Commentary: the role of percutaneous coronary intervention in ST-segment-elevation myocardial infarction

Rural EMS STEMI Patients - Why the Delay to PCI?

BACKGROUND

The objective of this study is to identify patient and EMS agency factors associated with timely reperfusion of patients with ST-elevation myocardial infarction (STEMI).

METHODS

We conducted a cohort study of adult patients (≥18 years old) with STEMI activations from 2016 to 2020. Data was obtained from a regional STEMI registry, which included eight rural county EMS agencies and three North Carolina percutaneous coronary intervention (PCI) centers. On each patient, prehospital and in-hospital time intervals were abstracted. The primary outcome was the ability to achieve the 90-minute EMS FMC to PCI time goal (yes vs. no). We used generalized estimating equations accounting for within-agency clustering to evaluate the association between patient and agency factors and meeting first medical contact (FMC) to PCI time goal while accounting for clustering within the agency.

RESULTS

Among 365 rural STEMI patients 30.1% were female (110/365) with a mean age of 62.5 ± 12.7 years. PCI was performed within the time goal in 60.5% (221/365) of encounters. The FMC to PCI time goal was met in 45.5% (50/110) of women vs 69.8% (178/255) of men (p < 0.001). The median PCI center activation time was 12 min (IQR 7-19) in the group that received PCI within the time goal compared to 21 min (IQR 10-37) in the cohort that did not. After adjusting for loaded mileage and other clinical variables (e.g., pulse rate, hypertension etc.), the male sex was associated with an improved chance of meeting the goal of FMC to PCI (aOR: 2.94; 95% CI 2.11-4.10) compared to the female sex.

CONCLUSION

Nearly 40% of rural STEMI patients transported by EMS failed to receive FMC to PCI within 90 min. Women were less likely than men to receive reperfusion within the time goal, which represents an important health care disparity.

Delayed first medical contact to reperfusion time increases mortality in rural emergency medical services patients with ST-elevation myocardial infarction

BACKGROUND

ST-elevation myocardial infarction (STEMI) guidelines recommend an emergency medical services (EMS) first medical contact (FMC) to percutaneous coronary intervention (PCI) time of ≤90 min. The primary objective of this study was to evaluate the association between FMC to PCI time and mortality in rural STEMI patients.

METHODS

We conducted a cohort study of patients ≥18 years old with STEMI activations from January 2016 to March 2020. Data were obtained from a rural North Carolina Regional STEMI Data Registry, which included eight rural EMS agencies and three PCI centers, the National Cardiovascular Data Registry, and the EMS electronic health record. Prehospital and in-hospital time intervals were digitally abstracted. The outcome of index hospitalization mortality was compared between patients who did and did not meet FMC to PCI time goal using Fisher's exact tests. Negative predictive value (NPV) for index hospitalization death was calculated with 95% confidence intervals (CIs). A receiver operating characteristic curve was constructed and an optimal FMC to PCI time goal was identified by maximizing NPV to prevent index hospitalization death.

RESULTS

Among 365 rural EMS STEMI patients, 30.1% (110/365) were female with a mean ± SD age of 62.5 ± 12.7 years. PCI was performed within the 90-min time goal in 60.5% (221/365) of patients. Among these patients, 3% (11/365) died during initial STEMI hospitalization, with 1.4% (3/221) mortality in the group that met the 90-minute time goal compared to 5.6% (8/144) in patients exceeding the time goal (p = 0.03). Meeting the 90-min time goal yielded a 98.6% (95% CI 96.1%-99.7%) NPV for index death. A 78-min FMC to PCI time was the optimal cut point, yielding a NPV for index mortality of 99.3% (95% CI 96.1%-100%).

CONCLUSIONS

Death among rural patients with STEMI was four times more likely when they did not receive PCI within 90 min.

Complete Revascularization in Patients Undergoing a Pharmacoinvasive Strategy for ST-Segment-Elevation Myocardial Infarction: Insights From the COMPLETE Trial

[Figure: see text].

