Infarct size measured by single photon emission computed tomographic imaging with (99m)Tc-sestamibi: A measure of the efficacy of therapy in acute myocardial infarction

Clinical, electrocardiographic, echocardiographic, and angiographic predictors for the final infarct size assessed by cardiac magnetic resonance in acute STEMI patients after primary percutaneous coronary intervention

BACKGROUND

Final infarct size (IS) after ST segment elevation myocardial infarction (STEMI) is a major predictor of mortality. Seeking early predictors for final IS can guide individualized therapeutic strategies for those recognized to be at higher risk.

RESULTS

Eighty STEMI patients successfully treated with primary percutaneous coronary intervention (pPCI) underwent baseline (within 48 h) 2D, 3D echocardiography with speckle tracking and then underwent cardiac magnetic resonance (CMR) at 3 months to assess the final IS. After recruitment, 4 patients were excluded for uncontainable claustrophobia while 76 patients completed the final analysis. The mean ± standard deviation age was 54.1 ± 10.9 years, 84% were males, 25% had diabetes, 26% were hypertensives, 71% were current smokers, 82% had dyslipidemia, and 18% had a family history of premature coronary artery disease. By 3 months, CMR was performed to accurately evaluate the final IS. In univariate regression analysis, the admission heart rate, baseline and post-pPCI ST elevation, STEMI location (anterior vs. inferior), highest peri-procedural troponin, large thrombus burden, baseline thrombolysis in myocardial infarction flow grade, the final myocardial blush grade, the 2D and 3D left ventricular ejection fraction (LVEF), and the 2D and 3D global longitudinal strain (GLS) parameters were significant predictors for the final IS. In the multivariate regression analysis, four models were constructed and recognized the residual post-PCI ST segment elevation, the highest peri-procedural troponin, the 2D-LVEF, 3D-LVEF, and 2D-GLS as significant independent predictors for final IS.

CONCLUSIONS

In STEMI patients who underwent successful pPCI, early predictors for the final IS are vital to guide therapeutic decisions. The residual post-pPCI ST elevation, the highest peri-procedural troponin, and the baseline 2D-LVEF, 3D-LVEF, and 2D-GLS can be excellent and timely tools to predict the final IS.

Single Bolus r-SAK Before Primary PCI for ST-Segment-Elevation Myocardial Infarction

BACKGROUND

It is uncertain whether adjunctive thrombolysis is beneficial for patients with ST-segment-elevation myocardial infarction undergoing percutaneous coronary intervention (PCI) within 120 minutes of presentation. This study was to determine whether in patients presenting with ST-segment-elevation myocardial infarction a single bolus recombinant staphylokinase (r-SAK) before timely PCI leads to improved patency of the infarct-related artery and reduces the infarct size.

METHODS

This is an open-label, prospective, multicenter, randomized study. We enrolled patients aged 18 to 75 years who were within 12 hours of symptom onset of ST-segment-elevation myocardial infarction and expected to undergo PCI within 120 minutes. Patients were administered loading doses of aspirin and ticagrelor and intravenous heparin and were randomized to receive 5 mg bolus of r-SAK or normal saline intravenously before PCI. The primary end point was Thrombolysis in Myocardial Infarction flow grade 2 to 3 or grade 3 in the infarct-related artery 60 minutes after thrombolysis. The infarct size was detected by cardiac magnetic resonance 5 days after randomization. The safety end point was major bleeding (Bleeding Academic Research Consortium ≥3) during 30-day follow-up.

RESULTS

A total of 283 patients were screened from 8 centers and 200 were randomized (median age, 58.5 years; 14% female). The median symptom to thrombolysis time was 252.5 (interquartile range, 142.8-423.8) minutes and thrombolysis to coronary arteriography was 50.0 (interquartile range, 37.0-66.0) minutes. Patients randomized to r-SAK compared with normal saline more often had Thrombolysis in Myocardial Infarction flow grade 2 to 3 (69.0% versus 29.0%; P<0.001) and Thrombolysis in Myocardial Infarction flow grade 3 (51.0% versus 18.0%; P<0.001) and had smaller infarct size (21.91±10.84% versus 26.85±12.37%; P=0.016). There was no increase in major bleeding (r-SAK, 1.0% versus control, 3.0%; P=0.616).

CONCLUSIONS

A single bolus r-SAK before primary PCI for ST-segment-elevation myocardial infarction improves infarct-related artery patency and reduces infarct size without increasing major bleeding.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05023681.

Automatic Quantitative Assessment for Diagnostic and Therapeutic Response in Rodent Myocardial Infarct Model

The purpose of this study was to investigate the most appropriate methodological approach for the automatic measurement of rodent myocardial infarct polar map using histogram-based thresholding and unsupervised deep learning (DL)-based segmentation. A rat myocardial infarction model was induced by ligation of the left coronary artery. Positron emission tomography (PET) was performed 60 min after the administration of 18F-fluoro-deoxy-glucose (18F-FDG), and PET was performed after injecting 64Cu-pyruvaldehyde-bis(N4-methylthiosemicarbazone). Single photon emission computed tomography was performed 60 min after injection of 99mTc-hexakis-2-methoxyisobutylisonitrile and 201Tl. Delayed contrast-enhanced magnetic resonance imaging was performed after injecting Gd-DTPA-BMA. Three types of thresholding methods (naive thresholding, Otsu's algorithm, and multi-Gaussian mixture model (MGMM)) were used. DL segmentation methods were based on a convolution neural network and trained with constraints on feature similarity and spatial continuity of the response map extracted from images by the network. The relative infarct sizes measured by histology and estimated R2 for 18F-FDG were 0.8477, 0.7084, 0.8353, and 0.9024 for naïve thresholding, Otsu's algorithm, MGMM, and DL segmentation, respectively. DL-based method improved the accuracy of MI size assessment.

Large Language Models in Neurology Research and Future Practice

Recent advancements in generative artificial intelligence, particularly using large language models (LLMs), are gaining increased public attention. We provide a perspective on the potential of LLMs to analyze enormous amounts of data from medical records and gain insights on specific topics in neurology. In addition, we explore use cases for LLMs, such as early diagnosis, supporting patient and caregivers, and acting as an assistant for clinicians. We point to the potential ethical and technical challenges raised by LLMs, such as concerns about privacy and data security, potential biases in the data for model training, and the need for careful validation of results. Researchers must consider these challenges and take steps to address them to ensure that their work is conducted in a safe and responsible manner. Despite these challenges, LLMs offer promising opportunities for improving care and treatment of various neurologic disorders.

