Late microvascular obstruction after acute myocardial infarction: relation with cardiac and inflammatory markers.

OBJECTIVES: We sought to assess the relation of late microvascular obstruction (l-MVO) size as quantified by cardiac magnetic resonance (CMR) imaging with cardiac and inflammatory marker concentrations after acute myocardial infarction (AMI). METHODS: CMR was performed in 118 consecutive patients within 8 days after successful interventional reperfused first acute ST-elevation AMI. Infarct volumes and l-MVO sizes were calculated from late enhancement (LE) sequences and functional parameters were determined from short-axis cine MR sequences. Creatine kinase (CK) and cardiac troponin T (cTnT), high-sensitivity C-reactive protein (hs-CRP) as well as lactate dehydrogenase (LD) concentrations were determined serially from day 1 to day 4 after symptom onset. RESULTS: L-MVO was detected in 66/118 patients (55.9%) and comprised 18.2 ± 10% of infarct size and 4.7 ± 3% of left ventricle myocardial mass. Each single-point, peak and cumulative release concentration of cTnT (r=0.44 to 0.73, p<0.0001), CK (r=0.21 to 0.76, p<0.0001), LD (r=0.36 to 0.82, all p<0.0001) as well as hs-CRP single-point values as assessed from day 1 to day 4 and its peak and cumulative release concentrations (r=0.24 to 0.49, p<0.003) significantly correlated with l-MVO size. Receiver operating curve (ROC) analysis indicated a cut-off value of 4.7 µg/l cTnT to best identify the presence of l-MVO (area under the curve (AUC) 0.904; 95% CI: 0.85-0.95; p<0.0001). CONCLUSION: L-MVO sizes significantly correlate with cardiac and inflammatory marker concentrations as determined early after AMI. cTnT concentration of >4.7 µg/l could help to identify patients in whom l-MVO is present.

Patterns of myocardial perfusion in the acute and chronic stage after myocardial infarction: a cardiac magnetic resonance study.

OBJECTIVES: The aim of the present study was to monitor the microvascular perfusion damage in the acute and chronic stage after myocardial infarction (MI) using first-pass dynamic magnetic resonance imaging (MRI). Furthermore we compared improvement of myocardial microcirculation and function in infarcted and non-infarcted left midventricular segments over a 4 months period. MATERIALS AND METHODS: Cardiac magnetic resonance imaging (CMR) was performed in 46 consecutive patients within 8 days after successful reperfused first acute ST-elevation MI and 4 months thereafter. First-pass images were obtained by using Turbo-FLASH sequence during a bolus injection of Gd-based contrast agent. Signal-intensity-to-time (SIT) curves of 276 left ventricular myocardial segments were generated. Furthermore, infarct volumes as well as parameters of regional left ventricular function of corresponding segments were calculated. RESULTS: SIT curves highly significantly correlate with MI size (r=-0.57, r=-0.43 respectively; all p<0.0001) as well as with segmental wall thickening (SWT) of corresponding segments at baseline and follow-up scans (r=0.20, r=0.15 respectively; all p<0.02). SWT differ highly significantly between segments with and those without LE at baseline (p<0.003) and follow-up examinations (p<0.008), presenting either clear improvements at follow-up (all p<0.0001). In contrast, infarcted segments showing microvascular obstruction evidenced neither significant recovery of SIT nor of SWT (p=NS). CONCLUSION: Our data indicate a close relationship between MI size and myocardial perfusion as well as function. Beyond epicardial artery patency, the assessment of quantitative parameters of myocardial perfusion and contractile function with the help of CMR appears to be a useful tool for estimating myocardial recovery after acute MI.

Regional functional recovery after acute myocardial infarction: a cardiac magnetic resonance long-term study.

