Clinical application of CMR in cardiomyopathies: evolving concepts and techniques : A position paper of myocardial and pericardial diseases and cardiac magnetic resonance working groups of Italian society of cardiology.

Cardiac magnetic resonance (CMR) has become an essential tool for the evaluation of patients affected or at risk of developing cardiomyopathies (CMPs). In fact, CMR not only provides precise data on cardiac volumes, wall thickness, mass and systolic function but it also a non-invasive characterization of myocardial tissue, thus helping the early diagnosis and the precise phenotyping of the different CMPs, which is essential for early and individualized treatment of patients. Furthermore, several CMR characteristics, such as the presence of extensive LGE or abnormal mapping values, are emerging as prognostic markers, therefore helping to define patients' risk. Lastly new experimental CMR techniques are under investigation and might contribute to widen our knowledge in the field of CMPs. In this perspective, CMR appears an essential tool to be systematically applied in the diagnostic and prognostic work-up of CMPs in clinical practice. This review provides a deep overview of clinical applicability of standard and emerging CMR techniques in the management of CMPs.

Mutation location and IKs regulation in the arrhythmic risk of long QT syndrome type 1: the importance of the KCNQ1 S6 region.

AIMS: Mutation type, location, dominant-negative IKs reduction, and possibly loss of cyclic adenosine monophosphate (cAMP)-dependent IKs stimulation via protein kinase A (PKA) influence the clinical severity of long QT syndrome type 1 (LQT1). Given the malignancy of KCNQ1-p.A341V, we assessed whether mutations neighbouring p.A341V in the S6 channel segment could also increase arrhythmic risk. METHODS AND RESULTS: Clinical and genetic data were obtained from 1316 LQT1 patients [450 families, 166 unique KCNQ1 mutations, including 277 p.A341V-positive subjects, 139 patients with p.A341-neighbouring mutations (91 missense, 48 non-missense), and 900 other LQT1 subjects]. A first cardiac event represented the primary endpoint. S6 segment missense variant characteristics, particularly cAMP stimulation responses, were analysed by cellular electrophysiology. p.A341-neighbouring mutation carriers had a QTc shorter than p.A341V carriers (477 ± 33 vs. 490 ± 44 ms) but longer than the remaining LQT1 patient population (467 ± 41 ms) (P < 0.05 for both). Similarly, the frequency of symptomatic subjects in the p.A341-neighbouring subgroup was intermediate between the other two groups (43% vs. 73% vs. 20%; P < 0.001). These differences in clinical severity can be explained, for p.A341V vs. p.A341-neighbouring mutations, by the p.A341V-specific impairment of IKs regulation. The differences between the p.A341-neighbouring subgroup and the rest of LQT1 mutations may be explained by the functional importance of the S6 segment for channel activation. CONCLUSION: KCNQ1 S6 segment mutations surrounding p.A341 increase arrhythmic risk. p.A341V-specific loss of PKA-dependent IKs enhancement correlates with its phenotypic severity. Cellular studies providing further insights into IKs-channel regulation and knowledge of structure-function relationships could improve risk stratification. These findings impact on clinical management.

The Risk of Sudden Unexpected Cardiac Death in Children: Epidemiology, Clinical Causes, and Prevention.

"Sudden unexplained death (SUD) is a tragic event for both the family and community, particularly when it occurs in young individuals. Sudden cardiac death (SCD) represents the leading form of SUD and is defined as an unexpected event without an obvious extracardiac cause, occurring within 1 hour after the onset of symptoms. In children, the main causes of SCD are inherited cardiac disorders, whereas coronary artery diseases (congenital or acquired), congenital heart diseases, and myocarditis are rare. The present review examines the current state of knowledge regarding SCD in children, discussing the epidemiology, clinical causes, and prevention strategies."

Exercise Training-Induced Repolarization Abnormalities Masquerading as Congenital Long QT Syndrome.

