Primary Percutaneous Coronary Intervention as a National Reperfusion Strategy in Patients With ST-Segment Elevation Myocardial Infarction

A Guide to Implementation Science for Phase 3 Clinical Trialists: Designing Trials for Evidence Uptake

The delayed and modest uptake of evidence-based treatments following cardiovascular clinical trials highlights the need for greater attention to implementation early in the development and testing of treatments. However, implementation science is not well understood and is often an afterthought following phase 3 trials. In this review, we describe the goals, frameworks, and methods of implementation science, along with common multilevel barriers and facilitators of implementation. We propose that some of the approaches used for implementation well after a trial has ended can be incorporated into the design of phase 3 trials to foster early post-trial implementation. Approaches include, but are not limited to, engaging broad stakeholders including patients, clinicians, and decision-makers in trial advisory boards; using less restrictive eligibility criteria that ensure both internal validity and generalizability; having trial protocols reviewed by regulators; integrating trial execution with the health care system; evaluating and addressing barriers and facilitators to deployment of the intervention; and undertaking cost-effectiveness and cost utility analyses across jurisdictions. We provide case examples to highlight concepts and to guide end-of-trial implementation.

10-Year Mortality After ST-Segment Elevation Myocardial Infarction Compared to the General Population

BACKGROUND

ST-segment elevation myocardial infarction (STEMI) is associated with high early mortality. However, it remains unclear if patients surviving the early phase have long-term excess mortality.

OBJECTIVES

This study aims to assess excess mortality in STEMI patients treated with primary percutaneous coronary intervention (PCI) compared with an age- and- sex-matched general population at landmark periods 0 to 30 days, 31 to 90 days, and 91 days to 10 years.

METHODS

Using the Western Denmark Heart Registry, we identified first-time PCI-treated patients who had primary PCI for STEMI from January 2003 to October 2018. Each patient was matched by age and sex to 5 individuals from the general population.

RESULTS

We included 18,818 patients with first-time STEMI and 94,090 individuals from the general population. Baseline comorbidity burden was similar in STEMI patients and matched individuals. Compared with the matched individuals, STEMI was associated with a 5.9% excess mortality from 0 to 30 days (6.0% vs 0.2%; HR: 36.44; 95% CI: 30.86-43.04). An excess mortality remained present from 31 to 90 days (0.9% vs 0.4%; HR: 2.43; 95% CI: 2.02-2.93). However, in 90-day STEMI survivors, the absolute excess mortality was only 2.1 percentage points at 10-year follow-up (26.5% vs 24.5%; HR: 1.04; 95% CI: 1.01-1.08). Use of secondary preventive medications such as statins, antiplatelet therapy, and beta-blockers was very high in STEMI patients throughout 10-year follow-up.

CONCLUSIONS

In primary PCI-treated STEMI patients with high use of guideline-recommended therapy, patients surviving the first 90 days had 10-year mortality that was only 2% higher than that of a matched general population.

Temporal trends in socioeconomic disparity in clinical outcomes for patients with acute coronary syndrome

AIMS

Socioeconomic factors are well-established determinants of clinical outcomes among patients with acute coronary syndrome (ACS) although quality of care has improved the last decades. This study aims to investigate 20-years temporal trends of socioeconomic disparity in 1-year incidence of major adverse cardiac events (MACE) among ACS patients in Denmark.

METHODS

This population-based cohort study included all incident ACS patients in the Danish National Patient Registry during 1998-2017. Socioeconomic disparity was assessed by income and educational level. Patients were followed 1-year for MACE; defined as all-cause mortality, recurrent ACS, revascularization, stroke, or cardiac arrest. Adjusted MACE incidence rates (aIR) and hazard rate ratios (aHR) were computed with 95 % confidence intervals (CI) for five-year-periods. Changes in trends were examined from interaction analyses between the HR for five-year-periods and income and education, respectively.

RESULTS

The study included 220,887 patients with first-time ACS. The incidence of MACE decreased within all income and education levels. In 1998-2002 the MACE aIR among patients with low income was 885[95%CI:863-907] versus 733[711-756]/1000-person-year among those with high income (aHR: 1.19[95%CI:1.15-1.23]). The aIRs decreased to 506[489-522] and 405[388-423]/1000-person-year, respectively, in 2013-2017 (aHR: 1.23[1.17-1.29]). The aIRs of MACE decreased correspondingly within all educational levels from 1998 to 2002 to 2013-2017. However, the socioeconomic disparity according to the interaction analyses persisted both according to income and educational level.

