Segment Length in Cine Strain Analysis Predicts Cardiac Resynchronization Therapy Outcome Beyond Current Guidelines.

BACKGROUND: Patients with a class I recommendation for cardiac resynchronization therapy (CRT) are likely to benefit, but the effect of CRT in class II patients is more heterogeneous and additional selection parameters are needed in this group. The recently validated segment length in cine strain analysis of the septum (SLICE-ESSsep) measurement on cardiac magnetic resonance cine imaging predicts left ventricular functional recovery after CRT but its prognostic value is unknown. This study sought to evaluate the prognostic value of SLICE-ESSsep for clinical outcome after CRT. METHODS: Two hundred eighteen patients with a left bundle branch block or intraventricular conduction delay and a class I or class II indication for CRT who underwent preimplantation cardiovascular magnetic resonance examination were enrolled. SLICE-ESSsep was manually measured on standard cardiovascular magnetic resonance cine imaging. The primary combined end point was all-cause mortality, left ventricular assist device, or heart transplantation. Secondary end points were (1) appropriate implantable cardioverter defibrillator therapy and (2) heart failure hospitalization. RESULTS: Two-thirds (65%) of patients had a positive SLICE-ESSsep ≥0.9% (ie, systolic septal stretching). During a median follow-up of 3.8 years, 66 (30%) patients reached the primary end point. Patients with positive SLICE-ESSsep were at lower risk to reach the primary end point (hazard ratio 0.36; P<0.001) and heart failure hospitalization (hazard ratio 0.41; P=0.019), but not for implantable cardioverter defibrillator therapy (hazard ratio, 0.66; P=0.272). Clinical outcome of class II patients with a positive ESSsep was similar to those of class I patients (hazard ratio, 1.38 [95% CI, 0.66-2.88]; P=0.396). CONCLUSIONS: Strain assessment of the septum (SLICE-ESSsep) provides a prognostic measure for clinical outcome after CRT. Detection of a positive SLICE-ESSsep in patients with a class II indication predicts improved CRT outcome similar to those with a class I indication whereas SLICE-ESSsep negative patients have poor prognosis after CRT implantation.

Two Forms of Monomorphic Ventricular Tachycardia in a Patient with Brugada Syndrome.

We herein report a 47-year-old man with relapsing polychondritis who developed monomorphic ventricular tachycardia (VT). His electrocardiogram in sinus rhythm showed a coved-type pattern, and there was no evidence of structural cardiac disease; therefore, he was diagnosed with Brugada syndrome. An electrophysiological study revealed a prolonged His-ventricular interval at the baseline. Two forms of VT were induced, which were shown to be bundle branch reentrant VT. A diagnosis of Brugada syndrome should not be ruled out in patients with monomorphic VTs, especially those with conduction abnormalities.

Computational Prediction of the Combined Effect of CRT and LVAD on Cardiac Electromechanical Delay in LBBB and RBBB.

Two case reports showed that the combination of CRT and LVAD benefits the end-stage heart failure patients with prolonged QRS interval significantly. In one of the reports, the patient had the LVAD removed due to the recovery of the heart function. However, the quantification of the combined devices has yet to be conducted. This study aimed at computationally predicting the effects of CRT-only or combined with LVAD on electromechanical behaviour in the failing ventricle with left bundle branch blocked (LBBB) and right bundle branch blocked (RBBB) conditions. The subjects are normal sinus rhythm, LBBB, RBBB, LBBB with CRT-only, RBBB with CRT-only, LBBB with CRT + LVAD, and RBBB with CRT + LVAD. The results showed that the CRT-only shortened the total electrical activation time (EAT) in the LBBB and RBBB conditions by 20.2% and 17.1%, respectively. The CRT-only reduced the total mechanical activation time (MAT) and electromechanical delay (EMD) of the ventricle under LBBB by 21.3% and 10.1%, respectively. Furthermore, the CRT-only reduced the contractile adenosine triphosphate (ATP) consumption by 5%, increased left ventricular (LV) pressure by 6%, and enhanced cardiac output (CO) by 0.2 L/min under LBBB condition. However, CRT-only barely affects the ventricle under RBBB condition. Under the LBBB condition, CRT + LVAD increased LV pressure and CO by 10.5% and by 0.9 L/min, respectively. CRT + LVAD reduced ATP consumption by 15%, shortened the MAT by 23.4%, and shortened the EMD by 15.2%. In conclusion, we computationally predicted and quantified that the CRT + LVAD implementation is superior to CRT-only implementation particularly in HF with LBBB condition.

