N-terminal pro-brain natriuretic peptide on admission in patients with acute myocardial infarction and correlation with scintigraphic infarct size, efficacy of reperfusion, and prognosis

Single-Cell Dissection of the Immune Response After Acute Myocardial Infarction

BACKGROUND

The immune system's role in ST-segment-elevated myocardial infarction (STEMI) remains poorly characterized but is an important driver of recurrent cardiovascular events. While anti-inflammatory drugs show promise in reducing recurrence risk, their broad immune system impairment may induce severe side effects. To overcome these challenges, a nuanced understanding of the immune response to STEMI is needed.

METHODS

For this, we compared peripheral blood mononuclear single-cell RNA-sequencing (scRNA-seq) and plasma protein expression over time (hospital admission, 24 hours, and 6-8 weeks post-STEMI) in 38 patients and 38 controls (95 995 diseased and 33 878 control peripheral blood mononuclear cells).

RESULTS

Compared with controls, classical monocytes were increased and CD56dim natural killer cells were decreased in patients with STEMI at admission and persisted until 24 hours post-STEMI. The largest gene expression changes were observed in monocytes, associating with changes in toll-like receptor, interferon, and interleukin signaling activity. Finally, a targeted cardiovascular biomarker panel revealed expression changes in 33/92 plasma proteins post-STEMI. Interestingly, interleukin-6R, MMP9 (matrix metalloproteinase-9), and LDLR (low-density lipoprotein receptor) were affected by coronary artery disease-associated genetic risk variation, disease status, and time post-STEMI, indicating the importance of considering these aspects when defining potential future therapies.

CONCLUSIONS

Our analyses revealed the immunologic pathways disturbed by STEMI, specifying affected cell types and disease stages. Additionally, we provide insights into patients expected to benefit most from anti-inflammatory treatments by identifying the genetic variants and disease stage at which these variants affect the outcome of these (drug-targeted) pathways. These findings advance our knowledge of the immune response post-STEMI and provide guidance for future therapeutic studies.

Prognostic significance of serial N-terminal pro-B-type natriuretic peptide levels in patients with acute myocardial infarction: A prospective study

OBJECTS

This study aimed to investigate the association between N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels at different sampling times and prognosis in patients with acute myocardial infarction (AMI) undergoing emergency percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Between March 2017 and January 2020, 1,105 patients with AMI who underwent emergency PCI were included. NT-proBNP levels were measured on days 0, 1, 2, 3, and 7. A composite of all-cause death, MI recurrence (reMI), and rehospitalization due to heart failure, known as major adverse cardiovascular events (MACE), was recorded. During the 36.8-month follow-up, 175 patients (15.8%) experienced MACEs. When patients were grouped based on quartiles of NT-proBNP levels on days 0 and 7, the results demonstrated that patients in quartile 4 showed a substantially increased MACE risk compared to those in quartile 1 (hazard ratio [HR] 2.27, 95% confidence interval [CI]:1.27-4.08, P = .006; HR 2.20, 95%CI:1.23-3.94, P = .008). There were U-shaped relationships between the HR for MACE and NT-proBNP levels on days 2, 3, and 7, as well as peak NT-proBNP (P _{for nonlinearity} = .007, .006, .004, and .009, respectively). A similar relationship was observed in the HR for reMI and NT-proBNP levels on days 2 and 3. For MACE at 3 years, serial NT-proBNP levels improved the predictive accuracy of the Global Registry of Acute Coronary Events (GRACE) risk score (concordance index [C-index]: 0.711; continuous net reclassification improvement [NRI]: 0.192, 95% CI: 0.022-0.445; integrated discrimination improvement [IDI]: 0.034, 95% CI: 0.016-0.064). For all-cause death at 3 years, the combination of NT-proBNP and GRACE score showed excellent performance, with C-index, continuous NRI, and IDI values of 0.801, 0.373 (95%CI: 0.072-0.853), and 0.051 (95%CI: 0.025-0.091), respectively.