Emerging molecular imaging targets and tools for myocardial fibrosis detection

Myocardial fibrosis is the heart's common healing response to injury. While initially seeking to optimize the strength of diseased tissue, fibrosis can become maladaptive, producing stiff poorly functioning and pro-arrhythmic myocardium. Different patterns of fibrosis are associated with different myocardial disease states, but the presence and quantity of fibrosis largely confer adverse prognosis. Current imaging techniques can assess the extent and pattern of myocardial scarring, but lack specificity and detect the presence of established fibrosis when the window to modify this process may have ended. For the first time, novel molecular imaging methods, including gallium-68 (68Ga)-fibroblast activation protein inhibitor positron emission tomography (68Ga-FAPI PET), may permit highly specific imaging of fibrosis activity. These approaches may facilitate earlier fibrosis detection, differentiation of active vs. end-stage disease, and assessment of both disease progression and treatment-response thereby improving patient care and clinical outcomes.

Radioiodinated hypericin as a tracer for detection of acute myocardial infarction: SPECT-CT imaging in a swine model

PURPOSE

Hypericin (Hyp) is a natural compound with a newly discovered necrosis-avidity, which can be exploited as a necrosis-avid tracer once labeled with radioactive iodine as has been tested in rodent models. This study was to evaluate the effect of radioiodinated Hyp (131I-Hyp) for imaging detection of acute myocardial infarction (AMI) in conditions closer to clinical scenarios.

METHODS

We established swine AMI models (n = 6) which were intravenously given 131I-Hyp and 99mTc-sestamibi and underwent SPECT-CT imaging with high- and low-energy collimators. The acquired SPECT images were fused with cardiac CT images and correlated with postmortem autoradiography and macro- and microscopic pathology. Tissue γ counting was performed to determine biodistribution of 131I-Hyp.

RESULTS

131I-Hyp based SPECT indicated clearly hot regions on ventricular walls which were all histologically proved as AMI. Complementally, the hot AMI regions on 131I-Hyp SPECT (infarct/myoc ratio of 15.3 ± 7.7) were inversely cold regions on 99mTc-sestamibi SPECT (infarct/myoc ratio of 0.029 ± 0.021). Autoradiography of heart slices showed 9.8 times higher 131I-Hyp uptake in infarcted over normal myocardium. With γ counting, the mean 131I-Hyp uptake in infarcts was 10.69 ID%/g, 12.05 times of that in viable myocardium.

CONCLUSION

131I-Hyp shows a potential for clinical detection of AMI once I-131 is substituted by its isotope like I-124 or I-123 for PET or SPECT, respectively.

Effect of changes in perfusion defect size during serial stress myocardial perfusion imaging on cardiovascular outcomes in patients treated with primary percutaneous coronary intervention after myocardial infarction

BACKGROUND

We evaluated the prognostic value of changes in perfusion defect size (PDS) on serial MPS in patients treated with primary percutaneous coronary intervention (PCI) after acute myocardial infarction (AMI).

METHODS

We enrolled 112 patients treated with primary PCI after AMI who underwent two stress MPS within 1 month and after 6 months. Improvement in PDS was defined as a reduction ≥5%. Remodeling was defined as an increase in left ventricular (LV) end-diastolic volume index ≥20%. Cardiac events included cardiac death, nonfatal MI, unstable angina, repeated revascularization, and heart failure.

RESULTS

During a median follow-up of 86 months, 22 events occurred. Event rate was higher (P < .01) in patients with worsening of PDS compared to those with unchanged or improved PDS. Moreover, patients with remodeling had a higher (P < .001) event rate compared to those without. At Cox analysis, worsening of PDS and remodeling resulted independent predictors of events (both P < .01). Patients with both worsening of PDS and remodeling had the worst event-free survival (P <.001).

CONCLUSION

In patients treated with primary PCI after AMI, worsening of PDS and remodeling are associated to higher risk of events at long-term follow-up. Gated stress MPS improves risk stratification in these patients.

Prognostic significance of myocardial salvage assessed by cardiac magnetic resonance in reperfused ST-segment elevation myocardial infarction

Aims

Myocardial salvage index (MSI) is attracting increasing attention for predicting prognosis in acute myocardial infarction (AMI); however, the evaluation of MSI is mainly based on contrast agent-dependent cardiac magnetic resonance (CMR) scanning sequences. This study aims to investigate the prognostic value of MSI in reperfused ST-segment elevation myocardial infarction (STEMI) through the contrast agent-free CMR technique.

Methods and results

Nighty-two patients with acute STEMI, who underwent CMR after primary percutaneous coronary intervention (PPCI), were finally enrolled. Patients were subcategorized into two groups according to median MSI. T1 and T2 mapping were conducted for measuring infarct size (IS) and area at risk (AAR). IS was significantly larger in < median MSI group than ≥ median MSI group (P < 0.001). AAR between the two groups showed no obvious differences (P = 0.108). Left ventricular ejection fraction (LVEF) was lower in < median MSI group than ≥ median MSI group (P = 0.014). There was an obvious inverse correlation between MSI and reperfusion time (R = –0.440, P < 0.001) and a strong inverse correlation between MSI and IS (R = –0.716, P = 0.011). As for the relationship LVEF, MSI showed positive but weak correlation (R = 0.2265, P < 0.001). Over a median follow-up period of 263 (227–238) days, prevalence of MACEs was significantly higher in the < median MSI group [HR: 0.15 (0.04–0.62); Log-rank P = 0.008]. The univariate Cox regression analysis revealed that LVEF, IS, and MSI were significant predictors for major adverse cardiovascular events (MACEs) (all P < 0.05). In the stepwise multivariate Cox regression analysis, LVEF and MSI were identified as independent parameters for predicting MACEs (both P < 0.05). In the receiver-operating characteristic analysis, LVEF, IS, and MSI showed prognostic value in predicting MACEs with AUCs of 0.809, 0.779, and 0.896, respectively, all (P < 0.05). A combination of MSI with LVEF showed the strongest prognostic value of MACEs (AUC: 0.901, sensitivity: 77.78%, specificity: 98.80%, P < 0.001). Delong’s test showed that the combination of LVEF with MSI had an incremental value than LVEF itself in predicting MACEs (P = 0.026).

Conclusion

Contrast agent-free CMR technique provides a reliable evaluation of MSI, which contributes to assessing the efficacy of reperfusion therapy and predicting the occurrence of MACEs.

Fluid-based assays and precision medicine of cardiovascular diseases: the ‘hope’ for Pandora’s box?

