Clopidogrel response variability, resistance, or both?

Dual antiplatelet therapy represents an important advance for patients with established cardiovascular disease. Variable platelet response and potential resistance to therapy have emerged with aspirin and clopidogrel. There is no clear and accepted definition of clopidogrel resistance, but patients with lower responses to clopidogrel are at risk for ischemic events, particularly when they undergo percutaneous coronary intervention. Inconsistent nomenclature about this lower response has led to confusion about its potential clinical importance. The concern about nomenclature is less important than answers to key questions such as its mechanisms, how and in whom to measure platelet function, what levels of inhibition are associated with failure of therapy, what levels are adequate for improved clinical outcomes, and in what ways therapy could be altered in patients with lower responses to improve measures of platelet function and clinical outcomes. One option may be to target more aggressive intervention (higher loading and maintenance doses of clopidogrel or alternative agents) to specific patients who are at greater risk and/or least responsive to standard therapies. Clinically useful risk stratification requires an easily performed and reproducible measure of platelet aggregation, as well as standardized definitions of response that correlate with clinical outcomes. Point-of-care assays of platelet function may ultimately improve the ability of clinicians to modify therapy on the basis of response.

Evaluation of prasugrel compared with clopidogrel in patients with acute coronary syndromes: design and rationale for the TRial to assess Improvement in Therapeutic Outcomes by optimizing platelet InhibitioN with prasugrel Thrombolysis In Myocardial Infarction 38 (TRITON-TIMI 38)

BACKGROUND

Dual antiplatelet therapy with aspirin and clopidogrel is standard for prevention of thrombotic complications of percutaneous coronary intervention (PCI). Prasugrel is a thienopyridine that is more potent, more rapid in onset, and more consistent in inhibition of platelets than clopidogrel. TRITON-TIMI 38 is designed to compare prasugrel with clopidogrel in moderate to high-risk patients with acute coronary syndrome (ACS).

STUDY DESIGN

TRITON-TIMI 38 is a phase 3, randomized, double-blind, parallel-group, multinational, clinical trial. Approximately 13,000 patients with moderate to high-risk ACS undergoing PCI (9500 unstable angina/non-ST-segment elevation myocardial infarction [MI], 3500 ST-segment elevation MI) will be randomized to prasugrel 60 mg loading dose followed by 10 mg daily or clopidogrel 300 mg loading dose followed by 75 mg daily for up to 15 months. The primary end point is the time of the first event of cardiovascular death, MI, or stroke. Analyses will be performed first in the unstable angina/non-ST-segment elevation MI cohort and, conditionally, on the whole ACS population. Major safety end points include TIMI major and minor bleeding unrelated to coronary artery bypass graft surgery.

CONCLUSIONS

TRITON-TIMI 38 is a phase 3 comparison of prasugrel versus clopidogrel in patients with moderate to high-risk ACS undergoing PCI. In addition, it is the first large-scale clinical events trial to assess whether a thienopyridine regimen that achieves a higher level of inhibition of platelet aggregation than the standard therapy results in an improvement in clinical outcomes.

Benefits of achieving the NCEP optional LDL-C goal among elderly patients with ACS

AIMS

To assess the efficacy and safety of the achievement of the NCEP goal of LDL-C <1.8 mmol/L in elderly patients with ACS.

METHODS AND RESULTS

The relationship between LDL-C at 30 days after ACS and subsequent clinical outcomes were compared among elderly patients (aged > or =70 years) vs. younger counterparts in the PROVE IT-TIMI 22 trial, using the composite endpoint of death, myocardial infarction, or unstable angina. Among 634 elderly patients, the achievement of the NCEP goal was associated with an 8% absolute and a 40% relative lower risk of events [Hazard ratio (HR) 0.60, 95% confidence interval (CI) 0.41-0.87, P = 0.008] vs. corresponding benefits of 2.3 and 26% in 3150 younger patients (HR 0.74, 95% CI 0.59-0.94, P = 0.013). The estimated number of events preventable among the elderly by the achievement of these goals was 80 events at 2 years for every 1000 patients at goal vs. those not at goal, compared with 23 events potentially prevented in younger patients. The incidence of major side effects among the elderly was similar to that in younger patients and did not differ with the intensity of the statin regimen.

CONCLUSION

Among elderly ACS patients, achieving the new NCEP LDL-C optional goal as part of a secondary prevention strategy can be both as safe and effective as in younger patients.