Noninvasive Identification of Ventricular Tachycardia-Related Anatomical Isthmuses in Repaired Tetralogy of Fallot: What Is the Role of the 12-Lead Ventricular Tachycardia Electrocardiogram.

OBJECTIVES: This study sought to evaluate the relation between 12-lead ventricular tachycardia (VT) electrocardiography (ECG) and VT-related anatomical isthmuses (AIs) in repaired tetralogy of Fallot (rTOF). BACKGROUND: Slow-conducting AIs are the dominant VT substrate in rTOF. Whether an AI is considered critical relies on pace mapping (PM) guided by the VT ECG. METHODS: VT ECGs, electroanatomical mapping data and PM results were analyzed in 25 rTOF patients (group 1) (age 57 ± 13 years). Selection of PM and ablation sites was guided by VT ECG. In 7 patients (group 2) (age 33 ± 14 years), PM was systematically performed within all AIs, irrespective of the VT ECG. RESULTS: In group 1, all 35 induced VTs (median VT cycle length 270 [interquartile range: 240 to 310] ms) were AI related. All 11 right bundle branch block (RBBB) VTs were related to AI3 (right ventricular septum if positive concordant [7 of 7]), coronary cusp if V2 transition break [3 of 4]). Left bundle branch block (LBBB) VTs with transition 

Prognostic significance of left anterior fascicular block and its relation with coronary artery disease in old patients based on 570 autopsy cases.

BACKGROUND: Left Anterior Fascicular Block (LAFB) occurs frequently among the elderly, and have a correlation with coronary artery disease (CAD), yet controversies regarding its clinical significance still remain. METHODS: We carried on a retrospective study involving 92 LAFB and 478 non-LAFB patients, in which anatomic, clinical and electrocardiographic characteristics were compared. RESULTS: LAFB subjects had more pathological CAD (66.3% vs 54.6%, P = 0.039), myocardial infarction (MI) (53.3% vs 37.9%, P = 0.007) and myocarditis (5.4% vs 1.7%, P = 0.043). Among the LAFB group, 58.1% of patients with CAD and 30.2% of patients with MI were clinically misdiagnosed, while 42.9% of patients with MI were clinically missed. Logistic regression showed CAD had no independent relevance with LAFB. LAFB subjects displayed heavier hearts [(451.1 ±â€¯101.3)g vs (407.1 ±â€¯102.3)g, P < 0.001], thicker left ventricular walls [(1.6 ±â€¯0.4)cm vs (1.4 ±â€¯0.3)cm, P = 0.001]. Kaplan-Meier survival analysis indicated significant differences in long-term survival time (χ2 = 12.223, P < 0.001) and cardiac mortality (χ2 = 20.982, P < 0.001) between LAFB and non-LAFB group. Cox multivariate analysis demonstrated LAFB was an independent risk factor of all-cause death (HR = 1.552, 95% CI = 1.208-1.994, P = 0.001) and cardiac death (HR = 2.287, 95% CI = 1.545-3.386, P < 0.001). The major death cause of LAFB was cardiac death (46.7%), including more MI (28.3% vs 13.4%, P = 0.008), myocarditis (4.3% vs 1.0%, P = 0.042) and cardiac rupture (6.7% vs 1.9%, P = 0.022). CONCLUSIONS: LAFB subjects had more pathological CAD and MI, but LAFB was not an independent relevant factor of CAD. LAFB lowered the accuracy to clinically diagnose CAD. LAFB patients gained heavier hearts, thicker left ventricular walls, and suffered increased risk of death and cardiac death.

The ability of the electrocardiogram in left bundle branch block to detect myocardial scar determined by cardiovascular magnetic resonance.

AIMS: We aimed to improve the electrocardiographic 2009 left bundle branch block (LBBB) Selvester QRS score (2009 LBSS) for scar assessment. METHODS: We retrospectively identified 325 LBBB patients with available ECG and cardiovascular magnetic resonance imaging (CMR) with late gadolinium enhancement from four centers (142 [44%] with CMR scar). Forty-four semi-automatically measured ECG variables pre-selected based on the 2009 LBSS yielded one multivariable model for scar detection and another for scar quantification. RESULTS: The 2009 LBSS achieved an area under the curve (AUC) of 0.60 (95% confidence interval 0.54-0.66) for scar detection, and R2 = 0.04, p < 0.001, for scar quantification. Multivariable modeling improved scar detection to AUC 0.72 (0.66-0.77) and scar quantification to R2 = 0.21, p < 0.001. CONCLUSIONS: The 2009 LBSS detects and quantifies myocardial scar with poor accuracy. Improved models with extensive comparison of ECG and CMR had modest performance, indicating limited room for improvement of the 2009 LBSS.