CONCLUSION

Although 1-year clinical outcomes following ACS has improved substantially over the last decades, socioeconomic disparity persisted both according to income and education level.

Time trends in income-related disparity in incidence of acute coronary syndrome

BACKGROUND

Higher incidence of acute coronary syndrome (ACS), among those with lower income, has been recognized in the most recent decades. Still, there is a paucity of data on temporal changes. This study aims to investigate 20-year time trends in income-related disparity in the incidence of ACS in Denmark.

METHODS

This Population-based repeated cross-sectional study included all patients with first-time ACS, aged ≥20 years, registered in the Danish National Patient Registry 1998-2017. Aggregated sociodemographic data for the Danish population was accessed from Statistics Denmark. Yearly incidence rates (IR) and incidence rate ratios (IRR), with the highest-income quartile as a reference, were standardized using cell-specific personal equivalent income according to year, sex and age group with 95% confidence intervals. Interaction analysis was executed for differences in IR of ACS between the lowest- and highest-income quartile over time.

RESULTS

A total of 220 070 patients hospitalized with ACS from 1998 to 2017 were identified. The yearly standardized ACS IRs decreased in all income quartiles. However, the IR remained higher in the lowest-income quartile compared to the highest for both men [1998: IRR 1.45 (95% confidence interval, CI 1.39-1.52) and 2017: 1.47 (1.40-1.54)] and women [1998: IRR 1.73 (1.64-1.82) and 2017: 1.76 (1.65-1.88)]. Interaction analysis showed that over the period the difference in IR between the lower- and the highest-income quartile decreased with 1-5 ACS cases per 100 000 person-year.

CONCLUSION

Income-related disparity in the incidence of ACS was present in Denmark between 1998 and 2017. Despite a marked overall decrease in the yearly ACS incidence, the extent of income-related disparity remained unchanged.

Mortality Trends After Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction

BACKGROUND

Observational studies have reported that mortality rates after ST-segment elevation myocardial infarction (STEMI) have been stable since 2006 to 2010.

OBJECTIVES

The aim of this study was to evaluate the temporal trends in 1-year, 30-day, and 31- to 365-day mortality after STEMI in Western Denmark where primary percutaneous coronary intervention (PCI) has been the national reperfusion strategy since 2003.

METHODS

Using the Western Denmark Heart Registry, the study identified first-time PCI-treated patients undergoing primary PCI (pPCI) for STEMI from 2003 to 2018. Based on the year of pPCI, patients were divided into 4 time-interval groups and followed up for 1 year using the Danish national health registries.

RESULTS

A total of 19,613 patients were included. Median age was 64 years, and 74% were male. One-year mortality decreased gradually from 10.8% in 2003-2006, 10.4% in 2007-2010, 9.1% in 2011-2014, to 7.7% in 2015-2018 (2015-2018 vs 2003-2006: adjusted HR [aHR]: 0.71; 95% CI: 0.62-0.82). The largest absolute mortality decline occurred in the 0- to 30-day period with a 2.3% reduction (aHR: 0.69; 95% CI: 0.59-0.82), and to a lesser extent in the 31- to 365-day period (risk reduction: 1.0%; aHR: 0.71; 95% CI: 0.56-0.90).

CONCLUSIONS

In a high-income European country with a fully implemented pPCI strategy, 1-year mortality in pPCI-treated patients with STEMI decreased substantially between 2003 and 2018. Approximately three-quarters of the absolute mortality reduction occurred within the first 30 days after pPCI. These results indicate that optimization of early management of pPCI-treated patients with STEMI offers great opportunities for improving overall survival in contemporary clinical practice.

Use of Helicopters to Reduce Health Care System Delay in Patients With ST-Elevation Myocardial Infarction Admitted to an Invasive Center

Timely reperfusion in ST-elevation myocardial infarction (STEMI) is essential. This study aimed to evaluate the reduction in system delay (time from emergency medical service [EMS] call to primary percutaneous coronary intervention [PPCI]) in patients with STEMI when using helicopter EMS (HEMS) rather than ground-based EMS (GEMS). This was a retrospective, nationwide cohort study of consecutive patients with STEMI treated with PPCI at 5 PPCI centers in Denmark. Polynomial spline curves were constructed to describe the association between system delay and distance to the PPCI center stratified by transportation mode. A total of 26,433 patients with STEMI were treated with PPCI between January 1, 1999, and December 31, 2016. In 16,436 patients field triaged directly to the PPCI center, the proportion treated within 120 minutes of the EMS call was 75% for those living 0 to 25 km from the PPCI center compared with 65% for all patients transported by GEMS (median transport distance 50 km [interquartile range 23 to 90]) and 64% for all patients transported by HEMS (median transport distance 119 km [interquartile range 99 to 142]). The estimated reduction in system delay owed to using HEMS rather than GEMS was 14, 16, 20, and 29 minutes for patients living 75, 100, 125, and 170 km from a PPCI center. In conclusion, this study confirmed that using HEMS ensures that most patients with STEMI, living up to 170 km from a PPCI center, can be treated within 120 minutes of their EMS call provided they are field triaged directly to the PPCI center.