CONCLUSIONS

Early and sequential measurement of NT-proBNP levels could assist in predicting MACE risk. Moreover, the relationship between MACE risk and NT-proBNP levels was U-shaped.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov NCT: 03593928.

Roles of Natriuretic Peptides and the Significance of Neprilysin in Cardiovascular Diseases

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) activate the guanylyl cyclase A receptor (GC-A), which synthesizes the second messenger cGMP in a wide variety of tissues and cells. C-type natriuretic peptide (CNP) activates the cGMP-producing guanylyl cyclase B receptor (GC-B) in chondrocytes, endothelial cells, and possibly smooth muscle cells, cardiomyocytes, and cardiac fibroblasts. The development of genetically modified mice has helped elucidate the physiological roles of natriuretic peptides via GC-A or GC-B. These include the hormonal effects of ANP/BNP in the vasculature, autocrine effects of ANP/BNP in cardiomyocytes, and paracrine effects of CNP in the vasculature and cardiomyocytes. Neprilysin (NEP) is a transmembrane neutral endopeptidase that degrades the three natriuretic peptides. Recently, mice overexpressing NEP, specifically in cardiomyocytes, revealed that local cardiac NEP plays a vital role in regulating natriuretic peptides in the heart tissue. Since NEP inhibition is a clinically accepted approach for heart failure treatment, the physiological roles of natriuretic peptides have regained attention. This article focuses on the physiological roles of natriuretic peptides elucidated in mice with GC-A or GC-B deletion, the significance of NEP in natriuretic peptide metabolism, and the long-term effects of angiotensin receptor-neprilysin inhibitor (ARNI) on cardiovascular diseases.

Development and validation of a novel risk score to predict 5-year mortality in patients with acute myocardial infarction in China: a retrospective study

BACKGROUND

The disease burden from ischaemic heart disease remains heavy in the Chinese population. Traditional risk scores for estimating long-term mortality in patients with acute myocardial infarction (AMI) have been developed without sufficiently considering advances in interventional procedures and medication. The goal of this study was to develop a risk score comprising clinical parameters and intervention advances at hospital admission to assess 5-year mortality in AMI patients in a Chinese population.

METHODS

We performed a retrospective observational study on 2,722 AMI patients between January 2013 and December 2017. Of these patients, 1,471 patients from Changsha city, Hunan Province, China were assigned to the development cohort, and 1,251 patients from Xiangtan city, Hunan Province, China, were assigned to the validation cohort. Forty-five candidate variables assessed at admission were screened using least absolute shrinkage and selection operator, stepwise backward regression, and Cox regression methods to construct the C2ABS2-GLPK score, which was graded and stratified using a nomogram and X-tile. The score was internally and externally validated. The C-statistic and Hosmer-Lemeshow test were used to assess discrimination and calibration, respectively.

RESULTS

From the 45 candidate variables obtained at admission, 10 potential predictors, namely, including Creatinine, experience of Cardiac arrest, Age, N-terminal Pro-Brain Natriuretic Peptide, a history of Stroke, Statins therapy, fasting blood Glucose, Left ventricular end-diastolic diameter, Percutaneous coronary intervention and Killip classification were identified as having a close association with 5-year mortality in patients with AMI and collectively termed the C2ABS2-GLPK score. The score had good discrimination (C-statistic = 0.811, 95% confidence intervals (CI) [0.786-0.836]) and calibration (calibration slope = 0.988) in the development cohort. In the external validation cohort, the score performed well in both discrimination (C-statistic = 0.787, 95% CI [0.756-0.818]) and calibration (calibration slope = 0.976). The patients were stratified into low- (≤148), medium- (149 to 218) and high-risk (≥219) categories according to the C2ABS2-GLPK score. The predictive performance of the score was also validated in all subpopulations of both cohorts.

