Abortion of acute ST segment elevation myocardial infarction after reperfusion: incidence, patients' characteristics, and prognosis

Association of neutrophil extracellular traps burden with clinical and angiographic characteristics in patients with ST-elevation myocardial infarction

BACKGROUND

The precise triggers for atherosclerotic plaque rupture and the underlying pathophysiology of coronary thrombogenesis remain elusive. Polymorphonuclear neutrophils, particularly their formation of neutrophil extracellular traps (NETs), have garnered attention in the context of coronary atherothrombosis. This study sought to explore the association of NETs burden with clinical and angiographic characteristics in ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (pPCI) and thrombus aspiration (TA).

METHODS

For this study, 336 consecutive STEMI patients undergoing pPCI were considered for TA. Aspirated thrombi underwent histological analysis and NETs quantification via immunohistochemistry. Potential associations of clinical variables and angiographic outcomes with NETs burden were assessed.

RESULTS

Manual TA was selectively performed in 72 cases with increased thrombotic burden, and 60 thrombi were suitable for analysis and included in the current study. Most thrombi specimens displayed lytic features (63%), and almost three out of four were identified as white thrombi. Increased NETs burden was significantly associated with prolonged pain-to-balloon time (>300 min), OR = 10.29 (95% CI 2.11-42.22, p = 0.001), and stress-induced hyperglycemia OR = 6.58 (95% CI 1.23-52.63, p < 0.01) after multivariate regression analysis. Additionally, distal embolization, and left ventricular ejection fraction ≤40% were more frequent among patients with an elevated NETs burden OR = 16.9 (95% CI 4.23-44.52, p < 0.01) and OR = 3.2 (95% CI 1.05-12.1, p = 0.05), respectively.

CONCLUSION

Elevated NETs burden in STEMI thrombi may be due to delayed reperfusion and stress-induced hyperglycemia, and it is associated with an increased risk of distal embolization and lower left ventricular ejection fraction. Further research is needed to elucidate the role of NETs as a potential therapeutic target in acute atherothrombosis.

The Canadian Cardiovascular Society Classification of Acute Atherothrombotic Myocardial Infarction Based on Stages of Tissue Injury Severity: An Expert Consensus Statement

Myocardial infarction (MI) remains a leading cause of morbidity and mortality. In atherothrombotic MI (ST-elevation MI and type 1 non-ST-elevation MI), coronary artery occlusion leads to ischemia. Subsequent cardiomyocyte necrosis evolves over time as a wavefront within the territory at risk. The spectrum of ischemia and reperfusion injury is wide: it can be minimal in aborted MI or myocardial necrosis can be large and complicated by microvascular obstruction and reperfusion hemorrhage. Established risk scores and infarct classifications help with patient management but do not consider tissue injury characteristics. This document outlines the Canadian Cardiovascular Society classification of acute MI. It is an expert consensus formed on the basis of decades of data on atherothrombotic MI with reperfusion therapy. Four stages of progressively worsening myocardial tissue injury are identified: (1) aborted MI (no/minimal myocardial necrosis); (2) MI with significant cardiomyocyte necrosis, but without microvascular injury; (3) cardiomyocyte necrosis and microvascular dysfunction leading to microvascular obstruction (ie, "no-reflow"); and (4) cardiomyocyte and microvascular necrosis leading to reperfusion hemorrhage. Each stage reflects progression of tissue pathology of myocardial ischemia and reperfusion injury from the previous stage. Clinical studies have shown worse remodeling and increase in adverse clinical outcomes with progressive injury. Notably, microvascular injury is of particular importance, with the most severe form (hemorrhagic MI) leading to infarct expansion and risk of mechanical complications. This classification has the potential to stratify risk in MI patients and lay the groundwork for development of new, injury stage-specific and tissue pathology-based therapies for MI.