Clinical outcome following late reperfusion with percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction

BACKGROUND

Up to 40% of patients with ST-segment elevation myocardial infarction (STEMI) present later than 12 hours after symptom onset. However, data on clinical outcomes in STEMI patients treated with primary percutaneous coronary intervention 12 or more hours after symptom onset are non-existent. We evaluated the association between primary percutaneous coronary intervention performed later than 12 hours after symptom onset and clinical outcomes in a large all-comer contemporary STEMI cohort.

METHODS

All STEMI patients treated with primary percutaneous coronary intervention in eastern Denmark from November 2009 to November 2016 were included and stratified by timing of the percutaneous coronary intervention. The combined clinical endpoint of all-cause mortality and hospitalisation for heart failure was identified from nationwide Danish registries.

RESULTS

We included 6674 patients: 6108 (92%) were treated less than 12 hours and 566 (8%) were treated 12 or more hours after symptom onset. During a median follow-up period of 3.8 (interquartile range 2.3-5.6) years, 30-day, one-year and long-term cumulative rates of the combined endpoint were 11%, 17% and 25% in patients treated 12 or fewer hours and 21%, 29% and 37% in patients treated more than 12 hours (P<0.001 for all) after symptom onset. Late presentation was independently associated with an increased risk of an adverse clinical outcome (hazard ratio 1.42, 95% confidence interval 1.22-1.66; P<0.001).

CONCLUSIONS

Increasing duration from symptom onset to primary percutaneous coronary intervention was associated with an increased risk of an adverse clinical outcome in patients with STEMI, especially when the delay exceeded 12 hours.

A simple score for the prediction of stent thrombosis in patients with ST elevation myocardial infarction: TIMI risk index

Introduction: The present study aimed to evaluate the potential utility of thrombosis in myocardial infarction (TIMI) risk index (TRI) for the prediction of stent thrombosis (ST) in ST elevation myocardial infarction (STEMI) patients who were treated with primary percutaneous coronary intervention ( pPCI ). Methods: This retrospective study was related to the clinical data of 1275 consecutive STEMI patients who underwent pPCI from January 2013 to January 2018. The TRI was calculated for each patient, and the following equation was used; TRI = heart rate x [age/10]2/systolic blood pressure. For the definition of ST, the criteria as proposed by the Academic Research Consortium were applied. Results: The incidence of ST was 3.2% (n=42 patients) in the study. The median value of the TRI was significantly elevated in patients with ST compared to those without ST (22 [17-32] vs. 16 [11-21], P<0.001, respectively). In a multivariate logistic regression analysis, the TRI was an independent predictor of ST (odds ratio [OR]: 1.061; 95% CI: 1.038-1.085; P<0.001). In a receiver operating characteristic curve analysis, the optimal value of the TRI for the prediction of ST was 25.8 with a sensitivity of 45.2% and a specificity of 86.4%. Conclusion: The present study finding has demonstrated that the TRI may be an independent predictor of ST in STEMI patients who were treated with pPCI . To the best of our knowledge, this is the first study in the literature in which the TRI and its relationship with ST was evaluated in STEMI patients treated with pPCI .

Cardiac Myosin-Binding Protein C to Diagnose Acute Myocardial Infarction in the Pre-Hospital Setting

