Relationship of myocardial ischemia and injury to coronary artery disease in patients with supraventricular tachycardia

The Role of Troponin Testing in Patients with Supraventricular Tachycardia, Systematic Review and Meta-Analysis

BACKGROUND

Supraventricular tachycardia (SVT) is commonly evaluated in the emergency department (ED). While troponin has been shown to be elevated in SVT, its usefulness for predicting coronary artery disease and future adverse cardiovascular outcomes has not been shown.

OBJECTIVES

We aimed to evaluate the prognostic utility of troponin measurement as part of SVT management in the ED.

METHODS

We performed a literature search in the PubMed and Scopus databases from inception to August 30, 2023, including all studies reporting troponin measurements in adult patients (age > 18 years) presenting to the ED with supraventricular tachycardia. The primary outcome of interest for this study was the prevalence of elevated troponin in patients with SVT. Secondary outcomes included the prevalence of major adverse cardiac events (MACE) and additional cardiac testing with significant findings.

RESULTS

We included 7 studies (500 patients) in our analysis. Six studies reported the number of patients with SVT and elevated troponin, with a pooled prevalence of 46% (95% CI 27-66%, I2 93%). The pooled prevalence of all MACE in our study was 6% (95% CI 1-25%), while the prevalence for MACE among patients with elevated serum troponin levels was 11% (95% CI 4-27%).

CONCLUSIONS

Troponin levels are frequently ordered for ED patients with SVT and are often elevated. However, this review suggests that they have low prognostic value in predicting MACE.

Coronary artery disease among patients admitted with atrial fibrillation and chest pain

INTRODUCTION

Patients who present to the emergency department with chest pain during an episode of atrial fibrillation (AF) impose a clinical challenge regarding the source of pain - being coronary artery disease (CAD) or AF in origin. The aim of this study was to identify clinical, imaging or laboratory markers which can predict significant CAD among patients with an AF episode and chest pain.

METHODS

We included 57 consecutive patients admitted to our hospital with AF and chest pain. All patients underwent coronary evaluation. Significant CAD was defined as >50% stenosis in a major coronary artery by coronary angiography or cardiac CT. We compared CAD and non-CAD groups and analyzed risk factorsby regression analysis.

RESULTS

Twenty-four patients (42%) were diagnosed with- and 33 patients (58%) without obstructive CAD. In a multivariate analysis of regional wall motion abnormality (RWMA), elevated troponin and hypertension were found to be predictors for CAD [odds ratio (OR), 22.4 (confidence interval (CI), 1.8-272.4; P  = 0.02); OR, 5.6 (CI, 1-31.0; P  = 0.05) and OR, 21.4 (CI, 1.6-284.6; P  = 0.02), respectively]. There were no significant differences regarding the rate of typical chest pain at presentation in the CAD vs. the non-CAD group [13 (54%) vs. 20 (60%), P  = 0.374], or in ECG ST-changes [12 (50%) vs.9 (27%), respectively; P  = 0.08].

CONCLUSION

In patients who present acutely with chest pain and AF, troponin elevation and RWMA appear to be highly predictive of obstructive CAD, whereas clinical symptoms and ECG changes are not predictive. These findings may be helpful for guiding the management of patients admitted with AF and chest pain.

ST-segment depression in atrioventricular nodal reentrant tachycardia: Important finding or just an artifact?

BACKGROUND

The ST segment is component of the QRS-T complex located between the QRS and the T wave. ST segment changes during tachycardia with narrow QRS mainly takes the form of ST segment depression. This phenomenon is often observed in young healthy people for whom an ischemic background is unlikely.

MATERIALS AND METHODS

The study included 104 patients (71 women and 33 men) with paroxysmal narrow QRS complex tachycardia. In all patients electrophysiological study was performed and the diagnosis of atrioventricular nodal reentrant tachycardia was established. The arrhythmogenic substrate was then eliminated successfully by subsequent ablation using radiofrequency energy which confirmed the diagnosis, all patients had measured QRS components - QR, RS and RJ during the tachycardia and during the sinusrhythm. All of the measurements were done in lead V5.

RESULTS

The difference RJ-QR during tachycardia and sinus rhythm correlated negatively with tachycardia cycle length (R = 0.356, P = .001), first slowly, then rapidly reaching the cycle value of about 300 ms, then it decreases, stabilizing at the cycle level of about 270. By separating the RJ-QR in tachycardia and in the sinus rhythm from the tachycardia cycle, we can see that the correlation described in this point is largely due to the correlation between the heart rate and RJ-QR length in tachycardia.