Impact of Chest Pain Protocol with Access to Telemedicine on Implementation of Pharmacoinvasive Strategy in a Private Hospital Network

BACKGROUND

Brazilian registries have shown a gap between evidence-based therapies and real treatments. We aim to compare the use of the pharmacoinvasive strategy and mortality in patients with ST elevation myocardial infarction (STEMI) transferred pre- and post-chest pain protocol with access to telemedicine (CPPT) in a private hospital network.

MATERIALS AND METHODS

A CPPT was implemented in 22 private emergency departments in 2012. Emergency physicians and nurses of all facilities were trained to disseminate the information to comply with a chest pain protocol focusing on reperfusion therapy (pharmacoinvasive strategy) for STEMI. To conduct clinical discussions using telemedicine, a cardiologist from a reference hospital in cardiology (RHC) was available 24 h/day, 7 days/week. Using the database of all consecutive admissions, we compared the data of patients with STEMI transferred to the RHC in 2011 (pre-CPPT) and 2013-2014 (post-CPPT).

RESULTS

We included 376 patients (113 pre-CPPT and 263 post-CPPT) with STEMI. All patients admitted in the RHC were transferred from the 22 emergency departments. Comparing pre-CPPT and post-CPPT, we did not find differences regarding age, gender, hypertension, dyslipidemia, diabetes, smoking, previous myocardial infarction, or Killip classification. However, the use of CPPT was associated with a greater use of pharmacoinvasive strategy (55.8% versus 38%; p = 0.002) and a trend toward lower in-hospital mortality (3% versus 8%; p = 0.06).

CONCLUSIONS

The implementation of a CPPT was associated with a significant increase in the use of pharmacoinvasive strategy in patients with STEMI and a trend toward reduced in-hospital mortality in a private hospital network.

Assessment of circumferential endocardial extent of myocardial edema and infarction in patients with reperfused acute myocardial infarction: a cardiovascular magnetic resonance study

T2 weighted (T2W) images on cardiovascular magnetic resonance (CMR) visualizes myocardial edema, which reflects the myocardial area at risk (AAR) in reperfused acute myocardial infarction (AMI). Late gadolinium enhancement (LGE) demonstrates myocardial infarction. LGE images cover the whole left ventricle, but T2W images are obtained from a few slices of the left ventricle due to the long sequence time, so the quantification of AAR of the entire left ventricle is difficult. We hypothesize that we can quantify AAR with only LGE images if there is a strong correlation between the circumferential endocardial extent of myocardial edema and infarction. Thirty patients with first AMI were enrolled. All patients underwent successfully reperfusion therapy and CMR was performed within the first week after the event. We measured the circumferential extent of edema and infarction on short-axis views (T2 angle and LGE angle), respectively. A total of 82 short-axis slices showed transmural edema on T2W images. Corresponding LGE images were analyzed for the circumferential extent of infarction. The median [interquartile range] of T2 angle and DE angle were 147° [116°-219°] and 134° [104°-200°] in patients with LAD culprit lesion, 91° [87°-101°] and 85° [80°-90°] in LCX, and 110° [94°-123°] and 104° [89°-118°] in RCA, respectively. T2 angle was well correlated with LGE angle (r = 0.99, P < 0.01). There is a strong correlation between the circumferential extent of edema and infarction in reperfused AMI. Thus, T2 weighted imaging can be skipped to quantify the amount of AAR.

Pros, cons, and organization of prehospital thrombolysis

BACKGROUND

Early initiation of reperfusion therapy in ST-segment elevation myocardial infarction improves outcome. Prehospital thrombolysis (PHT) is 1 strategy to deliver earlier reperfusion.

OBJECTIVE

The goal of this study was to discuss the pros and cons of PHT and to describe the implementation of a program of PHT in the Hunter Region of Australia.

METHODS

Recent literature on PHT was reviewed to present a critical assessment of the evidence to support PHT. Different models of PHT are presented including the experience of the introduction of the Hunter program.