Background Early triage is essential to improve outcomes in patients with suspected acute myocardial infarction (AMI). This study investigated whether cMyC (cardiac myosin-binding protein), a novel biomarker of myocardial necrosis, can aid early diagnosis of AMI and risk stratification. Methods and Results cMyC and high-sensitivity cardiac troponin T were retrospectively quantified in blood samples obtained by ambulance-based paramedics in a prospective, diagnostic cohort study. Patients with ongoing or prolonged periods of chest discomfort, acute dyspnoea in the absence of known pulmonary disease, or clinical suspicion of AMI were recruited. Discrimination power was evaluated by calculating the area under the receiver operating characteristics curve; diagnostic performance was assessed at predefined thresholds. Diagnostic nomograms were derived and validated using bootstrap resampling in logistic regression models. Seven hundred seventy-six patients with median age 68 [58;78] were recruited. AMI was the final adjudicated diagnosis in 22%. Median symptom to sampling time was 70 minutes. cMyC concentration in patients with AMI was significantly higher than with other diagnoses: 98 [43;855] versus 17 [9;42] ng/L. Discrimination power for AMI was better with cMyC than with high-sensitivity cardiac troponin T (area under the curve, 0.839 versus 0.813; P=0.005). At a previously published rule-out threshold (10 ng/L), cMyC reaches 100% sensitivity and negative predictive value in patients after 2 hours of symptoms. In logistic regression analysis, cMyC is superior to high-sensitivity cardiac troponin T and was used to derive diagnostic and prognostic nomograms to evaluate risk of AMI and death. Conclusions In patients undergoing blood draws very early after symptom onset, cMyC demonstrates improved diagnostic discrimination of AMI and could significantly improve the early triage of patients with suspected AMI.

Predictive value of routine point-of-care cardiac troponin T measurement for prehospital diagnosis and risk-stratification in patients with suspected acute myocardial infarction

OBJECTIVE

The purpose of this study was to determine the predictive value of routine prehospital point-of-care cardiac troponin T measurement for diagnosis and risk stratification of patients with suspected acute myocardial infarction.

METHODS AND RESULTS

All prehospital emergency medical service vehicles in the Central Denmark Region were equipped with a point-of-care cardiac troponin T device (Roche Cobas h232) for routine use in all patients with a suspected acute myocardial infarction. During the study period, 1 June 2012-30 November 2015, prehospital point-of-care cardiac troponin T measurements were performed in a total of 19,615 cases seen by the emergency medical service and 18,712 point-of-care cardiac troponin T measurements in 15,781 individuals were matched with an admission. A final diagnosis of acute myocardial infarction was confirmed in 2187 cases and a total of 2150 point-of-care cardiac troponin T measurements (11.0%) had a value ≥50 ng/l, including 966 with acute myocardial infarction (sensitivity: 44.2%, specificity: 92.8%). Patients presenting with a prehospital point-of-care cardiac troponin T value ≥50 ng/l had a one-year mortality of 24% compared with 4.8% in those with values <50 ng/l, log-rank: p<0.001. The following variables showed the strongest association with mortality in multivariable analysis: point-of-care cardiac troponin T≥50 ng/l (hazard ratio 2.10, 95% confidence interval: 1.90-2.33), congestive heart failure (hazard ratio 1.93, 95% confidence interval: 1.74-2.14), diabetes mellitus (hazard ratio 1.42, 95% confidence interval: 1.27-1.59) and age, one-year increase (hazard ratio 1.08, 95% confidence interval: 1.08-1.09).

CONCLUSIONS

Patients with suspected acute myocardial infarction and a prehospital point-of-care cardiac troponin T ≥50 ng/l have a poor prognosis irrespective of the final diagnosis. Routine troponin measurement in the prehospital setting has a high predictive value and can be used to identify high-risk patients even before hospital arrival so that they may be re-routed directly for advanced care at an invasive centre.

Denmark: coronary and structural heart interventions from 2010 to 2015

Interventional cardiology in Denmark has been carried out since the mid 1980s. Interventional cardiology is only performed at a few high-volume centres. Healthcare coverage is universal and is essentially free of charge. Hospitals are mostly publicly owned and financed by fixed budgets and, in part, an activity-based funding system. Approximately 30,000 coronary angiographies (CAG), 10,000 percutaneous coronary interventions (PCIs) of which approximately 25% are primary PCIs, and 500 transcatheter aortic valve implantations (TAVIs) are carried out each year. The numbers of CAG and PCI have reached a plateau in recent years, whereas structural heart interventions, in particular TAVI, are increasing. Around 90% of all patients treated with PCI have a stent implanted, with more than 95% of these being drug-eluting stents. There is a low but increasing use of bioabsorbable scaffolds and drug-eluting balloons.

