P5517Impact of admission during ON vs OFF hours on mortality in unselected ST-elevation myocardial infarction patients referred in percutaneous coronary intervention centers:insights from the ORBI registry

Background

The effect of admission during OFF-hours on patient's outcome in ST Segment Elevation Myocardial Infarction remains controversial when a strategy for reperfusion between primary Percutaneous Coronary Intervention (pPCI) and fibrinolysis is chosen. We aimed to evaluate the impact of time of admission on all cause mortality in unselected STEMI patients referred to pPCI centers.

Methods

Data from 10850 consecutive patients admitted in the nine interventional cardiology centers in Britany for STEMI in the 24 first hours following the beginning of symptoms were collected in a network registry. Characteristics and clinical outcome of patients admitted during ON-hours (Monday through Friday 8h am-6h30 pm) were compared to OFF-hours patients (night shifts, weekends and non-working Holydays). Clinical outcome was all-cause in hospital mortality, major bleeding, and mechanical complications in STEMI.

Results

A total of 4644 confirmed STEMI patients (57.2%) were admitted during OFF-hours and 6206 (42.8%) patients during ON-hours. Baseline characteristics were well balanced between the two groups including features of high risk STEMI such as ventricular fibrillation (3.7% vs 3.6% p=0, 8), cardiogenic shock (6.9% vs 7.6%, p=0.1), mechanical complications (3,2% vs 2,7%, p=0,2). The population was older in the ON group (63.7 vs 62.2, p<0.0001). Time from symptom onset to First Medical Contact (FMC) were slightly longer for patients presenting during on-hours (97 min vs. 95 min, p<0,03). Time from FMC to angiography was longer during OFF-hours compared to ON-hours (100 min vs. 92 min p<0,0001). Time from arrival in the PCI center to angioplasty was higher in the OFF period (40 mn vs 38 mn, p<0.0001). The reperfusion treatment was different between the two periods, with more fibrinolysis and less PCI in OFF group (PCI: 76.7% vs 79.6%, p<0,0001; Fibrinolysis: 11.4% vs 8.9%, p<0,0001).

The use of radial access (RA) was uniform in both group (66,8% and 66.6%; p=0,9) and not different whatever the admission time. The use of radial access increased meaningfully from 2008 for the two periods (RA OFF group: 84.4% vs 38,6%, RA ON group: 88.6% vs 38.7%) There was no impact of admission time on in-hospital all cause mortality in the entire population (5,3% vs 5,4% p=0,7), and on the Timi 3 flow for the patients treated with primary angioplasty (On group: 94% vs 94,3%, p=0.5). The bleeding complications were similar in both groups (2,5% vs 2,6%, p=0,8).

Conclusions

Even though the time of reperfusion is slightly longer in patients admitted for STEMI during off-hours, no difference was observed in the PTCA technique and success rates as well as in the in-hospital mortality and bleeding rates. A long term patient follow-up would be necessary before definite conclusions.

Altered Fibrin Architecture Is Associated With Hypofibrinolysis and Premature Coronary Atherothrombosis

OBJECTIVE

Hypofibrinolysis promotes atherosclerosis progression and recurrent ischemic events in premature coronary artery disease. We investigated the role of fibrin physical properties in this particular setting.

METHODS AND RESULTS

Biomarkers of recurrent thrombosis and premature coronary artery disease (CAD) were measured in 33 young post-myocardial infarction patients with angiographic-proven CAD and in 33 healthy volunteers matched for age and sex. Ex vivo plasma fibrin physical properties were assessed by measuring fibrin rigidity and fibrin morphological properties using a torsion pendulum and optical confocal microscopy. The fibrinolysis rate was derived from continuous monitoring of the viscoelastic properties after addition of lytic enzymes. Young CAD patients had a significant increase in plasma concentration of fibrinogen, von Willebrand factor, plasminogen activator inhibitor type 1, and lipoprotein(a) as compared with controls (P<0.05). Fibrin of young CAD patients was stiffer (P=0.002), made of numerous (P=0.002) and shorter fibers (P=0.04), and lysed at a slower rate than that of controls (P=0.03). Fibrin stiffness was an independent predictor for both premature CAD and hypofibrinolysis.

CONCLUSIONS

This first detailed study of clot properties in such a group of patients demonstrated that abnormal plasma fibrin architecture is an important feature of both premature CAD and fibrinolysis rate. The determinants of this particular phenotype warrant further investigation.

[Antithrombotics in pre-hospital phase of acute coronary syndromes]

Antithrombotic therapies are the corner stone of acute coronary syndrome management. We have the proof that many of them should be initiated during the prehospital care because their clinical benefit is time-dependent. The hypothesis that anticoagulation therapy is an effective treatment of STEMI, which benefit is time-dependent, is now validated. It is also fair to affirm that GP lIb/IIIa receptor inhibitors are the adjuvant therapy of choice for primary PCI. Indeed, these medications reduce short-term and long-term mortality. This clinical benefit is time dependent. Clopidogrel therapy is probably also a medication of the prehospital phase. It is well established now that the biological efficacy of this pro drug is loading dose dependent. It is also demonstrated that its clinical efficacy depends on the time delay between symptom onset and initiation of the therapy. However, the clinical benefit of prehospital administration remains to be established.

