Time-dependency,predictors and clinical impact of infarct transmurality assessed by magnetic resonance imaging in patients with ST-elevation myocardial infarction reperfused by primary coronary percutaneous intervention

Previous studies analyzing the relation between time-to-reperfusion, infarct size, microvascular obstruction (MO) and infarct transmurality in patients with ST-elevation myocardial infarction (STEMI) reperfused by primary percutaneous coronary intervention (PCI) reported inconsistent results. Furthermore, it remains unclear, if transmural infarction is associated with adverse clinical outcome. The present study included STEMI patients reperfused by primary PCI (n = 322) within 720 min after symptom-onset undergoing contrast-enhanced magnetic resonance imaging (CMR) at a median of 3 days after the index event [interquartile range (IQR) 2–4]. Patients were subcategorized into tertiles according to time-to-reperfusion. Infarct size and MO were assessed approximately 15 min after gadolinium-injection. Infarct transmurality was assessed by a score with late-enhancement grading as <25, 25–50, 51–75 and >75% transmurality analyzing all 17 left ventricular segments. Clinical follow-up was performed after 20 months (IQR 13;29). The primary endpoint was defined as a composite of death and congestive heart failure. The median time-to-reperfusion was 230 min (IQR 153;390). Infarct size and MO did not increase significantly with longer time-to-reperfusion (p = 0.16 and p = 0.44, respectively). In contrast to infarct size and MO, the infarct transmurality score progressed significantly with increasing ischemic time (p < 0.001). In multivariable logistic regression analysis, time-to-reperfusion was identified as an independent predictor for transmural infarction (p = 0.03). However, transmural infarction was not predictive of the primary composite clinical endpoint (p = 0.22). In conclusion, in STEMI patients reperfused by primary PCI, time-to-reperfusion was an independent predictor for transmural infarction but not for infarct size and MO. However, transmural infarction was not predictive of death and congestive heart failure.     

Impact of hyperglycemia at admission in patients with acute ST-segment elevation myocardial infarction as assessed by contrast-enhanced MRI

Background  

Blood glucose level at admission in ST-segment elevation myocardial infarction (STEMI) is a predictor of heart failure and mortality. This study was performed to investigate the impact of hyperglycemia at admission in non-diabetic patients on infarct size, microvascular obstruction, and long-term outcome using contrast-enhanced magnetic resonance imaging (CMR) in patients with acute STEMI.     

Infarct healing is a dynamic process following acute myocardial infarction

Background

The role of infarct size on left ventricular (LV) remodeling in heart failure after an acute ST-segment elevation myocardial infarction (STEMI) is well recognized. Infarct size, as determined by cardiovascular magnetic resonance (CMR), decreases over time. The amount, rate, and duration of infarct healing are unknown.

Methods

A total of 66 patients were prospectively enrolled after reperfusion for an acute STEMI. Patients underwent a CMR evaluation within 1 week, 4 months, and 14 months after STEMI.

Results

Mean infarct sizes for the 66 patients at baseline (acute necrosis), early follow-up (early scar), and late follow-up (late scar) were 25 ± 17 g, 17 ± 12 g, and 15 ± 11 g, respectively. Patients were stratified in tertiles, based on infarct size, with the largest infarcts having the greatest absolute decrease in mass at early and late scar. The percent reduction of infarct mass was independent of initial infarct size. There was an 8 g or 32% decrease in infarct mass between acute necrosis and early scar (p < 0.01) with a 2 g or 12% additional decrease in infarct mass between early and late scar (p < 0.01).

Conclusions

Infarct healing is a continuous process after reperfusion for STEMI, with greatest reduction in infarct size in the first few months. The dynamic nature of infarct healing through the first year after STEMI indicates that decisions based on infarct size, and interventions to reduce infarct size, must take into consideration the time frame of measurement.     

Intracoronary versus intravenous bolus abciximab application in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention: 6-month effects on infarct size and left ventricular function

Background

Administration of abciximab during primary percutaneous coronary intervention (PCI) reduces major adverse cardiac events (MACE) in patients with ST-elevation myocardial infarction (STEMI). Intracoronary (IC) abciximab bolus application during PCI results in high local drug concentration, improved perfusion, reduction of infarct size, and less microvascular obstruction early after infarction. Aim of this study was to investigate whether the early benefits of an IC abciximab administration in STEMI patients undergoing PCI are sustained at 6?months.

