Primary percutaneous coronary intervention without on-site cardiac surgery backup in unselected patients with ST-segment-Elevation Myocardial Infarction: The RIvoli ST-segment Elevation Myocardial Infarction (RISTEMI) registry

Abstract

Background

Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy for patients with ST-segment-elevation myocardial infarction (STEMI), but some concerns remain about its safety and efficacy in centers without on-site cardiac surgery (OCS).

Methods

The Infermi Hospital in Rivoli, Italy, is a community hospital without OCS with a high volume catheterization laboratory (> 800 PCI and > 150 primary PCI per year), which provides a 24-hour primary PCI service to a population of 583.000 and is only 14 km far from the nearest OCS hospital. We analyzed clinical and procedural data, as well as 30-day outcome, of all STEMI patients treated by primary PCI within 12 hours from symptom onset.

Results

From September 2001 to June 2010, 1302 patients with a suspect of STEMI underwent urgent coronary angiography. Of these, 1251 (96.1%), underwent primary PCI. A successful myocardial revascularization was achieved in 1172 patients (93.7%). Thirty-day mortality occurred in 7.1%. Multivariate predictors of 30-day mortality were: age ≥ 75 years (OR 3.96, p = 0.0003), left ventricular ejection fraction ≤ 40% (OR 35.0, p = 0.02), cardiogenic shock at presentation (OR 33.4, p < 0.0001), anterior STEMI (OR 1.82, p = 0.036) and total ischemic time ≤ 3 hours (OR 0.55, p = 0.05).

Conclusions

Primary PCI is a reperfusion strategy feasible and effective in unselected high-risk STEMI patients even in hospitals without OCS with a high volume of routine and emergency interventional procedures.

1 Introduction

Reperfusion therapy with primary percutaneous coronary intervention (PCI) has become the treatment of choice for patients with ST-segment elevation acute myocardial infarction (STEMI). Pooled analyses of clinical trials have indeed demonstrated the superiority of primary PCI over fibrinolytic therapy . However, the benefits of primary PCI are adversely affected by time delay in initiating the procedure . This delay can occur at several levels, including patient’s failure to rapidly seek for care once symptoms have begun, delays at the PCI hospitals after patient admission and delays in the transfer to PCI centers when in the initial hospital PCI is not performed. To overcome the delays in transport, efforts to provide primary PCI services at community hospitals without onsite cardiac surgery (OCS) have been developed. In some studies, when following appropriate indications and specific protocols, STEMI patients treated at hospitals without OCS showed outcomes comparable to those treated at facilities with OCS . However, the indication to perform primary PCI at centers without OCS remains controversial. Accordingly, international guidelines classify primary PCI in this context as a Class IIa indication . Aim of this study was to review clinical, angiographic and procedural characteristics, as well as clinical outcome, of consecutive patients with STEMI treated with primary PCI at an Italian community hospital without OCS.

2 Methods

The Infermi Hospital in Rivoli is a community hospital in the Piemonte Region, Italy, with a high volume catheterization laboratory (> 800 total PCIs and > 150 primary PCIs/year) without OCS and providing a network-wide primary PCI service to a population of 583.000. The catchment area also includes 5 community hospitals without PCI capability. The catheterization laboratory is fully equipped with the usual interventional armamentarium including intra-aortic balloon counterpulsation (IABC) and mechanical ventilation devices. The staff is composed of 3 skilled operators, each performing a total of more than 250 PCIs and more than 50 primary PCIs per year as well as nurses and technical staff available on call in a 24/7/365 fashion. An advanced life support ambulance service for emergency transport to OCS hospitals in Turin city (14 km) is always available.

We reviewed the data of all consecutive patients with STEMI admitted to our hospital between September 2001 and June 2010 and treated by primary PCI within 12 hours of symptom onset. Demographic, clinical and procedural data were prospectively collected in a dedicated database (Cardioplanet V.3.0.8, Ebit Aet S.p.A., Genoa, Italy). The study protocol was approved by the Ethics Committee of our Institution (ASL 103, Piemonte Region, Italy), and informed consent was obtained in all patients.

STEMI was defined as typical chest pain lasting more than 30 minutes associated with ≥ 0.1 mV ST-segment elevation in ≥ 2 contiguous electrocardiogram (ECG) leads or with new left bundle branch block.