Percutaneous coronary intervention in patients with acute coronary syndrome in Chinese Military Hospitals, 2011-2014: a retrospective observational study of a national registry

OBJECTIVES

Interventional treatment of patients with acute coronary syndrome (ACS) is surging dramatically in China in recent years, whereas nationwide assessments of the quality of percutaneous coronary intervention (PCI) procedural performance and outcomes are scarce. We aimed to provide an updated and real-world overview of the performance of PCI in patients with ACS since 2011 in China after the China PEACE study from 2001 to 2011.

METHODS

In this cross-sectional study, data were extracted from the National Registry of Cardiovascular Intervention in Military Hospitals database to create a national sample of 144 659 patients with ACS undergoing PCI at 117 military hospitals in all regions of China from calendar years 2011-2014. Patient characteristics, procedural performance, PCI outcomes and adverse events and temporal changes were analysed.

RESULTS

During 2011-2014, patients with ACS undergoing PCI increased dramatically. Small numbers of high-volume hospitals performed the majority of PCI procedures. However, only half of these patients were adequately covered and proportions for the use of assisted devices and novel medications were relatively small. Radial artery access was still increasing with time. Primary PCIs were performed on 45.4% ST-segment elevation myocardial infarction patients with PCI procedures. 3.8% lesion vessels involve left main artery. Implanted stents, the overall complications and in-hospital mortality were decreasing remarkably.

CONCLUSIONS

In Chinese military hospitals, interventional resources were limited with great regional disparities, there are still gaps to be filled to better serve patients with ACS. Our findings can serve as an indispensable supplement to a more comprehensive understanding of the practice of contemporary cardiac intervention in China.

Effects of ticagrelor versus clopidogrel on platelet function in fibrinolytic-treated STEMI patients undergoing early PCI

OBJECTIVES

Patients undergoing PCI early after fibrinolytic therapy are at high risk for both thrombotic and bleeding complications. We sought to assess the pharmacodynamic effects of ticagrelor versus clopidogrel in the fibrinolytic-treated STEMI patients undergoing early PCI.

METHODS AND RESULTS

Patients undergoing PCI within 24 hours of tenecteplase (TNK), aspirin, and clopidogrel for STEMI were randomized to receive additional clopidogrel 300 mg followed by 75 mg daily or ticagrelor 180 mg followed by 90 mg twice daily. The platelet reactivity units (PRU) were measured with the VerifyNow Assay before study drug administration (baseline) at 4 and 24 hours post-PCI. The primary end point was PRU ≤208 at 4 hours. A total of 140 patients (74 in ticagrelor and 66 in clopidogrel group) were enrolled. The mean PRU values at baseline were similar for the 2 groups (257.8±52.9 vs 259.5±56.7, P=.85, respectively). Post-PCI, patients on ticagrelor, compared to those on clopidogrel, had significantly lower PRU at 4 hours (78.7±88 vs 193.6±86.5, respectively, P<.001) and at 24 hours (34.5±35.0 and 153.5±75.5, respectively, P<.001). The primary end point was observed in 87.8% (n=65) in the ticagrelor-treated patients compared to 57.6% (n=38) of clopidogrel-treated patients, P<.001.

CONCLUSION

Fibrinolysis-treated STEMI patients who received clopidogrel and aspirin at the time of fibrinolysis and were undergoing early PCI frequently had PRU >208. In this high-risk population, ticagrelor provides more prompt and potent platelet inhibition compared with clopidogrel (Funded by Astra Zeneca; NCT01930591, https://clinicaltrials.gov/ct2/show/NCT01930591).

Chest Pain of Suspected Cardiac Origin: Current Evidence-based Recommendations for Prehospital Care

Introduction

In the United States, emergency medical services (EMS) protocols vary widely across jurisdictions. We sought to develop evidence-based recommendations for the prehospital evaluation and treatment of chest pain of suspected cardiac origin and to compare these recommendations against the current protocols used by the 33 EMS agencies in the state of California.