We sought to analyze the trend of functional recovery after successful reperfused ST-elevation myocardial infarction (STEMI) in an optimally treated patient group over a 14 month follow-up in relation to ischemia-time and the presence of microvascular obstruction (MVO). First-pass perfusion-, cine- and late enhancement (LE)- cardiac MR were performed in 40 patients (33 male and 7 female, 54.8 ± 12.3 years) within 6 days as well as 4 and 14 months after successful primary percutaneous coronary intervention for STEMI. Significant recovery of segmental wall thickening (SWT %) occurred exclusively in infarcted segments reperfused within 4 h after symptom onset (group 1 with pain-to-balloon time <2 h: 59 ± 4 to 70 ± 4%; P < 0.02) (group 2 with pain-to-balloon-time 2-4 h: 51 ± 4 to 59 ± 3%, P < 0.05) during the first 4 months, whereas changes thereafter were not significant (P = NS). Infarcted segments with MVO showed lowest regional myocardial function at any time of assessment (all P < 0.001) and a lack of significant recovery during the study period. Significant recovery of regional myocardial function is related to rapid revascularization of the infarct-related artery and the absence of MVO. Improvement of SWT occurred exclusively within the first 4 months after acute myocardial infarction and remained unchanged thereafter.

Cardiac troponin T and creatine kinase predict mid-term infarct size and left ventricular function after acute myocardial infarction: a cardiac MR study.

PURPOSE: To assess the relation of cardiac troponin T (cTnT) and creatine kinase (CK) release with infarct size and left ventricular function evaluated during the subacute phase as well as four months after acute myocardial infarction (AMI) by contrast-enhanced MRI (CE-MRI). MATERIALS AND METHODS: CMR of 80 patients (68 male, mean age 54.2 ± 11.7 years) was performed within 8 days and 4 months after first acute ST-elevation AMI with successful primary angioplasty. CK and cTnT concentrations were determined serially from admission to day 4 after symptom onset. RESULTS: All single time-points, estimated average release and peak concentrations of CK and cTnT markers correlated significantly with acute and mid-term infarct size (r = 0.43 to 0.79, all P < 0.001), ejection fraction (EF%) (r = -0.42 to -0.58, all P < 0.002) as well as with end-systolic volume (ESV) (r = 0.32 to 0.57, all P < 0.002) at all times of assessment. Patients with cTnT concentrations below the cutoff value of 3.26 µg/L measured 48 h after AMI-related symptom onset had a significant improvement in global (EF: P < 0.0001) myocardial function during the study period, whereas in those with cTnT ≥ 3.26 µg/L, functional recovery did not occur (P = 0.09). CONCLUSION: All single, mean and maximum concentrations of cTnT and CK measured within the first 4 days after AMI permit an accurate prediction of infarct size and left ventricular function as determined in the acute phase as well as four months after AMI by CE-MRI.

Predictive value of NT-pro BNP after acute myocardial infarction: relation with acute and chronic infarct size and myocardial function.

AIM OF THE STUDY: We sought to assess the relation of N-terminal brain natriuretic peptide (NT-pro BNP) determined on day 3 after onset of acute myocardial infarction (AMI) symptoms with acute and chronic infarct size and functional parameters assessed by cardiac magnetic resonance (CMR) imaging. Furthermore, we wanted to investigate its predictive value for recovery of myocardial function. METHODS: CMR was performed in 49 consecutive patients within 6 days and in a subgroup 4 (n = 27) and 12 (n = 22) months after first acute ST-elevation AMI and successful primary angioplasty. NT-pro BNP was measured in the subacute phase at 66 ± 8 h after onset of symptoms. RESULTS: Log-transformed NT-pro BNP (lgNT-pro BNP) significantly correlated with infarct size in % of left ventricular myocardial mass (r = 0.59 to 0.64; p < 0.004), with ejection fraction (EF) (r = -0.49 to -0.55; p < 0.004) as well as with segmental wall thickening (SWT, mm) (r = 0.41 to -0.52; p < 0.04) at any time of assessment. Multiple linear regression analysis revealed baseline EF and lgNT-pro BNP to predict global functional recovery. Patients with NT-pro BNP concentrations 1115 pg/ml did not show significant functional recovery (all p = NS). CONCLUSION: NT-pro BNP on day 3 after admission correlates with acute and chronic infarct size and myocardial function after AMI. Global and regional myocardial function did not recover in patients with higher NT-pro BNP (>1115 pg/ml) during subacute phase of AMI.