CONCLUSION

The C2ABS2-GLPK score is a Chinese population-based risk assessment tool to predict 5-year mortality in AMI patients based on 10 variables that are routinely assessed at admission. This score can assist physicians in stratifying high-risk patients and optimizing emergency medical interventions to improve long-term survival in patients with AMI.

Association of N-terminal pro-brain natriuretic peptide level with adverse outcomes in patients with acute myocardial infarction: A meta-analysis

BACKGROUND

Studies evaluating the association of blood level of N-terminal pro-brain natriuretic peptide (NT-proBNP) with adverse prognosis have yielded conflicting results in patients with acute myocardial infarction (AMI). This meta-analysis sought to evaluate the prognostic value of blood level of NT-proBNP in patients with AMI.

METHODS

Two authors independently searched articles in PubMed and Embase databases up to June 13, 2021. Studies evaluating the association of baseline NT-proBNP level with all-cause mortality or major adverse cardiovascular events (MACEs, including death, new or worsening heart failure, recurrent myocardial infarction, revascularization, stroke, etc.) among AMI patients were selected. Multivariable-adjusted risk ratio (RR) with 95% confidence interval (CI) was pooled by the highest vs. lowest category of NT-proBNP level.

RESULTS

A total of 19 studies enrolling 12,158 AMI patients were identified. When compared highest with the lowest category of NT-proBNP level, the pooled RR was 5.28 (95% CI 2.87-9.73) for in-hospital/30-day death, 2.62 (95% CI 2.04-3.37) for follow-up all-cause mortality, and 2.50 (95% CI 1.91-3.28) for follow-up MACEs, respectively. Subgroup analysis further confirmed the value of NT-proBNP in predicting all-cause mortality and MACEs.

CONCLUSIONS

Elevated NT-proBNP level is independently associated with an increased risk of all-cause mortality and MACEs. Determination of blood NT-proBNP level can improve risk stratification of AMI patients.

Novel Biomarkers, ST-Elevation Resolution, and Clinical Outcomes Following Primary Percutaneous Coronary Intervention

Background Despite restoration of epicardial flow following primary percutaneous coronary intervention (PPCI), microvascular reperfusion as reflected by ST-elevation resolution (ST-ER) resolution remains variable and its pathophysiology remains unclear. Methods and Results Using principal component analyses, we explored associations between 91 serum biomarkers drawn before PPCI clustered into 14 pathobiologic processes (including NT-proBNP [N-terminal pro-B-type natriuretic peptide] as an independent cluster), and (1) ST-ER resolution ≥50% versus <50%; and (2) 90-day composite of death, shock, and heart failure. Network analyses were performed to understand interbiomarker relationships between the ST-ER groups. Among the 1160 patients studied, 861 (74%) had ST-ER ≥50% at a median 40 (interquartile range, 23-70) minutes following PPCI, yet both groups had comparable post-PPCI TIMI (Thrombolysis in Myocardial Infarction) grade 3 flow (86.6% versus 82.9%; P=0.25). ST-ER ≥50% was associated with significantly lower pre-PPCI concentrations of platelet activation cluster (particularly P-selectin, von Willebrand factor, and platelet-derived growth factor A) and NT-proBNP, including after risk adjustment. Across both ST-ER groups, strong interbiomarker relationships were noted between pathways indicative of myocardial stretch, platelet activation, and inflammation, whereas with ST-ER <50% correlations between iron homeostasis and inflammation were observed. Of all 14 biomarker clusters, only NT-proBNP was significantly associated with the 90-day clinical composite. Conclusions Suboptimal ST-ER is common despite achieving post-PPCI TIMI grade 3 flow. The cluster of platelet activation proteins and NT-proBNP were strongly correlated with suboptimal ST-ER and NT-proBNP was independently associated with 90-day outcomes. This analysis provides insights into the pathophysiology of microvascular reperfusion in ST-segment-elevation myocardial infarction and suggests novel pre-PPCI risk targets potentially amenable to enhancing tissue-level reperfusion following PPCI.

