An integrated clinical approach to predicting the benefit of tirofiban in non-ST elevation acute coronary syndromes. Application of the TIMI Risk Score for UA/NSTEMI in PRISM-PLUS

AIMS

We evaluated the TIMI Risk Score for Unstable Angina and Non-ST Elevation Myocardial Infarction for predicting clinical outcomes and the efficacy of tirofiban in non-ST elevation acute coronary syndromes.

METHODS AND RESULTS

Developed in TIMI 11B, the risk score is calculated as the sum of seven presenting characteristics (age > or =65 years, > or =3 cardiac risk factors, documented coronary disease, recent severe angina, ST deviation > or =0.5 mm, elevated cardiac markers, prior aspirin use). The risk score was validated in the PRISM-PLUS database (n=1915) and tested for interaction with the efficacy of tirofiban+heparin vs heparin alone. The risk score revealed an increasing gradient of risk for death, myocardial infarction or recurrent ischaemia at 14 days ranging from 7.7-30.5% (P<0.001). Dichotomized at the median, patients with a score > or =4 derived a greater relative risk reduction with tirofiban (P((Interaction))=0.025). Among patients with normal creatine kinase myocardial bands, the risk score showed a 3.5-fold gradient of risk (P<0.001) and identified a population that derived significant benefit from tirofiban (RR 0.73, P=0.027).

CONCLUSION

The TIMI Risk Score is a simple clinical tool for risk assessment that may aid in the early identification of patients who should be considered for treatment with potent antiplatelet therapy.

Increased mortality after coronary artery bypass graft surgery is associated with increased levels of postoperative creatine kinase-myocardial band isoenzyme release: results from the GUARDIAN trial

OBJECTIVES

We sought to determine if elevated cardiac serum biomarkers after coronary artery bypass graft surgery (CABG) are associated with increased medium-term mortality and to identify patients that may benefit from better postoperative myocardial protection.

BACKGROUND

The relationship between the magnitude of cardiac serum protein elevation and subsequent mortality after CABG is not well defined, partly because of the lack of large, prospectively studied patient cohorts in whom postoperative elevations of cardiac serum markers have been correlated to medium- and long-term mortality.

METHODS

The GUARD during Ischemia Against Necrosis (GUARDIAN) study enrolled 2,918 patients assigned to the entry category of CABG and considered as high risk for myocardial necrosis. Creatine kinase-myocardial band (CK-MB) isoenzyme measurements were obtained at baseline and at 8, 12, 16 and 24 h after CABG.

RESULTS

The unadjusted six-month mortality rates were 3.4%, 5.8%, 7.8% and 20.2% for patients with a postoperative peak CK-MB ratio (peak CK-MB value/upper limits of normal [ULN] for laboratory test) of < 5, > or = 5 to <10, > or =10 to < 20 and > or =20 ULN, respectively (p < 0.0001). The relationship remained statistically significant after adjustment for ejection fraction, congestive heart failure, cerebrovascular disease, peripheral vascular disease, cardiac arrhythmias and the method of cardioplegia delivery. Receiver operating characteristic curve analysis revealed an area under the curve of 0.648 (p < 0.001); the optimal cut-point to predict six-month mortality ranged from 5 to 10 ULN.

CONCLUSIONS

Progressive elevation of the CK-MB ratio in clinically high-risk patients is associated with significant elevations of medium-term mortality after CABG. Strategies to afford myocardial protection both during CABG and in the postoperative phase may serve to improve the clinical outcome.

Oral glycoprotein IIb/IIIa antagonism in patients with coronary artery disease

Dose-finding studies and trials of interaction of oral glycoprotein IIb/IIIa antagonists with other antiplatelet agents have been limited. We hypothesized that these detailed assessments could be first performed in patients with stable coronary artery disease (CAD) and then extrapolated to the target population. To this end, we performed 2 sequential studies. The first study examined the dose-related effects on indexes of platelet and vascular function induced by the oral inhibitor RPR 109891, when given alone and in combination with aspirin, in patients (n = 100) with stable CAD. The second study (the Antagonism of the FIbrinogen Receptor after Myocardial Events trial) assessed the pharmacodynamics and safety of derived regimens in patients (n = 320) with unstable coronary syndromes. In patients with stable CAD, platelet aggregation was dose dependently inhibited by RPR 109891, and the dose-response relation was shifted to the right by the concomitant administration of aspirin (p = 0.0001). The degree of platelet inhibition induced by 3 doses of RPR 109891 (plus aspirin) was lower in patients with unstable than stable CAD. No drug-related major bleeding occurred in either study. RPR 109891 treatment was associated with acute and delayed thrombocytopenia. In conclusion, chronic treatment with an oral glycoprotein IIb/IIIa antagonist (1) induces antiplatelet effects that are potentiated by concomitant administration of aspirin, (2) may require dose adjustment in syndromes of platelet activation, (3) is associated with a low rate of clinically significant bleeding when doses inducing incomplete inhibition of platelet aggregation are used, and (4) requires frequent monitoring of platelet count unless reliable predictors of delayed thrombocytopenia become available.

Point-of-care measured platelet inhibition correlates with a reduced risk of an adverse cardiac event after percutaneous coronary intervention: results of the GOLD (AU-Assessing Ultegra) multicenter study

BACKGROUND

The optimal level of platelet inhibition with a glycoprotein (GP) IIb/IIIa antagonist necessary to minimize thrombotic complications in patients undergoing a percutaneous coronary intervention (PCI) is currently unknown.

METHODS AND RESULTS

Five hundred patients undergoing a PCI with the planned use of a GP IIb/IIIa inhibitor had platelet inhibition measured at 10 minutes, 1 hour, 8 hours, and 24 hours after the initiation of therapy with the Ultegra Rapid Platelet Function Assay (Accumetrics). Major adverse cardiac events (MACES: composite of death, myocardial infarction, and urgent target vessel revascularization) were prospectively monitored, and the incidence correlated with the measured level of platelet function inhibition at all time points. One quarter of all patients did not achieve >/=95% inhibition 10 minutes after the bolus and experienced a significantly higher incidence of MACEs (14.4% versus 6.4%, P=0.006). Patients whose platelet function was <70% inhibited at 8 hours after the start of therapy had a MACE rate of 25% versus 8.1% for those >/=70% inhibited (P=0.009). By multivariate analysis, platelet function inhibition >/=95% at 10 minutes after the start of therapy was associated with a significant decrease in the incidence of a MACE (odds ratio 0.46, 95% CI 0.22 to 0.96, P=0.04).

