Risk Factor For Ventricular Arrhythmias Research Articles

Impact of pregnancy and risk factors for ventricular arrhythmias in women with tetralogy of Fallot

ObjectivePatients with tetralogy of Fallot (TOF) have high survival rates 30 years after surgical repair. Many patients experience pregnancy; however, the effects of pregnancy on the long-term cardiovascular outcome are...

Arrhythmic phenotypes in patients with left ventricular non-compaction cardiomyopathy

Abstract Background Identification of pts with left ventricular non-compaction cardiomyopathy (NCCM) at high risk of life-threatening arrhythmic events is focused on clinical and instrumental criteria. The genetic component is not taken into account when deciding on a strategy for preventive measures. Purpose To analyze life-threatening arrhythmic events in pts with the arrhythmic variant of NCCM and to identify genetic factors that may increase the risk of life-threatening arrhythmic events. Methods The study included 159 pts, among whom 58 had malignant ventricular arrhythmias (mean age 43.54±11.95 years, 34/24/58.6% male). The NCCM criteria were confirmed using Echocardiography and CMR. Mutation search was carried out by the next generation sequencing (NGS) in 21 pts with nonsustained ventricular tachycardia (NVT). Results During the follow-up period (median follow-up of 36 months), life-threatening arrhythmic events (documented sustained VT, SCD with successful resuscitation and CD implantation, SCD) were registered in 29 pts (50%), and 10 pts had CD implanted. As a result of sequencing, 23.8% (5 out of 21) of pts with NVT revealed rare genetic variants with uncertain clinical significance (VUS) in 3 genes encoding ion channel proteins: KCNQ1, KCNH2 (9.5%), RYR2 (9.5%). In 9 (42.9%) pts, 10 identified mutations were localized in the genes responsible for the synthesis of sarcomeric proteins: MYBPC3 (23.8%), MYH7 (23.8%). 12 genetic variants were found in overlapping phenotypes between NCCM, ARVC and DCM: PKP2, DSP, PLN, TRPM4 (14.3%), RBM20, LDB3 (9.5%), DPP6, DTNA, NEXN in 11 (52.4%) pts. In this group of pts, the most common (81.8% of cases) were life-threatening arrhythmic events that required surgical intervention: 6 pts were implanted with CD for primary prevention of SCD, two pts - CRT-D, two pts with systolic dysfunction were performed with OHT and one patient was implanted with the Accucinch transcatheter direct mitral valve annuloplasty system. In pts with mutations in sarcomeric protein genes, CD was implanted in 4.7% of cases, and in 14.3% of pts with mutations in ion channel genes (p<0.01). Conclusion The presence of mutations in genes that control the functioning of ion channels in complex overlapping genotypes is an additional risk factor for ventricular arrhythmias in patients with NCCM. Determining the genetic component opens up new opportunities for personalizing the risk stratification of pts with NCCM. Funding Acknowledgement Type of funding source: None

Association of low Serum Magnesium level with occurrence of Ventricular Arrhythmia in patients with Acute Myocardial Infarction