Sex-Specific Response to Cardiac Resynchronization Therapy: Effect of Left Ventricular Size and QRS Duration in Left Bundle Branch Block.

OBJECTIVES: In this study, the authors sought to assess the impact of body and heart size on sex-specific cardiac resynchronization therapy (CRT) response rate, according to QRS duration (QRSd) as a continuum. BACKGROUND: Effects of CRT differ between sexes for any given QRSd. METHODS: New York Heart Association functional class III/IV patients with nonischemic cardiomyopathy and "true" left bundle branch block (LBBB) were evaluated. Left ventricular mass (LVM) and end-diastolic volume were measured echocardiographically. Positive response was defined by left ventricular ejection fraction (LVEF) improvement post-CRT. RESULTS: Among 130 patients (LVEF 19 ± 7.1%; QRSd 165 ± 20 ms; 55% female), CRT improved LVEF to 32 ± 14% (p < 0.001) during a median 2 years follow-up. Positive responses occurred in 103 of 130 (79%) (78% when QRSd <150 ms vs. 80% when QRSd ≥150 ms; p = 0.8). Body surface area (BSA), QRSd, and LVM were lower in women, but QRSd/LVM ratio greater (p < 0.0001). Sexes did not differ for pharmacotherapy and comorbidities, but female CRT response was greater: 90% (65 of 72) versus 66% (38 of 58) in males (p < 0.001). With QRSd as a continuum, the overall CRT-response relationship showed a progressive increase to plateau between 150 and 170 ms, then a decrease. Sex-specific differences were conspicuous: among females, a peak effect was observed between 135 and 150 ms, thereafter a decline, with the male response rate lower, but with a gradual increase as QRSd lengthened. Sex-specific differences were unaltered by BSA, but resolved with integration of LVM or end-diastolic volume. CONCLUSIONS: Sex differences in the QRSd-response relationship among CRT patients with LBBB were unexplained by application of strict LBBB criteria or by BSA, but resolved by QRSd normalization for heart size using LV mass or volume.

Case report: an unusual case of Brugada syndrome combined with a ventricular septal defect: A case report.

RATIONALE: Brugada syndrome (BrS) is a cardiac ion channel disease that is caused by an autosomal dominant genetic abnormality. A ventricular septal defect is a common congenital heart disease, in which genetic defects play a significant role. PATIENT CONCERNS: We report an extremely rare case of a 42-year-old male with congenital heart disease, who suffered recurrent syncope and gastrointestinal bleeding. His electrocardiogram showed an unusual right bundle branch block-like pattern and ST-segment elevation in leads V1-V3. DIAGNOSES: The patient was eventually diagnosed with Brugada Syndrome Combined with a Ventricular Septal Defect. INTERVENTIONS: The patient was treated with ICD implants. OUTCOMES: We extracted his blood and performed whole exome sequencing. Whole exome sequencing revealed mutations in genes, which encode ion channels and proteins important for embryonic heart development. However, a novel mutation in the SCN5A gene was also found. LESSONS: To our knowledge, this is the first genetically proven case of BrS combined with a ventricular septal defect.

Clinical Implications of Complete Left-Sided Reverse Remodeling With Cardiac Resynchronization Therapy: A MADIT-CRT Substudy.