RESULTS

Meta-analyses of clinical trials and registries have shown that PHT significantly decreases the time to thrombolysis, with reduction in the incidence of cardiogenic shock and a trend to a mortality benefit. The STREAM study reinforces current policy, which favors primary percutaneous coronary intervention (PCI) over thrombolysis, providing that PCI can be performed within an appropriate time interval; emphasizes that timely thrombolysis linked to an early invasive strategy provides an equivalent outcome when timely primary PCI is not possible; and supports other published experience that early-rescue PCI can be performed safely after administration of PHT. Although PHT can be implemented by trained paramedics working with on-board physicians, the Hunter Region has successfully used paramedics and ECG telemetry in consultation with hospital-based physicians. When the time to open the artery is ≤90 minutes, primary PCI is preferred. When the time to open the artery is >90 minutes, PHT with immediate transport postthrombolysis to a PCI-capable hospital is feasible and effective.

CONCLUSIONS

PHT delivered by trained paramedics with telemetery backup to assist ECG interpretation is feasible and delivers the prospect of early reperfusion.

Cardiac magnetic resonance imaging in ischemic heart disease: a clinical review

Cardiac magnetic resonance imaging (MRI) has emerged as a prime player in the clinical and preclinical detection of ischemic heart disease (IHD) as well in the prognosis assessment by offering a comprehensive approach for all spectrums of coronary artery disease (CAD) patients. The aim of this review is to provide the reader a state-of-the art on how the newest cardiac MRI techniques can be used to study IHD patients. In patients with suspected/stable CAD, functional and perfusion imaging both at rest and during vasodilatatory stress (adenosine, dypiridamole)/dobutamine stress can accurately depict ischemic myocardium secondary to significant coronary artery stenosis. In patients with acute MI, MRI is a robust tool for differentiating and sizing the jeopardized and the infarcted myocardium by using a combination of functional, edema, perfusion and Gd contrast imaging. Moreover, important prognostic factors like myocardial salvage, the presence of microvascular obstruction (MVO), post reperfusion myocardial hemorrhage, RV involvement and infarct related complications can be assessed in the same examination. In patients with chronic ischemic cardiomyopathy, the role of the MRI extends from diagnosis by means of Gadolinium contrast scar imaging to therapy and prognosis by functional assessment and viability testing with rest and dobutamine stress imaging. In all the circumstances mentioned, MRI derived information has been proven valuable in every day clinical decision making and prognosis assessment. Thus, MRI is becoming more and more an accepted alternative to other imaging modalities both in the acute and chronic setting.

Letter to the editors: the potential role for prehospital thrombolysis and time-critical stroke transfers in the northern Norway aeromedical retrieval system; In response to: Norum J, Elsbak TM: Air ambulance services in the Arctic: a Norwegian study. Int J Emerg Med 2011, 4:1

The role for prehospital thrombolysis for ST-elevation acute myocardial infarction and time-critical stroke transfers in the northern Norway aeromedical retrieval system as well as the aero-evacuation impact of increased Arctic expedition tourism could benefit from further discussion by Norum and Elsbak. Close ECG surveillance for ST elevation and retrieval thrombolysis en route to the accepting hospital could be of benefit for acute coronary syndrome patients in northern Norway who require prolonged aeromedical transfer. For patients who remain within a reasonable time frame for stroke thrombolysis (up to 4.5 h after symptom onset), expedited transfer for neuroimaging to determine eligibility is recommended.

An organized system of emergency care for patients with myocardial infarction: a reality?

An organized system of emergency care is an essential requirement for the modern treatment of ST-elevation acute myocardial infarction. There is a strong need to deliver reperfusion therapy as soon as possible, with primary percutaneous coronary intervention being the preferred option if performed in a timely manner and thrombolytic therapy, particularly in the prehospital setting, being a good alternative if the primary percutaneous coronary intervention-related delay exceeds the equipoise. In this situation, emergency medical services have a primary role in rescuing patients from cardiac arrest, performing prehospital diagnosis, triage and treatment and safely transporting them to the most appropriate cardiological center, including interhospital transfer. A complete reorganization of the healthcare systems in different countries is frequently needed to build an ST-elevation acute myocardial infarction system of care, focusing on fast transport, use of telemedicine and diversion protocols to skip the unsuited centers.