Methods

We performed 6-month follow-up of 154 STEMI patients undergoing PCI, who were randomised to either IC (n?=?77) or intravenous (IV) (n?=?77) bolus abciximab administration with subsequent 12-h intravenous infusion. The primary endpoint was infarct size at 6-month follow-up as assessed by delayed enhancement magnetic resonance imaging. Clinical end points were MACEs within 6?months after infarction.

Results

The median infarct size after 6?months was significantly reduced in the IC abciximab group (16.7 vs. 24.1%, p?=?0.002). A significant recovery of LV function was only observed in the IC abciximab group (p?<?0.001), and IC abciximab group patients had significantly less adverse remodelling as compared to standard IV abciximab treatment (p?=?0.03). These beneficial effects also translated into a strong trend towards a reduced MACE rate in the IC abciximab group at 6-month follow-up (10 vs. 21%, p?=?0.07).

Conclusions

Intracoronary abciximab application in STEMI patients undergoing PCI is superior to standard IV treatment with respect to infarct size, recovery of LV function and reverse remodelling 6?months after infarction.     

TNF-α, myocardial perfusion and function in patients with ST-segment elevation myocardial infarction and primary percutaneous coronary intervention

Aims

To characterize the time course of tumor necrosis factor-α (TNF-α) serum levels along with myocardial perfusion and contractile function in patients with ST-segment elevation myocardial infarction (STEMI) and successful primary percutaneous coronary intervention (PCI).

Methods

Serum levels of TNF-α, interleukin 6 (IL-6), and C-reactive protein (CRP) were measured in 42 patients with STEMI before, one and 6?days after successful PCI. Myocardial perfusion was assessed by contrast-enhanced echocardiography (ceEcho), contractile function by unenhanced two-dimensional (2DE) and real-time three-dimensional echocardiography. In a subset of 18 patients, infarct size was quantified by late gadolinium enhancement cardiovascular magnetic resonance imaging (LGE-CMR) on day six.

Results

TNF-α serum levels were in the upper normal range within the first 12?h from symptom onset and increased continuously until day six, while IL-6 and CRP increased subsequently with a peak on day one after STEMI. Serum TNF-α on day one after PCI correlated with perfusion defects, wall motion abnormalities, and infarct size (ceEcho: r?=?0.52, p?=?0.005; 2DE: r?=?0.56, p?=?0.002; LGE-CMR: r?=?0.83–0.86; p?p?=?0.006, adjusted R ² 0.638).

Conclusion

Our data reflect the clinical significance of early TNF-α elevation in patients with STEMI and primary PCI (Controlled Clinical Trials number, NCT00529607).     

The effect of microvascular obstruction and intramyocardial hemorrhage on contractile recovery in reperfused myocardial infarction: insights from cardiovascular magnetic resonance

Background

Following acute myocardial infarction (AMI), microvascular obstruction (MO) and intramyocardial hemorrhage (IMH) adversely affect left ventricular remodeling and prognosis independently of infarct size. Whether this is due to infarct zone remodeling, changes in remote myocardium or other factors is unknown. We investigated the role of MO and IMH in recovery of contractility in infarct and remote myocardium.

Methods

Thirty-nine patients underwent cardiovascular magnetic resonance (CMR) with T2-weighted and T2* imaging, late gadolinium enhancement (LGE) and myocardial tagging at 2, 7, 30 and 90 days following primary percutaneous coronary intervention for AMI. Circumferential strain in infarct and remote zones was stratified by presence of MO and IMH.