CONCLUSIONS

Substantial variability in the level of platelet function inhibition is achieved with GP IIb/IIIa antagonist therapy among patients undergoing PCI. The level of platelet function inhibition as measured by a point-of-care assay is an independent predictor for the risk of MACEs after PCI.

Evidence of platelet activation during treatment with a GPIIb/IIIa antagonist in patients presenting with acute coronary syndromes

OBJECTIVES

The study was done to determine the role of partial agonist activity in the lack of effectiveness of the oral GPIIb/IIIa antagonist orbofiban.

BACKGROUND

Orbofiban, an oral GPIIb/IIIa antagonist, was found to increase the mortality of patients with acute coronary syndromes (ACS) in the OPUS-TIMI-16 trial, despite the fact that it is a very potent anti-platelet agent and that IV agents have proven very effective.

METHODS

Patients (n = 520) with ACS were randomized to orbofiban 30 mg, 40 mg or 50 mg twice daily or 50 mg once daily or placebo. Platelet activity was assessed in 175 patients by examining GPIIb/IIIa receptor conformation, expression of CD63 antigen, and platelet aggregation.

RESULTS

Plasma concentrations of orbofiban at the highest dose (74 +/- 6 ng/ml peak, 61 +/- 5 ng/ml trough) exceeded the IC50 for platelet aggregation to adenosine diphosphate (ADP) (29 +/- 6 ng/ml) and thrombin-activating peptide (61 +/- 18 ng/ml). Orbofiban induced a conformational change in GPIIb/IIIa detected as the displacement of the monoclonal antibody mAb2; such conformational changes have been linked to partial agonist activity. Consistent with this, platelet expression of CD63 ex vivo was significantly increased at five time points during the study. In vitro, orbofiban increased platelet aggregation to a submaximal concentration of epinephrine (67 +/- 19% vs. 27 +/- 9%, n = 5) and increased thromboxane formation when the platelet GPIIb/IIIa were clustered using monoclonal antibodies to the receptor.

CONCLUSIONS

Orbofiban is both an antagonist and a partial agonist of platelet GPIIb/IIIa. At low concentrations of the drug, this partial agonist activity may enhance platelet aggregation. Along with suboptimal plasma drug levels, these findings may help explain the lack of efficacy seen with orbofiban in patients with ACS.

Effects of tirofiban plus heparin versus heparin alone on troponin I levels in patients with acute coronary syndromes

Elevated serum troponins following an acute coronary syndrome (ACS) predict a poor clinical outcome. Glycoprotein (GP) IIb/IIIa inhibitors reduce adverse clinical outcomes in patients with ACS, although their effect on serum troponin I (TnI) in this setting has not been described. We therefore studied the effects of the GP IIb/IIIa inhibitor tirofiban on serum TnI levels in a group of patients in the Platelet Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms trial. Serial blood samples were obtained in 53 patients receiving the combination therapy of tirofiban/heparin and in 52 receiving heparin alone, and were analyzed for baseline, peak, and mean concentrations of TnI. Baseline TnI levels were not different between the combination therapy and heparin-only groups (1.6 +/- 3.0 vs 3.1 +/- 6.7 ng/ml, p = 0.15). The peak TnI level was significantly lower in the combination therapy group than in the heparin group (5.2 +/- 8.3 vs 15.5 +/- 29.1 ng/ml, p = 0.017), and mean levels over the initial 24-hour period were also significantly lower in the combination therapy group (3.2 +/- 5.0 vs 8.5 +/- 14.8 ng/ml, p = 0.016). In univariate analysis, combination therapy was associated with lower TnI levels, whereas in a multivariate model, the lower peak and mean TnI levels as a consequence of tirofiban/heparin compared with heparin monotherapy remained significant (peak, p = 0.029; mean, p = 0.035). Among patients with negative TnI at baseline, treatment with the combination of tirofiban/heparin compared with heparin monotherapy still resulted in significantly lower peak (2.5 +/- 5.4 vs 14.6 +/- 32.8 ng/ml, p = 0.024) and mean (1.2 +/- 2.6 vs 6.9 +/- 15.8 ng/ml, p = 0.029) TnI levels. In patients with ACS, therapy with the combination of tirofiban and heparin (compared with heparin treatment alone) resulted in lower serum TnI levels, suggesting reduced myocardial injury.

Design of the blockade of the glycoprotein IIb/IIIa receptor to avoid vascular occlusion (BRAVO) trial

BACKGROUND

Platelets play a key role in the pathogenesis of atherosclerosis, thrombosis, and acute coronary and cerebrovascular syndromes. Inhibition of platelet function by acetylsalicylic acid (aspirin) has been shown to reduce the incidence atherothrombotic events in patients with coronary, cerebrovascular, or peripheral vascular disease. Thienopyridine agents, however, including ticlopidine and clopidogrel, inhibit the adenosine diphosphate receptor and have modestly superior effects compared with aspirin on reduction of death, myocardial infarction, and stroke among a broad group of patients with vascular disease. More effective antithrombotic agents are still required to treat patients at high risk for recurrent vascular events.

METHODS

Lotrafiban, a selective, nonpeptide antagonist of the human platelet fibrinogen receptor (glycoprotein [GP] IIb/IIIa [alphaIIb/beta3 integrin]), blocks the binding of fibrinogen to the GP IIb/IIIa receptor, which is the final common pathway of platelet aggregation. Lotrafiban at doses of up to 50 mg twice daily was well-tolerated in a 12-week, double-blind, placebo-controlled, dose-ranging study in patients with recent myocardial infarction, unstable angina, transient ischemic attack, or stroke when added to aspirin therapy. On the basis of these results, a dosing regimen was selected for the phase III Blockage of the Glycoprotein IIb/IIIa Receptor to Avoid Vascular Occlusion (BRAVO) trial based on pharmacodynamics and drug tolerability. In the pivotal BRAVO study, lotrafiban therapy is being evaluated in patients who have had a recent myocardial infarction, unstable angina, transient ischemic attack, or ischemic stroke, or who present at any time after a diagnosis of peripheral vascular disease combined with either cardiovascular or cerebrovascular disease.