BACKGROUND: Clinical implications of complete left-sided reverse remodeling due to cardiac resynchronization therapy with a defibrillator (CRT-D), defined as reduction in both left ventricular end-systolic volume (LVESV) and left atrial volume (LAV), are unknown. OBJECTIVES: This study aimed to evaluate the rate and predictive value of complete left-sided reverse remodeling on heart failure (HF) and death events in CRT-D patients with left bundle branch block (LBBB) enrolled in MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy). METHODS: The study population comprised 533 CRT-D patients with LBBB, 212 (40%) with complete left-sided reverse remodeling (above-median change in both LAV and LVESV), 115 (22%) with discordant reverse remodeling (above-median change in only LAV or LVESV), and 206 (38%) with lesser reverse remodeling (below-median LAV and LVESV change). The primary endpoint was HF or death; secondary endpoints included HF alone and death alone during long-term follow-up. RESULTS: Patients with complete left-sided reverse remodeling had a significantly lower rate of HF or death than those with discordant reverse remodeling or lesser reverse remodeling (p < 0.001). Multivariate Cox proportional hazard models consistently showed a decreased risk for HF and death in patients with complete reverse remodeling compared with discordant reverse remodeling or lesser reverse remodeling (hazard ratio: 0.66 per each group; 95% CI: 0.50 to 0.85; p = 0.002). This finding was similar for HF alone and death alone. CONCLUSIONS: In MADIT-CRT, >20% of CRT-D patients exhibited discordant reverse remodeling in the left ventricle and the left atrium. CRT-D patients with LBBB and complete left-sided reverse remodeling had a significantly lower risk of HF and death, HF alone, and death alone during long-term follow-up than patients with discordant or lesser reverse remodeling. (MADIT-CRT: Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy [MADIT-CRT]; NCT00180271).

The Complexity of the His Bundle: Understanding Its Anatomy and Physiology through the Lens of the Past and the Present.

In this paper, we describe the anatomy and physiology of the His bundle and describe the mechanisms by which permanent His-bundle pacing can be accomplished.

Generating Purkinje networks in the human heart.

The Purkinje network is an integral part of the excitation system in the human heart. Yet, to date, there is no in vivo imaging technique to accurately reconstruct its geometry and structure. Computational modeling of the Purkinje network is increasingly recognized as an alternative strategy to visualize, simulate, and understand the role of the Purkinje system. However, most computational models either have to be generated manually, or fail to smoothly cover the irregular surfaces inside the left and right ventricles. Here we present a new algorithm to reliably create robust Purkinje networks within the human heart. We made the source code of this algorithm freely available online. Using Monte Carlo simulations, we demonstrate that the fractal tree algorithm with our new projection method generates denser and more compact Purkinje networks than previous approaches on irregular surfaces. Under similar conditions, our algorithm generates a network with 1219±61 branches, three times more than a conventional algorithm with 419±107 branches. With a coverage of 11±3mm, the surface density of our new Purkije network is twice as dense as the conventional network with 22±7mm. To demonstrate the importance of a dense Purkinje network in cardiac electrophysiology, we simulated three cases of excitation: with our new Purkinje network, with left-sided Purkinje network, and without Purkinje network. Simulations with our new Purkinje network predicted more realistic activation sequences and activation times than simulations without. Six-lead electrocardiograms of the three case studies agreed with the clinical electrocardiograms under physiological conditions, under pathological conditions of right bundle branch block, and under pathological conditions of trifascicular block. Taken together, our results underpin the importance of the Purkinje network in realistic human heart simulations. Human heart modeling has the potential to support the design of personalized strategies for single- or bi-ventricular pacing, radiofrequency ablation, and cardiac defibrillation with the common goal to restore a normal heart rhythm.

Protective Role of False Tendon in Subjects with Left Bundle Branch Block: A Virtual Population Study.

False tendons (FTs) are fibrous or fibromuscular bands that can be found in both the normal and abnormal human heart in various anatomical forms depending on their attachment points, tissue types, and geometrical properties. While FTs are widely considered to affect the function of the heart, their specific roles remain largely unclear and unexplored. In this paper, we present an in silico study of the ventricular activation time of the human heart in the presence of FTs. This study presents the first computational model of the human heart that includes a FT, Purkinje network, and papillary muscles. Based on this model, we perform simulations to investigate the effect of different types of FTs on hearts with the electrical conduction abnormality of a left bundle branch block (LBBB). We employ a virtual population of 70 human hearts derived from a statistical atlas, and run a total of 560 simulations to assess ventricular activation time with different FT configurations. The obtained results indicate that, in the presence of a LBBB, the FT reduces the total activation time that is abnormally augmented due to a branch block, to such an extent that surgical implant of cardiac resynchronisation devices might not be recommended by international guidelines. Specifically, the simulation results show that FTs reduce the QRS duration at least 10 ms in 80% of hearts, and up to 45 ms for FTs connecting to the ventricular free wall, suggesting a significant reduction of cardiovascular mortality risk. In further simulation studies we show the reduction in the QRS duration is more sensitive to the shape of the heart then the size of the heart or the exact location of the FT. Finally, the model suggests that FTs may contribute to reducing the activation time difference between the left and right ventricles from 12 ms to 4 ms. We conclude that FTs may provide an alternative conduction pathway that compensates for the propagation delay caused by the LBBB. Further investigation is needed to quantify the clinical impact of FTs on cardiovascular mortality risk.