BACKGROUND: The diagnosis of long QT syndrome (LQTS) is rather straightforward. We were surprised by realizing that, despite long-standing experience, we were making occasional diagnostic errors by considering as affected subjects who, over time, resulted as not affected. These individuals were all actively practicing sports-an observation that helped in the design of our study. METHODS: We focused on subjects referred to our center by sports medicine doctors on suspicion of LQTS because of marked repolarization abnormalities on the ECG performed during the mandatory medical visit necessary in Italy to obtain the certificate of eligibility to practice sports. They all underwent our standard procedures involving both a resting and 12-lead ambulatory ECG, an exercise stress test, and genetic screening. RESULTS: There were 310 such consecutive subjects, all actively practicing sports with many hours of intensive weekly training. Of them, 111 had a normal ECG, different cardiac diseases, or were lost to follow-up and exited the study. Of the remaining 199, all with either clear QTc prolongation and/or typical repolarization abnormalities, 121 were diagnosed as affected based on combination of ECG abnormalities with positive genotyping (QTc, 482±35 ms). Genetic testing was negative in 78 subjects, but 45 were nonetheless diagnosed as affected by LQTS based on unequivocal ECG abnormalities (QTc, 472±33 ms). The remaining 33, entirely asymptomatic and with a negative family history, showed an unexpected and practically complete normalization of the ECG abnormalities (their QTc shortened from 492±37 to 423±25 ms [P<0.001]; their Schwartz score went from 3.0 to 0.06) after detraining. They were considered not affected by congenital LQTS and are henceforth referred to as "cases." Furthermore, among them, those who resumed similarly heavy physical training showed reappearance of the repolarization abnormalities. CONCLUSION: It is not uncommon to suspect LQTS among individuals actively practicing sports based on marked repolarization abnormalities. Among those who are genotype-negative, >40% normalize their ECG after detraining, but the abnormalities tend to recur with resumption of training. These individuals are not affected by congenital LQTS but could have a form of acquired LQTS. Care should be exercised to avoid diagnostic errors.

Enhancing rare variant interpretation in inherited arrhythmias through quantitative analysis of consortium disease cohorts and population controls.

PURPOSE: Stringent variant interpretation guidelines can lead to high rates of variants of uncertain significance (VUS) for genetically heterogeneous disease like long QT syndrome (LQTS) and Brugada syndrome (BrS). Quantitative and disease-specific customization of American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines can address this false negative rate. METHODS: We compared rare variant frequencies from 1847 LQTS (KCNQ1/KCNH2/SCN5A) and 3335 BrS (SCN5A) cases from the International LQTS/BrS Genetics Consortia to population-specific gnomAD data and developed disease-specific criteria for ACMG/AMP evidence classes-rarity (PM2/BS1 rules) and case enrichment of individual (PS4) and domain-specific (PM1) variants. RESULTS: Rare SCN5A variant prevalence differed between European (20.8%) and Japanese (8.9%) BrS patients (p = 5.7 × 10-18) and diagnosis with spontaneous (28.7%) versus induced (15.8%) Brugada type 1 electrocardiogram (ECG) (p = 1.3 × 10-13). Ion channel transmembrane regions and specific N-terminus (KCNH2) and C-terminus (KCNQ1/KCNH2) domains were characterized by high enrichment of case variants and >95% probability of pathogenicity. Applying the customized rules, 17.4% of European BrS and 74.8% of European LQTS cases had (likely) pathogenic variants, compared with estimated diagnostic yields (case excess over gnomAD) of 19.2%/82.1%, reducing VUS prevalence to close to background rare variant frequency. CONCLUSION: Large case-control data sets enable quantitative implementation of ACMG/AMP guidelines and increased sensitivity for inherited arrhythmia genetic testing.

Recommendations for participation in leisure-time physical activity and competitive sports of patients with arrhythmias and potentially arrhythmogenic conditions. Part 2: ventricular arrhythmias, channelopathies, and implantable defibrillators.

This paper belongs to a series of recommendation documents for participation in leisure-time physical activity and competitive sports by the European Association of Preventive Cardiology (EAPC). Together with an accompanying paper on supraventricular arrhythmias, this second text deals specifically with those participants in whom some form of ventricular rhythm disorder is documented, who are diagnosed with an inherited arrhythmogenic condition, and/or who have an implanted pacemaker or cardioverter defibrillator. A companion text on recommendations in athletes with supraventricular arrhythmias is published in the European Journal of Preventive Cardiology. Since both texts focus on arrhythmias, they are the result of a collaboration between EAPC and the European Heart Rhythm Association (EHRA). The documents provide a framework for evaluating eligibility to perform sports, based on three elements, i.e. the prognostic risk of the arrhythmias when performing sports, the symptomatic impact of arrhythmias while performing sports, and the potential progression of underlying structural problems as the result of sports.

