Increased deformation of the left ventricle during exercise test measured by global longitudinal strain can rule out significant coronary artery disease in patients with suspected unstable angina pectoris.

BACKGROUND: Noninvasive identification of significant coronary artery disease (CAD) in patients with unstable angina pectoris (UAP) is challenging. Exercise stress testing has been used for years in patients with suspected CAD but has low diagnostic accuracy. The use of Global longitudinal strain (GLS) by speckle tracking echocardiography is a highly sensitive and reproducible parameter for detection of myocardial ischemia. Our aim was to study if identification of normal or ischemic myocardium by measurement of GLS immediately after an ordinary bicycle exercise stress testing in patients with suspected UAP could identify or rule out significant CAD. METHODS: Seventy-eight patients referred for coronary angiography from outpatient clinics and the emergency department with chest pain, inconclusive ECG and normal values of Troponin-T was included. All patients underwent echocardiographic examination at rest and immediately after maximum stress by exercise on a stationary bicycle. Significant CAD was defined by diameter stenosis > 90% by coronary angiography. In patients with coronary stenosis between 50-90%, fractional flow reserve (FFR) was measured and defined abnormal < .80. Analysis of echocardiographic data were performed blinded for angiographic data. Patients were discharged diagnosed with CAD (n = 34) or non-coronary chest pain (NCCP, n = 44). RESULTS: In patients with NCCP, GLS at rest was -21.1 ± 1.7% and -25.5 ± 2.6% at maximum stress (P < .01). In patients with CAD, GLS at rest was -16.8 ± 4.0% and remained unchanged at maximum stress (-16.6 ± 4.6%, P = .69). In patients with NCCP, LVEF was 56.1% ± 6.0 and increased to 61.8% 5.2, P < .01. In CAD patients, LVEF at rest was 54.7% ± 8.6 and increased to 58.2% ± 9.5 during stress, P = .16. In NCCP patients, Wall Motion Score index decreased .02 ± .07, P = .03 during stress and was without significant changes in patients with CAD. Area under the curve (AUC) for distinguishing CAD for was .97 (.95-1.00), .63 (.49-.76), and .71 (.59-.83) for GLS, LVEF, and WMSi, respectively. CONCLUSION: In patients with suspected UAP, increased deformation of the left ventricle measured by GLS immediately after exercise stress testing identified normal myocardium without CAD. Reduced LV contractile function by GLS without increase after exercise identified significant CAD.

Global longitudinal strain is a more reproducible measure of left ventricular function than ejection fraction regardless of echocardiographic training.

BACKGROUND: Left ventricular ejection fraction (LVEF) is an established method for evaluation of left ventricular (LV) systolic function. Global longitudinal strain (GLS) by speckle tracking echocardiography seems to be an important additive method for evaluation of LV function with improved reproducibility compared with LVEF. Our aim was to compare reproducibility of GLS and LVEF between an expert and trainee both as echocardiographic examiner and analyst. METHODS: Forty-seven patients with recent Acute Coronary Syndrome (ACS) underwent echocardiographic examination by both an expert echocardiographer and a trainee. Both echocardiographers, blinded for clinical data and each other's findings, performed image analysis for evaluation of intra- and inter- observer variability. GLS was measured using speckle tracking echocardiography. LVEF was calculated by Simpson's biplane method. RESULTS: The trainee measured a GLS of - 19.4% (±3.5%) and expert - 18.7% (±3.2%) with an Intra class correlation coefficient (ICC) of 0.89 (0.74-0.95). LVEF by trainee was 50.3% (±8.2%) and by expert 53.6% (±8.6%), ICC coefficient was 0.63 (0.32-0.80). For GLS the systematic difference was 0.21% (- 4.58-2.64) vs. 4.08% (- 20.78-12.62) for LVEF. CONCLUSION: GLS is a more reproducible method for evaluation of LV function than LVEF regardless of echocardiographic training.