Background: Acute Myocardial Infarction is the leading cause of morbidity and mortality throughout the world. Its prevalence among developing countries has increased significantly over the past two decades. Acute myocardial infarction is associated with electrolyte imbalance most commonly hypomagnesemia and hypokalaemia. Both are associated with ventricular arrhythmia which can lead to increase hospital mortality and morbidity.
 Objectives: To find out association of hypomagnesemia with ventricular arrhythmia in patients with acute myocardial infarction. Methods: Patients with acute myocardial infarction admitted in the department of Cardiology, DMCH, within the study period and who fulfilled the inclusion and exclusion criteria were taken as study sample. Informed consent was taken from all patients and then the patients were evaluated by detailed history, clinical examination and relevant investigations. Serum magnesium level was measured after admission. The sample population was Grouped into Group A(Acute myocardial infarction with normal serum magnesium) and Group B(Acute myocardial infarction with hypomagnesemia). Patients were followed up regularly till discharge or death for evidence of ventricular arrhythmia. Then the obtained data was analysed with SPSS 22.0.
 Results: Among 110 patients of Acute MI, 44 patients were in Group A who had plasma magnesium level e”0.7 mmol/ l and 66 patients were in Group B who had plasma magnesium level <0.7 mmol/l. Incidence of hypoagnesemia was 60% and more common in male. Male vs female percentage of hypomagnesemia were 61% vs 39%. Mean age was 54.16±11.72 yrs vs 57.52±10.59 yrs in group A vs group B. On admission serum magnesium level was 0.9218 vs 0.523 mmol/L( group A vs group B). The study showed that group B patients were more haemodynamically unstable and mean SBP and DBP were found 89.39±19.93 and 60.67±11.56 mm-Hg respectively. Troponin I was markedly increased in group B than A (i.e 4.7±1.79 vs 14.6±4.3 vs ng/ml). Adverse cardiac events such as cardiogenic shock (group A vs group B = 11.36% vs 28.27%) and ventricular arrhythmias(group A vs group B = 34% vs 72.73%) were also higher in group B than group A. Mean hospital stay for group B patient was higher than group A(6.78±0.85 vs 5.31±0.35 days). The study result showed that ventricular arrhythmia is negatively correlated with serum magnesium and the correlation coefficient was - 0.541. It also showed that serum Magnesium is positively correlated with Potassium(r= 0.831, p<0.01) and Calcium(r= 0.902, p<0.001). Multiple logistic regression analysis showed that hypomagnesemia is an independent risk factor for ventricular arrhythmia.
 Conclusions: This study showed that in patients with acute myocardial infarction, hypomagnesemia is common and it is significantly associated with ventricular arrhythmia. So the presence of hypomagnesemia should alert the physicians to adopt corrective measures as it increases both mortality and morbidity.
 Bangladesh Heart Journal 2020; 35(1) : 39-46

P1107First results of molecular autopsy examinations in sudden cardiac death drawn from nationwide multidisciplinary and multicentric collaboration in the Czech Republic

Abstract Funding Acknowledgements Supported by Ministry of Health of the Czech Republic, grant nr. NV18-02-00237. All rights reserved." Introduction "Molecular autopsy" in sudden cardiac death (SCD) is an important diagnostic tool for primary prevention of cardiac arrest in victim´s relatives and requires multicentric and multidisciplinary collaboration. Purpose To establish a national network for SCD diagnostics, to assess the acceptance of genetic testing in at risk relatives and to elucidate the genetic etiology of SCD in a representative Czech cohort aged below 45 years. Patients and Methods Between 2016 and 2019 we ascertained 70 SCD (50 M / 20 F), with positive family history for cardiac arrest in 8/70 cases. Only one family did not agree with molecular autopsy. Genetic counselling and cardiological screening examination was carried out in first degree relatives of SCD survivors accompanied by custom-made targeted panel massively parallel DNA sequencing comprising 100 cardiac conditions-related genes. Presence of pathogenic variants was validated by Sanger DNA sequencing and through family segregation analyses. Results According to post-mortem diagnosis most victims died of HCM (17/70), ACM (16/70), no structural heart disease was found in 15/70 cases, DCM/LVNC in 9/70, 6/70 were SIDS cases, other rare diagnoses comprised aortic dissection, or myocarditis. Most of victims died at sleep, only 9/70 victims died during strenuous activities. About 50% of SCD victims did not have cardiac complaints before death. Very likely or certain molecular etiology (i.e. based on presence of ACMG.net Class 4 to 5 variants) was disclosed in 12/70 (17%) in RYR2, FLNC, TTN, KCNH2 and KCNQ1 genes, whilst potentially causative DNA variants (Classes 3-4) were observed in 13/70 (18%) cases. In SIDS we did not find any pathogenic variants. Interestingly, the KCNE1 p.Asp85Asn (LQT 5 lite) variant, was detected in 3/70 cases as a recognized risk factor for ventricular arrhythmias. Conclusion The multidisciplinary cooperation in Czech Republic has been established, family survivors are willing to receive genetic and cardiological care, while centralised molecular genetic analysis enables reliable results which are in accordance with other multicentric studies. The molecular autopsy should, especially in SIDS, be expanded to whole exome sequencing.