Evaluation of the National Cholesterol Education Program Adult Treatment Panel III algorithm for selecting candidates for statin therapy: insights from the A to Z trial

The National Cholesterol Education Program Adult Treatment Panel III recommends an algorithm to integrate iterative risk-stratification information with low-density lipoprotein (LDL) cholesterol levels to identify candidates for statin therapy. We used the Aggrastat to Zocor (A to Z) trial, in which all patients presented with an acute coronary syndrome (ACS) event in the absence of previous statin therapy, to evaluate the performance of this algorithm. Of 1,750 patients with ACS included in this analysis, 1,126 (64%) had an indication for statin therapy before enrollment and 624 (36%) did not have a statin indication before enrollment. We estimate that initiating statin therapy at moderate dosages (decreasing LDL by 1 mmol/L) according to the National Cholesterol Education Program Adult Treatment Panel III guidelines would have prevented approximately 15% of the ACS events leading to enrollment in the A to Z trial, whereas more intensive statin therapy (decreasing LDL by 1.5 mmol/L) would have prevented >21% of events. Aspirin use before enrollment was reported in only 38% of subjects with a statin indication. In conclusion, these observations represent missed opportunities for primary and secondary prevention and highlight the need for assessment of patient risk and better adherence to existing prevention guidelines.

Clinical Relevance of C-Reactive Protein During Follow-Up of Patients With Acute Coronary Syndromes in the Aggrastat-to-Zocor Trial

Background— Elevated levels of high-sensitivity C-reactive protein (hsCRP) are associated with higher risk of adverse outcomes in patients at risk for or with established coronary artery disease. Retrospective analyses suggest that this risk may be modified with statin therapy. However, a role for hsCRP in monitoring the success of therapy remains uncertain.

Methods and Results— We measured the serum concentration of hsCRP at 30 days (n=3813) and 4 months in patients with non–ST-elevation or ST-elevation acute coronary syndrome randomly assigned to an early intensive versus delayed conservative simvastatin strategy in the Aggrastat-to-Zocor Trial. Patients with hsCRP >3 mg/L at 30 days had significantly higher 2-year mortality rates than those with hsCRP 1 to 3 mg/L or hsCRP <1 mg/L (6.1% versus 3.7% versus 1.6%, P <0.0001). Results were similar with hsCRP measured at 4 months. After adjusting for age, gender, diabetes, smoking, cardiovascular history, index event, lipid levels, and randomly assigned treatment, patients with hsCRP >3 mg/L were at more than 3-fold higher risk of death (HR, 3.7; 95% CI, 1.9 to 7.2) compared with those with hsCRP <1 mg/L. “Average” levels of hsCRP (1 to 3 mg/L) were also associated with increased risk compared with those with hsCRP <1 mg/L (HR, 2.3; 95% CI, 1.2 to 4.6). Patients allocated to early intensive statin therapy were more likely to achieve hsCRP levels <1 mg/L at 30 days ( P =0.028) and 4 months ( P <0.0001).

Conclusions— Achieved levels of hsCRP at 30 days and 4 months after acute coronary syndrome are independently associated with long-term survival. Patients treated with more aggressive statin therapy are more likely to achieve lower levels of hsCRP.

The Role of Clopidogrel in Early and Sustained Arterial Patency After Fibrinolysis for ST-Segment Elevation Myocardial Infarction

OBJECTIVES

This study was designed to determine the relationship between clopidogrel and early ST-segment resolution (STRes) and the interaction of the two with clinical outcomes after fibrinolysis.

BACKGROUND

ST-segment resolution is an early noninvasive marker of coronary reperfusion.

METHODS

The CLARITY-TIMI 28 (Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis in Myocardial Infarction 28) trial randomized 3,491 patients with ST-segment elevation myocardial infarction (STEMI) undergoing fibrinolysis to clopidogrel versus placebo. ST-segment resolution was defined as complete (>70%), partial (30% to 70%), or none (<30%).