RESULTS

The efficacy evaluation will be based on a composite end point of clinical events (death by any cause, myocardial infarction, stroke, recurrent ischemia requiring hospitalization, or urgent ischemia-driven revascularization). The target enrollment is 9200 patients worldwide. Approximately 700 centers will participate and will be distributed within 30 countries across North America, Europe, Australia, and Asia.

Effect of micronized fenofibrate on plasma lipoprotein levels and hemostatic parameters of hypertriglyceridemic patients with low levels of high-density lipoprotein cholesterol in the fed and fasted state

A randomized, double-blind, placebo-controlled study was undertaken in 20 hypertriglyceridemic men [plasma triglyceride (TG), >2.3 mM] with low levels (<0.9 mM) of high-density lipoprotein cholesterol (HDL-C) to investigate the ability of micronized fenofibrate (Tricor or Lipidil; 200 mg/day) to affect atherogenic and thrombogenic plasma risk factors in the fed and fasted state. Each patient underwent (a) 4 weeks of dietary stabilization, (b) 8 weeks of treatment with fenofibrate or placebo, (c) a 5-week washout period, and (d) 8-weeks of treatment with the alternative medication. An oral fat-loading test (1 g fat/kg body weight) was carried out after both treatment periods. Before treatment, patients had a mean (+/- SD) total plasma TG of 3.31+/-0.93 mM; total C, 5.75+/-0.89 mM; HDL-C, 0.71+/-0.09 mM; and low-density lipoprotein (LDL)-C, 3.40+/-0.68 mM. Compared with placebo, fenofibrate reduced fasting TG levels by 36%, and triglyceride-rich lipoprotein (TRL, d<1.006 g/ml) -TG, and TRL-C levels by approximately 40%. In the postprandial state, fenofibrate reduced total TG, TRL-TG, TRL-C, TRL-apoC-III, and TRL-apoE levels by -35% (all values of p<0.01). Fasted and fed HDL-C and apoA-I levels were increased -10%, and total cholesterol/HDL cholesterol ratios were decreased -15% by fenofibrate. No significant differences were observed in mean LDL-C and LDL-apoB levels. A 6% increase in the LDL-C/LDL-apoB ratio during fenofibrate treatment indicated a shift to larger, more buoyant LDL particles. A small, but statistically significant (p<0.01) increase was observed in fasted and fed Lp(a) levels during fenofibrate treatment. Hemostatic parameters were not significantly affected by fenofibrate, except for a 12-15% decrease (p<0.05) in fibrinogen levels in the fasted and fed state, and a significant increase (43%; p<0.05) in fasting levels of plasminogen activator-inhibitor-1. These data demonstrate that micronized fenofibrate is highly effective, in both the fed and fasted state, in reducing TRL lipids and apolipoproteins, and in reducing plasma fibrinogen levels of men with an atherogenic lipoprotein profile.

Redefining medical treatment in the management of unstable angina

In 1994, the Agency for Health Care Policy and Research sponsored the development of guidelines for diagnosing and managing patients with unstable angina. Since their publication, several important developments have occurred. The prognostic value of biochemical assays for cardiac-specific troponins T and I have been shown in many studies. The possible role for C-reactive protein in determining prognosis deserves further investigation. Substantial clinical benefits have been obtained with intravenous inhibitors of the platelet glycoprotein (GP) IIb-IIIa receptor (abciximab, eptifibatide, tirofiban) and with one of the low-molecular-weight heparins (enoxaparin). The therapeutic potential of other low-molecular-weight heparins, direct thrombin inhibitors, and oral GP IIb-IIIa inhibitors remains to be clarified. On the basis of this evidence, consideration should be given to measuring serum levels of a cardiac troponin (either T or I) and using intravenous GP IIb-IIIa inhibitors and low-molecular-weight heparin in the standard management of patients with unstable angina.

Medical decision making in the choice of a thrombolytic agent for acute myocardial infarction. Quebec Acute Coronary Care Working Group

Little is known about how physicians make decisions when the evidence is incomplete or controversial. While thrombolysis improves survival following acute myocardial infarction (AMI), conflicting evidence exists as to any specific agent's superiority, particularly if cost-effectiveness is considered. Using a Bayesian hierarchical model, the authors examined the patient, physician, and hospital characteristics that are related to the decision-making process concerning the choice of thrombolytic agent in a prospective registry of 1,165 AMI patients receiving thrombolysis. Tissue plasminogen activator (t-PA) was administered to 432 patients (31.8%) and streptokinase (SK) to the remainder. The presence of an anterior infarction, a previous myocardial infarction, low blood pressure, a cardiologist decision maker, younger age, and receiving treatment within six hours after the start of symptoms were independent predictors of receiving t-PA. The levels of importance that physicians accorded to these patient characteristics differed according to their practicing institutions. Generally, they followed evidence-based medicine and reasonably targeted high-risk patients to receive the more expensive t-PA. However, they also preferentially treated younger patients, where only a small absolute advantage appears to exist.

Influence of baseline lipids on effectiveness of pravastatin in the CARE Trial. Cholesterol And Recurrent Events

OBJECTIVES

We sought to assess the influence of baseline lipid levels on coronary event rates and the effectiveness of pravastatin therapy in the Cholesterol And Recurrent Events (CARE) study.

BACKGROUND

The CARE study cohort provided a relatively unique opportunity to examine the relation between lipid levels and clinical events in a post-myocardial infarction (MI) population with relatively low cholesterol and low density lipoprotein (LDL) cholesterol values.

METHODS

There were 4,159 patients with a previous infarct and a total cholesterol level <240 mg/dl, LDL cholesterol level 115 to 174 mg/dl and triglyceride level <350 mg/dl randomly allocated to placebo (n=2,078) or pravastatin 40 mg/day (n=2,081). Time to either coronary death or nonfatal MI (primary end point) or to the secondary end point, which included undergoing a coronary revascularization procedure, was determined as a function of baseline lipids (total, LDL, high density lipoprotein [HDL] cholesterol and triglyceride levels).