Prehospital diagnosis of patients with acute myocardial infarction

Primary percutaneous intervention (PPCI) is the preferred treatment in patients with ST elevation myocardial infarction (STEMI) if this can be performed in a timely manner. The

Dyspnea, a high-risk symptom in patients suspected of myocardial infarction in the ambulance? A population-based follow-up study

BACKGROUND

Systematic management of patients suffering high-risk symptoms is essential in emergency medical services. Patients with chest pain receive algorithm-based work-up and treatment. Though dyspnea is recognized as an independent predictor of mortality, no generally accepted prehospital treatment algorithm exists and this may affect outcome. The objective of this study was to compare mortality in patients suspected of myocardial infarction (MI) presenting with dyspnea versus chest pain in the ambulance.

METHODS

Follow-up study in patients undergoing electrocardiogram-based telemedical triage because of suspected MI in an ambulance in the Central Denmark Region from 1 June 2008 to 1 January 2013. Primary outcome was 30-day mortality. Secondary outcomes were 4-year mortality and mortality rates in subgroups of patients with and without a confirmed MI. Absolute risk differences adjusted for comorbidity, age, systolic blood pressure and heart rate were calculated by a generalized linear regression model.

RESULTS

Of 17,398 patients, 12,230 (70%) suffered from chest pain, 1464 (8%) from dyspnea, 3540 (20%) from other symptoms and 164 (1%) from cardiac arrest. Among patients with dyspnea, 30-day mortality was 13% (CI 12-15) and 4-year mortality was 50% (CI 47-54) compared to 2.9% (CI 2.6-3.2) and 20% (CI 19-21) in patients with chest pain. MI was confirmed in 121 (8.3%) patients with dyspnea and in 2319 (19%) with chest pain. Patients with dyspnea and confirmed MI had a 30-day and 4-year mortality of 21 % (CI 15-30) and 60% (CI 50-70) compared to 5.0% (CI 4.2-5.8) and 23% (CI 21-25) in patients with chest pain and confirmed MI. Adjusting for age, comorbidity, systolic blood pressure and heart rate did not change these patterns.

CONCLUSION

Patients suspected of MI presenting with dyspnea have significantly higher short- and long-term mortality than patients with chest pain irrespective of a confirmed MI diagnosis. Future studies should examine if supplementary prehospital diagnostics can improve triage, facilitate early therapy and improve outcome in patients presenting with dyspnea.

Time to treatment-door-to-balloon time is not everything

International guidelines for the management of patients with ST-elevation myocardial infarction (STEMI) recommend various performance measures to monitor the quality of STEMI systems of care. Door-to-balloon (D2B) time (arrival at hospital to percutaneous coronary intervention, PCI) and overall health care system delay (first medical contact to reperfusion) are acknowledged as valuable performance measures when treating patients with primary percutaneous coronary intervention (PPCI). However, there is confusion regarding the exact definition of these performance measures, and moreover system delay and PCI-related delay (the extra delay acceptable to perform PPCI instead of fibrinolysis) are often used synonymously, which add confusion when considering reperfusion strategy. The present paper calls for a consensus regarding the use and definition of objective performance measures when treating patients with STEMI, and exemplifies why it is insufficient just to focus on D2B time.

Nationwide Analysis of Patients With ST-Segment–Elevation Myocardial Infarction Transferred for Primary Percutaneous Intervention

Background—

Current American College of Cardiology/American Heart Association guidelines recommend transfer and primary percutaneous coronary intervention (PCI) for ST-segment–elevation myocardial infarction (STEMI) patients within the time limit of first contact to device ≤120 minutes. We determined the hospital-level, patient-level, and process characteristics of timely versus delayed primary PCI for a diverse national sample of transfer patients confined to a travel distance that facilitates the process.

Methods and Results—

We studied 14 518 patients transferred from non–PCI-capable hospitals for primary PCI to 398 National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With The Guidelines hospitals between July 2008 and December 2012. Patients with estimated transfer times >60 minutes (by Google Maps driving times) were excluded from the analysis. Patients achieving first door-to-device time ≤120 minutes were compared with patients with delayed treatment; independent predictors of timely treatment were determined using generalized estimating equations logistic regression models. The median estimated transfer distance was 26.5 miles. First door-to-device ≤120 minutes was achieved in 65% of patients (n=9380); only 37% of the hospitals were high-performing hospitals (defined as risk-adjusted rate, ≥75% of transfer STEMI patients with ≤120-minute first door-to-device time). In addition to known predictors of delay (cardiogenic shock, cardiac arrest, and prolonged door-in door-out time), STEMI referral hospitals’ rural location and longer estimated transfer time were identified as predictors of delay. In this diverse national sample, regional and racial variations in care were observed. Finally, lower PCI hospital annual STEMI volume was a potent predictor of delay.