P480Aldosterone plasma level as risk factor of ventricular arrhythmias in heart failure with preserved ejection fraction

Abstract Background. Sudden cardiac death, one of the most common types of cardiac death, is most often triggered by ventricular arrhythmia. Plasma aldosterone level has been shown to be an independent risk factor of life-threatening ventricular arrhythmia in patients with left ventricular systolic dysfunction following acute myocardial infarction. Whether either effect also occurs in patients with heart failure and preserved ejection fraction (HFpEF) is currently unknown. Purpose. The study aims to investigate the relationship between plasma aldosterone level and ventricular arrhythmias in long-term HFpEF. Methods. The study included 158 patients (58 men and 100 women, mean age 62.3 ± 7.4 years) with HFpEF (> 50%). All patients had a history of hospitalization due to HFpEF during the last 12 months, left ventricular diastolic dysfunction and / or elevated NT-proBNP level. Median confirmed HFpEF duration was 5 (range 4-8) years. Patients had no history of primary aldosteronism and did not use the mineralocorticoid receptor antagonists during the last 6 weeks. Aldosterone plasma level was measured and 24-hour electrocardiographic monitoring was performed. Results. According to laboratory results 99 patients (67.1%, 95% confidence interval (CI) 59.6-74.2%) had normal (40-160 pg/ml) aldosterone plasma level (nAld) and 59 patients (37.3%, 95% CI 30.0-45.0%) had high (> 160 pg/ml) aldosterone level (hAld). hAld patients more often had QTc prolongation (44.1% versus 18.2%) and ventricular arrhythmias (83.1% vs 61.6%) compared to nAld patients (all Ps < 0.001). The number of ventricular premature complexes in 24 hours was higher in hAld group (median 214, range 64-758) compared to nAld (median 52, range 16-198, P < 0.003). hAld patients more often occurred bigemy, couple ventricular ectopy and nonsustained ventricular tachycardia (39.0% vs 19.0%, P = 0.01). In Cox regression models high aldosterone plasma level was the independent risk factors of QTc prolongation (odds ratio (OR) 1.6, 95% CI 1.1-5.7, P = 0.034) and prognostically unfavorable ventricular arrhythmias (OR 1.8, 95% CI 1.2-6.8, P = 0.024). Conclusion. In long-term HFpEF plasma aldosterone level is significantly related to QTc prolongation as well as ventricular arrhythmias.

Hypokalaemia and outcomes in older patients hospitalized for heart failure

AimsHypokalaemia is a risk factor for ventricular arrhythmias and sudden death in ambulatory patients with chronic heart failure (HF). The objective of this study was to examine the association between hypokalaemia and outcomes in hospitalized patients with decompensated HF in whom sudden death is less common.Methods and resultsOf the 5881 hospitalized patients with HF, 1052 had consistent hypokalaemia (both admission and discharge serum potassium <4.0 mmol/L), and 2538 had consistent normokalaemia (both admission and discharge serum potassium 4.0–5.0 mmol/L). Propensity scores for consistent hypokalaemia, estimated for each of 3590 (1052 + 2538) patients, were used to assemble a matched cohort of 971 pairs of patients with consistent hypokalaemia vs. consistent normokalaemia, balanced on 54 baseline characteristics (mean age, 75 years; 60% women; 28% African American). We repeated the above process to assemble 2327 pairs of patients with discharge potassium <4.0 vs. 4.0–5.0 mmol/L and 449 pairs of patients with discharge serum potassium <3.5 vs. 4.0–5.0 mmol/L. Hazard ratios (HR) and 95% confidence intervals (CIs) associated with hypokalaemia were estimated in matched cohorts. 30 day all‐cause mortality occurred in 5% and 4% of patients with consistent normokalaemia vs. consistent hypokalaemia, respectively (HR, 0.78; 95% CI, 0.52–1.18; P = 0.241). HRs (95% CI) for 30 day mortality associated with discharge serum potassium <4.0 and <3.5 mmol/L were 0.90 (0.70–1.16; P = 0.419) and 1.69 (0.94–3.04; P = 0.078), respectively. Hypokalaemia (<4.0 or <3.5 mmol/L) had no association with long‐term mortality or other outcomes.ConclusionsIn hospitalized older patients with HF, compared with normokalaemia (serum potassium 4.0–5.0 mmol/L), hypokalaemia (<4.0 or <3.5 mmol/L) had no significant associations with outcomes.