Biomarker assessment for early infarct size estimation in ST-elevation myocardial infarction

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) represents the biomarker of choice for infarct size (IS) estimation in patients with acute ST-elevation myocardial infarction (STEMI). However, admission values of hs-cTnT are only weakly associated with IS. The aim of this study was to investigate the incremental value of different biomarkers measured on admission for IS estimation in STEMI patients.

METHODS

In this prospective observational study, we included 161 consecutive STEMI patients treated with primary percutaneous coronary intervention (pPCI). The following biomarkers were assessed on admission: hs-cTnT, N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and neutrophil/lymphocyte ratio (NLR). IS was determined by cardiac magnetic resonance (CMR) imaging 3 (Interquartile range [IQR] 2 to 4) days after the index event.

RESULTS

Patients with large IS (>19% of left ventricular myocardium) showed significantly higher levels of admission hs-cTnT (399.6 vs. 53.4 ng/L, p < .001), NT-pro-BNP (140 vs. 86 ng/L, p = .008) and NLR (6.4 vs. 4.1, p < .001). The combination of hs-cTnT, NT-pro-BNP and NLR on admission resulted in a significantly higher area under the curve (0.78; 95% CI 0.704 to 0.838, (p = .01)) for the prediction of large IS than admission hs-cTnT alone (0.69; 95% CI 0.619 to 0.767).

CONCLUSIONS

In STEMI patients undergoing pPCI, a comprehensive biomarker approach on admission including hs-cTnT, NT-pro-BNP and NLR was significantly better for immediate infarct severity estimation as compared to hs-cTnT alone.

Usefulness of catestatin to predict malignant arrhythmia in patients with acute myocardial infarction

Catestatin (CST) displays potent vasodilatory effect and acts on lowering blood pressure in vivo. The clinical utility of CST in patients with acute myocardial infarction (AMI) has not been clearly delineated. The aim of this study was to investigate the predictive value of CST for the development of in-hospital malignant arrhythmia and other adverse cardiac events in patients with AMI. A total of 125 consecutive patients diagnosed with AMI were included. The clinical characteristics and previous history of the patients were collected. Malignant arrhythmia and other major adverse cardiac events (MACE) such as postinfarction angina pectoris or reinfarction and death were recorded during hospitalization. The levels of plasma CST, norepinephrine (NE) and amino-terminal pro-brain sodium peptides (NT-proBNP) were determined by sandwich ELISA. A multiple logistic regression model was used to predict the influence factors of malignant arrhythmia and other MACE during hospitalization of AMI patients. The results showed that the levels of plasma cystatin-C (CysC), high sensitivity C-reactive protein (hs-CRP), NE and NT-proBNP increased in a CST concentration dependent manner. The incidence of malignant arrhythmia significantly increased as the elevation of CST level (P<0.05). Age, CST and NT-proBNP were independent predictors for the MACE occurred during hospitalization. Increased blood glucose (≥6.1mmol/L) and CST were independent predictors for the complicated malignant arrhythmia of AMI patients. These data demonstrated that CST can be used as a new biological marker for prediction of malignant arrhythmia in patients with AMI.

Increased plasma levels of intermedin and brain natriuretic peptide associated with severity of coronary stenosis in acute coronary syndrome

Intermedin (IMD) is a newly discovered peptide with increased levels in plasma and cardiac tissue in mice with ischemia/reperfusion. Continuous administration of low dose IMD markedly elevated the mRNA abundance of myocardial BNP in rats. Plasma BNP levels may reflect the severity of degree of coronary stenosis in patients with acute coronary syndrome (ACS). However, the role of circulating IMD in coronary heart disease remains unclear. We aimed to examine the plasma content of IMD and brain natriuretic peptide (BNP) and its clinical significance in patients with ACS. We collected plasma samples from 41 patients with ACS and 31 controls and measured IMD and BNP levels by radioimmunoassay. The severity of coronary artery stenosis for patients with ACS was measured by coronary angiography. Plasma IMD and BNP levels were markedly higher in ACS patients than that in controls (P<0.05). The increased plasma IMD and BNP were positively correlated with degree of coronary stenosis in ACS patients (r=0.263 and r=0.238, respectively, both P<0.05). In addition, plasma levels of IMD were positively correlated with BNP levels.