Conclusions—

More than one third of US STEMI patients transferred for primary PCI fail to achieve first door-to-device time ≤120 minutes, despite estimated transfer times <60 minutes. Delays are related to process variables, comorbidities, and lower annual PCI hospital STEMI volumes.

Outcomes of patients calling emergency medical services for suspected acute cardiovascular disease

Adequate health care is increasingly dependent on prehospital systems and cardiovascular (CV) disease remains the most common cause for hospital admission. However the prevalence of CV dispatches of emergency medical services (EMS) is not well reported and survival data described in clinical trials and registries are subject to selection biases. We aimed to describe the prevalence and prognosis of acute CV disease and the effect of invasive treatment, in an unselected and consecutive prehospital cohort of 3,410 patients calling the national emergency telephone number from 2005 to 2008 with follow-up in 2013. Individual-level data from national registries were linked to the dedicated EMS database of primary ambulance dispatches supported by physician-manned emergency units. Outcome data were obtained from the Central Population Registry, the National Patient Registry, and the National Registry of Causes of Death. In patients calling the national emergency telephone number, a CV related ambulance alarm code was given in 2,541 patients of 3,410 patients (74.5%) resulting in 2,056 of 3,410 primary CV discharge diagnoses (60.3%) with a 30-day and 5-year all-cause mortality of 24.5% and 46.4%, respectively. Stroke, acute heart failure, and ST-segment elevation myocardial infarction (STEMI) carried a 25- to 50-fold adjusted mortality hazard during the first 4 days. In patients with suspected STEMI, 90.5% had an acute angiography performed. Nontransferred, nonreperfused patients with STEMI (9.1%) carried 80% short-term mortality. Noninvasive management of non-ST-segment elevation myocardial infarction was common (37.9%) and associated with an increased adjusted long-term mortality hazard (hazard ratio 4.17 [2.51 to 8.08], p <0.001). Survival in 447 out-of-hospital cardiac arrest patients (13.1%) was 11.6% at 30 days. In conclusion, patients with a CV ambulance alarm call code and a final CV discharge diagnosis constitute most patients handled by EMS with an extremely elevated short-term mortality hazard and a poor long-term prognosis. Although co-morbidities and frailty may influence triage, this study emphasizes the need for an efficient prehospital phase with focus on CV disease and proper triage of patients suitable for invasive evaluation if the outcomes of acute heart disease are to be improved further in the current international context of hospitals merging into highly specialized entities resulting in longer patient transfers.

The impact of direct admission to a catheterisation lab/CCU in patients with ST-elevation myocardial infarction on the delay to reperfusion and early risk of death: results of a systematic review including meta-analysis

Background

For each hour of delay from fist medical contact until reperfusion in ST-elevation myocardial infarction (STEMI) there is a 10% increase in risk of death and heart failure. The aim of this review is to describe the impact of the direct admission of patients with STEMI to a Catheterisation laboratory (cath lab) as compared with transport to the emergency department (ED) with regard to delays and outcome.

Methods

Databases were searched for from April-June 2012 and updated January 2014: 1) Pubmed; 2) Embase; 3) Cochrane Library; 4) ProQuest Nursing and 5) Allied Health Sources. The search was restricted to studies in English, Swedish, Danish and Norwegian languages.

The intervention was a protocol-based clinical pre-hospital pathway and main outcome measurements were the delay to balloon inflation and hospital mortality.

Results

Median delay from door to balloon was significantly shorter in the intervention group in all 5 studies reported. Difference in median delay varied between 16 minutes and 47 minutes.

In all 7 included studies the time from symptom onset or first medical contact to balloon time was significantly shorter in the intervention group. The difference in median delay varied between 15 minutes and 1 hour and 35 minutes. Only two studies described hospital mortality. When combined the risk of death was reduced by 37%.

Conclusion

An overview of available studies of the impact of a protocol-based pre-hospital clinical pathway with direct admission to a cath lab as compared with the standard transport to the ED in ST-elevation AMI suggests the following. The delay to the start of revascularisation will be reduced. The clinical benefit is not clearly evidence based. However, the documented association between system delay and outcome defends the use of the pathway.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-014-0067-x) contains supplementary material, which is available to authorized users.

Diagnostic accuracy of ST-segment elevation myocardial infarction by various healthcare providers

BACKGROUND

This study aimed to compare the accuracy of ECG interpretation for diagnosis of STEMI by different groups of healthcare professionals involved in the STEMI program at our institution.