Study of the time-relationship of the mechano-electrical interaction in an animal model of tetralogy of Fallot: implications for the risk assessment of ventricular arrhythmias.

The long-term outcome of tetralogy of Fallot (TOF) is determined by progressive right ventricular (RV) dysfunction through pulmonary regurgitation (PR) and the risk of malignant arrhythmia. Although mechano-electrical coupling in TOF is well-known, its time effect on the inducibility of arrhythmia remains ill-defined. The goal of this study was to investigate the mechano-electrical properties at different times in animals with chronic PR. PR was induced by a transannular patch with limited RV scarring in infant pigs. Haemodynamic assessment included biventricular pressure-volume loops after 3 (n = 8) and 6 months (n = 7) compared to controls (n = 5). The electrophysiological study included endocardial monophasic action potential registration, intraventricular conduction velocity and induction of ventricular arrhythmia by burst pacing. Progressive RV dilation was achieved at 6 months (RV end-diastolic volume 143 ± 13 ml/m2-RV end-systolic volume 96 ± 7 ml/m2; P < 0.001), in association with depressed RV contractility (preload recruitable stroke work-slope: 19 ± 1 and 11 ± 3 Mw.ml-1.s-1 for control and 6 m; P < 0.001) and left ventricular contractility (preload recruitable stroke work-slope: 60 ± 13 and 40 ± 11 Mw.ml-1.s-1 for control and 6 m; P = 0.005). Concomitant to QRS prolongation, monophasic action potential90-duration and dispersion at the RV and left ventricle were increased at 6 months. Intraventricular conduction was delayed only in the RV at 6 months (1.8 ± 0.2 and 2.4 ± 0.6 m/s for group 6M and the control group; P = 0.035). Sustained ventricular arrhythmias were not inducible. In animals yielding the sequelae of a contemporary operation for TOF, mechano-electrical alterations are progressive and affect predominantly the RV after midterm exposure of PR. Because ventricular arrhythmias were not inducible despite significant RV dilation, the data suggest that the haemodynamic RV deterioration effectively precedes the risk of inducing sustained arrhythmia after TOF repair and opens a window for renewed stratification of contemporary risk factors of ventricular arrhythmias in patients operated on with currently used pulmonary valve- and RV-related techniques.

Prevalence of mitral annular disjunction in patients with mitral valve prolapse and severe regurgitation.