Interleukin-6 is the strongest predictor of 30-day mortality in patients with cardiogenic shock due to myocardial infarction

Introduction

Cardiogenic shock (CS) remains the leading cause of death in patients hospitalized for myocardial infarction (MI). Systemic inflammation with inappropriate vasodilatation is observed in many patients with CS and may contribute to an excess mortality rate. The purpose of this study was to determine the predictive role of serial measurements of Nt-proBNP, interleukin-6 (IL-6), and procalcitonin (PCT) for 30-day mortality in patients with CS due to MI.

Methods

The present study is a prospective single-center study including 87 patients with MI complicated by CS treated with acute revascularization and intraaortic balloon counterpulsation (IABP) support. Predictive values of plasma levels at admission (T₀), after 24 hours (T₁), and after 72 hours (T₂) were examined according to 30-day mortality.

Results

Significant differences between survivors (n = 59) and nonsurvivors (n = 28) were seen for Nt-proBNP at T₀, for IL-6 at T₀ and T₁, and for PCT at T₁ and T₂. According to ROC analyses, the highest accuracy predicting 30-day mortality was seen at T₀ for IL-6, at T₁ for PCT, and at T₂ for PCT. In univariate analysis, significant values were found for Nt-proBNP at T₁, and for IL-6 and PCT at all points in time. Within the multivariate analysis, age, creatinine, and IL-6 were significant determinants of 30-day mortality, in which IL-6 showed the highest level of significance.

Conclusions

In patients with MI complicated by CS, IL-6 represented a reliable independent early prognostic marker of 30-day mortality. PCT revealed a significant value at later points in time, whereas Nt-proBNP seemed to be of lower relevance.

Cardiac biomarkers in acute myocardial infarction

Each year, a large number of patients are seen in the Emergency Department with presentations necessitating investigation for possible acute myocardial infarction. Patients can be stratified by symptoms, risk factors and electrocardiogram results but cardiac biomarkers also have a prime role both diagnostically and prognostically. This review summarizes both the history of cardiac biomarkers as well as currently available (established and novel) assays. Cardiac troponin, our current "gold standard" biomarker criterion for the diagnosis of myocardial infarction has high sensitivity and specificity for this diagnosis and therapies instituted in patients with elevated troponin have been shown to influence outcomes. Other markers of myocardial necrosis, inflammation and neurohormonal activity have also been shown to have either diagnostic or prognostic utility, but none have been shown to be superior to troponin. The measurement of multiple biomarkers and the use of point of care markers may accelerate current diagnostic protocols for the assessment of such patients.

High-concentration versus titrated oxygen therapy in ST-elevation myocardial infarction: a pilot randomized controlled trial

BACKGROUND

The optimal approach to oxygen therapy in ST-elevation myocardial infarction (STEMI) is uncertain.

METHODS

A randomized controlled trial was undertaken in which 136 patients presenting with their first STEMI uncomplicated by cardiogenic shock or marked hypoxia were randomized to receive high-concentration (6 L/min via medium concentration mask) or titrated oxygen (to achieve oxygen saturation 93%-96%) for 6 hours after presentation. The main outcome variables were 30-day mortality and infarct size assessed by troponin T level at 72 hours. Secondary outcomes included a meta-analysis of mortality data from this study and previous randomized controlled trials, and infarct size was assessed by magnetic resonance imaging at 4 to 6 weeks.