Progresses in liquid-based assays may provide novel useful non-invasive indicators of cardiovascular (CV) diseases. By analysing circulating cells or their products in blood, saliva and urine samples, we can investigate molecular changes present at specific time points in each patient allowing sequential monitoring of disease evolution. For example, an increased number of circulating endothelial cells may be a diagnostic biomarker for diabetic nephropathy and heart failure with preserved ejection fraction. The assessment of circulating cell-free DNA (cfDNA) levels may be useful to predict severity of acute myocardial infarction, as well as diagnose heart graft rejection. Remarkably, circulating epigenetic biomarkers, including DNA methylation, histone modifications and non-coding RNAs are key pathogenic determinants of CV diseases representing putative useful biomarkers and drug targets. For example, the unmethylated FAM101A gene may specifically trace cfDNA derived from cardiomyocyte death providing a powerful diagnostic biomarker of apoptosis during ischaemia. Moreover, changes in plasma levels of circulating miR-92 may predict acute coronary syndrome onset in patients with diabetes. Now, network medicine provides a framework to analyse a huge amount of big data by describing a CV disease as a result of a chain of molecular perturbations rather than a single defect (reductionism). We outline advantages and challenges of liquid biopsy with respect to traditional tissue biopsy and summarise the main completed and ongoing clinical trials in CV diseases. Furthermore, we discuss the importance of combining fluid-based assays, big data and network medicine to improve precision medicine and personalised therapy in this field.

Prediction of functional recovery after primary PCI using the estimate of myocardial salvage in gated SPECT early after acute myocardial infarction

PURPOSE

Primary percutaneous coronary intervention (PCI) in acute myocardial infarction (AMI) aims to achieve myocardial salvage (MS). Because the reference method for measuring MS requires myocardial perfusion imaging (MPI) after tracer injection before PCI, alternative approaches have been proposed, but none has gained wide acceptance. Gated SPECT MPI can assess infarct size (IS), but can also show myocardial stunning. Thus, we compared functional and perfusion abnormalities early after AMI to estimate MS, and to predict left ventricular ejection fraction (LVEF) recovery at follow-up.

METHODS

We studied 120 patients with AMI. Gated SPECT MPI was performed early (before hospital discharge) and at 6 months after AMI to measure IS, MS and functional outcome. MS was defined as the difference between the number of segments with abnormal thickening (i.e. the stunned area or area at risk) and the number of segments with abnormal perfusion (i.e. the final IS), expressed as a percentage of the total number of segments in the AHA model. LVEF was calculated using quantitative gated SPECT.

RESULTS

The area at risk was 40 ± 25%, IS was 17.3 ± 16% and MS was 22 ± 19%. Early LVEF was 46.6 ± 11.6% and late LVEF was 51.4 ± 11.6%, with 54 patients showing at least an increase in LVEF of more than 5 units. ROC analysis showed that MS was able to predict LVEF recovery with an area under the curve (AUC) of 0.79 (p < 0.0001), and using a cut off >23% detected LVEF recovery with 74% sensitivity and 71% specificity. Conversely, IS was associated with an AUC 0.53 (not significant).

CONCLUSION

MS assessed by a single early gated SPECT MPI study can accurately predict LVEF evolution after primary PCI for AMI.

CT-based SPECT attenuation correction and assessment of infarct size: results from a cardiac phantom study

RATIONALE

Myocardial perfusion SPECT is a commonly performed, well established, clinically useful procedure for the management of patients with coronary artery disease. However, the attenuation of photons from myocardium impacts the quantification of infarct sizes. CT-Attenuation Correction (AC) potentially resolves this problem. This contention was investigated by analyzing various parameters for infarct size delineation in a cardiac phantom model.

METHODS

A thorax phantom with a left ventricle (LV), fillable defects, lungs, spine and liver was used. The defects were combined to simulate 6 infarct sizes (5-20% LV). The LV walls were filled with 100120 kBq/ml ^99mTc and the liver with 10-12 kBq/ml ^99mTc. The defects were filled with water of 50% LV activity to simulate transmural and non-transmural infarction, respectively. Imaging of the phantom was repeated for each configuration in a SPECT/CT system. The defects were positioned in the anterior as well as in the inferior wall. Data were acquired in two modes: 32 views, 30 s/view, 180° and 64 views, 15 s/view, 360° orbit. Images were reconstructed iteratively with scatter correction and resolution recovery. Polar maps were generated and defect sizes were calculated with variable thresholds (40-60%, in 5% steps). The threshold yielding the best correlation and the lowest mean deviation from the true extents was considered optimal.

RESULTS

AC data showed accurate estimation of transmural defect extents with an optimal threshold of 50% [non attenuation correction (NAC): 40%]. For the simulation of non-transmural defects, a threshold of 55% for AC was found to yield the best results (NAC: 45%). The variability in defect size due to the location (anterior versus inferior) of the defect was reduced by 50% when using AC data indicating the benefit from using AC. No difference in the optimal threshold was observed between the different orbits.

CONCLUSION

Cardiac SPECT/CT shows an improved capability for quantitative defect size assessment in phantom studies due to the positive effects of attenuation correction.

Sources of variability in quantification of cardiovascular magnetic resonance infarct size - reproducibility among three core laboratories

BACKGROUND

Acute myocardial infarct (AMI) size depicted by late gadolinium enhancement cardiovascular magnetic resonance (CMR) is increasingly used as an efficacy endpoint in randomized trials comparing AMI therapies. Infarct size is quantified using manual planimetry (MANUAL), visual scoring (VISUAL), or automated techniques using signal-intensity thresholding (AUTO). Although AUTO is considered the most reproducible, prior studies did not account for the subjective determination of endocardial/epicardial borders, which all methods require. For MANUAL and VISUAL, prior studies did not address how to treat intermediate signal intensities due to partial volume.

METHODS

To assess sources of variability, AMI size was measured in 30 patients and 12 controls by 3 core-laboratories using 8 methods, each separated by more than 2 months time (n = 720 evaluations). The methods were: (1,2) AUTOSegment, AUTOFWHM (using Segment software or the full-width-at-half-maximum algorithm, respectively); (3,4) AUTO-UCSegment, AUTO-UCFWHM (user correction for endocardial border pixels, no-reflow, etc.); (5) MANUAL; (6) MANUAL-ISI (adjustment for intermediate signal-intensities); (7) VISUAL; (8) VISUAL-ISI.

RESULTS

Mean infarct size varied between 16.8% and 27.2% of LV mass depending on method. Even automated techniques with no user interaction for infarct borders resulted in significant within-patient variability given the need to subjectively trace endocardial/epicardial contours. The coefficient-of-variation (CV) was 10.6% and 14.6% for AUTOSegment and AUTOFWHM, respectively. For manual and visual categories, reproducibility was improved when intermediate signal-intensities were considered (MANUAL-ISI vs MANUAL: CV = 8.3% vs 14.4%; p = 0.03; VISUAL-ISI vs VISUAL: CV = 8.4% vs 10.9%; p = 0.01). For AUTO-UCSegment, MANUAL-ISI, and VISUAL-ISI (best technique in each category) within-patient variability due to the quantification method was less than 10% of total variability, and the required sample sizes for detecting a 5% absolute difference in infarct size were 62, 63, and 62 patients, respectively.

