Christian Eek

Oslo University Hospital, Kristiania (historical), Oslo County, Norway

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Publications (15)58.38 Total impact

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    ABSTRACT: Ischaemic myocardial segments tend to stretch as the intraventricular pressure rises steeply during the isovolemic contraction phase, before they contract during ejection. We hypothesized that the time they remain stretched, called duration of early systolic lengthening (DESL), correlates with final infarct size as defined by contrast enhanced magnetic resonance imaging (CE-MRI). We also assessed whether DESL could identify patients with acute coronary occlusion, and compared it with traditional measures for myocardial function.
    European Heart Journal – Cardiovascular Imaging 05/2014; · 2.39 Impact Factor
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    ABSTRACT: 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.
    Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography 01/2014; · 2.98 Impact Factor
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    ABSTRACT: The aim of this study was to test the hypothesis that strain echocardiography might improve arrhythmic risk stratification in patients after myocardial infarction (MI). Prediction of ventricular arrhythmias after MI is challenging. Left ventricular ejection fraction (LVEF) < 35% is the main parameter for selecting patients for implantable cardioverter-defibrillator therapy. In this prospective, multicenter study, 569 patients >40 days after acute MI were included, 268 of whom had ST-segment elevation MIs and 301 non-ST-segment elevation MIs. By echocardiography, global strain was assessed as average peak longitudinal systolic strain from 16 left ventricular segments. Time from the electrocardiographic R-wave to peak negative strain was assessed in each segment. Mechanical dispersion was defined as the standard deviation from these 16 time intervals, reflecting contraction heterogeneity. Ventricular arrhythmias, defined as sustained ventricular tachycardia or sudden death during a median 30 months (interquartile range: 18 months) of follow-up, occurred in 15 patients (3%). LVEFs were reduced (48 ± 17% vs. 55 ± 11%, p < 0.01), global strain was markedly reduced (-14.8 ± 4.7% vs. -18.2 ± 3.7%, p = 0.001), and mechanical dispersion was increased (63 ± 25 ms vs. 42 ± 17 ms, p < 0.001) in patients with arrhythmias compared with those without. Mechanical dispersion was an independent predictor of arrhythmic events (per 10-ms increase, hazard ratio: 1.7; 95% confidence interval: 1.2 to 2.5; p < 0.01). Mechanical dispersion and global strain were markers of arrhythmias in patients with non-ST-segment elevation MIs (p < 0.05 for both) and in those with LVEFs > 35% (p < 0.05 for both), whereas LVEF was not (p = 0.33). A combination of mechanical dispersion and global strain showed the best positive predictive value for arrhythmic events (21%; 95% confidence interval: 6% to 46%). Mechanical dispersion by strain echocardiography predicted arrhythmic events independently of LVEF in this prospective, multicenter study of patients after MI. A combination of mechanical dispersion and global strain may improve the selection of patients after MI for implantable cardioverter-defibrillator therapy, particularly in patients with LVEFs > 35% who did not fulfill current implantable cardioverter-defibrillator indications.
    JACC. Cardiovascular imaging 07/2013; · 14.29 Impact Factor
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    ABSTRACT: Mitral annular displacement (MAD) is a simple marker of left ventricular (LV) systolic function. The aim of this study was to test the hypothesis that MAD can distinguish patients with non-ST-segment elevation myocardial infarctions (NSTEMIs) from those with significant coronary artery disease without infarctions, identify coronary occlusion, and predict mortality in patients with NSTEMIs. MAD was compared with established indices of LV function. In this retrospective study, 167 patients with confirmed NSTEMIs were included at two Scandinavian centers. Forty patients with significant coronary artery disease but without myocardial infarctions were included as controls. Doppler tissue imaging was performed at the mitral level of the left ventricle in the three apical planes, and velocities were integrated over time to acquire MAD. LV ejection fraction, global longitudinal strain (GLS), and wall motion score index were assessed according to guidelines. MAD and GLS could accurately distinguish patients with NSTEMIs from controls. During 48.6 ± 12.1 months of follow-up, 22 of 167 died (13%). MAD, LV ejection fraction, and GLS were reduced and wall motion score index was increased among those who died compared with those who survived (P < .001, P < .001, P < .001, and P = .02, respectively). Multivariate Cox proportional-hazards analyses revealed that MAD was an independent predictor of death (hazard ratio, 1.36; 95% confidence interval, 1.07-1.73; P = .01). MAD and GLS were reduced and wall motion score index was increased in patients with coronary artery occlusion compared with those without occlusion (P = .006, P = .001, and P = .02), while LV ejection fraction did not differ (P = .20). MAD accurately identified patients with NSTEMIs, predicted mortality, and identified coronary occlusion in patients with NSTEMIs.
    Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography 06/2013; · 2.98 Impact Factor
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    ABSTRACT: Sensitive troponin assays have substantially improved early diagnosis of myocardial infarction. However, the role of sensitive cardiac troponin (cTn) assays in prediction of significant coronary lesions and long-term prognosis in non-ST-elevation acute coronary syndrome (NSTE-ACS) remains unresolved. This prospective study includes 458 consecutive patients with NSTE-ACS admitted for coronary angiography. Serum levels of 4 commercial available sensitive troponin assays were analyzed (Roche high-sensitive cTnT [hs-cTnT; Roche Diagnostics, Basel, Switzerland], Siemens cTnI Ultra [Siemens, Munich, Germany], Abbott-Architect cTnI [Abbott, Abbott Park, IL], Access Accu-cTnI [Beckman Coulter, Nyon, Switzerland]), as well as a standard assay (Roche cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP), before coronary angiography. The relationship between the analyzed biomarkers and significant coronary lesions on coronary angiography, as quantified by area under the receiver operating characteristic curve, was significantly higher with Roche hs-cTnT, Siemens cTnI Ultra, and Access Accu-cTnI as compared with standard troponin T assay (P < .001 for all comparisons). This difference was mainly caused by increased sensitivity below the 99th percentile. Also, NT-proBNP was associated with the presence of significant coronary lesions. Cardiac troponin values were correlated with cardiac death (primary end point) during 1373 (1257-1478) days of follow-up. In both univariate and multivariate Cox regression analyses, NT-proBNP was superior to both hs-cTnT and cTnI in prediction of cardiovascular mortality. Troponin values with all assays were correlated with the need for repeated revascularization (secondary end point) during follow-up. Sensitive cTn assays are superior to standard cTnT assay in prediction of significant coronary lesions in patients with NSTE-ACS. However, this improvement is primary caused by increased sensitivity below the 99th percentile. N-terminal pro-B-type natriuretic peptide is superior to cTns in prediction of long-term mortality.
    American heart journal 05/2013; 165(5):716-24. · 4.65 Impact Factor
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    ABSTRACT: BACKGROUND: Left ventricular (LV) remodeling takes place after acute myocardial infarction (MI), potentially leading to overt heart failure (HF). Enhanced inflammation may contribute to LV remodeling. Our hypothesis was that the immunomodulating effects of intravenous immunoglobulin (IVIg) would be beneficial in patients with impaired myocardial function after MI by reducing myocardial remodeling and improving myocardial function. METHODS: Sixty-two patients with acute MI treated by percutaneous coronary intervention, with depressed LV ejection fraction (LVEF) were randomized in a double-blinded fashion to IVIg as induction therapy and thereafter as monthly infusions or placebo for 26weeks. The primary end point was changes in LVEF from baseline to 6months as assessed by MRI. RESULTS: Our main findings were: (i) LVEF increased significantly from 38±10 (mean±SD) to 45±13% after IVIg and from 42±9 to 49±12% after placebo with no difference between the groups. (ii) The scar area decreased significantly by 3% and 5% in the IVIg and placebo group, respectively, with no difference between the groups. (iii) During the induction therapy (baseline to day 5), IVIg induced both inflammatory (e.g., increase in tumor necrosis factor α and monocyte chemoattractant protein-1) and anti-inflammatory (e.g., increase in interleukin-10 and decrease in leukocyte counts) variables, but during maintenance therapy there were no differences in changes of inflammatory mediators between IVIg and placebo. CONCLUSIONS: IVIg therapy after ST elevation MI managed by primary PCI does not affect LV remodeling or function. This illustrates the challenges of therapeutic intervention directed against the cytokine network, to prevent post-MI remodeling.
    International journal of cardiology 10/2012; · 6.18 Impact Factor
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    ABSTRACT: Our aim was to investigate the associations between B-type natriuretic peptide (NT-proBNP), troponin T (TnT) and C-reactive protein (CRP) and changes in left ventricular function and size after acute coronary syndrome. In 119 patients admitted for non-ST-elevation acute coronary syndrome, echocardiography and blood sampling were performed prior to coronary angiography. Echocardiography was repeated at follow-up after 8 ± 3 months. Left ventricular function was assessed by speckle tracking echocardiography. In 50 patients, infarct size was determined by magnetic resonance imaging. The associations between baseline levels of NT-proBNP, TnT and CRP and myocardial functional recovery, left ventricular intraventricular volumes and infarct size were determined by linear regression. All three biomarkers were associated with myocardial dysfunction at baseline. However, high levels of NT-proBNP were associated with better myocardial recovery, as measured by global longitudinal strain, even after adjusting for other factors potentially influencing myocardial recovery. Elevated levels of NT-proBNP at baseline are independently associated with improved myocardial performance 8 months after non-ST-elevation acute coronary syndrome.