COVID-19 and Cardiovascular Disease: a Global Perspective.

PURPOSE OF REVIEW: This review aims to assess the global impact of the COVID-19 pandemic on the cardiovascular diseases (CVDs), trying to assess the possible future trajectory of the CVDs and their management. RECENT FINDINGS: The COVID-19 pandemic has had a deleterious impact on the CV risk factors, with an increase in both sedentary and unhealthy food habits. The fear of contagion has decreased the access to the emergency systems with an increase in out-of-hospital-cardiac-arrests and late presentation of acute myocardial infarctions. The closure of the non-urgent services has delayed cardiac rehabilitation programmes and chronic clinical care. As a result of the COVID-19 pandemic impact on the population habits and on the management of CVDs, we will probably face an increase in CVD and heart failure cases. It is crucial to use all the non-traditional approaches, such as telemonitoring systems, in order to overcome the difficulties raised by the pandemic.

Appropriate use criteria for cardiovascular magnetic resonance imaging (CMR): SIC-SIRM position paper part 1 (ischemic and congenital heart diseases, cardio-oncology, cardiac masses and heart transplant).

Cardiac magnetic resonance (CMR) has emerged as new mainstream technique for the evaluation of patients with cardiac diseases, providing unique information to support clinical decision-making. This document has been developed by a joined group of experts of the Italian Society of Cardiology and Italian society of Radiology and aims to produce an updated consensus statement about the current state of technology and clinical applications of CMR. The writing committee consisted of members and experts of both societies who worked jointly to develop a more integrated approach in the field of cardiac radiology. Part 1 of the document will cover ischemic heart disease, congenital heart disease, cardio-oncology, cardiac masses and heart transplant.

Abnormal myocardial expression of SAP97 is associated with arrhythmogenic risk.

Synapse-associated protein 97 (SAP97) is a scaffolding protein crucial for the functional expression of several cardiac ion channels and therefore proper cardiac excitability. Alterations in the functional expression of SAP97 can modify the ionic currents underlying the cardiac action potential and consequently confer susceptibility for arrhythmogenesis. In this study, we generated a murine model for inducible, cardiac-targeted Sap97 ablation to investigate arrhythmia susceptibility and the underlying molecular mechanisms. Furthermore, we sought to identify human SAP97 (DLG1) variants that were associated with inherited arrhythmogenic disease. The murine model of cardiac-specific Sap97 ablation demonstrated several ECG abnormalities, pronounced action potential prolongation subject to high incidence of arrhythmogenic afterdepolarizations and notable alterations in the activity of the main cardiac ion channels. However, no DLG1 mutations were found in 40 unrelated cases of genetically elusive long QT syndrome (LQTS). Instead, we provide the first evidence implicating a gain of function in human DLG1 mutation resulting in an increase in Kv4.3 current (Ito) as a novel, potentially pathogenic substrate for Brugada syndrome (BrS). In conclusion, DLG1 joins a growing list of genes encoding ion channel interacting proteins (ChIPs) identified as potential channelopathy-susceptibility genes because of their ability to regulate the trafficking, targeting, and modulation of ion channels that are critical for the generation and propagation of the cardiac electrical impulse. Dysfunction in these critical components of cardiac excitability can potentially result in fatal cardiac disease.NEW & NOTEWORTHY The gene encoding SAP97 (DLG1) joins a growing list of genes encoding ion channel-interacting proteins (ChIPs) identified as potential channelopathy-susceptibility genes because of their ability to regulate the trafficking, targeting, and modulation of ion channels that are critical for the generation and propagation of the cardiac electrical impulse. In this study we provide the first data supporting DLG1-encoded SAP97's candidacy as a minor Brugada syndrome susceptibility gene.

Partial Pericardial Agenesis Mimicking Arrhythmogenic Right Ventricular Cardiomyopathy.