RESULTS

Electrocardiograms were valid for interpretation in 2,431 patients at 90 min and 2,087 at 180 min. There was no difference in the rate of complete STRes between the clopidogrel and placebo groups at 90 min (38.4% vs. 36.6% at 90 min). When patients were stratified by STRes category, treatment with clopidogrel resulted in greater benefit among those with evidence of early STRes, with greater odds of an open artery at late angiography in patients with partial (odds ratio [OR] 1.4, p = 0.04) or complete (OR 2.0, p < 0.001) STRes, but no improvement in those with no STRes at 90 min (OR 0.89, p = 0.48) (p for interaction = 0.003). Clopidogrel was also associated with a significant reduction in the odds of an in-hospital death or myocardial infarction in patients who achieved partial (OR 0.30, p = 0.003) or complete STRes at 90 min (OR 0.49, p = 0.056), whereas clinical benefit was not apparent in patients who had no STRes (OR 0.98, p = 0.95) (p for interaction = 0.027). By 30 days, the clinical benefit of clopidogrel was predominately seen in patients with complete STRes.

CONCLUSIONS

Clopidogrel appears to improve late coronary patency and clinical outcomes by preventing reocclusion of open arteries rather than by facilitating early reperfusion.

Application of the Thrombolysis in Myocardial Infarction risk index in non-ST-segment elevation myocardial infarction: evaluation of patients in the National Registry of Myocardial Infarction

OBJECTIVES

The purpose of this research was to evaluate the Thrombolysis In Myocardial Infarction risk index (TRI) to characterize the risk of death among patients with non-ST-segment elevation myocardial infarction (NSTEMI).

BACKGROUND

The TRI, calculated from baseline age, systolic pressure, and heart rate, was established in patients with ST-segment elevation myocardial infarction (STEMI) and is predictive of mortality. Patients presenting with NSTEMI are increasing compared to STEMI and constitute a group with varied risk.

METHODS

The TRI was calculated in 337,192 patients from the National Registry of Myocardial Infarction with NSTEMI. Values and outcomes were compared with 153,486 patients with STEMI classified by reperfusion status. Comparisons of baseline characteristics and clinical outcomes stratified by TRI were made.

RESULTS

There was a graded relationship between the TRI and mortality in patients with NSTEMI with a >30-fold difference in mortality rates between lowest and highest deciles (p < 0.0001). The index showed good discrimination (c = 0.73). Overall mortality in the group with NSTEMI was higher (10.9%) than patients with STEMI treated with (6.6%) but lower than for STEMI patients not receiving reperfusion therapy (18.7%). The higher risk in comparison to patients with STEMI treated with reperfusion therapy was explained largely by the higher-risk profile of the population with NSTEMI.

CONCLUSIONS

There is a graded relationship between TRI and mortality in patients with NSTEMI. This simple risk index provides important information about mortality in patients across the spectrum of myocardial infarction, STEMI and NSTEMI. Early identification of NSTEMI patients who are at high risk of in-hospital mortality may provide clinicians with important information for initial triage and treatment.

A Tale of Two Trials

Background— The Aggrastat to Zocor (A to Z) and Pravastatin or Atorvastatin Evaluation and Infection Therapy (PROVE IT) trials compared intensive and moderate statin therapy after acute coronary syndromes, with seemingly disparate results. We analyzed the design, implementation, and results of the two trials in an attempt to clarify the effects of early intensive statin therapy.

Methods and Results— Study design, end points, and definitions were compared. In each trial, comparisons were made between intensive and moderate arms for both trials’ primary end points and death/myocardial infarction. Analyses were performed over various time points: at the end of the trials, ≤4 months, and >4 months. Subjects in A to Z had higher-risk demographics. More PROVE IT subjects were enrolled in the United States and underwent prerandomization revascularization. The low-density lipoprotein (LDL) difference was greater in A to Z than in PROVE IT early (≤4 months) but less late. Significant C-reactive protein reduction was earlier in PROVE IT. With common end points, event rates were higher in A to Z, and early favorable separation of event curves was seen in PROVE IT but not in A to Z. Clinical end point rates and reductions were similar in both trials after 4 months.

Conclusions— An early benefit was seen in PROVE IT but not in A to Z. Late-phase results were similar. Factors that may explain this disparity include the intensity of therapy in the early phase, timing, and magnitude of LDL and C-reactive protein lowering, differences in early revascularization, and the play of chance. Taken together, the results of these trials support a strategy of early intensive statin therapy coupled with revascularization when appropriate in patients after acute coronary syndrome.