RESULTS

Quartile analysis indicated important effects for LDL cholesterol, in which a higher LDL was associated with greater cardiac event rates (in the placebo group, every 25-mg/dl increment in LDL was associated with a 28% increased risk [5% to 56%, p=0.015]) in the primary event. The differential event rates with respect to baseline LDL cholesterol for placebo and pravastatin groups reduced the difference in clinical outcomes at lower LDL cholesterol levels. In both the placebo and pravastatin groups, an inverse relation between baseline HDL cholesterol and cardiac events was observed (10 mg/dl lower baseline HDL cholesterol level was associated with a 10% [0% to 19%, p=0.046] increase in coronary death or nonfatal MI).

CONCLUSIONS

Within the LDL cholesterol levels in CARE (115 to 174 mg/dl), baseline values influenced both the risk of events in the placebo group as well as the clinical effectiveness of pravastatin therapy.

Glycoprotein IIb/IIIa inhibitors in unstable angina

The inhibitors of platelet membrane integrin receptor glycoprotein IIb/IIIa occupy the receptor, preventing fibrinogen binding and platelet aggregation. The inhibition is direct and may be advantageous over the partial inhibition induced by agents interfering at individual pathways to platelet aggregation. The inhibitors, and more specifically abciximab, the monoclonal antibody against the receptor, are effective to prevent the acute complications associated with percutaneous intervention procedures. Based on the positive results of these trials, which have enrolled a large proportion of patients with unstable angina, and on a few pilot studies in unstable angina, large trials have been completed and are ongoing in patients with an acute coronary syndrome. It is hoped that these drugs will prevent the acute complications associated with thrombus formation, and also, past the acute phase, prevent the recurrence of the disease and rapid progression of atherosclerosis.

Circadian variation in the onset of unstable angina and non-Q-wave acute myocardial infarction (the TIMI III Registry and TIMI IIIB)

Circadian variation has been demonstrated in several types of acute cardiovascular disease, including acute myocardial infarction (AMI), sudden cardiac death, silent ambulatory ischemia, and thrombotic stroke. In contrast, no diurnal variation was observed in 1 study of non-Q-wave AMI, and limited data are available for unstable angina. To assess whether circadian variation is present in unstable angina and non-Q-wave AMI, we examined the time of onset of ischemic pain in 7,731 patients who were prospectively identified in the Thrombolysis in Myocardial Ischemia (TIMI) III Registry, 3,318 of whom were enrolled in the prospective study, and in 1,473 patients enrolled in the TIMI IIIB trial. A circadian variation in the onset of pain was observed, with an increase in the number of patients experiencing the onset of pain in the morning hours between 6 A.M. and 12 noon (p <0.001). This circadian variation was observed both in patients with unstable angina and in those with evolving non-Q-wave AMI. A similar circadian pattern was observed in all subgroups tested. These findings were confirmed in the TIMI IIIB trial and complement previous studies suggesting that circadian variation exists in the onset of the full spectrum of myocardial ischemic syndromes.

Comparison of outcome of patients with unstable angina and non-Q-wave acute myocardial infarction with and without prior coronary artery bypass grafting (Thrombolysis in Myocardial Ischemia III Registry)

The aim of this study was to characterize patients with and without prior coronary artery bypass grafting (CABG) among a prospectively identified cohort of patients presenting with unstable angina or non-Q-wave myocardial infarction. Patients in the Thrombolysis in Myocardial Infarction phase III Registry Prospective Study presented within 96 hours of an episode of unstable angina or non-Q-wave acute myocardial infarction. Of 2,048 patients, 336 (16.4%) had prior CABG. Compared with those without prior CABG, patients were the same age, but were more likely to be men, white, diabetic, have a history of angina or myocardial infarction, to have received anti-ischemic medications in the prior week, and to receive intravenous heparin or nitroglycerin, or both, during hospitalization. They were equally likely to undergo coronary angioplasty or CABG. Death or nonfatal myocardial infarction occurred by day 10 in 4.5% of patients with prior CABG and 2.8% of patients without prior CABG (p = 0.11); and by day 42 in 7.7% and 5.1%, respectively (p = 0.03). The composite of death, myocardial infarction, or recurrent ischemia at 1 year was more common among patients with prior CABG (39.3% vs 30.2%, p = 0.002). By multiple logistic regression, prior CABG was not independently associated with the occurrence of death or myocardial infarction, or the composite of death, myocardial infarction, or recurrent ischemia either at 6 weeks or at 1 year. The likelihood of recurrent ischemic events is greater among patients with than without prior CABG, but is not likely explained by differences in baseline or treatment characteristics which reflect the degree of underlying cardiac disease.

Effects of thrombolytic therapy administered 6 to 24 hours after myocardial infarction on the signal-averaged ECG. Results of a multicenter randomized trial. LATE Ancillary Study Investigators. Late Assessment of Thrombolytic Efficacy

BACKGROUND

Thrombolytic therapy reduces mortality after acute myocardial infarction, even when treatment is initiated relatively late after onset of symptoms. The mechanism underlying this survival benefit is incompletely understood.

METHODS AND RESULTS

In a prospectively designed ancillary study of a randomized, placebo-controlled trial of late thrombolytic therapy (LATE), the signal-averaged (SA) ECG was recorded before hospital discharge in an effort to assess the effect of thrombolytic therapy on arrhythmia substrate. Three hundred ten patients were enrolled at 23 participating sites; 160 patients received placebo, and 150 patients received recombinant tissue-type plasminogen activator (rTPA) therapy 6 to 24 hours after onset of symptoms. Compared with placebo, rTPA tended to reduce the frequency of SAECG abnormality (filtered QRS duration > 120 milliseconds) by 37% (95% CI, -64%, +6%; P = .087) and the filtered QRS duration (105.7 +/- 13.8 versus 108.8 +/- 14.6 milliseconds, P = .05). In the prespecified subgroup of 185 patients with ST elevation on the qualifying ECG, rTPA resulted in a 52% reduction (95% CI, 4% to 77%, P = .011) of SAECG abnormality and a shorter filtered QRS duration (105.7 +/- 10.9 versus 110.7 +/- 15.9 milliseconds, P = .01). No benefit was seen in patients without ST elevation on ECG.