RESULTS

There were 1 of 68 and 2 of 68 deaths in the high-concentration and titrated oxygen groups, respectively; a meta-analysis including these data with those from the 2 previous studies showed an odds ratio for mortality of high-concentration oxygen compared with room air or titrated oxygen of 2.2 (95% CI 0.8-6.0). There was no significant difference between high-concentration versus titrated oxygen in troponin T (ratio of mean levels 0.74, 95% CI 0.50-1.1, P = .14), infarct mass (mean difference -0.8 g, 95% CI -7.6 to 6.1, P = .82), or percent infarct mass (mean difference -0.6%, 95% CI -5.6 to 4.5, P = .83).

CONCLUSION

This study found no evidence of benefit or harm from high-concentration compared with titrated oxygen in initially uncomplicated STEMI. However, our estimates have wide CIs, and as a result, large randomized controlled trials are required to resolve the clinical uncertainty.

Established and novel biomarkers in ST-elevation myocardial infarction

Cardiac biomarkers assist in the diagnosis of and risk stratification in acute coronary syndromes. In ST-elevation myocardial infarction (STEMI), rapid diagnosis and initiation of reperfusion via primary percutaneous coronary intervention or fibrinolysis is often based on the clinical history and presenting ECG, but measurement of biomarkers in the early and/or late phases of STEMI may allow the selection of patients who are at increased or decreased risk of subsequent complications. Although the measurement of only three biomarkers (troponin, natriuretic peptides and C-reactive protein) are currently included in practice guidelines, more than 20 other novel cardiac biomarkers have been proposed to provide improved risk stratification after a STEMI.

Biochemical markers in acute coronary syndrome

Owing to their higher risk for cardiac death or ischemic complications, patients with acute coronary syndrome (ACS) must be identified from other causes of chest pain. Patients with acute coronary syndrome are divided into categories based on their electrocardiogram; those with new ST-segment elevation and those who present with ST-segment depression. The subgroups of patients with ST-segment elevation are candidates for immediate reperfusion, while fibrinolysis appears harmful for those with non-ST elevation myocardial infarction. There is increasing evidence to encourage appropriate risk stratification before deciding on a management strategy (invasive or conservative) for each patient. The TIMI, GRACE or PURSUIT risk models are recommended as useful for decisions regarding therapeutic options. Cardiac biomarkers are useful additions to these clinical tools to correctly risk stratify ACS patients. Cardiac troponin is the biomarker of choice to detect myocardial necrosis and is central to the universal definition of myocardial infarction. The introduction of troponin assays with a lower limit of detection will allow for earlier diagnosis of patients who present with chest pain. Analytical and clinical validations of these new assays are currently in progress. The question is whether the lower detection limit of the troponin assays will be able to indicate myocardial ischemia in the absence of myocardial necrosis. Previous to the development of ultrasensitive cardiac troponin assays free fatty acids unbound to albumin and ischemia modified albumin were proposed as biochemical markers of ischemia. Advances in our knowledge of the pathogenesis of acute coronary thrombosis have stimulated the development of new biomarkers. Markers of left ventricular performance (N-terminal pro-brain natriuretic peptide) and inflammation (e.g. C-reactive protein) are generally recognized as risk indicators. Studies suggest that using a number of biomarkers clinicians can risk stratify patients over a broad range of short and long term cardiac events. Nevertheless, it is still under debate as to which biomarker combination is best preferred for risk prediction. This review will focus on recent practice guidelines for the management of patients with ACS as well as current advances in cardiac biomarkers, their integration into clinical care and their diagnostic, prognostic and therapeutic utility.