Clinical applications of antiplatelet therapy

Dual antiplatelet therapy with aspirin and a thienopyridine has become the standard of care for patients undergoing percutaneous intervention with stenting, regardless of indication. This article will examine the evidence for and against the use of aspirin and thienopyridines, with emphasis on platelet resistance and nonresponsiveness. Data suggest that in some patients, clopidogrel plus aspirin is not superior to aspirin alone. Resistance to aspirin and clopidogrel has been reported. Patients exhibiting aspirin resistance, as measured by an elevated platelet aggregate ratio, have a 10-fold increase in the risk of recurrent vascular events as compared to aspirin-sensitive patients. Clopidogrel nonresponsiveness has been a consistently observed phenomenon in studies utilizing various P2Y12 receptor-specific assays. Nonresponsiveness to clopidogrel treatment has been suggested as a risk factor for the occurrence of ischemic events and stent thrombosis.

Therapeutic goals for effective platelet inhibition: a consensus document

Clopidogrel combined with aspirin is the mainstay of antiplatelet therapy for patients who present with acute coronary syndromes as well as following either bare metal or drug-eluting stent placement. Limitations of clopidogrel therapy include the relatively long time course required to achieve maximal inhibition of platelet aggregation, individual variability in response to its effect, the risk of bleeding during its administration, and the irreversible nature of P2Y12 receptor binding, which leads to a prolonged time course for recovery of platelet function following discontinuation of clopidogrel. Several investigational P2Y12 receptor antagonists have pharmacological properties that may overcome some or all of these limitations. These novel agents such as prasugrel, AZD6140, and cangrelor are in advanced stages of clinical development for potential use in patients with coronary artery disease.

Can Low-Density Lipoprotein Be Too Low? The Safety and Efficacy of Achieving Very Low Low-Density Lipoprotein With Intensive Statin Therapy

OBJECTIVES

This study sought to evaluate the safety and efficacy of achieving very low calculated low-density lipoprotein (LDL) levels with intensive statin therapy.

BACKGROUND

Intensive statin therapy reduces clinical events occurring after acute coronary syndrome (ACS) and may result in LDL levels markedly lower than guideline levels. Prior epidemiologic and preclinical studies raise concerns about the safety of very low cholesterol levels.

METHODS

The Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis In Myocardial Infarction 22 (PROVE IT-TIMI 22) study compared intensive therapy (atorvastatin, 80 mg) and moderate therapy (pravastatin, 40 mg) in patients after ACS. Patients treated with atorvastatin were divided by four-month LDL values into groups: >100, >80 to 100 (reference-range-meeting guidelines), >60 to 80, >40 to 60, and <40 mg/dl. Baseline, clinical, and safety data were compared among groups achieving guideline recommendation levels or lower.

RESULTS

Among 1,825 patients with four-month LDL, 91% were at goal (<100 mg/dl). The distribution was >80 to 100 mg/dl (14%), >60 to 80 mg/dl (31%), >40 to 60 mg/dl (34%), and <40 mg/dl (11%). Those with lower LDL levels were more often male, older, and diabetic, and had lower baseline LDL levels. They had prior statin therapy and fewer prior myocardial infarctions (MI). There were no significant differences in safety parameters, including muscle, liver, or retinal abnormalities, intracranial hemorrhage, or death, in the very low LDL groups. The <40 mg/dl and 40 to 60 mg/dl groups had fewer major cardiac events (death, MI, stroke, recurrent ischemia, revascularization).

CONCLUSIONS

Compared with patients treated with an accepted LDL goal (80 to 100 mg/dl), there was no adverse effect on safety with lower achieved LDL levels, and apparent improved clinical efficacy. These data identify no intrinsic safety concern of achieving low LDL and, therefore, a strategy of intensive treatment need not be altered in patients achieving very low LDL levels.

Randomized comparison of prasugrel (CS-747, LY640315), a novel thienopyridine P2Y12 antagonist, with clopidogrel in percutaneous coronary intervention: results of the Joint Utilization of Medications to Block Platelets Optimally (JUMBO)-TIMI 26 trial

BACKGROUND

Despite the current standard antiplatelet regimen of aspirin and clopidogrel (with or without glycoprotein IIb/IIIa inhibitors) in percutaneous coronary intervention patients, periprocedural and postprocedural ischemic events continue to occur. Prasugrel (CS-747, LY640315), a novel potent thienopyridine P2Y(12) receptor antagonist, has the potential to achieve higher levels of inhibition of ADP-induced platelet aggregation than currently approved doses of clopidogrel.