    Scandinavian cardiovascular journal: SCJ 12/2011; 46(2):65-71. · 1.07 Impact Factor
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    ABSTRACT: Early prediction of infarct size directs therapy in patients with acute myocardial infarction (AMI). Global strain by echocardiography describes myocardial deformation and correlates with infarct size. However, peak strain measures deformation at a single time point, whereas ischemia and necrosis influence deformation throughout the heart cycle. It was hypothesized that the measurement of myocardial deformation throughout the heart cycle by mean strain is a more comprehensive expression of myocardial deformation. The aim of this study was to assess the ability of mean strain to predict infarct size and to identify large infarctions at admission and after revascularization in patients with AMI. Seventy-six patients with AMI were included. Echocardiographic measurements were performed at admission and after revascularization. Myocardial strain was calculated using speckle-tracking echocardiography. Infarct size was measured using contrast-enhanced magnetic resonance imaging ≥3 months after revascularization. There were significant correlations between infarct size and longitudinal global mean strain, longitudinal global strain, and left ventricular ejection fraction (P < .0001), both at admission and after revascularization. The correlations improved after revascularization. Longitudinal global mean strain had the best correlation with infarct size and the best ability to discriminate between different infarct size categories. At admission, a cutoff value of -7.6 had 89% sensitivity, 88% specificity, and an area under the receiver operating characteristic curve of 0.92 for the identification of large infarctions. Prediction of infarct size improved for all parameters after revascularization. Longitudinal global mean strain provides improved early prediction of infarct size in patients with AMI compared with longitudinal global strain and left ventricular ejection fraction.
    Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography 07/2011; 24(10):1118-25. · 2.98 Impact Factor
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    ABSTRACT: 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. 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 (β = 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. 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.
    European Heart Journal – Cardiovascular Imaging 05/2011; 12(7):483-9. · 2.39 Impact Factor
  • Journal of The American College of Cardiology - J AMER COLL CARDIOL. 01/2011; 57(14).
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    ABSTRACT: To compare infarct size and left ventricular ejection fraction in patients with non-ST-elevation myocardial infarction (NSTEMI) with and without acute coronary occlusions, and determine if myocardial strain by speckle-tracking echocardiography can identify acute occlusions in patients presenting with non-ST-elevation acute coronary syndrome (NSTE-ACS). 111 patients with suspected NSTE-ACS were enrolled shortly after admittance. Echocardiographic measurements were performed a median of 1 h (interquartile range 0.5-4) after admittance, and coronary angiography 36 ± 21 h after onset of symptoms. Territorial longitudinal and circumferential strain was calculated based on the perfusion territories of the three major coronary arteries in a 16-segment model of the left ventricle, and compared with traditional echocardiographic parameters. Long-term follow-up was by echocardiography and contrast-enhanced magnetic resonance imaging (ceMRI). Patients with NSTEMI due to acute coronary occlusion had higher peak troponin T than patients with NSTEMI without acute occlusions (4.9 ± 4.7 vs 0.9 ± 1.1 μg/l, p<0.001), larger infarct size by ceMRI (13 ± 8% vs 3 ± 3%, p<0.001) and poorer left ventricular ejection fraction (48 ± 6% vs 57 ± 6%, p<0.001) at follow-up. Territorial circumferential strain was the best parameter for predicting acute coronary occlusion. A territorial circumferential strain value >-10.0% had 90% sensitivity, 88% specificity and area under the curve=0.93 for identification of acute occlusions. Patients with NSTEMI due to acute coronary occlusions develop larger infarcts and more impaired left ventricular function than patients with NSTEMI without occlusions, regardless of infarct-related territory. Territorial circumferential strain by echocardiography enables very early identification of acute coronary occlusions in patients with NSTE-ACS and may be used for detection of patients requiring urgent revascularisation.
    Heart (British Cardiac Society) 10/2010; 96(19):1550-6. · 5.01 Impact Factor