Myocardial salvage by CMR correlates with LV remodeling and early ST-segment resolution in acute myocardial infarction

OBJECTIVES

The purpose of this study was to assess the association of myocardial salvage by cardiac magnetic resonance (CMR) with left ventricular (LV) remodeling and early ST-segment resolution in patients with acute myocardial infarction (MI).

BACKGROUND

Experimental studies revealed that MI size is strongly influenced by the extent of the area at risk (AAR), limiting its accuracy as a marker of reperfusion treatment efficacy in acute MI studies. Hence, an index correcting MI size for AAR extent is warranted. T2-weighted CMR and delayed-enhancement CMR, respectively, enable the determination of AAR and MI size, and the myocardial salvage index (MSI) is calculated by correcting MI size for AAR extent. Nevertheless, the clinical value of CMR-derived MSI has not been evaluated yet.

METHODS

In a prospective cohort of 137 consecutive patients with acutely reperfused ST-segment elevation MI, CMR was performed at 1 week and 4 months. T2-weighted CMR was used to quantify AAR, whereas MI size was detected by delayed-enhancement imaging. MSI was defined as AAR extent minus MI size divided by AAR extent. Adverse LV remodeling was defined as an increase in LV end-systolic volume of >or=15%. The degree of ST-segment resolution 1 h after reperfusion was also calculated.

RESULTS

AAR extent was consistently larger than MI size (32+/-15% of LV vs. 18+/-13% of LV, p<0.0001), yielding an MSI of 0.46+/-0.24. MI size was closely related to AAR extent (r=0.81, p<0.0001). After correction for the main baseline characteristics by multivariate analyses, MSI was a major and independent determinant of adverse LV remodeling (odds ratio: 0.64; 95% confidence interval: 0.49 to 0.84, p=0.001) and was independently associated with early ST-segment resolution (B coefficient=0.61, p<0.0001).

CONCLUSIONS

In patients with reperfused ST-segment elevation MI, CMR-derived MSI is independently associated with adverse LV remodeling and early ST-segment resolution, opening new perspectives on its use in studies testing novel reperfusion strategies.

Cardiovascular magnetic resonance of the myocardium at risk in acute reperfused myocardial infarction: comparison of T2-weighted imaging versus the circumferential endocardial extent of late gadolinium enhancement with transmural projection

BACKGROUND

In the situation of acute coronary occlusion, the myocardium supplied by the occluded vessel is subject to ischemia and is referred to as the myocardium at risk (MaR). Single photon emission computed tomography has previously been used for quantitative assessment of the MaR. It is, however, associated with considerable logistic challenges for employment in clinical routine. Recently, T2-weighted cardiovascular magnetic resonance (CMR) has been introduced as a new method for assessing MaR several days after the acute event. Furthermore, it has been suggested that the endocardial extent of infarction as assessed by late gadolinium enhanced (LGE) CMR can also be used to quantify the MaR. Hence, we sought to assess the ability of endocardial extent of infarction by LGE CMR to predict MaR as compared to T2-weighted imaging.

METHODS

Thirty-seven patients with early reperfused first-time ST-segment elevation myocardial infarction underwent CMR imaging within the first week after percutaneous coronary intervention. The ability of endocardial extent of infarction by LGE CMR to assess MaR was evaluated using T2-weighted imaging as the reference method.

RESULTS

MaR determined with T2-weighted imaging (34 +/- 10%) was significantly higher (p < 0.001) compared to the MaR determined with endocardial extent of infarction (23 +/- 12%). There was a weak correlation between the two methods (r2 = 0.17, p = 0.002) with a bias of -11 +/- 12%. Myocardial salvage determined with T2-weighted imaging (58 +/- 22%) was significantly higher (p < 0.001) compared to myocardial salvage determined with endocardial extent of infarction (45 +/- 23%). No MaR could be determined by endocardial extent of infarction in two patients with aborted myocardial infarction.

CONCLUSIONS

This study demonstrated that the endocardial extent of infarction as assessed by LGE CMR underestimates MaR in comparison to T2-weighted imaging, especially in patients with early reperfusion and aborted myocardial infarction.