METHODS AND RESULTS

Joint Utilization of Medications to Block Platelets Optimally-Thrombolysis In Myocardial Infarction 26 (JUMBO-TIMI 26) was a phase 2, randomized, dose-ranging, double-blind safety trial of prasugrel versus clopidogrel in 904 patients undergoing elective or urgent percutaneous coronary intervention. Patients were randomized to either standard dosing with clopidogrel or 1 of 3 prasugrel regimens. Subjects were monitored for 30 days for bleeding and clinical events. The primary end point of the trial was clinically significant (TIMI major plus minor) non-CABG-related bleeding events in prasugrel- versus clopidogrel-treated patients. Hemorrhagic complications were infrequent, with no significant difference between patients treated with prasugrel or clopidogrel in the rate of significant bleeding (1.7% versus 1.2%; hazard ratio, 1.42; 95% CI, 0.40, 5.08). In prasugrel-treated patients, there were numerically lower incidences of the primary efficacy composite end point (30-day major adverse cardiac events) and of the secondary end points myocardial infarction, recurrent ischemia, and clinical target vessel thrombosis.

CONCLUSIONS

In this phase 2 study, which was designed to assess safety when administered at the time of percutaneous coronary intervention, prasugrel and clopidogrel both resulted in low rates of bleeding. The results of this trial serve as a foundation for the large phase 3 clinical trial designed to assess both efficacy and safety.

Association of glomerular filtration rate on presentation with subsequent mortality in non-ST-segment elevation acute coronary syndrome; observations in 13,307 patients in five TIMI trials

AIMS

To determine the association of glomerular filtration rate (GFR) with clinical outcomes in the setting of non-ST-segment elevation acute coronary syndromes (NSTE-ACS).

METHODS AND RESULTS

Data were pooled from five NSTE-ACS TIMI trials (TIMI 11A and B, TIMI 12, OPUS-TIMI 16 and TACTICS-TIMI 18) and were available in 13 307 patients. GFR was assessed as a continuous and a categorical variable (normal: > or = 90 mL/min/1.73 m2, n=4952; mildly decreased: 60-89 mL/min/1.73 m2, n=6262; and moderately to severely decreased GFR: <60 mL/min/1.73 m2, n=2093). There was an independent association between decreasing GFR and mortality at 30 days (OR 1.19, 95% CI 1.12-1.27, p<0.001) and at 6 months (OR 1.16, 95% CI 1.11-1.22, p<0.001). The combination of TIMI risk score (TRS) and decreasing GFR provided further mortality risk stratification with highest 30-day and 6-month mortality rates among patients with the lowest GFR who also had a TRS > or = 5 (9.1% and 15.4%, respectively). Decreasing GFR was also independently associated with stroke and recurrent ischaemia at 30-days as well as with major bleeding (p<0.001).

CONCLUSION

In the setting of NSTE-ACS, impaired GFR is associated with higher mortality as well as higher rates of thrombotic and major bleeding events, independent of TRS.

Enoxaparin versus unfractionated heparin in patients treated with tirofiban, aspirin and an early conservative initial management strategy: results from the A phase of the A-to-Z trial

AIMS

In high risk patients with non-ST elevation acute coronary syndromes (ACS), enoxaparin is generally preferred to unfractionated heparin (UFH). However, less is known about the relative merits of these two forms of heparin in patients receiving concomitant glycoprotein IIb/IIIa inhibitors.

METHODS AND RESULTS

The A phase of the A-to-Z trial was an open label non-inferiority trial in which 3987 patients with non-ST elevation ACS were randomised to receive either enoxaparin or UFH in combination with aspirin and tirofiban. Inclusion required either ST depression or cardiac biomarker elevation. While the selection of an early management strategy (invasive or conservative) was at the discretion of the local investigator, investigators were asked to designate their plans for an invasive or conservative strategy on the case record form. An early conservative strategy was specified for 1778 patients (45%); this subgroup forms the population for the present analyses. Among patients with a planned conservative strategy, baseline characteristics were similar between those randomised to UFH (n = 872) and those randomised to enoxaparin (n = 906). The primary endpoint of death, new MI, or documented refractory ischaemia within 7 days of randomisation occurred in 10.6% of patients randomised to UFH and 7.7% of patients randomised to enoxaparin (HR 0.72; 95% CI 0.53-0.99; p = 0.04). The combined rate of TIMI major, minor, or loss no-site bleeding was 1.3% in patients treated with UFH and 1.8% in those treated with enoxaparin (p = ns).