CONCLUSIONS

In patients with atrioventricular nodal reentrant tachycardia, there is a significant ST-segment depression during tachycardia episodes and the degree of this change is related to tachycardia cycle length. The most probable explanation of the ST-segment depression is the overlap of the QRS complex on the preceded T wave. This phenomenon is also influenced by some intrinsic properties of the individual electrocardiogram. It is possible to rule out ischemic origin of the presented ST segment change.

Chest pain workup in the presence of atrial fibrillation: impacts on troponin testing, myocardial infarction diagnoses, and long-term prognosis

AIMS

Patients presenting to the emergency department (ED) with chest pain require evaluation for acute coronary syndrome (ACS). Atrial fibrillation (AF) can lead to troponin (cTn) elevation in the absence of ACS. There is limited evidence informing the impact of AF on the diagnostic performance of cTn testing for the diagnosis of Type 1 myocardial infarction (T1MI), or the association between AF and long-term outcomes in this context.

METHODS AND RESULTS

This study used the IMPACT and ADAPT study databases to compile a combined cohort of 3496 adults presenting to ED with chest pain between 2007 and 2014, with early cTn testing during ED workup. The mean age was 56.6 years, and 40.2% were female. Outcomes included adjudicated diagnoses for the index admission and mortality to 1-year after presentation. The specificity of initial cTn testing for T1MI diagnosis was lower for patients in AF compared with those not in AF (79.2% vs. 95.4%, P < 0.001), largely due to a relative increase in Type 2 myocardial infarction diagnoses. Sensitivity for T1MI did not differ between patients with or without AF (88.5% vs. 91.5%, P = 0.485). AF was associated with increased 1-year mortality (10.4% vs. 2.3%, P < 0.001), although this was not significant on multivariable analysis.

CONCLUSION

The specificity of serial cTn testing for the diagnosis of T1MI in patients presenting to ED with chest pain is reduced in the presence of AF. Further studies are needed to establish whether optimised cTn thresholds for patients with AF can improve workup and outcomes.

Underuse of Catheter Ablation as First-Line Therapy for Supraventricular Tachycardia

Background

Catheter ablation (CA) is a safe, effective, cost‐effective technique and may be considered a first‐line strategy for the treatment of symptomatic supraventricular tachycardias (SVT). Despite the high prospect of cure and the recommendations of international guidelines in considering CA as a first‐line treatment strategy, the average time between diagnosis and the procedure may be long. The present study aims to evaluate predictors related to non‐referral for CA as first‐line treatment in patients with SVT.

Methods and Results

The model was derived from a retrospective cohort of patients with SVT or ventricular pre‐excitation referred for CA in a tertiary center. Clinical and demographical features were used as independent variables and non‐referral for CA as first‐line treatment the dependent variable in a stepwise logistic regression analysis. Among 20 clinical‐demographic variables from 350 patients, 10 were included in initial logistic regression analysis: age, women, presence of pre‐excitation on ECG, palpitation, dyspnea and chest discomfort, number of antiarrhythmic drugs before ablation, number of concomitant symptoms, symptoms’ duration and evaluations in the emergency room due to SVT. After multivariable adjusted analysis, age (odds ratio [OR], 1.2; 95% CI 1.01–1.32; P=0.04), chest discomfort during supraventricular tachycardia (OR, 2.7; CI 1.6–4.7; P<0.001) and number of antiarrhythmic drugs before ablation (OR, 1.8; CI 1.4–2.3; P<0.001) showed a positive independent association for non‐referral for CA as SVT first‐line treatment.

Conclusions

The independent predictors of non‐referral for CA as first‐line treatment in our logistic regression analysis indicate the existence of biases in the decision‐making process in the referral process of patients who would benefit the most from catheter ablation. They very likely suggest a skewed medical decision‐making process leading to catheter ablation underuse.

