monitoring on day 1 and were clinically followed in the hospital for 10 to 14 days. Coronary angiography was performed on day 10 to 14. Atenolol and alinidine significantly decreased the basic heart rate without causing more sinus arrest or higher-degree atrioventricular block. The prevalence of atrial fibrillation in alinidine patients was lower than in the atenolol patients (P = .007) but not lower than in placebo patients (P = .11). There was no effect of either agent on the incidence and frequency distribution of ventricular or supraventricular premature beats or on the incidence and characteristics of nonsustained ventricular tachycardia, accelerated idioventricular rhythm, sustained ventricular tachycardia (VT), or ventricular fibrillation (VF). On day 1, seven VF episodes were recorded in six patients (2.5%) and five VT episodes in five patients (2%). VF always started at < 2.5 hours after start of thrombolytic treatment and VT always at > 2.5 hours (average of 6 hours). Five of the seven VF and three of the five VT episodes started with an R-on-T. However, for all VT, the morphology of the first beat was the same as that of the following beats, suggesting that the sustained arrhythmia was not induced by an extrasystole. After day 1 and before hospital discharge, VF and VT developed in one and six patients, respectively. Three of the seven patients who developed VF during the first 2 weeks underwent coronary angiography; all three had an occluded infarct-related artery. In contrast, only one of nine patients with early or late VT had an occluded vessel. Patients with VT and VF on day 1 had a significantly larger enzymatic infarct size than those without the arrhythmia (P = .02), and a similar trend was noted for VT or VF after day 1 (P = .19). However, none of the patients with VT or VF on day 1 developed a life-threatening arrhythmia later during the hospital stay. Also, none of the seven patients with VT or VF after day 1 had experienced a major rhythm disturbance during the first 24 hours.

CONCLUSIONS

(1) Our data do not support the hypothesis that beta-blockers or bradycardiac agents might reduce the incidence of major arrhythmias when used in conjunction with thrombolytic therapy. (2) The pathogeneses of VT and VF early during AMI are clearly distinct. (3) VT or VF during the first 2 weeks is a marker for a larger infarct. (4) We could not detect a relation between malignant arrhythmias on day 1 and recurrences within the following 2 weeks.