Mortality in Patients with Acute Coronary Syndrome-A Prospective 5-Year Follow-Up Study.

Our objective was to compare long-term outcomes in patients with non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) between two time periods in Southern Norway. There are limited contemporary data comparing long-term follow-up after revascularization in the last decades. This prospective follow-up study consecutively included both NSTEMI and STEMI patients during two time periods, 2014-2015 and 2004-2009. Patients were followed up for a period of 5 years. The primary outcome was all-cause mortality after 1 and 5 years. A total of 539 patients with acute myocardial infarction (AMI), 316 with NSTEMI (234 included in 2014 and 82 included in 2007) and 223 with STEMI (160 included in 2014 and 63 included in 2004). Mortality after NSTEMI was high and remained unchanged during the two time periods (mortality rate at 1 year: 3.5% versus 4.9%, p = 0.50; and 5 years: 11.4% versus 14.6%, p = 0.40). Among STEMI patients, all-cause mortality at 1 year was reduced in 2014 compared to 2004 (1.3% versus 11.1%, p < 0.001; and 5 years: 7.0% versus 22.2%, p = 0.004, respectively). Time to coronary angiography in NSTEMI patients remained unchanged between 2014 and 2007 (28.2 h [IQR 18.1-46.3] versus 30.3 h [IQR 18.0-48.3], p = 0.20), while time to coronary angiography in STEMI patients was improved in 2014 compared with 2004 (2.8 h [IQR 2.0-4.8] versus 21.7 h [IQR 5.4-27.1], p < 0.001), respectively. During one decade of AMI treatment, mortality in patients with NSTEMI remained unchanged while mortality in STEMI patients decreased, both at 1 and 5 years.

Deep Learning for Improved Precision and Reproducibility of Left Ventricular Strain in Echocardiography: A Test-Retest Study.

AIMS: Assessment of left ventricular (LV) function by echocardiography is hampered by modest test-retest reproducibility. A novel artificial intelligence (AI) method based on deep learning provides fully automated measurements of LV global longitudinal strain (GLS) and may improve the clinical utility of echocardiography by reducing user-related variability. The aim of this study was to assess within-patient test-retest reproducibility of LV GLS measured by the novel AI method in repeated echocardiograms recorded by different echocardiographers and to compare the results to manual measurements. METHODS: Two test-retest data sets (n = 40 and n = 32) were obtained at separate centers. Repeated recordings were acquired in immediate succession by 2 different echocardiographers at each center. For each data set, 4 readers measured GLS in both recordings using a semiautomatic method to construct test-retest interreader and intrareader scenarios. Agreement, mean absolute difference, and minimal detectable change (MDC) were compared to analyses by AI. In a subset of 10 patients, beat-to-beat variability in 3 cardiac cycles was assessed by 2 readers and AI. RESULTS: Test-retest variability was lower with AI compared with interreader scenarios (data set I: MDC = 3.7 vs 5.5, mean absolute difference = 1.4 vs 2.1, respectively; data set II: MDC = 3.9 vs 5.2, mean absolute difference = 1.6 vs 1.9, respectively; all P < .05). There was bias in GLS measurements in 13 of 24 test-retest interreader scenarios (largest bias, 3.2 strain units). In contrast, there was no bias in measurements by AI. Beat-to-beat MDCs were 1,5, 2.1, and 2.3 for AI and the 2 readers, respectively. Processing time for analyses of GLS by the AI method was 7.9 ± 2.8 seconds. CONCLUSION: A fast AI method for automated measurements of LV GLS reduced test-retest variability and removed bias between readers in both test-retest data sets. By improving the precision and reproducibility, AI may increase the clinical utility of echocardiography.

Postsystolic shortening is a strong predictor of recovery of systolic function in patients with non-ST-elevation myocardial infarction.