Prognostic Value of Cardiac Troponin and Risk Assessment in Pediatric Supraventricular Tachycardia

Cardiac troponin I (cTnI) elevation is common in an acute episode of supraventricular tachycardia (SVT). However, there is limited evidence regarding the prognostic value of cTnI and the predictors of SVT recurrence in pediatric patients. We screened the electronic medical records of all pediatric patients presenting to the emergency departments at five Taiwanese hospitals from 1 January 2010 to 31 May 2021. Our primary outcomes were the occurrence of major adverse cardiac events (MACEs) during the follow-up period and 30-day SVT recurrence. A total of 112 patients were included in our study. Of these, 29 (25.9%) patients had positive cTnI values. Patients with cTnI elevation had significantly more complaints of dyspnea (27.6% vs. 7.2%, p = 0.008) and gastrointestinal discomfort (24.1% vs. 4.8%, p = 0.006). There were significantly more intensive care unit admissions (41.4% vs. 16.9%, p = 0.007) among the cTnI-positive group. One MACE was found in the cTnI-negative group. For 30-day SVT recurrence, the cTnI-positive group had a higher recurrence rate, without a statistically significant difference (20.7% vs. 7.2%, p = 0.075). Multivariable logistic regression analysis showed hypotension as an independent predictor of 30-day SVT recurrence (OR = 4.98; Cl 1.02-24.22; p = 0.047). Troponin had low value for predicting the outcomes of pediatric patients with SVT. The only significant predictor for recurrent SVT was initial hypotension.

Cardiac Troponins: Contemporary Biological Data and New Methods of Determination

Laboratory diagnosis plays one of the key roles in the diagnosis of many diseases, including cardiovascular diseases (CVD). The methods underlying the in vitro study of many CVD biomarkers, including cardiac troponins (cTnI and cTnT), are imperfect and are continually being improved to enhance their analytical performance, with sensitivity and specificity being the most important. Recently developed improved cTnI and cTnT detection methods, referred to as highly sensitive methods (hs-cTnI, hs-cTnT), have changed many of our ideas about the biology of cardiac troponins and opened up a number of additional diagnostic capabilities for practical healthcare. This article systematizes some relevant data on the biology of cardiac troponins as well as on methods for determining cTnI and cTnT with an analysis of the diagnostic value of their analytical characteristics (limit of blank, limit of detection, 99th percentile, coefficient of variation, and others). Data on extracardiac expression of cTnI and cTnT, mechanisms of formation and potential clinical significance of gender, age, and circadian characteristics of hs-cTnI and hs-cTnT content in serum are discussed. Considerable attention is paid to the discussion of new diagnostic capabilities of hs-cTnI, hs-cTnT, including consideration of promising possibilities for their study in biological fluids that can be obtained by non-invasive methods. Also, some possibilities of using hs-cTnI and hs-cTnT as prognostic laboratory biomarkers in healthy people (for example, to assess the risk of developing CVD) and in patients suffering from a number of pathological conditions that cause damage to cardiomyocytes are examined, and the potential mechanisms underlying the increase in hs-cTnI and hs-cTnT are discussed.

Prognostic value of cardiac troponin levels in patients presenting with supraventricular tachycardias

BACKGROUND

An association between paroxysmal supraventricular tachycardias (PSVT) and elevated cardiac troponin I (cTnI) has been reported in small studies, even in the absence of significant coronary artery or structural heart disease. We sought to explore the prognostic significance of elevated cTnI among patients presenting with PSVT.

METHODS

This is a retrospective single-center observational study conducted between January 2014 and Decemebr 2016. 165 patients (60% men, mean age 55 ± 17 year-old) with an acute episode of regular supraventricular tachyarrhythmia were admitted to the emergency department at Rambam Medical Center. 131 patients had at least one serum cTnI value measured. Of those, 57 had a positive result, defined as serum cTnI of more than 0.028 ng/dL.

RESULTS

Multivariate analysis showed that heart rate > 150 beats per minute (bpm) on admission (OR = 3.9; 95% CI 1.1.6-9.5; p < 0.003) and history of coronary artery disease (CAD) (OR = 3.4; 95% CI 1.2-10.1; p = 0.026) were the only independent predictors of cTnI elevation. After mean follow-up period of 23 ± 7 months, the combined primary outcome of death, coronary intervention (PCI) or myocardial infarction (MI) occurred in 7 patients (12.3%) out of 57 patients with positive cTnI and in zero patients with negative cTn (p = 0.002). Cox proportional hazard model showed that elevated cTnI on admission was an independent predictor of adverse outcomes only in patients with known coronary artery disease (CAD) (HR = 3.3, p = 0.05).