Comparison of wall thickening and ejection fraction by cardiovascular magnetic resonance and echocardiography in acute myocardial infarction.

OBJECTIVES: The purpose of this study was to compare cardiovascular magnetic resonance (CMR) and echocardiography (echo) in patients treated with primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) with emphasis on the analysis of left ventricular function and left ventricular wall motion characteristics. METHODS: We performed CMR and echo in 52 patients with first AMI shortly after primary angioplasty and four months thereafter. CMR included cine-MR and T1-weighted first-pass and late-gadolinium enhancement (LGE) sequences. Global ejection fraction (EF(CMR), %) and regional left ventricular function (systolic wall thickening %, [SWT]) were determined from cine-MR images. In echo the global left ventricular function (EF(echo), %) and regional wall motion abnormalities were determined. A segment in echo was scored as "infarcted" if it was visually > 50% hypokinetic. RESULTS: EF(echo) revealed a poor significant agreement with EF(CMR) at baseline (r: 0.326; p < 0.01) but higher correlation at follow-up (r: 0.479; p < 0.001). The number of infarcted segments in echocardiography correlated best with the number of segments which showed systolic wall thickening < 30% (r: 0.498; p < 0.001) at baseline and (r: 0.474; p < 0.001) at follow-up. Improvement of EF was detected in both CMR and echocardiography increasing from 44.2 +/- 11.6% to 49.2 +/- 11% (p < 0.001) by CMR and from 51.2 +/- 8.1% to 54.5 +/- 8.3% (p < 0.001) by echocardiography. CONCLUSION: Wall motion and EF by CMR and echocardiography correlate poorly in the acute stage of myocardial infarction. Correlation improves after four months. Systolic wall thickening by CMR < 30% indicates an infarcted segment with influence on the left ventricular function.

Quantification of regional functional improvement of infarcted myocardium after primary PTCA by contrast-enhanced magnetic resonance imaging.

PURPOSE: To assess with cardiac magnetic resonance imaging (CMR) the relationship between treatment delay and improvement of regional left ventricular function after primary percutaneous transluminal coronary angioplasty (p-PTCA) for acute myocardial infarction (AMI). MATERIALS AND METHODS: We performed cine- and late-enhancement (LE) CMR in 40 patients with first AMI after restoring TIMI 3 flow with p-PTCA and at a follow-up 4 months later. Infarcted segments were determined from LE images. Regional left ventricular function was quantified from cine-CMR images. Segmentation followed the American Heart Association 17-segments model. Patients were divided into groups with delay <3 hours, 3-6 hours, 6-12 hours, and a delay >12 hours. RESULTS: Segmental wall thickening (SWT) significantly iproved only in segments reperfused within 6 hours (P < 0.001). Follow-up SWT was significantly higher if segments were reperfused early (<3 hours: 74 +/- 4%, 3-6 hours: 57 +/- 4%, 6-12 hours: 48 +/- 7%, <3 to 3-6: P < 0.003, and <3 to 6-12 hours: P < 0.001). The extent of improvement was greater if delay was <3 hours compared to segments with a delay of >3 hours (<3 hours: +21 +/- 3%, 3-6 hours: +8 +/- 4%, 6-12 hours: +6 +/- 3%; <3 hours to 3-6 hours, and 6-12 h, P < 0.02). CONCLUSION: We quantitatively demonstrated that time to p-PTCA treatment significantly influences regional functional recovery of infarcted myocardium at a 4-month follow-up.