Implications of the mechanical (PCI) vs thrombolytic controversy for ST segment elevation myocardial infarction on the organization of emergency medical services: the Boston EMS experience

With the many advances in rapid reperfusion therapy for management of acute ST segment elevation myocardial infarction (STEMI), there is a need to revisit the current plan for prehospital triage (point of entry). Until recently in Boston, and nationwide, there has been a policy that patients with suspected acute MI were brought to the nearest hospital. Then, if ST segment elevation was present, patients were treated with either thrombolytic therapy or primary percutaneous coronary intervention (PCI). Recent data, however, have shown that with advances in interventional devices, techniques and institutional experience, primary PCI is associated with improved outcomes compared with thrombolytic therapy for all patients with STEMI when provided at expert centers with high institutional volumes, with experienced interventional cardiologists as the operators, and with relatively short time to treatment. We describe the rationale for and the implementation of the Boston EMS STEMI Triage Plan and Treatment Registry. Many of the issues that prompted the implementation of the Boston STEMI plan are relevant to all EMS systems. Among these issues are the accuracy of prehospital identification of STEMI patients, the availability of mechanical reperfusion therapy, the appropriate triage of patients with complicated myocardial infarction or shock, as well as the local consensus regarding strength of the evidence favoring mechanical reperfusion. This article describes the history of the Boston EMS STEMI Triage Plan and Treatment Registry and suggests the need for other EMS systems to develop a systematic approach to patients with STEMI.

Prognostic significance and magnetic resonance imaging findings in aborted myocardial infarction after primary angioplasty

BACKGROUND

Aborted myocardial infarction (MI) is defined by major (> or =50%) ST-segment resolution and a lack of subsequent cardiac enzyme rise > or =2 the upper normal limit. This ultimate myocardial salvage has been observed in approximately 15% of ST-elevation MI (STEMI) patients after fibrinolysis. So far, the prognostic significance and magnetic resonance imaging (MRI) findings of an aborted MI after primary angioplasty have not been evaluated appropriately.

METHODS

We examined 420 consecutive STEMI patients undergoing primary angioplasty within 12 hours after symptom onset. All patients underwent MRI within 1 to 4 days. Clinical end points were major adverse cardiovascular events within 6 months after the index event.

RESULTS

Of the 420 STEMI patients, 58 (14%) fulfilled aborted MI criteria. As compared with true MI, patients with aborted MI had a significant lower infarct size, shorter pain-to-balloon time, and better left ventricular ejection fraction (P < .001, respectively). Aborted MI patients had a 6-month major adverse cardiovascular event rate of 1.7% versus 19.6% of true MI patients (P = .001). In aborted MI patients, MRI detected no myocardial scar in 30 (56%), and a minor necrosis/scar formation in 24 patients (44%).

CONCLUSION

The proven prognostic relevance of aborted MI makes it a meaningful end point and therapeutic target in future MI studies. MRI can further distinguish between true aborted MI with absence of myocardial scar and aborted MI with scar formations.

Prehospital evaluation and treatment of a presumed acute coronary syndrome: what are the options?

The earlier infarct-limiting therapy is started the better is the outcome among patients suffering from a threatened myocardial infarction. The introduction of a prehospital electrocardiogram has improved triage of patients with acute chest pain. With regard to medication, fibrinolytic agents have the best documentation. Their use when frequently followed by a percutaneous coronary intervention at a later stage may be a good alternative among patients with ST-elevation myocardial infarction. Other treatments of potential value in the prehospital setting are oxygen, narcotic analgesics, nitrates, aspirin, heparin, low molecular weight heparin, glycoprotein IIB, IIIA blockers, clopidogrel and beta-blockers. We need further studies, however, for most of these treatments including cost-benefit analysis, analysis of various logistic aspects and safety in order to confirm their value.