CONCLUSION

Among CMR core-laboratories, an important source of variability in infarct size quantification is the subjective delineation of endocardial/epicardial borders. When intermediate signal intensities are considered in manual planimetry and visual scoring, reproducibility and impact on sample size are similar to automated techniques.

Cardiac Fibrosis and Arrhythmogenesis

Myocardial injury, mechanical stress, neurohormonal activation, inflammation, and/or aging all lead to cardiac remodeling, which is responsible for cardiac dysfunction and arrhythmogenesis. Of the key histological components of cardiac remodeling, fibrosis either in the form of interstitial, patchy, or dense scars, constitutes a key histological substrate of arrhythmias. Here we discuss current research findings focusing on the role of fibrosis, in arrhythmogenesis. Numerous studies have convincingly shown that patchy or interstitial fibrosis interferes with myocardial electrophysiology by slowing down action potential propagation, initiating reentry, promoting after-depolarizations, and increasing ectopic automaticity. Meanwhile, there has been increasing appreciation of direct involvement of myofibroblasts, the activated form of fibroblasts, in arrhythmogenesis. Myofibroblasts undergo phenotypic changes with expression of gap-junctions and ion channels thereby forming direct electrical coupling with cardiomyocytes, which potentially results in profound disturbances of electrophysiology. There is strong evidence that systemic and regional inflammatory processes contribute to fibrogenesis (i.e., structural remodeling) and dysfunction of ion channels and Ca2+ homeostasis (i.e., electrical remodeling). Recognizing the pivotal role of fibrosis in the arrhythmogenesis has promoted clinical research on characterizing fibrosis by means of cardiac imaging or fibrosis biomarkers for clinical stratification of patients at higher risk of lethal arrhythmia, as well as preclinical research on the development of antifibrotic therapies. At the end of this review, we discuss remaining key questions in this area and propose new research approaches. © 2017 American Physiological Society. Compr Physiol 7:1009-1049, 2017.

Relationship between therapeutic effects on infarct size in acute myocardial infarction and therapeutic effects on 1-year outcomes: A patient-level analysis of randomized clinical trials

BACKGROUND

While infarct size in patients with ST-segment elevation myocardial infarction (STEMI) has been generally associated with long-term prognosis, whether a therapeutic effect on infarct size has a corresponding therapeutic effect on long-term outcomes is unknown.

METHODS

Using combined patient-level data from 10 randomized trials of primary percutaneous coronary intervention (PCI) for STEMI, we created multivariable Cox proportional hazard models for one-year heart failure hospitalization and all-cause mortality, which included clinical features and a variable representing treatment effect on infarct size. The trials included 2679 participants; infarct size was measured at a median 4 days post infarction.

RESULTS

Mean infarct size among the control groups ranged from 16% to 35% of the left ventricle, and from 12% to 36% among treatment groups. There was a significant relationship between treatment effect on infarct size and treatment effect on 1-year heart failure hospitalization (HR 0.85, 95% CI 0.77-0.93, P=.0006), but not on one-year mortality (HR 0.97, 95% CI 0.89-1.06). The treatment effect between infarct size and heart failure hospitalization was stable in sensitivity analyses adjusting for time from STEMI onset to infarct size assessment, and when considering heart failure as the main outcome and death as a competing risk.

CONCLUSIONS

We conclude that early treatment-induced effects on infarct size are related in direction and magnitude to treatment effects on heart failure hospitalizations. This finding enables consideration of using infarct size as a valid surrogate outcome measure in assessing new STEMI treatments.

Clinical predictors for the manifestation of late gadolinium enhancement after acute myocardial infarction

Despite prompt revascularization, some patients with acute myocardial infarction (AMI) develop myocardial scars, which can be visualized by late gadolinium enhancement (LGE) in cardiovascular magnetic resonance imaging (CMR). Our goal was to identify angiographic findings that were predictive for scar development in patients after reperfused AMI.We examined 136 patients after first ST-elevated myocardial infarction by CMR after a median of 4 days (range: 2-7). Patients with manifestation of LGE were matched to patients without LGE by means of age and gender. Clinical follow-up with a combined primary endpoint including myocardial reinfarction, congestive heart failure, stroke, death and development of left ventricular thrombus was reported after 24 months.Patients with manifestation of LGE had a significant longer time of symptom-to-intervention, a higher prevalence of anterior AMI, and more proximal culprit lesions. Furthermore, left ventricular ejection fraction was significantly decreased, and peak values of infarct markers were significantly higher in these patients. Preinterventional thrombolysis in myocardial infarction-0-flow was significantly more frequent in patients with LGE manifestation. The presence of 3-vessel disease (odds ratio 53.99, 95% confidence interval 8.22-354.63, P <.001), a proximal culprit lesion, and high creatine kinase myocardial band (CK-MB) values were identified as independent predictors of LGE. Follow-up demonstrated a higher incidence of clinical events in the group with LGE, with the most common cause of heart failure (38.2% vs 7.4%, P <.001).The extent of angiographic findings in AMI plays a major role in the manifestation of LGE. The presence of a multivessel disease, a proximal culprit lesion, and high values of CK-MB are strong independent predictors for LGE manifestation.

Infarct characterization using CT

Myocardial infarction (MI) is a major cause of death and disability worldwide. The incidence is not expected to diminish, despite better prevention, diagnosis and treatment, because of the ageing population in industrialized countries and unhealthy lifestyles in developing countries. Nowadays it is highly requested an imaging tool able to evaluate MI and viability. Technology improvements determined an expansion of clinical indications from coronary plaque evaluation to functional applications (perfusion, ischemia and viability after MI) integrating additional phases and information in the mainstream examination. Cardiac computed tomography (CCT) and cardiac MR (CMR) employ different contrast media, but may characterize MI with overlapping imaging findings due to the similar kinetics and tissue distribution of gadolinium and iodinated contrast media. CCT may detect first-pass perfusion defects, dynamic perfusion after pharmacological stress, and delayed enhancement (DE) of non-viable territories.