CONCLUSION

Elevated cTnI among patients presenting with PSVT appears to have prognostic significance only in patients with history of CAD. In this patient group elevated cTnI is associated with increased risk of adverse cardiac outcomes. We therefore believe serum cTnI should be measured selectively, such as in patients with symptoms of ischemic chest pain and a high pretest likelihood of having CAD.

Non-coronarogenic causes of increased cardiac troponins in clinical practice

Cardiospecific isoforms of troponins are the most sensitive and specific biomarkers for the diagnosis of myocardial infarction. However, though elevated troponin levels indicate myocardial damage, they do not determine the cause and mechanism of the damage. With the new highly sensitive methods, very minor damages of the heart muscle can be detected. Myocardial damage can occur in many non-coronarogenic diseases. In this review, we discuss the mechanisms of elevation, the diagnostic value of cardiac troponins in the renal failure, tachyarrhythmias, endocarditis, myocarditis, pericarditis, sepsis, neurogenic pathologies (stroke), pulmonary embolism. In addition, we pay attention to the main reasons for a false-positive increase of the concentration of cardiac troponins: heterophilic antibodies, rheumatoid factor, alkaline phosphatase, cross-reactions with skeletal muscle troponins.

Paroxysmal Supraventricular Tachycardia

Supraventricular tachycardia is a common emergency department (ED) pathology that frequently leads to hospital admission, but this may not be necessary in all cases. Here, we present a supraventricular tachycardia patient who was discharged from the ED after vagal maneuvers. This case demonstrates evidence that judicious emergency physicians can discharge supraventricular tachycardia patients home safely and gives impetus for a data-driven protocol for discharging these patients.

Challenges in high-sensitive troponin assay interpretation for intensive therapy

Cardiac troponins T and I are considered highly sensitive and specific markers for the diagnosis of acute myocardial infarction. Currently, a series of nonprimary cardiac abnormalities may manifest as an elevation in high-sensitive assays. The reduction in their detection limits has allowed earlier diagnosis and the use of evidence-based therapeutic measures; however, this characteristic has increased the spectrum of detectable noncoronary heart diseases, which poses challenges for characterizing acute coronary syndromes and creates a new role for these tests in known disorders in intensive care units, especially sepsis. Management of patients through a greater understanding of how these markers behave should be re-evaluated to ensure their correct interpretation.

ST Segment Elevation and Depressions in Supraventricular Tachycardia without Coronary Artery Disease

ST segment changes are well documented in literature during supraventricular tachycardias. We present a case of a 21-year-old male who presents with chest pain, shortness of breath, and dizziness with an ECG showing atrioventricular reentrant tachycardia and diffuse ST segment depressions. Patient spontaneously converted to sinus rhythm, but he was still complaining of crushing chest pain. ECG taken after conversion showed sinus rhythm at a rate of 65 and showed obvious persistence of ST depressions in majority of leads. Emergent left heart catheterization showed normal coronaries. Such ST depression is suggestive of global ischemia in small intracardiac vessels that cannot be evaluated by left heart catheterization.

Assessment of the Utility of Ordering a Troponin in Low- and Intermediate-Risk Patients Presenting to the Emergency Department with Supraventricular Tachycardia: A Retrospective Chart Review

BACKGROUND

A troponin assay is commonly sent for patients presenting to emergency departments (EDs) with supraventricular tachycardia (SVT). Multiple studies suggest that elevated troponin levels do not predict coronary artery disease in these patients. Patients with elevated troponins are more likely to have additional cardiac testing, which can lead to increased health care costs and unnecessary invasive procedures.

OBJECTIVE

Our objective was to evaluate low- to intermediate-risk patients (HEART [history, electrocardiography, age, risk factors and troponin] Score 1-6) presenting to the ED with SVT. Our hypothesis was that an elevated troponin would not predict major adverse cardiac events (MACE), but would be associated with increased hospital admission rates and lengths of stay.

METHODS

This was a retrospective cohort study of adult patients who presented with SVT to a large, urban, academic hospital ED over 4 years who had a troponin result. A total of 46 patients were included in the study.