CONCLUSIONS

Late thrombolytic therapy produced a more stable electrical substrate, which probably represents an important mechanism of mortality benefit.

Low-dose combined therapy with fluvastatin and cholestyramine in hyperlipidemic patients

OBJECTIVE

To compare the low-density lipoprotein (LDL) cholesterol-lowering efficacy of low-dose combinations of cholestyramine and fluvastatin.

DESIGN

Randomized, double-blind, parallel group, placebo-controlled trial with a 24-week double-blind treatment period divided into three phases.

SETTING

Office-based clinics.

PATIENTS

Hypercholesterolemic, with LDL cholesterol of 4.14 mmol/L or greater (> or = 160 mg/dL) and plasma triglycerides of 3.39 mmol/L or less (< or = 300 mg/dL). Four hundred sixty patients were screened; 224 patients were randomized into a double-blind treatment period; 203 completed the study; 6 dropped out because of adverse events.

INTERVENTION

Patients were treated with 10 mg or 20 mg of fluvastatin alone, 8 g or 16 g of cholestyramine alone, or combinations of these fluvastatin and cholestyramine dosages (six treatment groups).

MEASUREMENTS

Changes in lipid variables, particularly LDL cholesterol.

RESULTS

The 10-mg and 20-mg fluvastatin monotherapy groups showed considerable reductions in LDL cholesterol initially (-20.1% [SD, 8.8%] and -20.2% [SD, 10.1%], respectively); these reductions were maintained. Reductions in LDL cholesterol that resulted from the addition of cholestyramine, 8 g/d, to 10 mg of fluvastatin and 20 mg of fluvastatin were greater than those observed with monotherapy (10-mg fluvastatin--[10-mg fluvastatin plus cholestyramine], 9.1%; 95% CI, 3.8% to 14.4%) and 20-mg fluvastatin--[20-mg fluvastatin plus cholestyramine], 11.6%; CI, 6.5% to 16.8%). The increase in cholestyramine dose to 16 g/d in the three combination groups provided only a modest additional response.

CONCLUSIONS

Low-density lipoprotein cholesterol reductions of about 25% to 30% can be achieved with low-dose combination therapy with fluvastatin and cholestyramine. The addition of low-dose resin appears to produce greater overall cholesterol reduction than does a simple doubling of the fluvastatin dosage. The low-dose combination treatment was highly successful in achieving the goals of the National Cholesterol Education Program guidelines.

Coronary thrombolysis: prehospital use

Strong evidence supports the concept that earlier application of fibrinolytic treatment can maximize the benefits derived. The results of two level I trials have shown that prehospital thrombolysis is feasible and safe. Although the trials have not proven that prehospital thrombolysis improves prognosis, they have shown that early identification of eligible patients can greatly accelerate the process of drug administration.

[The intracoronary infusion of superoxide dismutase during the initial liberation of oxygen free radicals induced by reperfusion. The effect on the infarct size after 60 minutes of coronary occlusion in the pig model]

The role of oxygen free radicals (OFR) generated early during myocardial reperfusion in the genesis of myocardial necrosis was studied in 26 pigs submitted to transient coronary occlusion followed by one of three different reperfusion protocols. In group A, a selective intracoronary infusion of a Ringer solution was started after 60 min of coronary occlusion, and reperfusion was performed 4 min later. The infusion was maintained during the first 6 min of reperfusion at a rate of 3 ml/min. In group B, the Ringer solution administered during reperfusion contained a high concentration (2.778 U/ml) of superoxide dismutase (SOD). In group C, reperfusion was performed after 60 min of coronary occlusion with no intracoronary infusion. Twenty-four hours later the heart was excised and the area at risk and infarct size were measured by in vivo fluorescein injection and triphenyl-tetrazolium chloride staining respectively. The area at risk was similar in the 3 groups: 15.03 +/- 2.6%, 13.26 +/- 3.3% and 16.34 +/- 6.7% of ventricular mass in groups A, B, and C, respectively (p = 0.42). No differences between groups were observed in infarct size, either when measured as a percent of ventricular mass (10.04 +/- 3.8%, 9.31 +/- 3.8% and 10.1 +/- 2.4% in groups A, B, and C, p = 0.91) or as a percent of the area at risk (64.63 +/- 18.5%, 67.81 +/- 16.1%, and 61.35 +/- 6.7%, respectively, p = 0.72). Thus, the intracoronary administration of SOD during the early reperfusion has not beneficial effect on infarct size. This results suggest that the early burst of OFR is not a major determinant of infarct size in the pig.

Avoiding interpretive pitfalls when assessing arrhythmia suppression after myocardial infarction: insights from the long-term observations of the placebo-treated patients in the Cardiac Arrhythmia Pilot Study (CAPS)

The Cardiac Arrhythmia Pilot Study (CAPS) was a 1 year trial that analyzed the safety and effectiveness of arrhythmia suppression in 502 patients surviving acute myocardial infarction who had greater than or equal to 10 ventricular premature depolarizations/h or greater than or equal to 5 runs of ventricular tachycardia on a Holter recording obtained 6 to 60 days after the acute infarction. Because 100 of these patients received placebo in a double-blind fashion for 1 year, a comprehensive objective analysis was performed of spontaneous arrhythmia changes based on real data rather than statistical estimates. In the CAPS placebo group, 19% developed some serious clinical event in 1 year (death, heart failure, proarrhythmia) that could likely be attributable to antiarrhythmic drug toxicity. A significant reduction in the frequency of ventricular premature depolarizations (p = 0.004) occurred in the first few weeks of "therapy" with a further significant (p less than 0.04) decrease between 3 to 12 months. After initiation of placebo antiarrhythmic therapy, 27% had "apparent ventricular premature depolarization suppression" (greater than or equal to 70% reduction) after one Holter recording evaluation and nearly half (48%) after six Holter recordings to assess suppression were performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Sinus node dysfunction and sudden cardiac death following treatment with encainide

Encainide, a class Ic drug, is generally thought of as having little effect on sinus node function. In this article, we present the clinical course and electrophysiological findings of a patient who had cardiac arrest after 1 week of encainide therapy for ventricular extrasystoles. No ventricular tachyarrhythmias were induced during programmed ventricular stimulation (baseline study and while receiving encainide therapy). Prior to encainide therapy, sinus node function was normal, but clinical observations after admission for cardiac arrest and subsequent electrophysiological study revealed that encainide had caused striking impairments in sinus node function. During a 6-month follow-up without antiarrhythmic drug treatment, this patient has had an uneventful course. We concluded that encainide can cause severe and life-threatening sinus node dysfunction.