Relation of Left Ventricular Mass and Infarct Size in Anterior Wall ST-Segment Elevation Acute Myocardial Infarction (from the EMBRACE STEMI Clinical Trial)

Biomarker measures of infarct size and myocardial salvage index (MSI) are important surrogate measures of clinical outcomes after a myocardial infarction. However, there is variability in infarct size unaccounted for by conventional adjustment factors. This post hoc analysis of Evaluation of Myocardial Effects of Bendavia for Reducing Reperfusion Injury in Patients With Acute Coronary Events (EMBRACE) ST-Segment Elevation Myocardial Infarction (STEMI) trial evaluates the association between left ventricular (LV) mass and infarct size as assessed by areas under the curve for creatine kinase-MB (CK-MB) and troponin I release over the first 72 hours (CK-MB area under the curve [AUC] and troponin I [TnI] AUC) and the MSI. Patients with first anterior STEMI, occluded left anterior descending artery, and available LV mass measurement in EMBRACE STEMI trial were included (n = 100) (ClinicalTrials.govNCT01572909). MSI, end-diastolic LV mass on day 4 cardiac magnetic resonance, and CK-MB and troponin I concentrations were evaluated by a core laboratory. After saturated multivariate analysis, dominance analysis was performed to estimate the contribution of each independent variable to the predicted variance of each outcome. In multivariate models that included age, gender, body surface area, lesion location, smoking, and ischemia time, LV mass remained independently associated with biomarker measures of infarct size (CK-MB AUC p = 0.02, TnI AUC p = 0.03) and MSI (p = 0.003). Dominance analysis demonstrated that LV mass accounted for 58%, 47%, and 60% of the predicted variances for CK-MB AUC, TnI AUC, and MSI, respectively. In conclusion, LV mass accounts for approximately half of the predicted variance in biomarker measures of infarct size. It should be considered as an adjustment variable in studies evaluating infarct size.

Non-contrast cardiac CT immediately after percutaneous coronary intervention: does it predict the risk of left ventricular remodeling in patients with ST-elevation myocardial infarction?

To assess the clinical utility of non-contrast cardiac CT (CCT) immediately after successful percutaneous coronary intervention (PCI) for predicting the risk of left ventricle (LV) remodeling in the management of patients with acute myocardial infarction (AMI), 35 patients with AMI underwent non-contrast CCT immediately after PCI. Volume and transmural extent of myocardial delayed enhancement (DE) were assessed on non-contrast CCT. Serial echocardiography and serologic biomarkers were evaluated at baseline and at 2 and 12 months after AMI. Based on an increase in left ventricular end-diastolic volume (LVEDV) ≥20 % at 2 months, patients were classified into two groups: LV remodeling (group 1, n = 14) and no LV remodeling (group 2, n = 21). Clinical characteristics, imaging parameters, and serologic biomarkers were compared between the two groups. Higher incidence of hypertension, longer time to reperfusion, and higher Killip classification at admission were observed for group 1 than for group 2, but these differences were not statistically significant (P > 0.05). Greater volume and transmural extent of DE on non-contrast CCT and poorer resolution of ST-segment elevation on ECG were observed in group 1 compared to group 2, but these results were not statistically significant (P > 0.05). Measurement of biochemical markers showed that probrain natriuretic peptide (proBNP), initial high sensitivity C reactive protein (hs-CRP), and maximum troponin T level were significantly higher in group 1 than in group 2 (P < 0.05) at 2 months. Based on the trend of greater volume and transmural extent of DE in group 1 compared to group 2, non-contrast CCT immediately after PCI, in combination with serologic biomarkers (proBNP, hs-CRP, and troponin T) might be useful for managing patients with AMI.

Association of interleukin 8 and myocardial recovery in patients with ST-elevation myocardial infarction complicated by acute heart failure

Background

No data from controlled trials exists regarding the inflammatory response in patients with de novo heart failure (HF) complicating ST-elevation myocardial infarction (STEMI) and a possible role in the recovery of contractile function. We therefore explored the time course and possible associations between levels of inflammatory markers and recovery of impaired left ventricular function as well as levosimendan treatment in STEMI patients in a substudy of the LEvosimendan in Acute heart Failure following myocardial infarction (LEAF) trial.

Methods

A total of 61 patients developing HF within 48 hours after a primary PCI-treated STEMI were randomised double-blind to a 25 hours infusion of levosimendan or placebo. Levels of IL-6, CRP, sIL-6R, sgp130, MCP-1, IL-8, MMP-9, sICAM-1, sVCAM-1 and TNF-α were measured at inclusion (median 22 h, interquartile range (IQR) 14, 29 after PCI), on day 1, day 2, day 5 and 6 weeks. Improvement in left ventricular function was evaluated as change in wall motion score index (WMSI) by echocardiography.

Results

Only circulating levels of IL-8 at inclusion were associated with change in WMSI from baseline to 6 weeks, r = ÷0.41 (p = 0.002). No association, however, was found between IL-8 and WMSI at inclusion or peak troponin T. Furthermore, there was a significant difference in change in WMSI from inclusion to 6 weeks between patients with IL-8 levels below, compared to above median value, ÷0.44 (IQR÷0.57, ÷0.19) vs. ÷0.07 (IQR÷0.27, 0.07), respectively (p<0.0001). Levosimendan did not affect the levels of inflammary markers compared to control.

Conclusion

High levels of IL-8 in STEMI patients complicated with HF were associated with less improvement in left ventricular function during the first 6 weeks after PCI, suggesting a possible role of IL-8 in the reperfusion-related injury of post-ischemic myocardium. Further studies are needed to confirm this hypothesis.

Trial Registration

ClinicalTrials.gov NCT00324766

Cardiac CT for myocardial ischaemia detection and characterization--comparative analysis

The assessment of patients presenting with symptoms of myocardial ischaemia remains one of the most common and challenging clinical scenarios faced by physicians. Current imaging modalities are capable of three-dimensional, functional and anatomical views of the heart and as such offer a unique contribution to understanding and managing the pathology involved. Evidence has accumulated that visual anatomical coronary evaluation does not adequately predict haemodynamic relevance and should be complemented by physiological evaluation, highlighting the importance of functional assessment. Technical advances in CT technology over the past decade have progressively moved cardiac CT imaging into the clinical workflow. In addition to anatomical evaluation, cardiac CT is capable of providing myocardial perfusion parameters. A variety of CT techniques can be used to assess the myocardial perfusion. The single energy first-pass CT and dual energy first-pass CT allow static assessment of myocardial blood pool. Dynamic cardiac CT imaging allows quantification of myocardial perfusion through time-resolved attenuation data. CT-based myocardial perfusion imaging (MPI) is showing promising diagnostic accuracy compared with the current reference modalities. The aim of this review is to present currently available myocardial perfusion techniques with a focus on CT imaging in light of recent clinical investigations. This article provides a comprehensive overview of currently available CT approaches of static and dynamic MPI and presents the results of corresponding clinical trials.

Implications of ventricular arrhythmia “bursts” with normal epicardial flow, myocardial blush, and ST-segment recovery in anterior ST-elevation myocardial infarction reperfusion: A biosignature of direct myocellular injury “downstream of downstream”

Aims:

Establishing epicardial flow with percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is necessary but not sufficient to ensure nutritive myocardial reperfusion. We evaluated whether adding myocardial blush grade (MBG) and quantitative reperfusion ventricular arrhythmia “bursts” (VABs) surrogates provide a more informative biosignature of optimal reperfusion in patients with Thrombolysis in Myocardial Infarction (TIMI) 3 flow and ST-segment recovery (STR).