Methods

We performed a literature review of the current evidence in the prehospital treatment of chest pain and augmented this review with guidelines from various national and international societies to create our evidence-based recommendations. We then compared the chest pain protocols of each of the 33 EMS agencies for consistency with these recommendations. The specific protocol components that we analyzed were use of supplemental oxygen, aspirin, nitrates, opiates, 12-lead electrocardiogram (ECG), ST segment elevation myocardial infarction (STEMI) regionalization systems, prehospital fibrinolysis and β-blockers.

Results

The protocols varied widely in terms of medication and dosing choices, as well as listed contraindications to treatments. Every agency uses oxygen with 54% recommending titrated dosing. All agencies use aspirin (64% recommending 325mg, 24% recommending 162mg and 15% recommending either), as well as nitroglycerin and opiates (58% choosing morphine). Prehospital 12-Lead ECGs are used in 97% of agencies, and all but one agency has some form of regionalized care for their STEMI patients. No agency is currently employing prehospital fibrinolysis or β-blocker use.

Conclusion

Protocols for chest pain of suspected cardiac origin vary widely across California. The evidence-based recommendations that we present for the prehospital diagnosis and treatment of this condition may be useful for EMS medical directors tasked with creating and revising these protocols.

Recent advances in the diagnosis and treatment of acute myocardial infarction

The Third Universal Definition of Myocardial Infarction (MI) requires cardiac myocyte necrosis with an increase and/or a decrease in a patient’s plasma of cardiac troponin (cTn) with at least one cTn measurement greater than the 99^th percentile of the upper normal reference limit during: (1) symptoms of myocardial ischemia; (2) new significant electrocardiogram (ECG) ST-segment/T-wave changes or left bundle branch block; (3) the development of pathological ECG Q waves; (4) new loss of viable myocardium or regional wall motion abnormality identified by an imaging procedure; or (5) identification of intracoronary thrombus by angiography or autopsy. Myocardial infarction, when diagnosed, is now classified into five types. Detection of a rise and a fall of troponin are essential to the diagnosis of acute MI. However, high sensitivity troponin assays can increase the sensitivity but decrease the specificity of MI diagnosis. The ECG remains a cornerstone in the diagnosis of MI and should be frequently repeated, especially if the initial ECG is not diagnostic of MI.

There have been significant advances in adjunctive pharmacotherapy, procedural techniques and stent technology in the treatment of patients with MIs. The routine use of antiplatelet agents such as clopidogrel, prasugrel or ticagrelor, in addition to aspirin, reduces patient morbidity and mortality. Percutaneous coronary intervention (PCI) in a timely manner is the primary treatment of patients with acute ST segment elevation MI. Drug eluting coronary stents are safe and beneficial with primary coronary intervention. Treatment with direct thrombin inhibitors during PCI is non-inferior to unfractionated heparin and glycoprotein IIb/IIIa receptor antagonists and is associated with a significant reduction in bleeding. The intra-coronary use of a glycoprotein IIb/IIIa antagonist can reduce infarct size. Pre- and post-conditioning techniques can provide additional cardioprotection. However, the incidence and mortality due to MI continues to be high despite all these recent advances. The initial ten year experience with autologous human bone marrow mononuclear cells (BMCs) in patients with MI showed modest but significant increases in left ventricular (LV) ejection fraction, decreases in LV end-systolic volume and reductions in MI size. These studies established that the intramyocardial or intracoronary administration of stem cells is safe. However, many of these studies consisted of small numbers of patients who were not randomized to BMCs or placebo. The recent LateTime, Time, and Swiss Multicenter Trials in patients with MI did not demonstrate significant improvement in patient LV ejection fraction with BMCs in comparison with placebo. Possible explanations include the early use of PCI in these patients, heterogeneous BMC populations which died prematurely from patients with chronic ischemic disease, red blood cell contamination which decreases BMC renewal, and heparin which decreases BMC migration. In contrast, cardiac stem cells from the right atrial appendage and ventricular septum and apex in the SCIPIO and CADUCEUS Trials appear to reduce patient MI size and increase viable myocardium. Additional clinical studies with cardiac stem cells are in progress.