RESULTS

Patients with a positive troponin (>0.05 ng/mL) had a hospital admission rate of 86% versus 21% for patients with negative troponin (p = 0.006); rate of cardiology consult of 86% versus 21% (p < 0.001); and a mean total length of stay of 4157 min versus 1347 min (p = 0.04). At 3 months, none of the patients with a positive troponin had an MACE, death from any cause, or positive results of cardiac testing.

CONCLUSIONS

Patients with a positive troponin result had significantly more admissions, cardiology consults, and longer hospital stays. These patients did not have an increased prevalence of MACE.

Review article: The utility of troponin and other investigations in patients presenting to the emergency department with supraventricular tachycardia

Patients with supraventricular tachycardia commonly present to the ED. There is a lack of consensus regarding assessment of these patients. Our aim was to determine the utility of troponin and four other investigations (full blood examination, electrolyte levels, thyroid function tests and chest X-rays) commonly requested for these patients. MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (January 1992-March 2017) were searched for randomised controlled trials and observational studies (of sample size greater than 10). Our search strategy yielded no randomised controlled trials and seven observational studies with significant statistical heterogeneity among selected studies (I² 87.3%, P < 0.001). Included studies investigated a total of 1155 patients. All studies reported on the utility of troponin testing in this patient population. The pooled proportion of patients investigated with troponin was 0.66 (95% confidence interval 0.44-0.88). The pooled proportion of positive troponin tests was 0.32 (95% confidence interval 0.23-0.41). Only one study reported on the utility of the remaining four investigations with abnormal results as follows: thyroid stimulating hormone 14%, haemoglobin 6%, white cell count 19% and chest X-ray 22%. Investigations are commonly requested for patients presenting with supraventricular tachycardia. Troponin testing is commonly performed with a high proportion of positive findings although these results did not appear to be associated with major adverse cardiac events. Heterogeneity among studies and low levels of evidence precluded conclusions on full blood examinations, electrolyte levels, thyroid testing and utility of chest X-rays in this patient population.

Evaluation of left ventricular longitudinal deformation in patients with and without ST segment depression during supraventricular tachycardia

BACKGROUND

The cumulative effect of repeated demand ischemia on left ventricular (LV) systolic function has been previously demonstrated. We evaluated the longitudinal deformation of LV myocardial fibers at systole and diastole using two-dimensional speckle-tracking echocardiography (2DSTE) in patients with and without ST-segment depression during supraventricular tachycardia.

METHODS

We recruited 104 consecutive patients, who were admitted to our hospital for the ablation of atrioventricular nodal reentrant tachycardia or atrioventricular reentrant tachycardia. The patients were thereafter evaluated by transthoracic echocardiography and 2DSTE, and longitudinal systolic strain and strain rate as well as early and late diastolic strain rates were measured.

RESULTS

We found no statistically significant differences in longitudinal systolic strain and strain rate as well as in early and late diastolic strain rates between the two study groups.

CONCLUSIONS

The longitudinal deformation properties of LV muscle fibers were not different between patients with and without ST-segment depression during supraventricular tachycardia. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:343-349, 2017.

Usefulness of laboratory and radiological investigations in the management of supraventricular tachycardia

OBJECTIVE

Although ED patients presenting with supraventricular tachycardia (SVT) are commonly investigated, the value of these investigations has been questioned. We aimed to determine the frequency and utility of investigations in patients with SVT.

METHODS

We undertook an explicit retrospective medical record audit of patients with SVT who presented to a single ED (January 2004 to June 2014). Data on demographics, presenting complaints, investigations and outcomes were extracted. The outcomes were nature and utility of investigations.

RESULTS

A total of 633 patients were enrolled (mean [SD] age 55.4 [17.7] years, 62% female). Laboratory investigations were common: electrolytes (83.7% of patients), full blood count (81.2%), magnesium (57.5%), calcium (39.3%) and thyroid function (30.3%). These investigations revealed many mildly abnormal results but resulted in electrolyte supplementation in only 19 patients: eight with mild hypokalaemia (potassium 3.0-3.5 mmol/L) and 11 with mild hypomagnesia (magnesium 0.49-1.1 mmol/L). Troponin was ordered for 302 (47.7%) patients, many of whom had no history or risk factors for cardiac disease, or ischaemic symptoms associated with their SVT. The troponin was normal, mildly and moderately elevated in 65.2, 24.5 and 10.2% of cases, respectively. Only seven (1.1%) patients were diagnosed with acute myocardial ischemia. Although 190 (30.0%) patients had a chest X-ray (CXR), it was normal in 78.4% of cases. All CXR abnormalities were incidental and not relevant to the immediate ED management.