Absence of the pericardium is a rare congenital disease in which the fibroserum membrane covering the heart is partially or totally absent. It is characterized by few echocardiography (ECG) and imaging features that can mislead the diagnosis to an inherited cardiac disease, such as arrhythmogenic right ventricular cardiomyopathy. Although it has often a benign course, this congenital defect should be identified as in some cases herniation and strangulation can be life-threatening and cause sudden cardiac death. Red flags on ECG (sinus bradycardia, variable T-wave inversion), chest x-ray (Snoopy sign, absence of tracheal deviation, and esophagus impression), and transthoracic echocardiogram (unusual windows, teardrop left ventricle, and elongated atria) should rise the suspicion of pericardium absence. The correct diagnosis, confirmed by cardiac magnetic resonance, is mandatory as the consequences on the sport activity certification, the management, and the treatment are extremely different.

From patient-specific induced pluripotent stem cells to clinical translation in long QT syndrome Type 2.

AIMS: Having shown that Lumacaftor rescued the hERG trafficking defect in the induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) of two LQT2 patients, we tested whether the commercial association Lumacaftor + Ivacaftor (LUM + IVA) could shorten the QTc in the same two patients. METHODS AND RESULTS: After hospital admission and 1 day of baseline recordings, half dose LUM + IVA was administered on Day 1, followed by full dose (LUM 800 mg + IVA 500 mg) for 7 days. A continuous 12-lead Holter ECG allowed a large number of blind QTc measurements. Lumacaftor + Ivacaftor shortened QTc significantly in both patients: in V6 from 551 ± 22 ms to 523 ± 35 ms in Patient 1 (Pt1) and from 472 ± 21 ms to 449 ± 20 ms in Patient 2 (Pt2); in DII from 562 ± 25 ms to 549 ± 35 ms in Pt1 and from 485 ± 32 ms to 452 ± 18 ms in Pt2. In both patients, the percentage of QTc values in the lower tertile increased strikingly: in V6 from 33% to 68% and from 33% to 76%; in DII from 33% to 50% and from 33% to 87%. In the wash-out period a rebound in QTc was observed. On treatment, both patients developed diarrhoea, Pt1 more than Pt2. CONCLUSION: This represents the first attempt to validate in patients the in vitro results of a drug repurposing strategy for cardiovascular disorders. Lumacaftor + Ivacaftor shortened significantly the QTc in the two LQT2 patients with a trafficking defect, largely confirming the findings in their iPSC-CMs but with smaller quantitative changes. The findings are encouraging but immediate translation into clinical practice, without validation in more patients, would be premature.

Reference values of cardiac volumes, dimensions, and new functional parameters by MR: A multicenter, multivendor study.

PURPOSE: To define reference values of cardiac volumes, dimensions, and new morpho-functional parameters normalized for age, gender, and body surface area by cine-bSSFP (balanced steady-state free-precession) magnetic resonance (MR). MATERIALS AND METHODS: We enrolled 308 healthy subjects subdivided by gender and by six age classes: class I, >15-20 years; class II, >20-30 years; class III, >30-40 years; class IV, >40-50 years; class V, >50-60 years; and class VI >60 years. Dimensional, volumetric and morpho-functional parameters of the left (LV) and right (RV) ventricles were measured using cine-bSSFP MRI at 1.5T. RESULTS: The LV and RV end-diastolic volume indexes (EDVi) were inversely related to age (P < 0.0001 r = -0.34 and P < 0.0001 r = -0.37, respectively). In addition, the LV mass index decreased with age (P = 0.0004, r = -0.21). The LV longitudinal shortening was not significantly different among groups: ≥15% in all populations (95% confidence interval [CI]: 16-31). The sphericity index measured in end-diastole was higher in females than in males (P < 0.03): the upper limit was 40% for males and 42% for females. The normality cutoff of LV global function index was ≥33% in males and ≥35% in females. The end-diastolic volume (EDV) of RV and LV was balanced (RV/LV ratio 0.85-1.15) without differences in the population. The LV EDV/mass was 1.0-1.8 in males and 1.0-2.1 in females. CONCLUSION: This study provides potential age- and gender-specific reference. LEVEL OF EVIDENCE: 2 J. Magn. Reson. Imaging 2017;45:1055-1067.

Electrocardiographic differentiation of idiopathic right ventricular outflow tract ectopy from early arrhythmogenic right ventricular cardiomyopathy.