Temporal trends in treatment of ST-elevation myocardial infarction among men and women in Switzerland between 1997 and 2011

BACKGROUND

Few data are available concerning the impact of gender on temporal trends in patients with acute ST-segment elevation myocardial infarction (STEMI).

METHODS

All STEMI patients consecutively enrolled in the AMIS (Acute Myocardial Infarction in Switzerland) Plus project from 1997-2011 were included. Temporal trends in presentation, treatment and outcomes were analyzed using multiple logistic regressions with generalized estimations.

RESULTS

Of 21,620 STEMI patients, 5786 were women and 15,834 men from 78 Swiss hospitals. Women were 8.6 years older, presented 48 minutes later with less pain, but more dyspnea, and more frequently had atrial fibrillation (5.5 vs. 3.9%, p<0.001), heart failure (Killip class >2) (9.7 vs. 7.3%, p<0.001), and moderate or severe comorbidities (24.8 vs. 18.2%, p<0.001). Women were less likely to undergo primary reperfusion treatment after adjustment for baseline characteristics and admission year (OR 0.80, 95% CI 0.71-0.90, p<0.001) or receive early and discharge drugs, such as thienopyridines, angiotensin-converting-enzyme inhibitors, angiotensin II receptor antagonists, and statins. In 1997, thrombolysis was performed in 51% of male and 39% of female patients; its use rapidly decreased during the 1990s and has now become negligible. Primary percutaneous coronary intervention increased from under 10% in both genders in 1997 to over 70% in females and over 80% in males since 2006. Patients admitted in cardiogenic shock increased by 8% per year in both genders. The incidence of both reinfarction and cardiogenic shock developing during hospitalization decreased significantly over 15 years while in-hospital mortality decreased from 10 to 5% in men and from 18 to 7% in women. This corresponds to a relative reduction of 5% per year for males (OR 0.95, 95% CI 0.92-0.99, p=0.006) and 6% per year for female STEMI patients (OR 0.94, 95% CI 0.91-0.97, p<0.001). Despite higher crude in-hospital mortality, female gender per se was not an independent predictor of in-hospital mortality (OR 1.07, 95% CI 0.84-1.35, p=0.59).

CONCLUSION

Substantial changes have occurred in presentation, treatment, and outcome of men and women with STEMI in Switzerland over the past 15 years. Although parallel trends were seen in both groups, ongoing disparities in certain treatments remain. However, these did not translate into worse risk-adjusted in-hospital mortality, suggesting that the gender gap in STEMI care may be closing.

Recent Advances in the Treatment of ST-Segment Elevation Myocardial Infarction

ST-segment elevation myocardial infarction (STEMI) represents the most urgent condition for patients with coronary artery disease. Prompt diagnosis and therapy, mainly with primary angioplasty using stents, are important in improving not only acute survival but also long-term prognosis. Recent advances in angioplasty devices, including manual aspiration catheters and drug-eluting stents, and pharmacologic therapy, such as potent antiplatelet and anticoagulant agents, have significantly enhanced the acute outcome for these patients. Continuing efforts to educate the public and to decrease the door-to-balloon time are essential to further improve the outcome for these high-risk patients. Future research to normalize the left ventricular function by autologous stem cell therapy may also contribute to the quality of life and longevity of the patients surviving STEMI.

Efficacy of early invasive management post-fibrinolysis in men versus women with ST-elevation myocardial infarction: a subgroup analysis from Trial of Routine Angioplasty and Stenting after Fibrinolysis to Enhance Reperfusion in Acute Myocardial Infarction (TRANSFER-AMI)

BACKGROUND

The TRANSFER-AMI study demonstrated that early routine percutaneous coronary intervention post-fibrinolysis (pharmacoinvasive strategy) is superior to conservative management for ST-elevation myocardial infarction. However, it is not clear whether treatment efficacy differs between men and women.