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    ABSTRACT: The optimal timing of coronary angiography in patients with non-ST elevation (NSTE) acute coronary syndromes (ACS) is debated. American Heart Association and American College of Cardiology guidelines recommend an early invasive strategy <12 to 48 hours after the onset of symptoms. The objective of the present study was to determine possible changes in myocardial function in patients with NSTE ACS awaiting coronary angiography. One hundred two patients with suspected NSTE ACS were enrolled, including 56 with NSTE myocardial infarctions (NSTEMIs), 23 with unstable angina pectoris, and 23 with noncoronary chest pain. Global and regional myocardial function was measured as longitudinal and circumferential strain using speckle-tracking echocardiography. Measurements were performed at admission and immediately before coronary angiography (30 + or - 16 hours after admission). In patients with NSTEMIs, there was deterioration in longitudinal global strain from -16.1 + or - 2.6% at admission to -15.0 + or - 2.6% before coronary angiography (p <0.001). This was due to deterioration in longitudinal strain in the territory supplied by the infarct-related artery from -14.2 + or - 4.2% to -12.0 + or - 4.1% (p <0.001). Patients with NSTEMIs due to acute coronary occlusion underwent prominent worsening in longitudinal and circumferential strains (-15.7 + or - 2.9% to -13.9 + or - 3.0%, p = 0.001, and -16.7 + or - 4.0% to -15.0 + or - 3.9%, p = 0.01, respectively) compared to patients with NSTEMIs without occlusions. There were no changes in strain in patients with unstable angina pectoris or noncoronary chest pain. In patients with NSTEMIs without acute coronary occlusions, myocardial function improved after revascularization, whereas patients with acute occlusions demonstrated no improvement. In conclusion, myocardial function deteriorates in patients with NSTEMIs awaiting coronary angiography. Patients with acute coronary occlusions have the most prominent deterioration, and this subgroup shows no recovery of function after revascularization.
    The American journal of cardiology 05/2010; 105(9):1212-8. · 3.58 Impact Factor
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    ABSTRACT: Infarct size is a strong predictor of mortality and major adverse cardiovascular events after myocardial infarction. Acute reperfusion therapy limits infarct size and improves survival, but its use has been confined to patients with ST-segment-elevation myocardial infarction. The purpose of this study was to assess the relationship between echocardiographic parameters of left ventricular (LV) systolic function obtained before revascularization and final infarct size in patients with non-ST-segment-elevation myocardial infarction, as well as the ability of these parameters to identify patients with substantial infarction. Sixty-one patients with non-ST-segment-elevation myocardial infarction were examined by echocardiography immediately before revascularization, 2.1+/-0.6 days after hospitalization. LV systolic function was assessed by ejection fraction, wall motion score index, and circumferential, longitudinal, and radial strain in a 16-segment LV model. Global strain represents average segmental strain values. Infarct size was assessed after 9+/-3 months by late-enhancement MRI, as a percentage of total LV myocardial volume. A good correlation was found between infarct size and wall motion score index (r=0.74, P<0.001) and global longitudinal strain (r=0.68, P<0.001). Global longitudinal strain >-13.8% and wall motion score index >1.30 accurately identified patients with substantial infarction (> or =12% of myocardium, n=13; area under the receiver operator curve, 0.95 and 0.92, respectively). Echocardiographic parameters of LV systolic function correlate to infarct size in patients with non-ST-segment-elevation myocardial infarction. Global longitudinal strain and wall motion score index are both excellent parameters to identify patients with substantial myocardial infarction, who may benefit from urgent reperfusion therapy.
    Circulation Cardiovascular Imaging 03/2010; 3(2):187-94. · 5.80 Impact Factor
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    ABSTRACT: A 48-year-old previously healthy woman suffered witnessed cardiac arrest in hospital. She achieved return of spontaneous circulation and was transferred to the intensive care unit. During the following 3 hours, she suffered a cardiac electrical storm with 98 episodes of Torsade de Pointes ventricular tachycardia rapidly degenerating to ventricular fibrillation. She was converted with a total of 99 defibrillations. There was no response to the use of any recommended anti arrhythmic drugs. However, the use of bretylium surprisingly stabilized her heart rhythm and facilitated placing of a temporary pacemaker. Overdrive pacing prevented further arrhythmias and was life saving. A number of beneficial factors may have contributed to the good neurological outcome. Further investigations gave no explanation for her cardiac electrical storm.
    Scandinavian Journal of Trauma Resuscitation and Emergency Medicine 02/2010; 18:7. · 1.68 Impact Factor
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    ABSTRACT: 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). 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. Strain echocardiography identifies NSTE-ACS patients with acute coronary occlusion, who may benefit from urgent reperfusion therapy.
    European Heart Journal – Cardiovascular Imaging 02/2010; 11(6):501-8. · 2.39 Impact Factor

Publication Stats

73 Citations
58.38 Total Impact Points

Institutions

  • 2010–2014
    • Oslo University Hospital
      • Department of Cardiology
      Kristiania (historical), Oslo County, Norway
  • 2011–2013
    • University of Oslo
      Kristiania (historical), Oslo County, Norway
  • 2010–2011
    • Sørlandet Hospital
      Arendal, Aust-Agder county, Norway