AIMS: Differentiation between necrotic and viable myocardium is difficult in the setting of acute myocardial infarction (MI). Post-systolic shortening (PSS) has been proposed as a marker of recovery after revascularization, but has not previously been assessed in patients with NSTEMI prior to revascularization. In this study, we aimed to examine the relation between PSS and improvement of contractile function after successful revascularization. METHODS AND RESULTS: Thirty-five patients with non-segment elevation MI and regional systolic dysfunction were examined immediately prior to revascularization, and at follow-up 9 ± 3 months after successful revascularization. Regional systolic function was assessed by speckle tracking echocardiography as regional strain, expressed as mean peak negative longitudinal strain in segments supplied by the culprit artery. Recovery of systolic function was assessed as the difference between regional strain at follow-up and baseline (ΔStrain). Post-systolic shortening was defined as shortening in diastole beyond minimum systolic length. By multivariate regression analysis, several other variables that may affect viability were also assessed. Post-systolic shortening was observed in 32 patients (91%), mean -1.9 ± 1.4%. Mean ΔStrain was -3.3 ± 2.9%. After adjustment for baseline systolic function, PSS (ß = 0.77, P= 0.022), and angiographic severity were independent predictors of viability by multiple regression analysis. Interestingly, troponin T was not a significant predictor. CONCLUSIONS: Post-systolic shortening is associated with improved myocardial function after revascularization in patients with acute MI. It predicts long-term systolic function, and provides information on the potential benefit of the procedure.

The advantage of global strain compared to left ventricular ejection fraction to predict outcome after acute myocardial infarction.

The aim of the study was to compare the ability of global strain and left ventricular ejection fraction (LVEF) to predict outcome after acute myocardial infarction (AMI). Left ventricular (LV) function was measured using strain by Doppler and LVEF in 77 patients. Measurements were performed at admission and after 10 ± 5 days. Outcome was measured as the combined end point of cardiac death, reinfarction and hospitalization for heart failure, unstable angina or life threatening arrhythmia. The patients were followed for 3.29 ± 1.59 years (range 0-5.22 years) and 17 cardiac events were registered. The cutoff value of LVEF was 44% for optimal prediction of outcome. We used LVEF ≤ 44% vs. > 44% and the corresponding global strain value ≥ -15.6% vs. < -15.6% to predict cumulative event-free survival. Both methods significantly predicted cardiac combined events at admittance and after 10 days with no difference. After 10 days, however, global strain remained the only significant predictor of outcome in a multivariate logistic regression model (P < 0.0001, odds ratio 1.79). Interobserver reproducibility measured as intraclass correlation was better for global strain than for LVEF (0.92 vs. 0.71). In conclusion, the measurement of global strain in patients with AMI may predict cardiac combined events to the same extent as LVEF in the acute phase and superior to LVEF after 10 days. In addition, global strain demonstrates better interobserver reproducibility and may become an improved bedside tool to evaluate LV function as a prognostic marker after AMI.

Myocardial Function Imaging in Echocardiography Using Deep Learning.

Deformation imaging in echocardiography has been shown to have better diagnostic and prognostic value than conventional anatomical measures such as ejection fraction. However, despite clinical availability and demonstrated efficacy, everyday clinical use remains limited at many hospitals. The reasons are complex, but practical robustness has been questioned, and a large inter-vendor variability has been demonstrated. In this work, we propose a novel deep learning based framework for motion estimation in echocardiography, and use this to fully automate myocardial function imaging. A motion estimator was developed based on a PWC-Net architecture, which achieved an average end point error of (0.06±0.04) mm per frame using simulated data from an open access database, on par or better compared to previously reported state of the art. We further demonstrate unique adaptability to image artifacts such as signal dropouts, made possible using trained models that incorporate relevant image augmentations. Further, a fully automatic pipeline consisting of cardiac view classification, event detection, myocardial segmentation and motion estimation was developed and used to estimate left ventricular longitudinal strain in vivo. The method showed promise by achieving a mean deviation of (-0.7±1.6)% compared to a semi-automatic commercial solution for N=30 patients with relevant disease, within the expected limits of agreement. We thus believe that learning-based motion estimation can facilitate extended use of strain imaging in clinical practice.