CONCLUSION

Patients with uncomplicated SVT are over-investigated. Guidelines for ED SVT investigation are recommended. Further research is recommended to determine the indications for each investigation in the setting of SVT.

High-sensitivity troponin and novel biomarkers for the early diagnosis of non-ST-segment elevation myocardial infarction in patients with atrial fibrillation

AIMS

To evaluate the diagnostic performance of high-sensitivity troponin I (hsTnI) and other novel biomarkers for diagnosing non-ST-segment elevation myocardial infarction (NSTEMI) in patients with atrial fibrillation.

METHODS

In an acute chest pain cohort (N=1673), mean age 61.4±13.6 (34% female), we measured hsTnI and 13 established and novel biomarkers reflecting ischaemia, necrosis, inflammation, myocardial stress, angiogenesis on admission and after three hours in order to investigate their diagnostic accuracy for NSTEMI.

RESULTS

In atrial fibrillation patients (N=299) hsTnI on admission had the best discriminatory ability for NSTEMI (area under the curve 0.97) with only two novel biomarkers, copeptin and heart-type fatty acid binding protein, having area under the curve >0.70. Measured biomarkers showed comparable discriminatory ability in atrial fibrillation and non-atrial fibrillation patients. The combination of hsTnI on admission with additional biomarkers did not clinically significantly improve diagnostic performance. In atrial fibrillation patients, hsTnI concentrations ⩽21.7 ng/L (99th percentile in a healthy German cohort) on admission gave a negative predictive value of ~100% (95% confidence interval 97-100%). The combination of hsTnI on admission and absolute change of hsTnI concentration after three hours of ⩾40 ng/L resulted in a positive predictive value of 81.2% and sensitivity of 88.6%. Diagnostic accuracy was validated in an independent cohort (N=1076).

CONCLUSION

The diagnostic accuracy of hsTnI in patients with acute chest pain and atrial fibrillation is high and comparable to those without atrial fibrillation. Absolute change in hsTnI concentration enhanced diagnostic performance. No clinically relevant improvement was achieved by adding other biomarkers.

Predictors of significant coronary artery disease in atrial fibrillation: Are cardiac troponins a useful measure

BACKGROUND

Cardiac Troponin I (cTnI) is frequently measured in patients presenting with symptomatic atrial fibrillation (AF). The significance of elevated cTnI levels in this patient cohort is unclear. We investigated the value of cTnI elevation in this setting and whether it is predictive for significant coronary artery disease (sCAD).

METHODS

We conducted a retrospective, single-center, case-control study of 231 patients who presented with symptomatic AF to The Prince Charles Hospital emergency department, Brisbane, Australia between 2006 and 2014. Patients who underwent serial cTnI testing and assessment for CAD were included. Clinical variables that are known to predict CAD and could potentially predict cTnI elevation were collected. Binary logistic regression was performed to identify predictors of sCAD and cTnI elevation.

RESULTS

Cardiac Troponin I elevation above standard cut off was not predictive for sCAD after adjustment for other predictors (OR 1.62, 95% CI 0.79-3.32. p=0.19). However, the highest cTnI concentration value (cTnI peak) was predictive for sCAD (OR 2.02, 95% CI 1.02-3.97, p=0.04). Dyspnea on presentation (OR 4.52, 95% CI 1.87-10.91, p=0.001), known coronary artery disease (OR 3.44, 95% CI 1.42-8.32, p=0.006), and ST depression on the initial electrocardiogram (OR 2.57, 95% CI 1.11-5.97, p=0.028) predicted sCAD in our cohort, while heart rate on initial presentation was inversely correlated with sCAD (OR 0.99, 95% CI 0.971-1.00, p=0.034).

CONCLUSION

Troponin elevation is common in patients presenting to hospital with acute symptomatic AF and it is not a reliable indicator for underlying sCAD in this patient cohort. However, cTnI peak was a predictor of significant coronary artery disease.