[Prevalence of asymptomatic atherothrombotic lesions and risk of vascular events in patients with documented coronary artery disease]

Coronary arteries are the most frequent location of atherosclerosis. Coronary artery disease is the first cause of death related to atherothrombosis. In addition, patients with a prior history of acute coronary syndromes exhibit a 10% annual risk of recurrence. Although there seems to be a close correlation between the extension of CAD and the severity of atherosclerotic lesions in extra coronary arterial beds, the prevalence of these extracoronary asymptomatic lesions depends on their location. Hence, the prevalence of renal artery disease defined as stenosis > or = 50% or of peripheral artery disease defined as an ABI < 0.9 is estimated to be 20% up to 30%, whereas the prevalence of both carotid artery disease defined as stenosis > or = 70% or aortic aneurysm is estimated to be 5%. Conversely, the annual absolute risk of stroke among CAD patients is estimated at 1% while it remains unknown for vascular events related to PAD or aortic lesions. These data suggest that a systematic screening for asymptomatic extracoronary atherosclerotic lesions among CAD patients cannot be justified without a better knowledge of the prevalence of these lesions. In addition, the identification of the predicting factors for the presence and the development of these asymptomatic lesions is warranted. Finally, the potential benefit in terms of therapeutic intervention of such screening needs to be evaluated. These important issues warrant further clinical studies with appropriate design.

Impact of prior use or recent withdrawal of oral antiplatelet agents on acute coronary syndromes

BACKGROUND

Oral antiplatelet agents (OAAs) can prevent further vascular events in cardiovascular disease. How prior use or recent discontinuation of OAA affects clinical presentation of acute coronary syndromes (ACS) and clinical outcomes (death, myocardial infarction [MI]) is unclear.

METHODS AND RESULTS

We studied and followed up for up to 30 days a cohort of 1358 consecutive patients admitted for a suspected ACS; of these, 930 were nonusers, 355 were prior users of OAA, and 73 had recently withdrawn OAA. Nonusers were at lower risk, more frequently presented with ST-elevation MI on admission, and more frequently had Q-wave MI at discharge than prior users (36.6% versus 17.5%, P<0.001; and 47.8% versus 28.2%, P<0.001, respectively). However, there was no difference regarding the incidence of death or MI at 30 days between nonusers and prior users (10.3% versus 12.4%, P=NS). In addition, prior users experienced more major bleeds within 30 days compared with nonusers (3.4% versus 1.4%, respectively; P=0.04). Recent withdrawers were admitted on average 11.9+/-0.8 days after OAA withdrawal. Interruption was primarily a physician decision for scheduled surgery (n=47 of 73). Despite a similar cardiovascular risk profile, recent withdrawers had higher 30-day rates of death or MI (21.9% versus 12.4%, P=0.04) and bleedings (13.7% versus 5.9%, P=0.03) than prior users. After multivariate analysis, OAA withdrawal was found to be an independent predictor of both mortality and bleedings at 30 days.

CONCLUSIONS

Among ACS patients, prior users represent a higher-risk population and present more frequently with non-ST-elevation ACS than nonusers. Although patients with a recent interruption of OAA resemble those chronically treated by OAA, they display worse clinical outcomes.

Anti-Xa Activity Relates to Survival and Efficacy in Unselected Acute Coronary Syndrome Patients Treated With Enoxaparin

Background— Low-molecular-weight heparin (LMWH) is recommended in the treatment of unstable angina (UA)/non–ST-segment–elevation myocardial infarction (NSTEMI), but no relationship has ever been shown between anticoagulation levels obtained with LMWH treatment and clinical outcomes.

Methods and Results— In all, 803 consecutive patients with UA/NSTEMI were treated with subcutaneous enoxaparin and were followed up for 30 days. The recommended dose of enoxaparin of 1 mg/kg BID was used throughout the population except when physicians decided on dose reduction because of a history of a recent bleeding event or because of a high bleeding risk. Anti–factor Xa activity was >0.5 IU/mL in 93% of patients; subtherapeutic anti-Xa levels (<0.5 IU/mL) were associated with lower doses of enoxaparin. The 30-day mortality rate was significantly associated with low anti-Xa levels (<0.5 IU/mL), with a >3-fold increase in mortality compared with the patients with anti-Xa levels in the target range of 0.5 to 1.2 IU/mL ( P =0.004). Multivariate analysis revealed low anti-Xa activity as an independent predictor of 30-day mortality at least as strong as age, left ventricular function, and renal function. In contrast, anti-Xa activity did not predict major bleeding complications within the range of anti-Xa levels observed in this study.

Conclusions— In this large unselected cohort of patients with UA/NSTEMI patients, low anti-Xa activity on enoxaparin treatment is independently associated with 30-day mortality, which highlights the need for achieving at least the minimum prescribed anti-Xa level of 0.5 IU/mL with enoxaparin whenever possible.