METHODS

We selected 21 ECGs from patients with typical symptoms of MI that were diagnosed with STEMI, and 10 ECGs of STEMI mimics. STEMI mimic ECGs were repeated in the package with a story of typical and atypical chest pain. ECGs were interpreted to diagnose STEMI and identify need for initiation of the cardiac catheterization lab (CCL). Participants identified confidence in STEMI recognition, and average number of ECGs read per week.

RESULTS

A total of 64 participants completed the study package. Cardiologists were more likely to provide correct interpretation compared to other groups. False positive diagnoses were more likely made by paramedics when compared to cardiologists (p < 0.01). There was a positive correlation between increased exposure to ECGs and accurate STEMI diagnosis (r = 0.482, p < 0.001). A threshold of ≥ 20 ECGs read per week showed a statistically significant improvement in accuracy (p < 0.001). Self-reported confidence correlated positively with accuracy (r = 0.402, p =< 0.001). Changing the ECG narrative of the STEMI mimic ECGs had a significant effect on interpretation between groups (p = 0.043).

CONCLUSIONS

Our study showed that healthcare profession and number of ECGs reviewed per week are predictive of the accuracy of ECG interpretation of STEMI. Cardiologists are the most accurate diagnosticians, and are the least likely to falsely activate the CCL. Weekly exposure of ≥ 20 ECGs may improve diagnostic accuracy regardless of underlying experience.

How can we optimize the processes of care for acute coronary syndromes to improve outcomes?

Acute coronary syndromes (ACS), either ST-elevation myocardial infarction or non-ST-elevation ACS, are still one of the most common cardiac emergencies with substantial morbidity and mortality. The availability of evidence-based treatments, such as early and intense platelet inhibition and anticoagulation, and timely reperfusion and revascularization, has substantially improved outcomes in patients with ACS. The implementation of streamlined processes of care for patients with ST-elevation myocardial infarction and non-ST-elevation ACS over the last decade including both appropriate tools, especially cardiac troponin, for rapid diagnosis and risk stratification and for decision support, and the widespread availability of modern antithrombotic and interventional treatments, have reduced morbidity and mortality to unprecedented low levels. These changes in the process of care require a synchronized approach, and research using a team-based strategy and effective regional networks has allowed healthcare systems to provide modern treatments for most patients with ACS. There are still areas needing improvement, such as the delivery of care to people in rural areas or with delayed time to treatment.

Quantitative point-of-care troponin T measurement for diagnosis and prognosis in patients with a suspected acute myocardial infarction

Improvement of prehospital triage is essential to ensure rapid management of patients with acute myocardial infarction (AMI). This study evaluates the feasibility of prehospital quantitative point-of-care cardiac troponin T (POC-cTnT) analysis, its ability to identify patients with AMI, and its capacity to predict mortality. The study was performed in the Central Denmark Region from May 2010 to May 2011. As a supplement to electrocardiography, a prehospital POC-cTnT measurement was performed by a paramedic in patients with suspected AMI. AMI was diagnosed according to the universal definition of myocardial infarction using the ninety-ninth percentile upper reference level as diagnostic cut point. The paramedics performed POC-cTnT measurements in 985 subjects with a symptom duration of 70 minutes (95% CI, 35 to 180); of whom, 200 (20%) had an AMI. The prehospital sample was obtained 88 minutes (range, 58 to 131) before the sample made on admission to the hospital. The sensitivity for detection of patients with an AMI was 39% (95% CI, 32% to 46%) and the diagnostic accuracy of the POC-cTnT values was 0.67 (95% CI, 0.64 to 0.71). Adjusted survival analysis showed a strong significant association between elevated prehospital POC-cTnT level above the detection level of 50 ng/L and mortality in patients with a suspected AMI irrespective of whether an AMI was diagnosed. In conclusion, large-scale quantitative prehospital POC-cTnT testing by paramedics is feasible. An elevated prehospital POC-cTnT value contains diagnostic information and is highly predictive of mortality in patients with a suspected AMI.