Results

Overall, infarct zone strain recovered with time (p < 0.001). In the presence of MO with IMH and without IMH, epicardial strain recovered (p = 0.03, p < 0.01 respectively), but mid-myocardial or endocardial strain did not (mid-myocardium: p = 0.05, p = 0.12; endocardium: p = 0.27, p = 0.05, respectively). By day 90, infarcts with MO had more attenuated strain in all myocardial layers compared to infarcts without MO (p < 0.01); those with IMH were attenuated further (p < 0.01). Remote myocardial strain was similar across groups at all time-points (p > 0.2). Infarct transmural extent did not correlate with strain (p > 0.05 at each time point). In multivariable logistic regression, MO and IMH were the only significant independent predictors of attenuated 90-day infarct zone strain (p = 0.004, p = 0.011, respectively).

Conclusions

Strain improves within the infarct zone overall following reperfusion with or without MO or IMH. Mid-myocardial and endocardial infarct contractility is diminished in the presence of MO, and further in the presence of IMH. MO and IMH are greater independent predictors of infarct zone contractile recovery than infarct volume or transmural extent.     

Assessment of myocardium at risk with contrast enhanced steady-state free precession cine cardiovascular magnetic resonance compared to single-photon emission computed tomography

Background

Final infarct size following coronary occlusion is determined by the duration of ischemia, the size of myocardium at risk (MaR) and reperfusion injury. The reference method for determining MaR, single-photon emission computed tomography (SPECT) before reperfusion, is impractical in an acute setting. The aim of the present study was to evaluate whether MaR can be determined from the contrast enhanced myocardium using steady-state free precession (SSFP) cine cardiovascular magnetic resonance (CMR) performed one week after the acute event in ST-elevation myocardial infarction (STEMI) patients with total coronary occlusion.

Results

Sixteen patients with STEMI (age 64 ± 8 years) received intravenous 99 m-Tc immediately before primary percutaneous coronary intervention. SPECT was performed within four hours. MaR was defined as the non-perfused myocardial volume derived with SPECT. CMR was performed 7.8 ± 1.2 days after the myocardial infarction using a protocol in which the contrast agent was administered before acquisition of short-axis SSFP cines. MaR was evaluated as the contrast enhanced myocardial volume in the cines by two blinded observers. MaR determined from the enhanced region on cine CMR correlated significantly with that derived with SPECT (r² = 0.78, p < 0.001). The difference in MaR determined by CMR and SPECT was 0.5 ± 5.1% (mean ± SD). The interobserver variability of contrast enhanced cine SSFP measurements was 1.6 ± 3.7% (mean ± SD) of the left ventricle wall volume.

Conclusions

Contrast enhanced SSFP cine CMR performed one week after acute infarction accurately depicts MaR prior to reperfusion in STEMI patients with total occlusion undergoing primary PCI. This suggests that a single CMR examination might be performed for determination of MaR and infarct size.     

Direct admission versus transfer of AMI patients for primary PCI

Background  

Guidelines for the treatment of patients with ST-elevation myocardial infarction (STEMI) recommend primary PCI as first choice therapy. This recommendation has been linked to defined time limits achievable in a logistic network for the treatment of ACS. In the present study we analyzed the difference in 6 months outcome between STEMI patients who were admitted directly to a PCI center and those requiring transfer for primary PCI.     

Gender differences in patients with acute ST-elevation myocardial infarction complicated by cardiogenic shock

Introduction  

The aim of our analysis is to assess gender differences in baseline characteristics, acute therapies, and clinical outcome in patients with acute ST-elevation myocardial infarction (STEMI) complicated by cardiogenic shock.     

Prognostic value of minimal blood flow restoration in patients with acute myocardial infarction after reperfusion therapy

Purpose  

The prognostic impact of low-flow reperfusion after percutaneous coronary intervention (PCI) in patients with ST-segment elevation acute myocardial infarction (STEMI) is unknown. The aim of the study was to investigate the impact of low-flow reperfusion after PCI in patients with STEMI.     

Short-term prognosis of contemporary interventional therapy of ST-elevation myocardial infarction: does gender matter?

Background  

A higher mortality risk for women with acute ST-elevation myocardial infarction (STEMI) has been a common finding in the past, even after acute percutaneous coronary intervention (PCI). We set out to analyze whether there are gender differences in real-world contemporary treatment and outcomes of STEMI.     

Relative role of NT-pro BNP and cardiac troponin T at 96 hours for estimation of infarct size and left ventricular function after acute myocardial infarction.