Epoprostenol (prostacyclin) in unstable angina

The purpose of this randomized, double-blind multicenter trial was to investigate the potential therapeutic effect of epoprostenol (prostacyclin, PGI2) in patients with unstable angina, as compared with placebo, and to investigate the safety of this agent. Of the 184 patients enrolled, 28 did not fit the study criteria; of the remaining 156 patients, 30 received prostacyclin in an open-label fashion. In the double-blind portion of the study, 63 patients each received prostacyclin or placebo. The drug or its vehicle was infused intravenously up to 5 ng/kg/min dose for 72 hours with a tapering off period for the last 12 hours. Both treatment groups from the double-blind portion were comparable in regard to the demographic data, length of infusion, and total dose received. There were no significant differences between the placebo and prostacyclin group in the following clinical endpoints: levels of cardiac enzymes throughout hospitalization period (with the exception of lower SGOT level in the prostacyclin group at day 2), and severity of angina (throughout the study), and at the end of the study (day 30). The number of patients who had congestive heart failure, new myocardial infarction, balloon pump insertion, coronary artery bypass grafting, or percutaneous coronary angioplasty was similar in both groups. Similar results in regard to the efficacy endpoints were also apparent in the prostacyclin group that was treated under open-label fashion. There was also no difference in the New York Heart Association (NYHA) functional status at the end of the double-blind study.(ABSTRACT TRUNCATED AT 250 WORDS)

Design features of a controlled clinical trial to assess the effect of a calcium entry blocker upon the progression of coronary artery disease

This report presents the design and methodological features of a double-blind, randomized, placebo-controlled, trial in 383 patients with coronary artery disease. The study's principal objective is to determine whether chronic treatment with a calcium entry blocker can retard the progression of coronary artery disease. The study population consists of patients with coronary artery disease and a baseline coronary arteriogram that qualifies them as being at high risk for disease progression. After satisfying all entry criteria, patients were randomized to receive either the calcium entry blocker nicardipine or placebo. All indicated concomitant medications except calcium entry blockers are permitted. Patients are being followed clinically for 24 months before undergoing a second coronary arteriogram. The effect of the treatments on a variety of clinical and angiographic parameters will be determined.

Design of a multicenter, double-blind study to assess the effects of prophylactic diltiazem on early reinfarction after non-Q-wave acute myocardial infarction: diltiazem reinfarction study

This protocol describes the design of an international study to examine the potential prophylactic effect of 14 days of diltiazem therapy to prevent early reinfarction in patients initially presenting with non-Q-wave acute myocardial infarction. Reinfarction was defined by the detection of a secondary elevation of plasma MB-creatine kinase. The results of clinical trials, instrumental in this protocol design, that established the increased propensity for early reinfarction after initial non-Q-wave infarction are described and the implications of the present study are discussed.

Diltiazem and reinfarction in patients with non-Q-wave myocardial infarction. Results of a double-blind, randomized, multicenter trial

We performed a multicenter, double-blind, randomized study to evaluate the effect of diltiazem on reinfarction after a non-Q-wave myocardial infarction. Nine centers enrolled 576 patients: 287 received diltiazem (90 mg every six hours) and 289 received placebo. Treatment was initiated 24 to 72 hours after the onset of infarction and continued for up to 14 days. The primary end point, reinfarction, was defined as an abnormal reelevation of MB creatine kinase in plasma within 14 days. Reinfarction occurred in 27 patients in the placebo group (9.3 percent) and in 15 in the diltiazem group (5.2 percent)--a 51.2 percent reduction in cumulative life-table incidence (P = 0.0297; 90 percent confidence interval, 7 to 67 percent). Diltiazem reduced the frequency of refractory postinfarction angina (a secondary end point) by 49.7 percent (P = 0.0345; 90 percent confidence interval, 6 to 73 percent). Mortality was similar in the two groups (3.1 and 3.8 percent, respectively, in the placebo and diltiazem groups), but adverse drug reactions (most of which were mild) were more common in the diltiazem group. Nevertheless, the drug was well tolerated, despite concurrent treatment with beta-blockers in 61 percent of the patients. We conclude that diltiazem was effective in preventing early reinfarction and severe angina after non-Q-wave infarction and that it was also safe and generally well tolerated.

Circadian variation in variant angina

Thirteen hospitalized patients with variant angina were studied to assess circadian variation in disease activity. Over 48 hours, all angina attacks were noted, a continuous Holter electrocardiogram was recorded and 2 ergonovine tests were performed 12 hours apart, 1 at 4 AM and the other at 4 PM. Only 2 patients gave a clearcut history of more frequent nocturnal or early morning attacks. During the study period, 1.8 +/- 1.6 AM and 0.62 +/- 1.2 PM angina episodes per patient were reported (p less than 0.02), but a circadian pattern was apparent in only 4 patients. However, Holter analysis revealed 5.3 +/- 13.8 AM and 2.6 +/- 8.5 PM episodes of ST elevation per patient (p less than 0.05) and 8.1 +/- 13.9 AM and 3.2 +/- 8.5 PM episodes of ST elevation, ST depression or T-wave pseudonormalization (p less than 0.01). Ten of 11 patients with Holter abnormalities had more frequent AM than PM attacks (p less than 0.01). ST elevation developed during all 13 of the 4-AM and 12 of 13 of the 4-PM ergonovine tests. In 10 cases the ergonovine threshold at which the attack occurred was lower in the morning, in no case was it lower in the afternoon, and in 3 patients the morning and afternoon doses were identical (p less than 0.01). Thus, circadian variation in disease activity both for spontaneous and provoked attacks is present in most patients with variant angina, even though it is often not clinically apparent.