Methods and results:

Anterior STEMI patients with final TIMI 3 flow had protocol-blinded analyses of simultaneous MBG, continuous 12-lead electrocardiogram (ECG) STR, Holter VABs, and day 5–14 SPECT imaging infarct size (IS) assessments. Over 20 million cardiac cycles from >4500 h of continuous ECG monitoring in subjects with STR were obtained. IS and clinical outcomes were examined in patients stratified by MBG and VABs. VABs occurred in 51% (79/154) of subjects. Microcirculation (MBG 2/3) was restored in 75% (115/154) of subjects, of whom 53% (61/115) had VABs. No VABs were observed in subjects without microvascular flow (MBG of 0). Of 115 patients with TIMI 3 flow, STR, and MBG 2/3, those with VABs had significantly larger IS (median: 23.0% vs 6.0%, p=0.001). Multivariable analysis identified reperfusion VABs as a factor significantly associated with larger IS ( p=0.015).

Conclusions:

Despite restoration of normal epicardial flow, open microcirculation, and STR, concomitant VABs are associated with larger myocardial IS, possibly reflecting myocellular injury in reperfusion settings. Combining angiographic and ECG parameters of epicardial, microvascular, and cellular response to STEMI intervention provides a more predictive “biosignature” of optimal reperfusion than do single surrogate markers.

Is it Feasible to Use the Commercially Available Autoquantitation Software for the Evaluation of Myocardial Viability on Small-Animal Cardiac F-18 FDG PET Scan?

PURPOSE

To evaluate the reliability of quantitation of myocardial viability on cardiac F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scans with three different methods of visual scoring system, autoquantitation using commercially available autoquantitation software, and infarct-size measurement using histogram-based maximum pixel threshold identification on polar-map in rat hearts.

METHODS

A myocardial infarct (MI) model was made by left anterior descending artery (LAD) ligation in rat hearts. Eighteen MI rats underwent cardiac FDG-PET-computed tomography (CT) twice within a 4-week interval. Myocardium was partitioned into 20 segments for the comparison, and then we quantitated non-viable myocardium on cardiac FDG PET-CT with three different methods: method A-infarct-size measurement using histogram-based maximum pixel threshold identification on polar-map; method B-summed MI score (SMS) by a four-point visual scoring system; method C-metabolic non-viable values by commercially available autoquantitation software. Changes of non-viable myocardium on serial PET-CT scans with three different methods were calculated by the change of each parameter. Correlation and reproducibility were evaluated between the different methods.

RESULTS

Infarct-size measurement, visual SMS, and non-viable values by autoquantitation software presented proportional relationship to each other. All the parameters of methods A, B, and C showed relatively good correlation between each other. Among them, infarct-size measurement (method A) and autoquantitation software (method C) showed the best correlation (r = 0.87, p < 0.001). When we evaluated the changes of non-viable myocardium on the serial FDG-PET-CT- however, autoquantitation program showed less correlation with the other methods. Visual assessment (method B) and those of infarct size (method A) showed the best correlation (r = 0.54, p = 0.02) for the assessment of interval changes.

CONCLUSIONS

Commercially available quantitation software could be applied to measure the myocardial viability on small animal cardiac FDG-PET-CT scan. This kind of quantitation showed good correlation with infarct size measurement by histogram-based maximum pixel threshold identification. However, this method showed the weak correlation when applied in the measuring the changes of non-viable myocardium on the serial scans, which means that the caution will be needed to evaluate the changes on the serial monitoring.

Validation of an automated method to quantify stress-induced ischemia and infarction in rest-stress myocardial perfusion SPECT

BACKGROUND

Myocardial perfusion SPECT (MPS) is one of the frequently used methods for quantification of perfusion defects in patients with known or suspected coronary artery disease. This article describes open access software for automated quantification in MPS of stress-induced ischemia and infarction and provides phantom and in vivo validation.

METHODS AND RESULTS

A total of 492 patients with known or suspected coronary artery disease underwent both stress and rest MPS. The proposed perfusion analysis algorithm (Segment) was trained in 140 patients and validated in the remaining 352 patients using visual scoring in MPS by an expert reader as reference standard. Furthermore, validation was performed with simulated perfusion defects in an anthropomorphic computer model. Total perfusion deficit (TPD, range 0-100), including both extent and severity of the perfusion defect, was used as the global measurement of the perfusion defects. Mean bias ± SD between TPD by Segment and the simulated TPD was 3.6 ± 3.8 (R(2) = 0.92). Mean bias ± SD between TPD by Segment and the visual scoring in the patients was 1.2 ± 2.9 (R (2)= 0.64) for stress-induced ischemia and -0.3 ± 3.1 (R(2) = 0.86) for infarction.

CONCLUSION

The proposed algorithm can detect and quantify perfusion defects in MPS with good agreement to expert readers and to simulated values in a computer phantom.

Assessment of myocardial viability and left ventricular function in patients supported by a left ventricular assist device

BACKGROUND

Chronically supported left ventricular assist device (LVAD) patients may be candidates for novel therapies aimed at promoting reverse remodeling and myocardial recovery. However, the effect of hemodynamic unloading with a LVAD on myocardial viability and LV function in chronically supported LVAD patients has not been fully characterized. We aimed to develop a non-invasive imaging protocol to serially quantify native cardiac structure, function, and myocardial viability while at reduced LVAD support.

METHODS

Clinically stable (n = 18) ambulatory patients (83% men, median age, 61 years) supported by a HeartMate II (Thoratec, Pleasanton, CA) LVAD (median durations of heart failure 4.6 years and LVAD support 7 months) were evaluated by echocardiography and technetium-99m ((99m)Tc)-sestamibi single photon emission computed tomography (SPECT) imaging at baseline and after an interval of 2 to 3 months. Echocardiographic measures of LV size and function, including speckle tracking-derived circumferential strain, were compared between ambulatory and reduced LVAD support at baseline and between baseline and follow-up at reduced LVAD support. The extent of myocardial viability by SPECT was compared between baseline and follow-up at reduced LVAD support.

RESULTS

With reduction in LVAD speeds (6,600 rpm; interquartile range: 6,200, 7,400 rpm), LV size increased, LV systolic function remained stable, and filling pressures nominally worsened. After a median 2.1 months, cardiac structure, function, and the extent of viable myocardium, globally and regionally, was unchanged on repeat imaging while at reduced LVAD speed.

CONCLUSIONS

In clinically stable chronically supported LVAD patients, intrinsic cardiac structure, function, and myocardial viability did not significantly change over the pre-specified time frame. Echocardiographic circumferential strain and (99m)Tc-sestamibi SPECT myocardial viability imaging may provide useful non-invasive end points for the assessment of cardiac structure and function, particularly for phase II studies of novel therapies aimed at promoting reverse remodeling and myocardial recovery in LVAD patients.