BACKGROUND: N-terminal brain-type natriuretic peptide (NT-pro BNP) and cardiac troponin T (cTnT) after acute myocardial infarction (AMI) have proven useful for prediction of prognosis and may be valuable for assessment of left ventricular function and infarct size. The aim of the present study was to correlate infarct size and left ventricular function determined by cine and late gadolinium enhanced CMR with plasma levels of TNT and NT-pro BNP levels after AMI. METHODS: We studied 44 patients (pts) with first ST- and non-ST-segment elevation myocardial infarction (STEMI=23 pts.,NSTEMI=21 pts.). We measured NT-pro BNP and cTnT on a single occasion at 96 hours after onset of symptoms. RESULTS: There was a moderate inverse correlation between NT-pro BNP and LV-EF in STEMI (r=-0.67, p=0.0009) and NSTEMI (r=-0.85, p<0.0001). Likewise, cTnT showed a significant inverse correlation with LV-EF in STEMI (r=-0.54, p=0.014) but not in NSTEMI. With cTnT there was a strong linear correlation with infarct mass and relative infarct size in STEMI (r=0.92, p<0.0001) and NSTEMI (r=0.59, p<0.0093). NT-pro BNP demonstrated a good relationship with infarct mass (r=0.79, p<0.0001) and relative infarct size (r=0.75, p<0.0001) in STEMI, but not in NSTEMI. CONCLUSION: A single NT-pro BNP and cTnT value at 96 hours after onset of symptoms proved useful for estimation of LV-EF and infarct size. In direct comparison, NT-pro BNP disclosed a better performance for estimation of LV-EF whereas cTnT was superior for assessment of infarct mass and relative infarct size, suggesting an implementation of a dual marker strategy for diagnostic and prognostic work-up.     

Contrast-enhanced magnetic resonance imaging reveals early decrease of transmural extent of reperfused acute myocardial infarction

In patients with myocardial infarction infarct size and transmural extent are of high prognostic value for clinical outcome and recovery of contractile function of the affected myocardium either spontaneously or after revascularisation. Delayed contrast-enhancement magnetic resonance imaging (DCE-MRI) is a non-invasive imaging technique of high accuracy for determination of myocardial infarct size and transmural extent. As decisions whether revascularisation procedures are promising in patients with coronary artery disease are increasingly based on the transmural infarct extent assessed by DCE-MRI we sought to examine whether the timing of MRI after acute myocardial infarction would influence the transmural extent. We performed DCE-imaging on a clinical 1.5 T scanner in patients at day-1 and day-7 after reperfused STEMI. We assessed the total number of segments displaying DCE as well as differentiated by the transmural infarct extent. The total number of affected segments as well as the number of segments with only subendocardial DCE did not change between day-1 and day-7. In contrast, we observed a significant decrease of the number of segments with DCE of ≥75% transmurality and a significant increase of segments with DCE grade III (51%–75% transmurality). We conclude that the transmural infarct extent is not stable over the first days after STEMI which should be taken into account when assessing viability in clinical and research settings. C. Merten and H. Steen contributed equally     

Impact of <Emphasis Type="Italic">N</Emphasis>-acetylcysteine on contrast-induced nephropathy defined by cystatin C in patients with ST-elevation myocardial infarction undergoing primary angioplasty

Background  

The aim of this study was to assess the effects of N-acetylcysteine (N-ACC) on contrast-induced nephropathy (CIN) defined by Cystatin C (Cys-C) serum levels and to evaluate the influence of Cys-C on clinical outcome in patients with ST-elevation myocardial infarction (STEMI).     

Effects of combined deferiprone with deferoxamine on right ventricular function in thalassaemia major

Background

Thrombus aspiration (TA) has been shown to improve microvascular perfusion during primary percutaneous coronary intervention (PCI) for patients with ST-segment elevation myocardial infarction (STEMI). The objective of our study was to assess the relationship between TA and myocardial edema, myocardial hemorrhage, microvascular obstruction (MVO) and left ventricular remodeling in STEMI patients using cardiovascular magnetic resonance (CMR).