CONCLUSIONS

When a conservative approach to catheterisation and PCI was planned for ACS patients receiving tirofiban and aspirin, enoxaparin was associated with superior efficacy and similar bleeding vs UFH.

Early intensive vs a delayed conservative simvastatin strategy in patients with acute coronary syndromes: phase Z of the A to Z trial

CONTEXT

Limited data are available evaluating how the timing and intensity of statin therapy following an acute coronary syndrome (ACS) event affect clinical outcome.

OBJECTIVE

To compare early initiation of an intensive statin regimen with delayed initiation of a less intensive regimen in patients with ACS.

DESIGN, SETTING, AND PARTICIPANTS

International, randomized, double-blind trial of patients with ACS receiving 40 mg/d of simvastatin for 1 month followed by 80 mg/d thereafter (n = 2265) compared with ACS patients receiving placebo for 4 months followed by 20 mg/d of simvastatin (n = 2232), who were enrolled in phase Z of the A to Z trial between December 29, 1999, and January 6, 2003.

MAIN OUTCOME MEASURE

The primary end point was a composite of cardiovascular death, nonfatal myocardial infarction, readmission for ACS, and stroke. Follow-up was for at least 6 months and up to 24 months.

RESULTS

Among the patients in the placebo plus simvastatin group, the median low-density lipoprotein (LDL) cholesterol level achieved while taking placebo was 122 mg/dL (3.16 mmol/L) at 1 month and was 77 mg/dL (1.99 mmol/L) at 8 months while taking 20 mg/d of simvastatin. Among the patients in the simvastatin only group, the median LDL cholesterol level achieved at 1 month while taking 40 mg/d of simvastatin was 68 mg/dL (1.76 mmol/L) and was 63 mg/dL (1.63 mmol/L) at 8 months while taking 80 mg/d of simvastatin. A total of 343 patients (16.7%) in the placebo plus simvastatin group experienced the primary end point compared with 309 (14.4%) in the simvastatin only group (40 mg/80 mg) (hazard ratio [HR], 0.89; 95% confidence interval [CI] 0.76-1.04; P =.14). Cardiovascular death occurred in 109 (5.4%) and 83 (4.1%) patients in the 2 groups (HR, 0.75; 95% CI, 0.57-1.00; P =.05) but no differences were observed in other individual components of the primary end point. No difference was evident during the first 4 months between the groups for the primary end point (HR, 1.01; 95% CI, 0.83-1.25; P =.89), but from 4 months through the end of the study the primary end point was significantly reduced in the simvastatin only group (HR, 0.75; 95% CI, 0.60-0.95; P =.02). Myopathy (creatine kinase >10 times the upper limit of normal associated with muscle symptoms) occurred in 9 patients (0.4%) receiving simvastatin 80 mg/d, in no patients receiving lower doses of simvastatin, and in 1 patient receiving placebo (P =.02).

CONCLUSIONS

The trial did not achieve the prespecified end point. However, among patients with ACS, the early initiation of an aggressive simvastatin regimen resulted in a favorable trend toward reduction of major cardiovascular events.

Performance of the thrombolysis in myocardial infarction risk index in the National Registry of Myocardial Infarction-3 and -4: a simple index that predicts mortality in ST-segment elevation myocardial infarction

OBJECTIVES

We sought to evaluate a simple risk index based on age and vital signs in a community sample of patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

A simple risk index based on age and vital signs (heart rate x [age/10](2)/systolic blood pressure) developed from patients with STEMI accurately predicts mortality in clinical trials of fibrinolysis. The application of such a tool in an unselected population is necessary to evaluate its utility in clinical practice.

METHODS

To evaluate the Thrombolysis In Myocardial Infarction (TIMI) risk index for routine practice, we tested it in the National Registry of Myocardial Infarction (NRMI)-3 and -4. The risk index was evaluated as a continuous variable in patients with STEMI from NRMI and in subgroups based on age and reperfusion status.