Effects of tirofiban maintenance duration on myocardial perfusion defect severity in anterior myocardial infarction

INTRODUCTION

Percutaneous coronary intervention (PCI) does not often produce optimal results, despite restoration of coronary blood flow at myocardial recovery, because of impaired microvascular perfusion. This study aimed to investigate and evaluate with (99m)Tc-sestamibi scan whether the results of PCI can be changed by maintenance infusion of tirofiban for 24 or 48 h in patients presenting with anterior ST-elevation myocardial infarction (STEMI).

METHODS

The study included 84 patients with anterior STEMI who were candidates for primary PCI and whose occlusion was in the proximal or mid-left anterior descending artery. Patients were given 25 μg/kg/3 min tirofiban and randomized to receive maintenance infusion at 0.15 μg/kg/min for 24 or 48 h. A resting (99m)Tc sestamibi scan was performed on the 5th day post-procedure before discharge. The primary efficacy endpoint was a patient's score on a 5-point scoring system for perfusion defect severity. Major adverse cardiac events (MACE) were defined as death from any cause, re-infarction, and clinically driven target-vessel revascularization within the first 6 months.

RESULTS

Baseline characteristics of the patients were similar in the two infusion groups (n = 42 per group). There was no significant difference in the symptom onset-to-presentation time or door-to-balloon time between the two groups. With the exception of basal anteroseptal and basal anterior segments, significant reductions were obtained on the 5-point scoring system for perfusion defect severity in segments and in the summed rest scores. No significant differences were observed between the two groups in the incidence of MACE at 6 months. The safety profile did not differ between 24 and 48 h infusions of tirofiban.

CONCLUSION

The use of tirofiban, when administered at a high bolus dose and maintained for 48 h, was safe and significantly reduced perfusion defect severity in patients with anterior STEMI presenting early after symptom onset and undergoing primary PCI.

Optimizing benefit from CRT: role of speckle tracking echocardiography, the importance of LV lead position and scar

Cardiac resynchronization therapy is demonstrated to be effective in patients with advanced heart failure. Correcting mechanical dyssynchrony is proposed as the predominant mechanism of response. Achieving optimum left ventricular lead position, at the site of maximal mechanical dyssynchrony but away from transmural scar, is identified as one of the main determinants of both symptomatic and prognostic benefit. Strategies employing multimodality cardiac imaging techniques have been used to identify this optimal pacing site, in addition to any potential anatomical limitations to successful implantation. Speckle tracking echocardiography offers prospective lead targeting, incorporating pathophysiological determinants of cardiac resynchronization therapy response. This review considers the key factors in defining optimum left ventricular lead location, emphasizing the role of myocardial scar. The use of speckle tracking echocardiography and the potential for this technique to be incorporated into routine practice to guide the implant strategy in an individual patient is discussed.

Salvage assessment with cardiac MRI following acute myocardial infarction underestimates potential for recovery of systolic strain

OBJECTIVES

Our aim was to evaluate the relationship between the degree of salvage following acute ST elevation myocardial infarction (STEMI) and subsequent reversible contractile dysfunction using cardiac magnetic resonance (CMR) imaging.

METHODS

Thirty-four patients underwent CMR examination 1-7 days after primary percutaneous coronary intervention (PPCI) for acute STEMI with follow-up at 1 year. The ischaemic area-at-risk (AAR) was assessed with T2-weighted imaging and myocardial necrosis with late gadolinium enhancement. Myocardial strain was quantified with complementary spatial modulation of magnetisation (CSPAMM) tagging.

RESULTS

Ischaemic segments with poor (<25 %) or intermediate (26-50 %) salvage index were associated with worse Eulerian circumferential (Ecc) strain immediately post-PPCI (-9.1 % ± 0.6, P = 0.033 and -11.8 % ± 1.3, P = 0.003, respectively) than those with a high (51-100 %) salvage index (-14.4 % ± 1.3). Mean strain in ischaemic myocardium improved between baseline and follow-up (-10.1 % ± 0.5 vs. -16.2 % ± 0.5 %, P < 0.0001). Segments with poor salvage also showed an improvement in strain by 1 year (-9.1 % ± 0.6 vs. -15.3 % ± 0.6, P = 0.033) although they remained the most functionally impaired.

CONCLUSIONS

Partial recovery of peak systolic strain following PPCI is observed even when apparent salvage is less than 25 %. Late gadolinium enhancement (LGE) may not equate to irreversibly injured myocardium and salvage assessment performed within the first week of revascularisation may underestimate the potential for functional recovery.

KEY POINTS

• MRI can measure how much myocardium is damaged after a heart attack. • Heart muscle that appears initially non-viable may sometimes partially recover. • Enhancement around the edges of infarcts may resolve over time. • Evaluating new cardio-protective treatments with MRI requires appreciation of its limitations.

CT of coronary heart disease: Part 1, CT of myocardial infarction, ischemia, and viability

OBJECTIVE

This article reviews the CT-based approaches aimed at the assessment of myocardial infarction, ischemia, and viability described in the recent literature.

CONCLUSION

Rapid advances in CT technology not only have improved visualization of coronary arteries but also increasingly enable noncoronary myocardial applications, including analysis of wall motion and the state of the myocardial blood supply. These advancements hold promise for eventually accomplishing the goal of comprehensively evaluating coronary heart disease with a single noninvasive modality.

Prognostic value of myocardial contrast delayed enhancement with 64-slice multidetector computed tomography after acute myocardial infarction

OBJECTIVES

This study evaluated the clinical value of myocardial contrast delayed enhancement (DE) with multidetector computed tomography (MDCT) for predicting clinical outcome after acute myocardial infarction (AMI).

BACKGROUND

Although some studies have described the use of MDCT for assessment of myocardial viability after AMI, clinical experience remains limited.

METHODS

In 102 patients with first AMI, 64-slice MDCT without iodine reinjection was performed immediately following successful percutaneous coronary intervention (PCI). We measured the size of myocardial contrast DE on MDCT and compared it with clinical outcome. Primary composite cardiac events were cardiac death or hospitalization for worsening heart failure.

RESULTS

Among the 102 patients (24 ± 10 months follow-up), 19 patients experienced primary composite cardiac events (cardiac death, n = 7; heart failure, n = 12). Kaplan-Meier analysis showed higher risk of cardiac events for patients in the third tertile of myocardial contrast DE size (≥ 36 g) than for those in the other 2 tertiles (p < 0.0001). Multivariable Cox proportional hazards regression analysis indicated that myocardial contrast DE size (adjusted hazard ratio [HR] for tertile 3 vs. 1: 16.1, 95% confidence interval [CI]: 1.45 to 72.4, p = 0.022; HR for tertile 3 vs. 2: 5.06, 95% CI: 1.25 to 22.7, p = 0.039) was a significant independent predictor for cardiac events after adjustment for Thrombolysis In Myocardial Infarction risk score, left ventricular ejection fraction, total defect score on single-photon emission CT with technetium tetrofosmin, and transmural extent of myocardial contrast DE on MDCT.