Methods

Sixty patients were enrolled post primary PCI and underwent CMR on a 1.5 T scanner at 48 hours and 6 months. Patients were retrospectively stratified into 2 groups: those that received TA (35 patients) versus that did not receive thrombus aspiration (NTA) (25 patients). Myocardial edema and myocardial hemorrhage were assessed by T2 and T2* quantification respectively. MVO was assessed via a contrast-enhanced T1-weighted inversion recovery gradient-echo sequence.

Results

At 48 hours, infarct segment T2 (NTA 57.9 ms vs. TA 52.1 ms, p = 0.022) was lower in the TA group. Also, infarct segment T2* was higher in the TA group (NTA 29.3 ms vs. TA 37.8 ms, p = 0.007). MVO incidence was lower in the TA group (NTA 88% vs. TA 54%, p = 0.013). At 6 months, left ventricular end-diastolic volume index (NTA 91.9 ml/m2 vs. TA 68.3 ml/m2, p = 0.013) and left ventricular end systolic volume index (NTA 52.1 ml/m2 vs. TA 32.4 ml/m2, p = 0.008) were lower and infarct segment systolic wall thickening was higher in the TA group (NTA 3.5% vs. TA 74.8%, p = 0.003).

Conclusion

TA during primary PCI is associated with reduced myocardial edema, myocardial hemorrhage, left ventricular remodeling and incidence of MVO after STEMI.     

Thrombus aspiration during primary percutaneous coronary intervention is associated with reduced myocardial edema,hemorrhage, microvascular obstruction and left ventricular remodeling

Background

Thrombus aspiration (TA) has been shown to improve microvascular perfusion during primary percutaneous coronary intervention (PCI) for patients with ST-segment elevation myocardial infarction (STEMI). The objective of our study was to assess the relationship between TA and myocardial edema, myocardial hemorrhage, microvascular obstruction (MVO) and left ventricular remodeling in STEMI patients using cardiovascular magnetic resonance (CMR).

Methods

Sixty patients were enrolled post primary PCI and underwent CMR on a 1.5 T scanner at 48 hours and 6 months. Patients were retrospectively stratified into 2 groups: those that received TA (35 patients) versus that did not receive thrombus aspiration (NTA) (25 patients). Myocardial edema and myocardial hemorrhage were assessed by T2 and T2* quantification respectively. MVO was assessed via a contrast-enhanced T1-weighted inversion recovery gradient-echo sequence.

Results

At 48 hours, infarct segment T2 (NTA 57.9 ms vs. TA 52.1 ms, p = 0.022) was lower in the TA group. Also, infarct segment T2* was higher in the TA group (NTA 29.3 ms vs. TA 37.8 ms, p = 0.007). MVO incidence was lower in the TA group (NTA 88% vs. TA 54%, p = 0.013).At 6 months, left ventricular end-diastolic volume index (NTA 91.9 ml/m2 vs. TA 68.3 ml/m2, p = 0.013) and left ventricular end systolic volume index (NTA 52.1 ml/m2 vs. TA 32.4 ml/m2, p = 0.008) were lower and infarct segment systolic wall thickening was higher in the TA group (NTA 3.5% vs. TA 74.8%, p = 0.003).

Conclusion

TA during primary PCI is associated with reduced myocardial edema, myocardial hemorrhage, left ventricular remodeling and incidence of MVO after STEMI.     

Myocardial salvage after primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction presenting early versus late after symptom onset