AIMS: The differentiation between idiopathic right ventricular outflow tract (RVOT) arrhythmias and early arrhythmogenic right ventricular cardiomyopathy (ARVC) can be challenging. We aimed to assess whether QRS morphological features and coupling interval of ventricular ectopic beats (VEBs) can improve differentiation between the two conditions. METHODS AND RESULTS: Twenty desmosomal-gene mutation carriers (13 females, mean age 43 years) with no or mild ARVC phenotypic expression and 33 age- and sex-matched subjects with idiopathic RVOT arrhythmias were studied. All patients exhibited isolated monomorphic VEBs with left bundle branch block/inferior axis morphology. The predictive value of ectopic QRS morphology and coupling interval was evaluated. Five ectopic QRS features were significantly more common in desmosomal-gene mutation carriers than in idiopathic RVOT-ventricular arrhythmia patients: maximal QRS duration >160 ms (60 vs. 27%, P = 0.02), intrinsicoid deflection time >80 ms (65 vs. 24%, P = 0.01), initial QRS slurring (40 vs. 12%, P = 0.04), QS pattern in lead V1 (90 vs. 36%, P < 0.001), and QRS axis >90° in limb leads (60 vs. 24%, P = 0.01). In the multivariate analysis, intrinsicoid deflection time >80 ms [odds ratio (OR) = 9.9], QS pattern in lead V1 (OR = 28), and QRS axis >90° (OR = 5.7) remained independent predictors of early ARVC. The coupling interval did not differ between the two groups. CONCLUSIONS: In patients with RVOT VEBs and no major electrocardiographic or echocardiographic abnormalities, the ectopic QRS morphology aids in the differential diagnosis between idiopathic RVOT arrhythmias and early ARVC.

Abnormal septal convexity into the left ventricle occurs in subclinical hypertrophic cardiomyopathy.

BACKGROUND: Sarcomeric gene mutations cause hypertrophic cardiomyopathy (HCM). In gene mutation carriers without left ventricular (LV) hypertrophy (G + LVH-), subclinical imaging biomarkers are recognized as predictors of overt HCM, consisting of anterior mitral valve leaflet elongation, myocardial crypts, hyperdynamic LV ejection fraction, and abnormal apical trabeculation. Reverse curvature of the interventricular septum (into the LV) is characteristic of overt HCM. We aimed to assess LV septal convexity in subclinical HCM. METHODS: Cardiovascular magnetic resonance was performed on 36 G + LVH- individuals (31 ± 14 years, 33 % males) with a pathogenic sarcomere mutation, and 36 sex and age-matched healthy controls (33 ± 12 years, 33 % males). Septal convexity (SCx) was measured in the apical four chamber view perpendicular to a reference line connecting the mid-septal wall at tricuspid valve insertion level and the apical right ventricular insertion point. RESULTS: Septal convexity was increased in G + LVH- compared to controls (maximal distance of endocardium to reference line: 5.0 ± 2.5 mm vs. 1.6 ± 2.4 mm, p ≤ 0.0001). Expected findings occurred in G + LVH- individuals: longer anterior mitral valve leaflet (23.5 ± 3.0 mm vs. 19.9 ± 3.1 mm, p ≤ 0.0001), higher relative wall thickness (0.31 ± 0.05 vs. 0.29 ± 0.04, p ≤ 0.05), higher LV ejection fraction (70.8 ± 4.3 % vs. 68.3 ± 4.4 %, p ≤ 0.05), and smaller LV end-systolic volume index (21.4 ± 4.4 ml/m(2) vs. 23.7 ± 5.8 ml/m(2), p ≤ 0.05). Other morphologic measurements (LV angles, sphericity index, and eccentricity index) were not different between G + LVH- and controls. CONCLUSIONS: Septal convexity is an additional previously undescribed feature of subclinical HCM.

Myocardial T1 mapping.

Cardiovascular magnetic resonance is a well-established tool for the quantification of focal fibrosis. With the introduction of T1 mapping, diffuse myocardial processes can be detected and quantified. In particular, infiltration and storage disorders with large disease-related changes, and diffuse fibrosis where measurement is harder but the potential impact larger. This has added a new dimension to the understanding and assessment of various myocardial diseases. T1 mapping promises to detect early disease, quantify disease severity and provide prognostic insights into certain conditions. It also has the potential to be a robust surrogate marker in drug development trials to monitor therapeutic response and be a prognostic marker in certain diseases. T1 mapping is an evolving field and numerous factors currently preclude its standardization. In this review, we describe the current status of T1 mapping and its potential promises and pitfalls.