RESULTS

A total of 153,486 patients with STEMI were eligible. As anticipated, STEMI patients in NRMI had a higher risk index profile, as compared with those in the clinical trial (median 26.9 vs. 20, p < 0.0001). Classification of NRMI patients with STEMI into risk groups revealed a significant graded relationship with mortality (0.9% to53.2%, p(trend) < 0.0001, c statistic 0.79). The discriminatory capacity of the risk index was particularly strong in the 81,679 patients receiving reperfusion therapy (0.6% to60%, p(trend) < 0.0001, c statistic 0.81). For the 71,807 patients not receiving reperfusion therapy, a strong graded relationship remained (1.9% to 52.2%, p(trend) < 0.0001, c statistic 0.71). Among the elderly, although the distribution of scores was shifted toward higher risk, the performance remained (0% to 53.1%, p(trend)< 0.0001, c statistic 0.71).

CONCLUSIONS

A simple risk index from baseline clinical variables routinely obtained at the first patient encounter predicted mortality in a large unselected heterogeneous group of patients with STEMI.

Unstable angina and non-ST-segment elevation myocardial infarction: part II. Coronary revascularization, hospital discharge, and post-hospital care

In the guideline developed by the American College of Cardiology and the American Heart Association, the management of suspected unstable angina and non-ST-segment elevation myocardial infarction (UA/NSTEMI) has four components: initial evaluation and management; hospital care; coronary revascularization; and hospital discharge and post-hospital care. Part II of this two-part article discusses coronary revascularization, hospital discharge, and post-hospital care. Decisions must be made about the use of coronary angiography and coronary revascularization in patients hospitalized with UA/NSTEMI. With an early conservative strategy, medical management is employed. Coronary angiography and revascularization are reserved for use in patients with evidence of ischemia at rest (or with minimal activity) and patients with a strongly positive stress test. With an early invasive strategy, coronary angiography and revascularization are recommended within 48 hours in patients without contraindications. Hospital discharge planning involves coordination of medical care, preparation of the patient for resumption of normal activities, and evaluation of the need for long-term risk factor reduction. Discharge medications should be continued to control ongoing symptoms (anti-ischemic agents) and prevent recurrent events (aspirin, clopidogrel, beta blocker, and an angiotensin-converting enzyme inhibitor or statins in selected patients).

Unstable angina and non-ST-segment elevation myocardial infarction: part I. Initial evaluation and management, and hospital care

Each year, more than 1 million patients are admitted to U.S. hospitals because of unstable angina and non-ST-segment elevation myocardial infarction (UA/NSTEMI). To help standardize the assessment and treatment of these patients, the American College of Cardiology and the American Heart Association convened a task force to formulate a management guideline. This guideline, which was published in 2000 and updated in 2002, highlights recent medical advances and is a practical tool to help physicians provide medical care for patients with UA/NSTEMI. Management of suspected UA/NSTEMI has four components: initial evaluation and management; hospital care; coronary revascularization; and hospital discharge and post-hospital care. Part I of this two-part article discusses the first two components of management. During the initial evaluation, the history, physical examination, electrocardiogram, and cardiac biomarkers are used to determine the likelihood that the patient has UA/NSTEMI and to aid in risk assessment when the diagnosis is established. Hospital care consists of appropriate initial triage and monitoring. Medical treatment includes anti-ischemic therapy (oxygen, nitroglycerin, beta blocker), antiplatelet therapy (aspirin, clopidogrel, platelet glycoprotein IIb/IIIa inhibitor), and antithrombotic therapy (heparin, low-molecular-weight heparin).

Pathophysiology, prognostic significance and clinical utility of B-type natriuretic peptide in acute coronary syndromes

The natriuretic hormones are a family of vasoactive peptides that can be measured circulating in the blood. Because they serve as markers of hemodynamic stress, the major focus of the use of natriuretic peptide levels [predominantly B-type natriuretic peptide (BNP) and N-terminal (NT)-pro-BNP] has been as an aid to the clinical diagnosis and management of congestive heart failure (CHF). Recently, however, the measurement of natriuretic peptides in the acute coronary syndromes (ACS) has been shown to provide information complementary to traditional biomarkers (of necrosis) such as cardiac troponins and creatine kinase (CK). Studies in several types of acute coronary syndromes [ST-segment elevation myocardial infarction (STEMI), non-ST elevation MI (NSTEMI) and unstable angina (UA)] have shown that elevated levels of natriuretic peptides are independently associated with adverse outcomes, particularly mortality. Additional information is obtained from the use natriuretic peptides in combination with other markers of risk including biomarkers of necrosis and inflammation. This review will summarize the scientific rationale and clinical evidence supporting measurement of natriuretic peptides for risk stratification in acute coronary syndromes. Future research is needed to identify therapies of particular benefit for patients with ACS and natriuretic peptide elevation.