METHODS

In this pre-specified subgroup analysis, we compared the efficacy of a pharmacoinvasive strategy in men versus women with acute ST-elevation myocardial infarction who were randomized to a pharmacoinvasive versus standard management following fibrinolysis. The primary end point was a composite of death, recurrent myocardial infarction, recurrent ischemia, heart failure and shock at 30 days. We tested for treatment heterogeneity between men and women using the Breslow-Day test. We also performed multivariable analysis adjusting for GRACE risk score and its interaction with treatment assignment, and evaluated for death/recurrent myocardial reinfarction as a secondary outcome.

RESULTS

Of the 1059 patients, 843 were men and 216 were women. Compared to men, women were older, had worse Killip class, higher GRACE risk score, and higher rates of death and death/myocardial reinfarction at 30 days. The primary end point did not differ significantly between men and women (13.4% vs 16.7%, P = .22). Compared to standard treatment, a pharmacoinvasive strategy was associated with a lower rate of the primary end point in men (17.5% vs 9.4%, respectively, P < .001), but not in women (16.2% vs 17.1%, P = .86). There was a trend toward an interaction between treatment assignment and sex for the composite primary end point (P = .06). After adjustment for the significant interaction between GRACE risk score and treatment (P < .001), there was no significant interaction between sex and treatment for all the end points (all P > .40).

CONCLUSION

The borderline heterogeneity in treatment efficacy of a pharmacoinvasive strategy in men versus women was no longer evident after adjustment for the difference in baseline risk. This suggests that sex per se was not an important determinant of the efficacy of a pharmacoinvasive strategy. Owing to the small number of women in this trial, further study in this area is needed.

Achieving high quality in ST-segment elevation myocardial infarction care: one urban academic medical center experience

Management of acute myocardial infarction with ST elevation (STEMI) remains a challenge for academic institutions. There are numerous factors at play from the time electrocardiogram is obtained to the time the patient arrives to a catheterization laboratory and the balloon is inflated. Academic hospitals that are located in large urban centers have to deal with staff living long distances from the facility, and therefore, assembling the catheterization team after-hours and on the weekends becomes a difficult task to achieve. There are other factors that contribute to time delays, such as, administering electrocardiograms in timely fashion, having emergency physicians activate the catheterization team, instead of contacting the cardiologist to discuss the case, and other time-sensitive factors. All of the aforementioned issues contribute to the delay. Yet, primary percutaneous coronary intervention is clearly demonstrated as the modality of choice in treatment of STEMI, which improves patient's morbidity and mortality. Therefore, it is imperative that institutions do all they can to improve their protocols and meet the core measures in the treatment of STEMI patients, including the door-to-balloon time of less than 90 minutes. Our institution started a quality improvement program for STEMI care in 1993 and has showed progressive improvement in use of aspirin, beta-blockers, angiotensin-converting enzyme inhibitors, and other medication, culminating in 95% to 100% use of these medications in 2003-2004, when we operated in accordance with the Get With The Guidelines program. Door-to-balloon time in less than 90 minutes became a new phase in our quality improvement process, and we achieved 100% compliance in the last 2 years.

Impact of primary coronary angioplasty delay on myocardial salvage, infarct size, and microvascular damage in patients with ST-segment elevation myocardial infarction: insight from cardiovascular magnetic resonance

OBJECTIVES

We investigated the extent and nature of myocardial damage by using cardiovascular magnetic resonance (CMR) in relation to different time-to-reperfusion intervals.

BACKGROUND

Previous studies evaluating the influence of time to reperfusion on infarct size (IS) and myocardial salvage in patients with ST-segment elevation myocardial infarction (STEMI) have yielded conflicting results.