Comparative sensitivity of exercise, cold pressor and ergonovine testing in provoking attacks of variant angina in patients with active disease

Exercise, ergonovine and the cold pressor test have been used to provoke variant angina attacks. The sensitivity of these three tests was compared in 34 hospitalized patients with well documented, active variant angina who had recently undergone coronary arteriography. The three tests were usually performed on three consecutive days, and 28 of the 34 had the three tests within 1 week. Angina was provoked by ergonovine in all 34 patients, by exercise in 17 and by cold pressor test in only five (p less than 0.005). ST elevation developed during the ergonovine test in 32 (94%), during exercise in 10 (29%) and during the cold pressor test in only three (9%). With ergonovine, one patient had only ST depression and one had no ECG changes. During the cold pressor test two patients had pseudonormalization of abnormally negative T waves and 29 had no ECG changes. Exercise induced T-wave pseudonormalization in four patients, ST depression in nine others and no ECG changes in 11. ST elevation was more frequent with ergonovine than with either of the other tests (p less than 0.0001). ST elevation or T-wave pseudonormalization occurred more often with exercise than with cold (p less than 0.05), but both occurred less often than with ergonovine (p less than 0.0001). We conclude that the sensitivity of the ergonovine test is very high in patients with active variant angina and that exercise will provoke angina with ST elevation in about 30% of these cases. In contrast, the sensitivity of the cold pressor test is too low to be of much clinical value in the diagnosis of variant angina.

Sulfinpyrazone decreases epinephrine-induced platelet aggregation after myocardial infarction

Platelet studies were performed during a controlled double-blind randomized clinical trial of sulfinpyrazone (Anturane Reinfarction Trial) in 41 patients who had recent myocardial infarction. Aggregation of platelet-rich plasma by thrombin (0.185, 0.246 U/ml), collagen, adenosine diphosphate, and adrenaline (0.23, 0.46, and 0.91 microgram/ml) was estimated after a 12 hour fast including abstinence from drugs and cigarette smoking. The tests were carried out 2 weeks after myocardial infarction and 6, 12, and 24 months later. At the last visit, washed platelet suspensions were also tested for aggregation to thrombin (0.03, 0.015 U/ml) +/- epinephrine (0.55 microgram/ml) and their production of malonyldialdehyde was estimated. A significant (p less than 0.02) reduction (50%) of the aggregation response of platelet-rich plasma to epinephrine was found in the group treated with sulfinpyrazone (n = 21) as compared with the placebo group (n = 20). Also, adrenaline evoked a milder (p less than 0.01) potentiation of aggregation by thrombin of the washed platelet suspensions in the sulfinpyrazone versus the placebo group. Other assays including platelet coagulant activity were not useful in discriminating between the 2 groups. It is concluded that sulfinpyrazone (200 mg 4 times daily) normalizes the platelet response to epinephrine; a relation with the drug-reported reduction of sudden death after myocardial infarction is suggested.

Clinical characteristics of patients with variant angina complicated by myocardial infarction or death within 1 month

Of 132 consecutive patients hospitalized during a 5 year period because of active variant angina, 18 died or had a myocardial infarction within 1 month. In 4 patients an episode of pain and S-T elevation unrelieved by calcium antagonist drugs and intravenous nitroglycerin persisted for more than 1 hour, inducing cardiogenic shock and death before the appearance of Q waves and elevated serum enzyme levels. In the other 14 patients myocardial infarction developed in the electrocardiographic leads in which S-T elevation had occurred during attacks of variant angina. Clinical features were not helpful in distinguishing the 18 patients with complications from the other 114. Angina at rest had been present for less than 1 month in 7 of the 18 patients with infarction compared with 31 of 114 in the other group (probability [p] not significant [NS]). Before infarction the artery presumed to be perfusing the involved territory contained a fixed stenosis of 70 percent or more of luminal diameter in 8 of the 14 patients with complications who had coronary arteriograms compared with 50 of 112 in the other group (p = NS). In 13 of the 18 patients, complications occurred in spite of large doses of calcium antagonist drugs. In 11 of these 13, attacks of variant angina were monitored for 3 to 17 days both before and during treatment. All 11 had fewer attacks with treatment and 5 had no attacks. Daily attacks per patient decreased from 4.6 +/- 4.3 to 0.5 +/- 0.7 (mean +/- standard deviation) (p less than 0.01). It is concluded that in variant angina of recent onset myocardial infarction occurs frequently and unpredictably. Myocardial infarction may occur in the absence of severe fixed lesions and in spite of apparent clinical improvement with administration of calcium antagonist drugs.

Ergonovine testing to detect spontaneous remissions of variant angina during long-term treatment with calcium antagonist drugs

A subgroup of 22 patients with variant angina who had responded well to calcium antagonist drugs were studied to determine if ergonovine testing could help assess the need for continued therapy. Before treatment all 22 patients exhibited angina with S-T elevation during ergonovine testing done in the coronary care unit according to a previously described protocol with sequential ergonovine doses of 0.0125, 0.025, 0.05, 0.1, 0.2, 0.3 and 0.4 mg administered at 5 minute intervals. After 9.4 +/- 4.7 (range 1 to 24) months of treatment (nifedipine 7 patients, diltiazem 3, verapamil 8, perhexiline 3, nifedipine and diltiazem 1), all patients were free from anginal attacks. Medication was discontinued and ergonovine testing repeated 24 to 48 hours later (3 weeks for perhexiline). In 12 of the 22 patients, angina or S-T segment shifts did not occur during the second ergonovine test to a maximal dose of 0.4 mg. Treatment was not restarted in these patients and all 12 remain free of variant anginal attacks 4.2 +/- 2.9 (range 1 to 13) months later. In seven patients angina and S-T elevation occurred during the second ergonovine test, in the same electrocardiographic leads as during the test before treatment. In three patients the ergonovine test induced angina with S-T depression in the leads where S-T elevation had occurred during the previous test. Treatment was reinstituted in these 10 patients with a positive test. No complications resulted from ergonovine testing in any patient. We conclude that in many patients with variant angina, symptoms will disappear spontaneously and the ergonovine test will revert to negative. Treatment with calcium antagonist drugs can probably be safely discontinued in some patients with variant angina; ergonovine testing appears to be helpful in identifying such patients. Longer periods of follow-up are required to confirm that symptoms do not recur.