Artificial Intelligence for Automatic Measurement of Left Ventricular Strain in Echocardiography.

OBJECTIVES: This study sought to examine if fully automated measurements of global longitudinal strain (GLS) using a novel motion estimation technology based on deep learning and artificial intelligence (AI) are feasible and comparable with a conventional speckle-tracking application. BACKGROUND: GLS is an important parameter when evaluating left ventricular function. However, analyses of GLS are time consuming and demand expertise, and thus are underused in clinical practice. METHODS: In this study, 200 patients with a wide range of left ventricle (LV) function were included. Three standard apical cine-loops were analyzed using the AI pipeline. The AI method measured GLS and was compared with a commercially available semiautomatic speckle-tracking software (EchoPAC v202, GE Healthcare. RESULTS: The AI method succeeded to both correctly classify all 3 standard apical views and perform timing of cardiac events in 89% of patients. Furthermore, the method successfully performed automatic segmentation, motion estimates, and measurements of GLS in all examinations, across different cardiac pathologies and throughout the spectrum of LV function. GLS was -12.0 ± 4.1% for the AI method and -13.5 ± 5.3% for the reference method. Bias was -1.4 ± 0.3% (95% limits of agreement: 2.3 to -5.1), which is comparable with intervendor studies. The AI method eliminated measurement variability and a complete GLS analysis was processed within 15 s. CONCLUSIONS: Through the range of LV function this novel AI method succeeds, without any operator input, to automatically identify the 3 standard apical views, perform timing of cardiac events, trace the myocardium, perform motion estimation, and measure GLS. Fully automated measurements based on AI could facilitate the clinical implementation of GLS.

Strain echocardiography improves prediction of arrhythmic events in ischemic and non-ischemic dilated cardiomyopathy.

BACKGROUND: Recent evidence suggests that an implantable cardioverter defibrillator (ICD) in non-ischemic cardiomyopathy (NICM) may not offer mortality benefit. We aimed to investigate if etiology of heart failure and strain echocardiography can improve risk stratification of life threatening ventricular arrhythmia (VA) in heart failure patients. METHODS: This prospective multi-center follow-up study consecutively included NICM and ischemic cardiomyopathy (ICM) patients with left ventricular ejection fraction (LVEF) <40%. We assessed LVEF, global longitudinal strain (GLS) and mechanical dispersion (MD) by echocardiography. Ventricular arrhythmia was defined as sustained ventricular tachycardia, sudden cardiac death or appropriate shock from an ICD. RESULTS: We included 290 patients (67 ± 13 years old, 74% males, 207(71%) ICM). During 22 ± 12 months follow up, VA occurred in 32(11%) patients. MD and GLS were both markers of VA in patients with ICM and NICM, whereas LVEF was not (p = 0.14). MD independently predicted VA (HR: 1.19; 95% CI 1.08-1.32, p = 0.001), with excellent arrhythmia free survival in patients with MD <70 ms (Log rank p < 0.001). Patients with NICM and MD <70 ms had the lowest VA incidence with an event rate of 3%/year, while patients with ICM and MD >70 ms had highest VA incidence with an event rate of 16%/year. CONCLUSION: Patients with NICM and normal MD had low arrhythmic event rate, comparable to the general population. Patients with ICM and MD >70 ms had the highest risk of VA. Combining heart failure etiology and strain echocardiography may classify heart failure patients in low, intermediate and high risk of VA and thereby aid ICD decision strategies.

Strain echocardiography predicts acute coronary occlusion in patients with non-ST-segment elevation acute coronary syndrome.