Comparison of the usefulness of N-terminal pro-brain natriuretic peptide to other serum biomarkers as an early predictor of ST-segment recovery after primary percutaneous coronary intervention

Data on the ability of serum biomarkers to predict microvascular obstruction by ST-segment recovery after primary percutaneous coronary intervention (PCI) is largely absent. Therefore, we determined the association between 5 serum biomarkers, obtained before emergency coronary angiography, and immediate ST-segment recovery in patients who had undergone primary PCI for ST-segment elevation myocardial infarction. We measured N-terminal pro-brain natriuretic peptide (NT-pro-BNP), cardiac troponin T, creatinine kinase-MB fraction, high-sensitivity C-reactive protein, and serum creatinine from blood samples obtained through the arterial sheath at the start of primary PCI. Serial 12-lead electrocardiograms were recorded in the catheterization laboratory before arterial puncture and at the end of the PCI. ST-segment recovery was defined as incomplete if <50%. Of 662 included patients with ST-segment elevation myocardial infarction, 338 (51%) had incomplete ST-segment recovery. An elevated NT-pro-BNP level (> or = 608 ng/L) was the strongest predictor of incomplete ST-segment recovery (adjusted odds ratio 2.6, 95% confidence interval 1.6 to 4.1; p <0.001) compared to other serum biomarkers and clinical predictors. An elevated NT-pro-BNP level was more strongly predictive in patients without a history of coronary artery disease or hypertension (adjusted odds ratio 4.7, 95% confidence interval 2.4 to 9.2; p <0.001). NT-pro-BNP was the best contributor to both net reclassification (0.43; p <0.001) and integrated discrimination improvement (0.04; p <0.001) when added to a multivariate model with clinical predictors of incomplete ST-segment recovery. In conclusion, NT-pro-BNP was the strongest independent predictor of ST-segment recovery at the end of primary PCI for ST-segment elevation myocardial infarction compared to the other serum biomarkers reflecting myocardial cell damage, renal function, and inflammation.

Correlation between serum cardiac markers and myocardial infarct size quantified by myocardial perfusion imaging in patients with hypertrophic cardiomyopathy after alcohol septal ablation

Myocardial infarct (MI) size is a well-established prognostic marker but the association of serum markers with MI size, as measured by myocardial perfusion imaging (MPI), has not been well studied in patients with hypertrophic cardiomyopathy (HC) after alcohol septal ablation (ASA). Creatine kinase (CK), CK-MB, troponin I, and brain natriuretic peptide were measured before and at multiple points after ASA in patients with HC and were correlated with MI size measured by MPI. MPI at rest was performed in 54 patients with HC at a median of 2 days after ASA. CK, CK-MB, and troponin I increased after ASA to peak levels at 12 hours and their cumulative levels (area under the curve) showed significant correlation with size of MI by MPI (r = 0.544, 0.408, and 0.477, p <0.001, 0.003, and 0.001, respectively). The best marker was level of CK at 12 hours (r = 0.609, p <0.0001) after ASA. Brain natriuretic peptide level did not change significantly after ASA (p = 1.0) and only weakly correlated with MI size by MPI (r = 0.130, p = 0.007). In conclusion, CK, CK-MB, and troponin I measured at 12 hours, at peak, and as the area under the curve correlated well with infarct size, but CK level at 12 hours was the best marker. CK continues to be a useful marker of MI size despite the introduction of newer, more specific markers, especially when infarct onset is known with certainty as in patients with HC undergoing ASA.

Limitation of myocardial infarct size in the clinical setting: current status and challenges in translating animal experiments into clinical therapy

This review takes a critical look at the current effectiveness of reperfusion therapy for acute myocardial infarction and at the potential for cardioprotective agents to improve it. Reperfusion alone limits the median value of infarct size to approximately 50% of the ischemic region. However, the range of infarct sizes is very wide, and one-fourth of these patients have more than 75% of the ischemic zone infarcted despite successful coronary reperfusion. Available studies suggest that mortality and morbidity is increased when more than 20% of the left ventricle is infarcted. Therefore, to be effective infarct size-limiting therapy would have to reduce infarction to or below this 20% target. To achieve this goal in the quartile of patients with the biggest infarcts the cardioprotective agent would have to be potent enough to reduce infarct size from its current value of 75% of the ischemic zone to 40% or less. While ischemic preconditioning and some pretreatment drugs might be potent enough to achieve this goal, few of the agents given at the clinically relevant time of at or just before reperfusion have exhibited such potency. Several cardioprotective agents have recently been evaluated in clinical trials but their results have been disappointing. Some of the poor clinical trial performance may stem from study designs which fail to identify those patients falling within the upper quartile of infarct sizes, presumably the only group that would be expected to actually benefit from a reduction in infarct size. Other possible causes could be that co-morbidities or drugs patients are taking may block the pathways involved in the anti-infarct effect or that the drugs simply do not protect even in animal models. Few agents have been thoroughly tested in clinically relevant animal models prior to their testing in man.