Positive predictive value of clinically suspected ST-segment elevation myocardial infarction using angiographic verification

Fibrinolysis has not been used for the treatment of ST-segment elevation myocardial infarction (STEMI) in Denmark since 2005. We aimed to assess the positive predictive value of clinically suspected STEMI among consecutive patients in a real-world setting where all patients with suspected STEMI undergo acute coronary angiography. We evaluated the clinical diagnosis of consecutive patients with suspected STEMI admitted to Aarhus University Hospital between September 1, 2010, and August 31, 2011. Conclusive STEMI was defined as a patient with an identifiable culprit lesion by angiography. Of 615 patients with suspected STEMI, 483 (79%) had conclusive STEMI, and 132 (21%) did not have an identifiable culprit lesion. A higher proportion of patients with conclusive STEMI were men, whereas patients without conclusive STEMI were more likely to have diabetes mellitus (16% vs 10%; p = 0.04), left bundle branch block (24% vs 2%; p <0.001), hypertension (48% vs 36%; p = 0.01), or a history of coronary artery bypass surgery (8% vs 2%; p = 0.001). Compared with the overall 79% with conclusive STEMI, patients with left bundle branch block or a history of coronary artery bypass surgery had positive predictive values of only 26% and 41%, respectively. Our findings thus indicate that a substantial number of patients would have received fibrinolysis, without any potential benefit but with the inherent risk of bleeding complications, if acute angiography had not been an option.

Reperfusion delay in patients treated with primary percutaneous coronary intervention: insight from a real world Danish ST-segment elevation myocardial infarction population in the era of telemedicine

BACKGROUND

Reperfusion delay in ST-segment elevation myocardial infarction (STEMI) predicts adverse outcome. We evaluated time from alarm call (system delay) and time from first medical contact (PCI-related delay), where fibrinolysis could be initiated, to balloon inflation in a pre-hospital organization with tele-transmitted electrocardiograms, field triage and direct transfer to a 24/7 primary percutaneous coronary intervention (PPCI) center.

METHODS AND RESULTS

This was a single center cohort study with long-term follow-up in 472 patients. The PPCI center registry was linked by person identification number to emergency medical services (EMS) and National Board of Health databases in the period of 2005-2008. Patients were stratified according to transfer distances to PPCI into zone 1 (0-25 km), zone 2 (65-100 km) and zone 3 (101-185 km) and according to referral by pre-hospital triage. System delay was 86 minutes (interquartile range (IQR) 72-113) in zone 1, 133 (116-180) in zone 2 and 173 (145-215) in zone 3 (p<0.001). PCI-related delay in directly referred patients was 109 (92-121) minutes in zone 2, but exceeded recommendations in zone 3 (139 (121-160)) and for patients admitted via the local hospital (219 (171-250)). System delay was an independent predictor of mortality (p<0.001).

CONCLUSIONS

Pre-hospital triage is feasible in 73% of patients. PCI-related delay exceeded European Society of Cardiology (ESC) guidelines for patients living >100 km away and for non-directly referred patients. Sorting the PPCI centers catchment area into geographical zones identifies patients with long reperfusion delays. Possible solutions are pharmaco-invasive regiments, research in early ischemia detection, airborne transfer and EMS personnel education that ensures pre-hospital triage.

Strategies TO reduce time delays in patients with AcuTe coronary heart disease treated with primary PCI--the STOP WATCH study: a multistage action research project

OBJECTIVE

To identify, evaluate and reduce system delay times in an ST-elevation myocardial infarction (STEMI) network by targeted reorganisation of logistics and personal feedback to staff on time delays.

DESIGN

Multistage action research project. Three study phases were used (exploration, tailored intervention and evaluation).

SETTING

Single centre study, Sweden.

PATIENTS

Consecutive patients (N=156) with prehospital STEMI onset treated with primary percutaneous coronary intervention (PCI).

INTERVENTIONS

Areas of delays were identified through participant observations and collaborative discussions. To increase the awareness of delay factors, continuous feedback on time delays was given. Elements of the logistics' reorganisation were (1) prioritised ECG recording by emergency medical services personnel, (2) central evaluation of ECG in all patients and (3) start of PCI procedure when two of three PCI team members were on site. Multiple key time measurements were made before (N=67) and after (N=89) the intervention.

MAIN OUTCOMES

Time difference (minutes) in system delay between the preintervention and postintervention phases.

RESULTS

Time from first medical contact (FMC) to a patent artery and time from FMC-to-catheter laboratory (cath-lab) arrival decreased by 6 and 12 min, respectively (ns). Time from FMC-to-ECG recording remained unchanged after the intervention. Time from ECG to decision for primary PCI was reduced by 6 min, p=0.004 and time from ECG-to-cath-lab arrival by 11 min, p=0.02. Total time from diagnosis to a patent artery decreased by 11 min (ns).

CONCLUSIONS

Identification of time delays in an STEMI network with awareness of delay factors, reorganisation of logistics and continuous feedback can reduce system delay times significantly.