CONCLUSIONS

Myocardial contrast DE size on MDCT immediately after primary PCI may provide promising information for predicting clinical outcome in patients with AMI.

Tc-99m SPECT sestamibi for the measurement of infarct size

There are a variety of approaches to assess the efficacy of reperfusion therapy, and myocardial protection, in acute myocardial infarction. This review summarizes the available evidence validating the use of technetium-99m sestamibi single-photon emission computed tomography (SPECT) for this purpose. Multiple lines of evidence have validated its clinical utility. SPECT sestamibi infarct size has been used as an endpoint in multiple randomized clinical trials. A smaller number of clinical trials have used both early and later imaging with SPECT sestamibi to assess myocardium at risk and myocardial salvage. SPECT sestamibi has a number of limitations which must be recognized. Nevertheless, SPECT sestamibi infarct size is a well-validated measurement with a long track record of performance as an endpoint in multicenter, randomized clinical trials.

Elevated levels of PAI-1 activity and t-PA antigen are associated with newly diagnosed abnormal glucose regulation in patients with ST-elevation myocardial infarction

BACKGROUND

Both Type 2 diabetes and cardiovascular disease have been associated with enhanced coagulation and suppressed fibrinolysis.

OBJECTIVES

To investigate a possible relationship between selected hemostatic variables and abnormal glucose regulation (AGR) in patients with acute ST-elevation myocardial infarction (STEMI) without known diabetes and to study changes in selected hemostatic variables from baseline to follow-up in STEMI patients with or without AGR.

METHODS

Plasminogen activator inhibitor-1 (PAI-1) activity, tissue plasminogen activator (t-PA) antigen, prothrombin fragment 1+2 (F(1+2)) and von Willebrand factor (vWF) were measured in fasting blood samples from 199 STEMI patients 16.5 h (median time) after admission and 3 months later. All patients were classified into normal glucose regulation (NGR) or AGR based on an oral glucose tolerance test at follow-up, according to the WHO criteria.

RESULTS

High PAI-1 activity (≥ 75th percentile) measured in-hospital was associated with AGR (n = 49) with an adjusted odds ratio of 2.2 (95% confidence interval, 1.1, 4.4). In addition, high levels of t-PA antigen (≥ 75th percentile) were associated with AGR (adjusted odds ratio, 3.5; 95% confidence inteval, 1.5, 8.2), but only in men. Changes in the levels of F(1+2) were significantly more pronounced in patients with AGR compared with NGR (adjusted P = 0.04).

CONCLUSION

Elevated levels of PAI-1 activity and t-PA antigen measured in-hospital in STEMI patients were associated with AGR classified at 3-month follow-up. Additionally, changes in the levels of F(1+2) were more pronounced in patients with AGR compared with NGR. The data suggest an enhanced prothrombotic state after an acute STEMI in patients with AGR without known diabetes.

Impact of newly diagnosed abnormal glucose regulation on long-term prognosis in low risk patients with ST-elevation myocardial infarction: A follow-up study

BACKGROUND

Patients with acute myocardial infarction and newly detected abnormal glucose regulation have been shown to have a less favourable prognosis compared to patients with normal glucose regulation. The importance and timing of oral glucose tolerance testing (OGTT) in patients with acute myocardial infarction without known diabetes is uncertain. The aim of the present study was to evaluate the impact of abnormal glucose regulation classified by an OGTT in-hospital and at three-month follow-up on clinical outcome in patients with acute ST elevation myocardial infarction (STEMI) without known diabetes.

METHODS

Patients (n = 224, age 58 years) with a primary percutanous coronary intervention (PCI) treated STEMI were followed for clinical events (all-cause mortality, non-fatal myocardial re-infarction, recurrent ischemia causing hospital admission, and stroke). The patients were classified by a standardised 75 g OGTT at two time points, first, at a median time of 16.5 hours after hospital admission, then at three-month follow-up. Based on the OGTT results, the patients were categorised according to the WHO criteria and the term abnormal glucose regulation was defined as the sum of impaired fasting glucose, impaired glucose tolerance and type 2-diabetes.

RESULTS

The number of patients diagnosed with abnormal glucose regulation in-hospital and at three-month was 105 (47%) and 50 (25%), respectively. During the follow up time of (median) 33 (27, 39) months, 58 (25.9%) patients experienced a new clinical event. There were six deaths, 15 non-fatal re-infarction, 33 recurrent ischemia, and four strokes. Kaplan-Meier analysis of survival free of composite end-points showed similar results in patients with abnormal and normal glucose regulation, both when classified in-hospital (p = 0.4) and re-classified three months later (p = 0.3).

CONCLUSIONS

Patients with a primary PCI treated STEMI, without previously known diabetes, appear to have an excellent long-term prognosis, independent of the glucometabolic state classified by an OGTT in-hospital or at three-month follow-up.

TRIAL REGISTRATION

The trial is registered at http://www.clinicaltrials.gov, NCT00926133.

A multicenter, randomized, controlled study of mechanical left ventricular unloading with counterpulsation to reduce infarct size prepercutaneous coronary intervention for acute myocardial infarction: rationale and design of the Counterpulsation Reduces Infarct Size Acute Myocardial Infarction trial

BACKGROUND

Despite advances in care processes to improve reperfusion in patients with acute myocardial infarction (AMI), the short-term and 1-year mortality remains high, in part, because of reperfusion injury, microvascular obstruction, and infarct expansion. Intraaortic balloon counterpulsation (IABC) is an adjunct to revascularization and has reduced microvascular obstruction and infarct size in animal models of AMI.

METHODS

CRISP AMI is a multicenter randomized trial that aims to determine if IABC initiated before percutaneous coronary intervention (PCI) for reperfusion compared with routine PCI in patients with anterior ST-segment elevation AMI reduces infarct size as measured by cardiac magnetic resonance imaging. Patients are randomly assigned to receive IABC initiated before primary PCI and continued for at least 12 hours or routine PCI with standard-of-care medical therapy in both groups. The primary efficacy end point is infarct size measured by cardiac magnetic resonance imaging at 3 to 5 days post-PCI. The secondary clinical end point is the composite of major adverse clinical events including death, reinfarction, and heart failure at 6 months. According to sample size calculation, 300 patients will be randomized at 50 sites across 10 countries.

CONCLUSION

The CRISP AMI study will determine if IABC before reperfusion in patients with anterior AMI reduces infarct size.