Insights into the change in brain natriuretic peptide after ST-elevation myocardial infarction (STEMI): why should it be better than baseline?This paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum

While baseline N-terminal brain natriuretic peptide (NT-proBNP) is useful in the prognosis of acute ST-elevation myocardial infarction (STEMI), it is unclear whether a relationship exists between serial NT-proBNP, reperfusion success, and prognosis. We prospectively defined a NT-proBNP analysis in the WEST (Which Early ST-elevation myocardial infarction Therapy) trial that enrolled 304 acute STEMI patients. NT-proBNP (pg/mL) was measured at baseline prior to treatment (n = 258) and 72 to 96 h (n = 247) and 30 days (n = 221) after treatment (ΔNT-proBNP = 72 h value – the baseline NT-proBNP). Reperfusion success was measured by ST-segment resolution at 180 min, infarct size by peak creatine kinase (CK) during the first 24 h, and QRS score at discharge (QRSd). The primary endpoint was a 30 day clinical composite. The ability of either baseline NT-proBNP or ΔNT-proBNP to predict the primary endpoint was compared using single-variable logistic regression and the c-statistic. Median (interquartile range) NT-proBNP in pg/mL was 87 (39–316) at baseline, 864 (338–1857) at 72 h, and 585 (264–1212) at 30 days. ST resolution was inversely correlated with ΔNT-proBNP (r = –0.23, p = 0.002) and 30 day NT-proBNP (30 day NT-proBNP 1016, 828, and 397 for <30%, 30%–70%, ≥70% STR, respectively, p < 0.001). Infarct size was correlated with ΔNT-proBNP by CK (r = 0.41, p < 0.001) and QRSd (r = 0.31, p < 0.001); the 30 day NT-proBNP relationship was similar for CK (r = 0.48, p < 0.001) and QRSd (p = 0.003). The baseline NT-proBNP was associated with an increased 30-day composite endpoint (Q1, 19%; Q2, 20%; Q3, 15%; Q4, 38%; p = 0.03 for trend) as was ΔNT-proBNP (Q1, 16%; Q2, 18%; Q3, 19%; Q4, 37%; p = 0.009 for trend). The c-statistic for baseline, 72 to 96 h, and ΔNT-proBNP was 0.59, 0.61, and 0.62 for the 30-day composite and 0.64, 0.62, and 0.62 for the 90-day composite, respectively. ΔNT-proBNP clearly predicts short-term adverse cardiac events and is superior to baseline NT-proBNP, but similar to the 72 to 96 h NT-proBNP in predicting clinical events after STEMI. This likely reflects the variability in NT-proBNP at presentation and the ability to integrate subsequent important physiologic sequelae of STEMI such as reperfusion and infarct size.

[The role of B type natriuretic peptide in the assessment of post myocardial infarction prognosis]

Recently cardiac peptides have received close attention as cardiovascular markers. Brain (B type) natriuretic peptide is a neurohormone synthesized predominantly in ventricular myocardium. Previous studies have shown that this hormone can provide prognostic information in patients with myocardial infarction. The aim of this review is to evaluate the impact of plasma levels of BNP on prediction of left ventricular ejection fraction and remodelling and major cardiac events after myocardial infarction.