Pre-hospital thrombolysis delivered by paramedics is associated with reduced time delay and mortality in ambulance-transported real-life patients with ST-elevation myocardial infarction

AIMS

There are sparse data on the impact of pre-hospital thrombolysis (PHT) in real-life patients. We therefore evaluated treatment delays and outcome in a large cohort of ambulance-transported real-life patients with ST-elevation myocardial infarction (STEMI) according to PHT delivered by paramedics or in-hospital thrombolysis.

METHODS AND RESULTS

Prospective cohort study used data from the Swedish Register of Cardiac intensive care on patients admitted to the coronary care units of 75 Swedish hospitals in 2001-2004. Ambulance-transported thrombolytic-treated patients younger than age 80 with a diagnosis of acute myocardial infarction were included. Patients with PHT (n=1690) were younger, had a lower prevalence of co-morbid conditions, fewer complications, and a higher ejection fraction (EF) than in-hospital-treated patients (n=3685). Median time from symptom onset to treatment was 113 min for PHT and 165 min for in-hospital thrombolysis. One-year mortality was 7.2 vs. 11.8% for PHT and in-hospital thrombolysis, respectively. In a multivariable analysis, after adjusting for baseline characteristics and rescue angioplasty, PHT was associated with lower 1-year mortality (odds ratio 0.71, 0.55-0.92, P=0.008).

CONCLUSION

When compared with regular in-hospital thrombolysis, pre-hospital diagnosis and thrombolysis with trained paramedics in the ambulances are associated with reduced time to thrombolysis by almost 1 h and reduced adjusted 1-year mortality by 30% in real-life STEMI patients.

Aborted myocardial infarction: a new target for reperfusion therapy

Reperfusion therapy for ST-elevation acute coronary syndromes aims at early and complete recanalization of the infarct-related artery in order to salvage myocardium and improve both early and late clinical outcomes. Myocardial necrosis is usually confirmed and quantified by myocardial enzyme release in plasma. However, over 10% of patients treated with reperfusion therapy fail to develop an enzyme rise, but do exhibit transient ECG changes, which are consistent with an aborted myocardial infarction. The earlier the reperfusion therapy is instituted, the higher the incidence of aborted infarction. Treatment within an hour after symptom onset may result in 25% of aborted infarction and is in combination with complete (70%) ST-segment resolution associated with better survival. This endpoint is easy to define and occurs promptly in time. The faster that effective treatment is initiated, the more likely aborted infarction will occur. Given that mortality, re-infarction, and stroke are declining in incidence, we suggest the introduction of aborted infarction as an endpoint in clinical trials of ST-elevation acute coronary syndromes.

Duration of ischemia is a major determinant of transmurality and severe microvascular obstruction after primary angioplasty: a study performed with contrast-enhanced magnetic resonance

OBJECTIVES

This study sought to assess the relationship between duration of ischemia and both myocardial transmural necrosis (TN) and severe microvascular obstruction (SMO), by contrast-enhanced magnetic resonance (CE-MR), in patients with acute myocardial infarction (AMI) treated with angioplasty (PCI), and to estimate the risk of TN and SMO with the duration of ischemia.

BACKGROUND

The impact of ischemic time on myocardial and microvascular injury is not well characterized in people.

METHODS

We performed CE-MR in 77 patients with first AMI, 5 +/- 3 days after successful PCI. The AMI was labeled as transmural if hyperenhancement at CE-MR was extended to > or =75% of the thickness in two or more ventricular segments. The SMO was identified as areas of late hypoenhancement surrounded by hyperenhanced tissue. The relationship between ischemic time and CE-MR evidence of SMO or TN was evaluated by logistic regression.

RESULTS

Thirteen patients were excluded because of preprocedural Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 of the infarct-related artery. For the remaining 64 patients, the mean time to treatment was 190 +/- 110 min, 45 (65%) patients had TN and 23 (39%) had SMO. Mean pain to balloon time was 90 +/- 40 min, 110 +/- 107 min, and 137 +/- 97 min in patients without TN and SMO, with TN but without SMO, or with both TN and SMO, respectively (p = 0.001). Multivariate analysis showed that time delay was significantly associated both with TN (odds ratio per 30 min, 1.37, p = 0.032), and SMO (odds ratio per 30 min, 1.21; p = 0.021).