Differential Expression of Cardiac Biomarkers by Gender in Patients With Unstable Angina/Non–ST-Elevation Myocardial Infarction

Background— Diagnosis of coronary artery disease in women is more difficult because of lower specificity of symptoms and diagnostic accuracy of noninvasive testing. We sought to examine the relationship between gender and cardiac biomarkers in patients with unstable angina (UA)/non–ST-segment elevation myocardial infarction (NSTEMI).

Methods and Results— In the TACTICS-TIMI 18, OPUS-TIMI 16, and TIMI 11 studies, baseline samples were analyzed in the Thrombolysis In Myocardial Infarction (TIMI) biomarker core laboratory. We examined the relationship between gender and elevated biomarkers. Of 1865 patients from TACTICS-TIMI 18, 34% were women. Fewer women had elevated creatine kinase-MB or troponins, whereas more had elevated high-sensitivity C-reactive protein or brain natriuretic peptide. Presence of ST-segment deviation and TIMI risk scores were not significantly different. This pattern was confirmed in TIMI 11 and OPUS-TIMI 16. The prognostic value of the markers in TACTICS-TIMI 18 was similar in women and men. When a multimarker approach was examined, a greater proportion of high-risk women were identified. Marker-positive patients of both genders had improved outcome with an invasive strategy; however, marker-negative women appeared to have improved outcomes with a conservative strategy.

Conclusions— In patients with UA/NSTEMI, there was a different pattern of presenting biomarkers. Men were more likely to have elevated creatine kinase-MB and troponins, whereas women were more likely to have elevated C-reactive protein and brain natriuretic peptide. This suggests that a multimarker approach may aid the initial risk assessment of UA/NSTEMI, especially in women. Further research is necessary to elucidate whether gender-related pathophysiological differences exist in presentation with acute coronary syndromes.

Association of creatinine and creatinine clearance on presentation in acute myocardial infarction with subsequent mortality

OBJECTIVES

We hypothesized that impaired renal function would also be associated with poorer clinical outcomes among patients with ST-segment elevation myocardial infarction (STEMI) treated with fibrinolysis.

BACKGROUND

Previous studies have demonstrated that impaired renal function is associated with poorer clinical outcomes in the setting of unstable angina and non-STEMI and after percutaneous coronary intervention.

METHODS

Data were drawn from the Thrombolysis In Myocardial Infarction (TIMI)-10, TIMI-14, and Intravenous nPA for the Treatment of Infarcting Myocardium Early (InTIME-II) trials.

RESULTS

Within each TIMI risk score (TRS) for STEMI category (0 to 2, 3 to 4, >/=5), 30-day mortality increased stepwise among patients with normal (creatinine [Cr] </=1.2 mg/dl), mildly (Cr >1.2 to 2 mg/dl), and severely (Cr >2.0 mg/dl) impaired renal function (p < 0.001) and in patients with normal (creatinine clearance [CrCl] >/=90 ml/min), mildly (60 to <90 ml/min), moderately (30 to <60 ml/min), and severely (<30 ml/min) impaired CrCl (p < 0.001). Impaired renal function was associated with increased mortality after adjusting for previously identified correlates of mortality (using Cr: odds ratio [OR] for mild impairment 1.52, 95% confidence interval [CI] 1.30 to 1.77, p < 0.001; OR for severe impairment 3.73, 95% CI 2.55 to 5.45, p < 0.001; using CrCl: OR for mild impairment 1.38, 95% CI 1.10 to 1.73, p = 0.006; OR for moderate impairment 2.06, 95% CI 1.59 to 2.66, p < 0.001; OR for severe impairment 3.81, 95% CI 2.57 to 5.65, p < 0.001).

CONCLUSIONS

In the setting of STEMI, elevated Cr and/or impaired CrCl on presentation is associated with increased mortality, independent of other conventional risk factors and TRS. This association does not appear to be mediated by reduced fibrinolytic efficacy among patients with impaired renal function or by the presence of congestive heart failure on presentation.