Primary percutaneous coronary intervention (PCI) is the treatment of choice in patients with ST-elevation myocardial infarction (STEMI) presenting within 12 h of symptom onset. A benefit in the subacute stage is less clear. The aim of the present analysis was to compare myocardial salvage and infarct size between patients with early and late reperfusion after STEMI. We compared cardiac magnetic resonance (CMR) data from a randomized controlled trial (RCT) in STEMI patients presenting within 12 h (n?=?695) and a RCT of subacute STEMI patients presenting between 12 and 48 h (n?=?93) after symptom onset. CMR imaging was performed 3.9?±?6.3 days after myocardial infarction. Analyses were performed for an unmatched cohort comprising all patients (n?=?788) and a cohort matched for area at risk (n?=?186). In the overall cohort, area at risk was similar in both groups [37.1?±?16.1% of left ventricular mass (%LV) vs. 38.3?±?16.2%LV; p?=?0.50]. Compared to STEMI patients with early reperfusion, patients with late PCI demonstrated larger infarct size (18.0?±?12.5%LV vs. 28.9?±?16.9%LV; p?<?0.01) and higher extent of microvascular obstruction (1.5?±?2.9%LV vs. 2.7?±?4.1%LV; p?=?0.01). Myocardial salvage index was significantly smaller in patients with late reperfusion (52.1?±?25.9 vs. 27.4?±?26.0; p?<?0.01). Analysis of the matched cohorts confirmed the decreased myocardial salvage (p?<?0.01) and increased infarct size (p?<?0.01) in case of late reperfusion. Compared to patients with timely primary PCI, late reperfusion after STEMI results in decreased myocardial salvage and increased infarct size. However, salvageable myocardium was also found in subacute stages of STEMI.     

One-year clinical outcomes with abciximab in acute myocardial infarction: results of the BRAVE-3 randomized trial

Purpose

In the Bavarian Reperfusion Alternatives Evaluation (BRAVE)-3 study upstream administration of abciximab additional to 600 mg clopidogrel loading did not reduce the infarct size in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary interventions. The aim of this study was to investigate 1-year clinical outcomes in the BRAVE-3 study patients.

Methods

A total of 800 patients with acute STEMI within 24 h from symptom onset, all treated with 600 mg of clopidogrel were randomized in a double-blind fashion to receive either abciximab (n = 401) or placebo (n = 399) in the intensive care unit before being sent to the catheterization laboratory.

Results

The main outcome of interest of the present study, the composite of death, recurrent myocardial infarction, stroke or revascularization of the infarct-related artery (IRA) at 1 year, was 23.0% (92 patients) in the abciximab versus 25.7% (102 patients) in the placebo group [relative risk (RR) = 0.90, 95% confidence interval (CI) 0.67–1.20; P = 0.46]. The combined incidence of death, recurrent myocardial infarction or stroke was 9.3% in the abciximab group versus 6.0% in the placebo group (RR = 1.55, 95% CI 0.93–2.58; P = 0.09). There was a significant reduction of the IRA revascularization with abciximab compared to placebo (16.3 vs. 22.3%, RR = 0.71, 95% CI 0.52–0.98; P = 0.04).

Conclusion

In patients with STEMI, all receiving 600 mg clopidogrel, abciximab did not improve overall clinical outcomes at 1 year after primary coronary stenting.     

STEMI could be the primary presentation of acute aortic dissection

Background

Stanford type A aortic dissection (TAAD) may lead to coronary artery occlusion and malfunction. However, TAAD manifesting as acute ST-segment elevation myocardial infarction (STEMI) has not been studied. In the present study, we reported 8 TAAD cases with STEMI as the primary presentation, and analyzed their clinical characteristics and outcome.

Contrast-enhanced cardiovascular magnetic resonance in the hyperacute phase of ST-elevation myocardial infarction

Cardiovascular magnetic resonance (CMR) very early after primary percutaneous coronary intervention (PPCI) may lead to instability or early stent complications. However, CMR in the hyperacute phase of STEMI may improve risk stratification. We investigated feasibility and safety of CMR in the hyperacute phase of STEMI immediately after PPCI. One hundred and twenty eight consecutive patients immediately after PPCI for STEMI. Sixty four underwent CMR <12 h after PPCI versus 64 matched controls. Outcomes were followed over 6 months. CMR in hyperacute STEMI was not associated with in-hospital death, infarct expansion, or urgent revascularization (P = NS). CMR (32 ml gadolinium contrast) immediately after PPCI (180 ml iodine contrast) did not increase nephropathy. CMR did not increase major adverse cardiac events (5 vs. 8%, P = 0.16) or recurrence of angina (6 vs. 8%, P = 0.73) at 6 months. CMR immediately after PPCI is feasible and safe, allowing very early risk stratification in STEMI. Dr. Larose is supported by the Heart and Stroke Foundation of Canada (Quebec) and the Quebec Heart Institute Foundation.