AIMS: Patients with acute coronary occlusion may lack typical signs of myocardial infarction in the electrocardiogram. We tested the ability of different echocardiographic modalities to identify coronary occlusion by quantifying myocardial dysfunction in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). METHODS AND RESULTS: One hundred and fifty patients were examined by echocardiography immediately prior to coronary angiography, 2.2 +/- 0.7 days (mean +/- SD) after hospitalization for a first NSTE-ACS. Thirty-three patients (22%) had acute coronary occlusion. These patients had impaired left ventricular function as ejection fraction was reduced (54.9 +/- 9.6 vs. 59.1 +/- 7.6%, P = 0.02). Regional myocardial function was assessed in a 16-segment model by two methods: longitudinal strain by speckle tracking echocardiography and wall motion score (WMS) by visual assessment. Patients with acute coronary occlusion had an increased number of adjacent dysfunctional segments. The median size of the dysfunctional area by strain was 7 [inter-quartile range (IQR) 4.5-9] vs. 2 (IQR 0-5) segments (P < 0.001). An area of >or=4 adjacent dysfunctional segments (strain greater than or equal to -14%) had the best ability to identify patients with acute coronary occlusion, with sensitivity 85% and specificity 70%. WMS demonstrated slightly less accuracy than strain. CONCLUSION: Strain echocardiography identifies NSTE-ACS patients with acute coronary occlusion, who may benefit from urgent reperfusion therapy.

Real-Time Automatic Ejection Fraction and Foreshortening Detection Using Deep Learning.

Volume and ejection fraction (EF) measurements of the left ventricle (LV) in 2-D echocardiography are associated with a high uncertainty not only due to interobserver variability of the manual measurement, but also due to ultrasound acquisition errors such as apical foreshortening. In this work, a real-time and fully automated EF measurement and foreshortening detection method is proposed. The method uses several deep learning components, such as view classification, cardiac cycle timing, segmentation and landmark extraction, to measure the amount of foreshortening, LV volume, and EF. A data set of 500 patients from an outpatient clinic was used to train the deep neural networks, while a separate data set of 100 patients from another clinic was used for evaluation, where LV volume and EF were measured by an expert using clinical protocols and software. A quantitative analysis using 3-D ultrasound showed that EF is considerably affected by apical foreshortening, and that the proposed method can detect and quantify the amount of apical foreshortening. The bias and standard deviation of the automatic EF measurements were -3.6 ± 8.1%, while the mean absolute difference was measured at 7.2% which are all within the interobserver variability and comparable with related studies. The proposed real-time pipeline allows for a continuous acquisition and measurement workflow without user interaction, and has the potential to significantly reduce the time spent on the analysis and measurement error due to foreshortening, while providing quantitative volume measurements in the everyday echo lab.

Intra-aortic balloon counterpulsation as a bridge to heart transplantation does not impair long-term survival.

AIMS: There are few studies of the use of intra-aortic balloon pump (IABP) treatment as a bridge to heart transplantation (HTx). This is the first study to compare long-term clinical and haemodynamic outcomes in IABP-treated HTx patients and electively transplanted patients. METHODS AND RESULTS: This was a retrospective study of all adult HTx recipients between 2001 and 2007. Thirty-two patients (aged 50 +/- 13 years) treated with IABP, as a bridge to HTx due to severe hypo-perfusion, were compared with 135 electively transplanted patients (aged 54 +/- 11 years). The mean time from onset of IABP to HTx was 21 +/- 16 days. Clinical condition improved during IABP treatment. Serum creatinine decreased from 128 +/- 56 to 102 +/- 29 micromol/L (P < 0.01), aspartate transaminase from 682 +/- 1299 to 63 +/- 89 U/L (P = 0.01), and ALAT from 483 +/- 867 to 126 +/- 284 U/L (P = 0.02). Intra-aortic balloon pump treatment related complications were few. Mortality was similar in the IABP and control groups at 30 days post-HTx (6.2 vs.3.7%, P = 0.54), at 1 year (9.4 vs.11.1%, P = 0.80), and beyond. Long-term clinical and haemodynamic indices were similar in the two groups. CONCLUSION: Intra-aortic balloon pump treatment stabilizes patients in end-stage heart failure, is safe, well tolerated, and is successful in bridging acutely decompensated patients to transplantation. Complications are few and manageable. Following IABP and HTx, short- and long-term survival, biochemical and invasive and non-invasive haemodynamic outcomes were similar to those in electively transplanted patients.