Door-to-balloon (D2B) time was defined as the time interval from arrival to the hospital (the initial referral hospital for transferred patients) to the first balloon inflation during primary PCI. Symptoms-onset-to-balloon time was defined as the time interval from symptom onset to first balloon inflation during primary PCI.

Cardiogenic shock was defined as systolic blood pressure < 90 mmHg (without inotropic drugs or intra-aortic balloon pump support) secondary to severe ventricular dysfunction and associated with signs of end-organ hypoperfusion (e.g., cold and diaphoretic extremities, altered mental status, anuria). Multivessel disease (MVD) was defined as the angiographic detection of a significant stenosis (≥ 50% of lumen diameter) in at least one major coronary artery in addition to that responsible for STEMI, or the presence of significant stenoses in at least 2 major coronary arteries if the infarct related artery could not be assessed with certainty.

Lesion characteristics were evaluated according to the ACC/AHA classification . All STEMI patients who complained symptoms for ≤ 12 hours were immediately transferred to the catheterization laboratory for urgent coronary angiography. The indications to manual thrombus aspiration (TA) were driven by few parameters evaluated after diagnostic angiography as already reported : a) visual estimation of infarct related artery (IRA) diameter ≥ 3 mm; b) the absence of severe proximal tortuosity and/or calcifications; c) complete vessel occlusion with distal convex contrast stain and the presence of visual thrombus in case of a patent IRA. However, the final decision to the use of TA as well as of IABC support was left to the discretion of the operator. In patients with MVD, PCI was performed only in the infarct-related artery (IRA), unless refractory cardiogenic shock was present or the IRA could not be identified with certainty. In stable patients, further revascularization procedures were planned according to the clinical conditions and the results of noninvasive stress tests. A successful procedure was defined as a residual stenosis of treated vessels < 40% associated with a Thrombolysis In Myocardial Infarction (TIMI) 3 grade flow .

All patients were routinely treated with aspirin (325 mg upon arrival, and then 100 mg daily), clopidogrel (loading dose of 300 or 600 mg, and then 75 mg daily) and with an intravenous bolus of unfractionated heparin (100 U/kg body weight, or 60 U/kg body weight if also abciximab was given). Intravenous administration of abciximab was recommended, but its use was left to the discretion of the operator. Heparin therapy was stopped after the procedure, but, in case of IABC use, it was continued until its removal. When used, abciximab infusion was continued for 12 hours after the procedure. Beta-adrenergic blockers, ACE inhibitors and statins were used as in-hospital standard therapy, if not contraindicated.

All patients underwent an echocardiogram before coronary angiography to assess the left ventricular ejection fraction by Simpson’s rule and to exclude mechanical complications (i.e., cardiac tamponade, interventricular septum or left ventricular free wall rupture, acute mitral regurgitation due to papillary muscle rupture).

2.1 Clinical end-points

The primary end point of the study was 30-day mortality. Furthermore, we evaluated the occurrence of stent thrombosis and of major bleedings. Stent thrombosis was defined as definite and probable according to the Academic Research Consortium ; major bleedings were defined according to the Thrombolysis In Myocardial Infarction (TIMI) classification .

2.2 Statistical analysis

Data are reported as means (with standard deviations) or proportions. Comparisons between patients with and without events were performed by t-test and chi-square test for continuous and discrete variables, respectively. Multivariate logistic regression analysis was applied to identify independent predictors of 30-day mortality. To this scope all variables showing p values < 0.1 at standard statistical analysis were entered into the multivariate model and included age ≥ 75 years, female gender, hypertension, diabetes, anterior location of STEMI, cardiac arrest, ETI, cardiogenic shock, LVEF ≤ 40%, total ischemic time (time from symptoms onset to reperfusion with PCI), multivessel disease, left main coronary artery disease, pre-PCI TIMI flow < 2, use of IABC, lack of use of glycoprotein IIb-IIIa inhibitors, and lack of stent implantation. Stepwise multiple linear regression was used to identify significant differences in mortality across the study period. Statistical significance was assessed at a p value < 0.05. Statistical analyses were performed using the SAS software, Version 9.1 (SAS Institute Inc., Cary, NC).