METHODS

Seventy patients with STEMI successfully treated with primary percutaneous coronary intervention within 12 h from symptom onset underwent CMR 3 +/- 2 days after hospital admission. Patients were subcategorized into 4 time-to-reperfusion (symptom onset to balloon) quartiles: < or =90 min (group I, n = 19), >90 to 150 min (group II, n = 17), >150 to 360 min (group III, n = 17), and >360 min (group IV, n = 17). T2-weighted short tau inversion recovery and late gadolinium enhancement CMR were used to characterize reversible and irreversible myocardial injury (area at risk and IS, respectively); salvaged myocardium was defined as the normalized difference between extent of T2-weighted short tau inversion recovery and late gadolinium enhancement.

RESULTS

Shorter time-to-reperfusion (group I) was associated with smaller IS and microvascular obstruction and larger salvaged myocardium. Mean IS progressively increased overtime: 8% (group I), 11.7% (group II), 12.7% (group III), and 17.9% (group IV), p = 0.017; similarly, MVO was larger in patients reperfused later (0.5%, 1.5%, 3.7%, and 6.6%, respectively, p = 0.047). Accordingly, salvaged myocardium markedly decreased when reperfusion occurred >90 min of coronary occlusion (8.5%, 3.2%, 2.4%, and 2.1%, respectively, p = 0.004).

CONCLUSIONS

In patients with STEMI treated with primary percutaneous coronary intervention, time to reperfusion determines the extent of reversible and irreversible myocardial injury assessed by CMR. In particular, salvaged myocardium is markedly reduced when reperfusion occurs >90 min of coronary occlusion.

Field triage reduces treatment delay and improves long-term clinical outcome in patients with acute ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention

OBJECTIVES

We evaluated the independent impact of field triage on treatment delay and long-term clinical outcome in a large contemporary, consecutive population of ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (pPCI).

BACKGROUND

Reduction of treatment delay is crucial for patients with STEMI.

METHODS

From January 2005 to July 2008, 1,437 STEMI patients were treated with pPCI at a single high-volume invasive center. We present the 1-year outcome in this observational registry study.

RESULTS

A total of 616 patients were admitted by field triage and 821 by emergency departments. Baseline and angiographic variables were similar in the 2 populations. Patients admitted by field triage had a significantly shorter median door-to-balloon time compared with patients admitted by emergency department triage (83 min, interquartile range 67 to 100 min vs. 103 min, interquartile range 80 to 135 min; p<0.001). Door-to-balloon times of less than the recommended 90 min were achieved in 61% of field triage patients, but only in 36% of nonfield-triage patients (p<0.001). After adjustment for relevant baseline variables, patients admitted by field triage had a reduced risk of reaching the combined end point of all-cause mortality or nonfatal myocardial infarction (hazard ratio: 0.67; 95% confidence interval: 0.46 to 0.97; p=0.035).

CONCLUSIONS

This study shows that field triage of STEMI patients to pPCI significantly reduces treatment delay and improves outcome. These results emphasize the value of field triage as an important tool in the quest to improve clinical outcomes in STEMI patients undergoing pPCI.

Long-Term Prognosis in an ST-Segment Elevation Myocardial Infarction Population Treated With Routine Primary Percutaneous Coronary Intervention

Background— We sought to describe the long-term prognosis after routine primary percutaneous coronary intervention (pPCI) in a contemporary consecutive population of patients with presumed ST-segment elevation myocardial infarction, compare it with similar results from the landmark DANAMI-2 trial, and to identify a possible impact of time of presentation and referral pattern.

Methods and Results— Long-term prognosis in 1019 presumed ST-segment elevation myocardial infarction patients, treated according to modern routine pPCI during the year 2004, was analyzed and compared with similar data from the DANAMI-2 trial. Furthermore, we analyzed the impact of patient presentation to the angioplasty center during “off hours” (4 pm to 8 am plus weekends and holidays) and the impact of being referred from noninvasive hospitals. At 3 years, 20.4% in the routinely treated population versus 19.6% in the DANAMI-2 trial reached the combined end point of death, reinfarction, or stroke ( P =0.68), whereas the all-cause mortality was 13.0% and 13.7%, respectively ( P =0.65). Patients admitted during off hours had the same risk of reaching the combined end point of death, reinfarction, or stroke compared with patients admitted during office hours (hazards ratio, 1.04; 95% CI, 0.8 to 1.5; P =0.81). Door-to-balloon times of less than 90 minutes were achieved in 60% among patients admitted directly to an invasive center but only in 40% among transferred patients ( P <0.001). Despite this difference, no difference in unadjusted or adjusted long-term prognosis was found between the 2 groups.