Automatic QRS Selvester scoring system in patients with left bundle branch block.

AIMS: The Selvester QRS scoring system uses quantitative criteria from the standard 12-lead electrocardiogram (ECG) to estimate the myocardial scar size of patients, including those with left bundle branch block (LBBB). Automation of the scoring system could facilitate the clinical use of this technique which requires a set of multiple QRS patterns to be identified and measured. METHODS AND RESULTS: We developed a series of algorithms to automatically detect and measure the QRS parameters required for Selvester scoring. The 'QUantitative and Automatic REport of Selvester Score' was designed specifically for the analysis of ECGs from patients meeting new strict criteria for complete LBBB. The algorithms were designed using a training (n = 36) and a validation (n = 180) set of ECGs, consisting of signal-averaged 12-lead ECGs (1000 Hz sampling) recorded from 216 LBBB patients from the MADIT-CRT. We assessed the performance of the methods using expert manually adjudicated ECGs. The average of absolute differences between automatic and adjudicated Selvester scoring was 1.2 ± 1.5 points. The range of average differences for continuous measurements of wave locations and interval durations varied between 0 and 6 ms. Erroneous detection of Q, R, S, R', and S' waves (oversensed or missed) were 3, 1, 1, 16, and 6%, respectively. Seven percent of notches detected in the first 40 ms were misdetected. CONCLUSION: We propose an efficient computerized method for the automatic measurement of the Selvester score in patients with the strict LBBB.

Arrhythmic Mitral Valve Prolapse and Sudden Cardiac Death.

BACKGROUND: Mitral valve prolapse (MVP) may present with ventricular arrhythmias and sudden cardiac death (SCD) even in the absence of hemodynamic impairment. The structural basis of ventricular electric instability remains elusive. METHODS AND RESULTS: The cardiac pathology registry of 650 young adults (≤40 years of age) with SCD was reviewed, and cases with MVP as the only cause of SCD were re-examined. Forty-three patients with MVP (26 females; age range, 19-40 years; median, 32 years) were identified (7% of all SCD, 13% of women). Among 12 cases with available ECG, 10 (83%) had inverted T waves on inferior leads, and all had right bundle-branch block ventricular arrhythmias. A bileaflet involvement was found in 70%. Left ventricular fibrosis was detected at histology at the level of papillary muscles in all patients, and inferobasal wall in 88%. Living patients with MVP with (n=30) and without (control subjects; n=14) complex ventricular arrhythmias underwent a study protocol including contrast-enhanced cardiac magnetic resonance. Patients with either right bundle-branch block type or polymorphic complex ventricular arrhythmias (22 females; age range, 28-43 years; median, 41 years), showed a bileaflet involvement in 70% of cases. Left ventricular late enhancement was identified by contrast-enhanced cardiac magnetic resonance in 93% of patients versus 14% of control subjects (P<0.001), with a regional distribution overlapping the histopathology findings in SCD cases. CONCLUSIONS: MVP is an underestimated cause of arrhythmic SCD, mostly in young adult women. Fibrosis of the papillary muscles and inferobasal left ventricular wall, suggesting a myocardial stretch by the prolapsing leaflet, is the structural hallmark and correlates with ventricular arrhythmias origin. Contrast-enhanced cardiac magnetic resonance may help to identify in vivo this concealed substrate for risk stratification.

The relationship of QRS morphology with cardiac structure and function in patients with heart failure.