CONCLUSIONS

In AMI patients with impaired coronary perfusion undergoing PCI, the risk of TN and SMO increases with the duration of the ischemic time.

Aborted myocardial infarction: a clinical-magnetic resonance correlation

This report illustrates a magnetic resonance image of aborted myocardial infarction after primary angioplasty. Myocardial oedema in the absence of late enhancement seems to be the magnetic resonance marker of the myocardium at risk of infarction that has been reperfused within 30 minutes and aborted in the clinic.

Plaque instability frequently occurs days or weeks before occlusive coronary thrombosis: a pathological thrombectomy study in primary percutaneous coronary intervention

BACKGROUND

Acute ST-elevation myocardial infarction (STEMI) is caused by sudden occlusive coronary thrombosis, after plaque disruption; however, a considerable time interval between plaque disturbance and the onset of symptoms has been suggested. We therefore studied the age of intracoronary thrombi, aspirated during angioplasty in patients with acute STEMI.

METHODS AND RESULTS

Percutaneous intracoronary thrombectomy during angioplasty was performed in 211 consecutive STEMI patients within 6 hours after onset of anginal symptoms. The aspirated material was histologically screened on thrombus and plaque components, and thrombus age was classified as fresh (<1 day), lytic thrombus (1 to 5 days), and organized thrombus (>5 days). In all patients, intracoronary-derived material was retrieved in the filter of the collection bottle. Thrombus was identified in 199 (95%) of 211 patients. In 12 patients (5%), only plaque components were identified, and in 85 patients (41%), both thrombus and plaque material were aspirated. In 18 (9%) of 199 patients, the thrombus was organized, and in 70 patients (35%), the thrombus showed lytic changes, whereas in 98 (49%), a completely fresh thrombus was found. In 14 (7%) of 199 patients, the thrombus showed combined features of both fresh thrombus and organized thrombus.

CONCLUSIONS

In at least 50% of patients with acute STEMI, coronary thrombi were days or weeks old. This indicates that sudden coronary occlusion is often preceded by a variable period of plaque instability and thrombus formation, initiated days or weeks before onset of symptoms.

Reduction of treatment delay in patients with ST-elevation myocardial infarction: impact of pre-hospital diagnosis and direct referral to primary percutanous coronary intervention

AIMS

The majority of patients with ST-elevation myocardial infarction (STEMI) are admitted to local hospitals without primary percutaneous coronary intervention (primary PCI) facilities. Acute transferral to an interventional centre is necessary to treat these patients with primary PCI. The present study assessed the reduction in treatment delay achieved by pre-hospital diagnosis and referral directly to an interventional centre.

METHODS AND RESULTS

Two local hospitals without primary PCI facilities were serving the study region. Pre-hospital diagnoses were established with the use of telemedicine, by ambulance physicians, or by general practitioners. Primary PCI was accepted as the preferred reperfusion therapy in patients with STEMI. From 31 October 2002 to 31 January 2004 all patients transported by ambulance and transferred for primary PCI were registered. Patients with STEMI were divided into three groups: (A) patients diagnosed at a local hospital (n = 55), (B) patients diagnosed pre-hospitally and admitted to a local hospital (n = 85), and (C) patients diagnosed pre-hospitally and referred directly to the interventional centre (n = 21). When comparing group A with group B and C, no difference was found in age, sex, infarct location, or distance from the scene of event to the interventional centre, whereas the median time from ambulance call to first balloon inflation was 41 min shorter in group B compared with group A (P<0.001) and 81 min shorter in group C compared with group A (P<0.001).

CONCLUSION

In a cohort of patients scheduled for admission to a local hospital and subsequent transferral to an interventional centre for primary PCI, those diagnosed pre-hospitally had shorter treatment delay compared with those diagnosed in hospital, both in the setting of initial admission to a local hospital, and to an even larger extent in the setting of referral directly to the interventional centre.