Conclusions— This study shows that ST-segment elevation myocardial infarction patients treated with contemporary routine pPCI achieve a similar long-term prognosis as patients in the landmark randomized pPCI trial (DANAMI-2). Furthermore, the long-term prognosis was the same regardless of whether the pPCI was performed during off hours or office hours. Thus, pPCI including transportation of patients from noninvasive centers can be applied successfully in a real-life population.

Routine early angioplasty after fibrinolysis for acute myocardial infarction

BACKGROUND

Patients with a myocardial infarction with ST-segment elevation who present to hospitals that do not have the capability of performing percutaneous coronary intervention (PCI) often cannot undergo timely primary PCI and therefore receive fibrinolysis. The role and optimal timing of routine PCI after fibrinolysis have not been established.

METHODS

We randomly assigned 1059 high-risk patients who had a myocardial infarction with ST-segment elevation and who were receiving fibrinolytic therapy at centers that did not have the capability of performing PCI to either standard treatment (including rescue PCI, if required, or delayed angiography) or a strategy of immediate transfer to another hospital and PCI within 6 hours after fibrinolysis. All patients received aspirin, tenecteplase, and heparin or enoxaparin; concomitant clopidogrel was recommended. The primary end point was the composite of death, reinfarction, recurrent ischemia, new or worsening congestive heart failure, or cardiogenic shock within 30 days.

RESULTS

Cardiac catheterization was performed in 88.7% of the patients assigned to standard treatment a median of 32.5 hours after randomization and in 98.5% of the patients assigned to routine early PCI a median of 2.8 hours after randomization. At 30 days, the primary end point occurred in 11.0% of the patients who were assigned to routine early PCI and in 17.2% of the patients assigned to standard treatment (relative risk with early PCI, 0.64; 95% confidence interval, 0.47 to 0.87; P=0.004). There were no significant differences between the groups in the incidence of major bleeding.

CONCLUSIONS

Among high-risk patients who had a myocardial infarction with ST-segment elevation and who were treated with fibrinolysis, transfer for PCI within 6 hours after fibrinolysis was associated with significantly fewer ischemic complications than was standard treatment. (ClinicalTrials.gov number, NCT00164190.)

Review of tenecteplase (TNKase) in the treatment of acute myocardial infarction

TNKase is a genetically engineered variant of the alteplase molecule. Three different mutations result in an increase of the plasma half-life, of the resistance to plasminogen-activator inhibitor 1 and of the thrombolytic potency against platelet-rich thrombi. Among available agents in clinical practice, TNKase is the most fibrin-specific molecule and can be delivered as a single bolus intravenous injection. Several large-scale clinical trials have enrolled more than 27,000 patients with acute myocardial infarction, making the use of this drug truly evidence-based. TNKase is equivalent to front-loaded alteplase in terms of mortality and is the only bolus thrombolytic drug for which this equivalence has been formally demonstrated. TNKase appears more potent than alteplase when symptoms duration lasts more than 4 hours. Also, TNKase significantly reduces the rate of major bleeds and the need for blood transfusions. The efficacy of TNKase may be further improved by enoxaparin substitution for unfractionated heparin, provided that enoxaparin dose adjustment is made for patients more than 75 years old. Hitherto, the small available randomized studies and international clinical registries suggest that pre-hospital TNKase is as effective as primary angioplasty, thus laying the foundations for a new fibrinolytic, TNKase-based strategy as the backbone of reperfusion in acute myocardial infarction.