Ergonovine testing in a coronary care unit

This study describes the results of ergonovine testing in 100 consecutive patients who underwent this procedure in a coronary care unit. All patients had recently undergone coronary arteriography. A bolus injection of ergonovine was administered at 5 minute intervals in the following doses (mg): 0.0125, 0.025, 0.05, 0.1, 0.2, 0.3 and 0.4. The criterion for a positive test was the appearance of S-T elevation greater than 1 mm. The test was positive in all 17 patients known to have variant angina and in 18 (40 percent) of 45 patients who had a history of chest pain judged strongly suggestive of variant angina but who had no electrocardiogram recorded during pain. Of 38 patients with a history of chest pain classified as not entirely typical of variant angina, only 1 (2.6 percent) had a positive test. Of the 64 patients with a negative ergonovine test, 47 had chest pain and 25 had nausea but none had more serious complications. Ventricular arrhythmia accompanied S-T elevation in 18 of the 36 patients with a positive test but occurred in only 4 of the 64 with a negative test (p < 0.0005). No patient needed treatment with antiarrhythmic drugs. Four of the 36 patients with a positive test had serious complications: severe transient hypotension (2 patients), recurrent episodes of angina with S-T elevation (1 patient) and a subendocardial infarction (1 patient). Thus, ergonovine testing is useful in patients with a typical clinical history of variant angina but without an electrocardiogram recorded during pain. In this study, a small but definite incidence of serious complications occurred during a positive test.

Hemodynamic effects of a single oral dose of nifedipine following acute myocardial infarction

The hemodynamic effects of a single oral dose of 20 mg of nifedipine were studied in 21 stable patients after an acute myocardial infarction before withdrawal of Swan-Ganz and intra-arterial catheters. The drug appears safe, and no significant untoward effects were noted. Significant hemodynamic changes were present between 15 and 120 minutes after ingestion with a peak at 60 minutes. Mean arterial pressure decreased from 81+/-2.7 (SEM) to 71+/-2.3 mm Hg (P<0.001), and systemic vascular resistances decreased from 1438+/-88 to 1144+/-63 dynes/sec/cm5 (P<0.001). Cardiac index increased from 2.7+/-0.1 to 3.1+/-0.1 L/min/sq m (P<0.01) and heart rate from 79 +/- 3 to 82 +/- 4 (P<0.01). The pressure-rate product decreased from 10.3 X 10(3) to 9.5 X 10(3) (P<0.05), and pulmonary wedge pressure was unchanged from 12 mm Hg. The hemodynamic changes were similar whether patients were receiving propranolol or not. The afterload reducing effect was potentially most beneficial in the subgroup of patients with depressed left ventricular function where cardiac index increased by 20 percent.

Hemodynamics and coronary flow following diltiazem administration in anesthetized dogs and in humans

In this study, the systemic and coronary hemodynamic changes associated with the administration of diltiazem, a recent calcium antagonist, were evaluated in three different situations as follows: following a 200 microgram/kg intravenous bolus of the drug in 12 open-chest anesthetized dogs; following two successive intravenous infusions of diltiazem (15 microgram/kg/min and 30 microgram/kg/min), each for a period of ten minutes, in eight patients with angina pectoris investigated by coronary arteriography; and following a single oral dose of 120 mg of diltiazem in 17 patients undergoing hemodynamic monitoring in the coronary care unit after a recent myocardial infarction. Diltiazem was found to be a coronary vasodilator acting on the large coronary arteries and on collaterals. Its effects on myocardial oxygen requirements were variable; as a rule, the predominant effect was a drop in systemic vascular resistance or in heart rate. When systemic vascular resistance changed little, heart rate tended to decrease significantly; however, when systemic vascular resistance decreased notably, heart rate remained unchanged because of a relfex attempt to increase systemic blood pressure. Cardiac performance and left ventricular end-diastolic pressure were not affected and this lack of change in cardiac inotropism may confer and advantage to diltiazem over other calcium antagonistic drugs in patients with coronary heart disease.

Previously undiagnosed variant angina as a cause of chest pain after coronary artery bypass surgery

Variant angina was diagnosed after coronary artery bypass surgery in six patients over a 22-month period. Although all six patients had at least occasional angina at rest preoperatively, all but one had predominantly exertional angina. After surgery, rest angina with transient ST-segment elevation appeared in all six after an asymptomatic interval of 1 week to 4 years. In two patients the involved artery had not been bypassed, in two patients it was perfused by a patent graft and in two patients the graft to the involved vessel was occluded. Treatment with calcium antagonist drugs (four cases) or isosorbide dinitrate (one case) eliminated symptoms; one patient spontaneously became asymptomatic. The diagnosis of variant angina should be considered when rest angina occurs after bypass surgery, particularly if exertional angina is absent and grafts are patent.

Non-invasive pulsed Doppler study of mitral stenosis and mitral regurgitation: preliminary study

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Noninvasive assessment of aortocoronary bypass graft patency using pulsed Doppler echocardiography

To evaluate noninvasively aortocoronary bypass graft patency, pulsed Doppler echocardiography was performed at the time of postoperative coronary angiography in 120 consecutive patients. Ultrasonic examination of 163 vein grafts was possible. One hundred twenty-seven patent and 14 occluded grafts were correctly identified. Eleven patent grafts could not be recorded, and 11 occluded grafts were falsely diagnosed as patent. The method had an overall sensitivity of 92% and a specificity of 56%. This high sensitivity level may be increased to almost 100% by enhanced technical skill and experience. The low specificity level, although the method must be tested in a larger number of bypass grafts, stresses the importance of correctly identifying other sources of diastolic blood flow. Diastolic flows from the superior vena cava, internal mammary veins, tricuspid valve, mitral valve and right ventricle may be eliminated by careful adjustment of the depth, site and size of the pulsed Doppler electronic sampling gate. Standard echocardiographic landmarks for avoiding confusion with the coronary arteries are also described.