Characterization of Cardiac Troponin Elevation in the Setting of Pediatric Supraventricular Tachycardia

Cardiac troponin (cTn) is currently considered the gold standard biomarker for detection of myocardial necrosis. Patients with supraventricular tachycardia (SVT) often present with symptoms resulting in cTn assessment; however, there are no data on the results of such testing in childhood. We hypothesized that cTn elevation would be common in the pediatric SVT population and would portend a benign prognosis. A retrospective review of all pediatric patients (≤21 years) presenting with SVT was performed. Clinical and electrocardiographic variables from the emergency department (ED) presentation were reviewed and clinical outcomes during subsequent follow-up assessed. Of 128 patients seen in the ED for SVT, cTn was assessed in 48 (38 %). Of patients with cTn assessment, 14 (29 %) patients demonstrated cTn elevation. Univariate predictors of cTn elevation included presentation with respiratory or gastrointestinal symptoms (50 vs 12 % and 42 vs 9 %; p = 0.008 and p = 0.01, respectively), lower mean arterial blood pressure (73 vs 85 mm Hg, p = 0.009), higher age-adjusted tachycardia rate (z score 9.3 vs 7.2, p < 0.001), and longer tachycardia duration (4.2 vs 1.0 h, p = 0.02). Multivariate logistic regression confirmed the association of age-adjusted tachycardia rate (odds ratio [OR] 3.8 per heart rate z score, confidence interval [CI] 1.9-11.8, p = 0.003) and duration (OR 1.5 per hour, CI 1.1-2.5, p = 0.03). Clinical outcome was excellent with no adverse sequelae during a median of 2.9 years of follow-up. Cardiac Tn elevation is common in the pediatric population presenting with SVT. Episode severity, characterized by respiratory or gastrointestinal symptoms, lower mean blood pressure, and increased tachycardia rate and duration are predictive. Clinical follow-up is favorable.

Diagnosis and management of type II myocardial infarction: increased demand for a limited supply of evidence

Type 2 myocardial infarction (type 2 MI) is defined as myocardial necrosis that results from an imbalance of myocardial oxygen supply and demand. Although type 2 MI is highly prevalent and strongly associated with mortality, the pathophysiology remains poorly understood. Discrepancies in definitions, frequency of screening, diagnostic approaches, and methods of adjudication lead to confusion and misclassification. To date, there is no consensus on the diagnostic criteria for type 2 MI. No guidelines exist for the optimal management of this condition, and further investigation is urgently needed. This review explores the existing evidence on the pathophysiology, diagnosis, prognosis, and management of type 2 MI.

Review article: elevated troponin: diagnostic gold or fool's gold?

Troponin is a highly sensitive biomarker of myocardial injury and has been used extensively in everyday clinical practice in the community as well as in hospitals for the diagnosis of acute myocardial infarction (AMI) and for risk stratification of patients with acute coronary symptoms. Dynamic elevations in biomarkers (troponin) are considered fundamental to the diagnosis of AMI. Unfortunately, many clinical conditions can cause troponin elevation in the absence of myocardial ischaemia, and elevated levels sometimes pose a diagnostic dilemma. In some cases, inappropriate diagnosis of 'AMI' based primarily on a raised troponin can have a deleterious impact on an individual, including on driving, insurance and other medicolegal matters. An incorrect diagnosis of myocardial infarction can also lead to the oversight of serious life-threatening alternative causes of troponin elevation (e.g. pulmonary embolism). This article discusses the role of troponin in our everyday clinical practice in the ED.

Troponin elevation in coronary vs. non-coronary disease

Acute myocardial infarction is defined as myocardial cell death due to prolonged myocardial ischaemia. Cardiac troponins (cTn) are the most sensitive and specific biochemical markers of myocardial injury and with the new high-sensitivity troponin methods very minor damages on the heart muscle can be detected. However, elevated cTn levels indicate cardiac injury, but do not define the cause of the injury. Thus, cTn elevations are common in many disease states and do not necessarily indicate the presence of a thrombotic acute coronary syndrome (ACS). In the clinical work it may be difficult to interpret dynamic changes of troponin in conditions such as stroke, pulmonary embolism, sepsis, acute perimyocarditis, Tako-tsubo, acute heart failure, and tachycardia. There are no guidelines to treat patients with elevated cTn levels and no coronary disease. The current strategy of treatment of patients with elevated troponin and non-acute coronary syndrome involves treating the underlying causes. The aim of this paper is to review data from studies of non-ACS patients with acutely elevated troponin who in clinical practice may be difficult to discriminate from ACS patients.