[Simple electrophysiologic examination of patients with palpitation or tachycardia]. / Forenklet elektrofysiologisk undersøkelse ved hjertebankanfall.

BACKGROUND: Discomfort because of palpitation and tachycardia is a frequent phenomenon. Clinical practice for diagnosing tachycardia has a low sensitivity, and patients without a correct diagnosis are often not treated optimally. MATERIAL AND METHODS: Results from all 24-hour-ECGs taken at Telemark Hospital in the period 1.8.04-31.7.05 were reviewed. Indications and findings were retrieved from the hospital database. 252 of totally 614 ECGs were performed for the indications palpitation and tachycardia. 137 patients with an unclear diagnosis were offered a simple electrophysiologic examination with stimulation of the right atrium by a pacemaker electrode. 38 of these patients were included and underwent the examination. An additional 18 patients were referred to a simple electrophysiologic examination based on the same criteria. RESULTS: 24-hour-ECG provided a diagnosis for 29 patients with palpitation and tachycardia. A simple electrophysiologic examination uncovered reentry tachycardia in nine patients and paroxystic atrial flutter in three patients. A total of 56 electrophysiologic examinations were performed, uncovering 12 cases of tachycardia suitable for ablation. Two patients had to undergo DC-conversion, no other complication was observed. INTERPRETATION: A simplified electrophysiologic examination of this group of patients will uncover tachycardia suitable for ablation in approximately 20 % of the patients, and increase diagnostic yield of supraventricular tachycardia by 64 %.

[Elderly patients with acute myocardial infarction receive less medical therapy]. / Mindre akuttbehandling til eldre med hjerteinfarkt.

BACKGROUND: Elderly patients with acute myocardial infarction represent a large and increasing group in Norwegian hospitals. Few studies of treatment have included patients above 75 years. The objective of this study was to determine differences in the treatment of patients older and younger than 75 years with acute myocardial infarction. We also wanted to determine the in-hospital mortality in these patient groups. MATERIAL AND METHODS: A retrospective chart review of all 957 patients with acute myocardial infarction admitted to Sørlandet sykehus Arendal, Norway was conducted for the period November 1998 to December 2003. We recorded clinical facts, information on treatment and in-hospital mortality. RESULTS: Patients older than 75 years represented 43% of all patients with acute myocardial infarction. These patients received less acute medical therapy than younger patients. 26,4% of the patients older than 75 years died in the hospital. INTERPRETATION: Elderly patients represent a large proportion of patients with acute myocardial infarction, but they receive less medical therapy than younger patients.

[Treatment of cardiac failure with an intra-aortic balloon pump]. / Behandling av hjertesvikt med intraaortal ballongpumpe.

BACKGROUND: Cardiogenic shock is associated with high mortality. This retrospective study examined the effect of an intra aortic balloon pump (IABP) in patients with decompensated heart failure and hypotension, with or without cardiogenic shock. MATERIAL AND METHODS: 94 patients were treated with IABP from January 1998 to December 2002, at the Department of Cardiology, Rikshospitalet University Hospital, Oslo, Norway. The indications for use of IABP were decompensated heart failure with hypotension with or without cardiogenic shock in patients with acute myocardial infarction (n = 41), ventricular septal rupture or mitral insufficiency as a complication to acute cardiac failure (n = 23), severe heart failure waiting for heart transplant (n = 10), unstable angina pectoris (n = 8), myocarditis (n = 6) and miscellaneous (n = 6). RESULTS: Mortality after 30 days was 24 % for all patients, with little variation between the above-mentioned subgroups. Median duration for IABP was 96 hours. Systolic blood pressure and diuresis per hour increased significantly from before to after application of IABP (35 +/- 34 mL/hour versus 95 +/- 77 mL/hour, p < 0.001 and 90 +/- 20 mmHg versus 115 +/- 22 mmHg, p < 0.001). The rate of complications requiring treatment was low with use of IABP (5 out of 94 patients). INTERPRETATION: Treatment with IABP in patients with decompensated heart failure and hypotension is an efficient stabilising treatment and safe to use.