INTRODUCTION: The relationship of QRS morphology with cardiac structure and function in patients with heart failure is uncertain. METHODS: Patients with a clinical diagnosis of heart failure and objective evidence of cardiac dysfunction [either a left ventricular ejection fraction (LVEF) <50 % or an amino-terminal pro-brain natriuretic peptide (NT-proBNP) ≥400 pg/ml] who had been investigated by cardiac magnetic resonance imaging (CMRI) were identified. QRS duration ≥120 ms was grouped morphologically as left (LBBB), right bundle branch block (RBBB) or indeterminate. RESULTS: Of 877 patients, 320 (36 %) had QRS ≥ 120 ms. Compared to patients with LBBB, those with RBBB had a lower median [inter-quartile range (IQR)] right ventricular (RV) ejection fraction [RBBB: 46 (37-57); LBBB: 52 (42-61) %; p = 0.014], greater median (IQR) RV mass [RBBB: 53 (42-73); LBBB: 45 (36-56) g; p < 0.001], higher median (IQR) plasma NT-proBNP [RBBB: 2013 (659-3573); LBBB: 1159 (589-2207) pg/ml, p = 0.026], more signs of peripheral congestion and higher prevalence of atrial fibrillation but had similar LVEF. During a median follow-up of 1302 days (IQR: 742-2237), 311 patients died. Compared with patients who had QRS < 120 ms, those with RBBB [HR 1.98, 95 % CI (1.37-2.86); p < 0.001] had a higher mortality. Age and NT-proBNP were the strongest independent predictors of mortality; neither QRS nor CMRI variables improved prediction. CONCLUSIONS: In patients with heart failure and QRS ≥ 120 ms, RBBB is associated with more severe RV dysfunction and congestion and a worse prognosis. However, neither QRS morphology nor CMRI data provide independent prognostic information in a multivariable analysis including NT-proBNP.

Arrhythmogenic substrate at the interventricular septum as a target site for radiofrequency catheter ablation of recurrent ventricular tachycardia in left dominant arrhythmogenic cardiomyopathy.

BACKGROUND: Left dominant arrhythmogenic cardiomyopathy (LDAC) is a rare condition characterised by progressive fibrofatty replacement of the myocardium of the left ventricle (LV) in combination with ventricular arrhythmias of LV origin. CASE PRESENTATION: A thirty-five-year-old male was referred for evaluation of recurrent sustained monomorphic ventricular tachycardia (VT) of 200 bpm and right bundle branch block (RBBB) morphology. Cardiac magnetic resonance imaging showed late gadolinium enhancement distributed circumferentially in the epicardial layer of the LV free wall myocardium including the rightward portion of the interventricular septum (IVS). The clinical RBBB VT was reproduced during the EP study. Ablation at an LV septum site with absence of abnormal electrograms and a suboptimum pacemap rendered the VT of clinical morphology noninducible. Three other VTs, all of left bundle branch block (LBBB) pattern, were induced by programmed electrical stimulation. The regions corresponding to abnormal electrograms were identified and ablated at the mid-to-apical RV septum and the anteroseptal portion of the right ventricular outflow tract. No abnormalities were found at the RV free wall including the inferolateral peritricuspid annulus region. Histological examination confirmed the presence of abnormal fibrous and adipose tissue with myocyte reduction in endomyocardial samples taken from both the left and right aspects of the IVS. CONCLUSION: LDAC rarely manifests with sustained monomorphic ventricular tachycardia. In this case, several VTs of both RBBB and LBBB morphology were amenable to endocardial radiofrequency catheter ablation.

A clinical and laboratory approach used to elucidate discordant results of high-sensitivity troponin T and troponin I.

BACKGROUND: Careful interpretation of discordant results in high-sensitivity troponin measurements is necessary in cases of suspect immunoassay interferences. We describe several procedures taken in a case of a polymorbid patient with chest pain, without clear evidence of myocardial necrosis and with increased high-sensitivity cardiac troponin T (hs-cTnT). We checked the Vafaie's algorithm for the evaluation of suspect interference in troponin measurements. METHODS: We conducted a case report analysis, additional measurements, a dilution test and pretreatment of plasma with blocking agents. RESULTS: Concentration of hs-cTnT (99 th percentile of "healthy" population 14 ng/L) increased from 120.1 ng/L to 280.4 ng/L during an 8-month period and decreased to 216.3 ng/L during the following month with repeatedly negative troponin I (TnI), hs-cTnI, myoglobin and creatine kinase MB (CK-MB). Suspected false positivity of hs-cTnT was further confirmed by treatment of plasma with an antiheterophile blocking agent (hs-cTnT before treatment 280.4 ng/L, after 16.53/16.23 ng/L). This outcome was further confirmed by the manufacturer's experiments. CONCLUSIONS: The false-positive results of hs-cTnT were caused by the presence of extremely rare high molecular weight protein, presumably IgM, most likely HAMA (human anti-mouse antibody). Only the pre-treatment of plasma with a blocking agent provided a reliable indication of the interference. Cooperation among clinicians, laboratory personnel and the manufacturer is essential.