[Registration of hospital time reduces the delay of thrombolytic treatment in myocardial infarction]. / Registrering av tidsbruk reduserer forsinkelsen ved trombolytisk behandling av hjerteinfarkt.

BACKGROUND: The use of thrombolysis in patients with acute myocardial infarction reduces mortality and morbidity. Rapid treatment after the onset of symptoms increases the benefit gained from thrombolysis. MATERIAL AND METHODS: The time delay in the administration of thrombolysis to 138 acute myocardial infarction patients in the hospital in Arendal, Norway was established with a retrospective chart review from January 1995 to December 1996. The results were published locally with a special focus on the time delay. To assess the effect of increased focus, a prospective registration of time delay was performed from November 1998 to December 2003. In this period, 356 acute myocardial infarctions were recorded. Second, the effect of changing the site of administering thrombolytic therapy from the coronary care unit to the emergency department was evaluated from January 2002 to December 2003. RESULTS: The time delay in administration of thrombolysis was reduced from a median delay of 54 minutes in the first period to a median delay of 27 minutes in the second period. No differences were found in time delay between the coronary care unit and the emergency department. INTERPRETATION: The time taken to administer thrombolysis to patients admitted with acute myocardial infarctions can be reduced by focusing on the delay. Changing site of treatment did not affect time delay.

[A 54-year old man with severe circulatory collapse]. / En 54 år gammel mann med alvorlig sirkulasjonssvikt.

The frequent use of mechanical circulatory assistive devices in the treatment of patients in cardiogenic shock increases the need for advanced air and ground transport services. In this article we describe a critically ill patient with acute myocardial infarction. He was treated with intraaortic balloon pump at the local hospital before transfer to a university hospital by air. Close cooperation between the university hospital, the Norwegian Air Ambulance and the Norwegian aviation authorities has facilitated this service.

Early assessment of strain echocardiography can accurately exclude significant coronary artery stenosis in suspected non-ST-segment elevation acute coronary syndrome.

BACKGROUND: Many patients with suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) do not have significant coronary artery disease. The current diagnostic approach of repeated electrocardiography and cardiac biomarker assessment requires observation for >6 to 12 hours. This strategy places a heavy burden on hospital facilities. The objective of this study was to investigate whether myocardial strain assessment by echocardiography could exclude significant coronary artery stenosis in patients presenting with suspected NSTE-ACS. METHODS: Sixty-four patients presenting to the emergency department with suspected NSTE-ACS without known coronary artery disease, inconclusive electrocardiographic findings, and normal cardiac biomarkers at arrival were enrolled. Twelve-lead electrocardiography, troponin T assay, and echocardiography were performed at arrival, and all patients underwent coronary angiography. Significant coronary stenosis was defined as >50% luminal narrowing. Global myocardial peak systolic longitudinal strain was measured using speckle-tracking echocardiography. Left ventricular ejection fraction and wall motion score index were calculated. RESULTS: No significant stenosis in any coronary artery was found in 35 patients (55%). Global peak systolic longitudinal strain was superior to conventional echocardiographic parameters in distinguishing patients with and without significant coronary artery stenosis (area under the curve, 0.87). Sensitivity and specificity were calculated as 0.93 and 0.78, respectively, and positive predictive value and negative predictive value as 0.74 and 0.92, respectively. Feasibility of the strain measurements was excellent, with 97% of segments analyzed. CONCLUSIONS: Myocardial strain by echocardiography may facilitate the exclusion of significant coronary artery stenosis among patients presenting with suspected NSTE-ACS with inconclusive electrocardiographic findings and normal cardiac biomarkers.