Mitral annular disjunction (MAD) is routinely diagnosed by cardiac imaging, mostly by echocardiography, and shown to be a risk factor for ventricular arrhythmias. While MAD is associated with mitral valve (MV) prolapse (MVP), it is unknown which patients with MAD are at higher risk and which additional imaging features may help identify them. The value of cardiac computed tomography (CCT) for the diagnosis of MAD is unknown. Accordingly, we aimed to: (1) develop a standardized CCT approach to identify MAD in patients with MVP and severe mitral regurgitation (MR); (2) determine its prevalence and identify features that are associated with MAD in this population. We retrospectively studied 90 patients (age 63 ± 12years) with MVP and severe MR, who had pre-operative CCT (256-slice scanner) of sufficient quality for analysis. The presence and degree of MAD was assessed by rotating the view plane around the MV center to visualize disjunction along the annulus. Additionally, detailed measurements of MV apparatus and left heart chambers were performed. Univariate logistic regression analysis was performed to determine which parameters were associated with MAD. MAD was identified in 18 patients (20%), and it was typically located adjacent to a prolapsed or flail mitral leaflet scallop. Of these patients, 75% had maximum MAD distance > 4.8mm and 90% > 3.8mm. Female gender was most strongly associated with MAD (p = 0.04). Additionally, smaller end-diastolic mitral annulus area (p = 0.045) and longer posterior leaflet (p = 0.03) were associated with greater MAD. No association was seen between MAD and left ventricular size and function, left atrial size, and papillary muscle geometry. CCT can be used to readily detect MAD, by taking advantage of the 3D nature of this modality. A significant portion of MVP patients referred for mitral valve repair have MAD. The presence of MAD is associated with female gender, smaller annulus size and greater posterior leaflet length.

Magnetic Resonance Imaging Risk Factors for Ventricular Arrhythmias in Tetralogy of Fallot

Sudden cardiac death (SCD) is the most common cause of late mortality in tetralogy of Fallot (TOF). Pulmonary regurgitation (PR) was previously found to be the most common hemodynamic abnormality associated with ventricular arrhythmias (VA), but cardiovascular magnetic resonance (CMR)-based studies did not show this association. The aim of this study is to investigate the risk factors for VA in TOF using CMR. Electronic records of TOF patients and their CMR studies between July 2006 and October 2018 in one center were retrospectively reviewed. Demographic, clinical and CMR data of patients were collected. Outcome was defined as sustained ventricular tachycardia (VT), aborted SCD and SCD. From a total of 434 TOF patients with complete CMR studies, 19 (4.4%) patients developed a positive outcome (12 sustained VT, 4 aborted SCD, 3 SCD) at a median age of 24years. The number of surgical interventions was significantly greater in patients who developed VA. Right ventricular volumes were significantly larger in patients who suffered a positive outcome. Odds ratio for developing VA was 6.905 for RVEDVI ≥ 160ml/m2 and 6.141 for RVESVI ≥ 80ml/m2 (P = 0.0014 and 0.0012, respectively). Event-free survival was longer in patients with smaller right ventricular volumes. In conclusion, right ventricular dimensions are the most significant factors associated with the development of VA in TOF. The number of surgical interventions is also related to an increased risk.

Hypoglycaemia and cardiac arrhythmias in diabetes.

Hypoglycaemia remains an inevitable risk in insulin-treated type 1 diabetes and type 2 diabetes and has been associated with multiple adverse outcomes. Whether hypoglycaemia is a cause of fatal cardiac arrhythmias in diabetes, or merely a marker of vulnerability, is still unknown. Since a pivotal report in 1991, hypoglycaemia has been suspected to induce cardiac arrhythmias in patients with type 1 diabetes, the so-called ‘dead-in-bed syndrome’. This suspicion has subsequently been supported by the coexistence of an increased mortality and a three-fold increase in severe hypoglycaemia in patients with type 2 diabetes receiving intensive glucose-lowering treatment in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. Studies have investigated the association between hypoglycaemia-induced cardiac arrhythmias. In a rat-model, severe hypoglycaemia resulted in a specific pattern of cardiac arrhythmias including QT-prolongation, ventricular tachycardia, second- and third-degree AV block and ultimately cardiorespiratory arrest. In clinical studies of experimentally induced hypoglycaemia, QTc-prolongation, a risk factor of ventricular arrhythmias, is an almost consistent finding. The extent of QT-prolongation seems to be modified by several factors, including antecedent hypoglycaemia, diabetes duration and cardiac autonomic neuropathy. Observational studies indicate diurnal differences in the pattern of electrocardiographic alterations during hypoglycaemia with larger QTc-prolongations during daytime, whereas the risk of bradyarrhythmias may be increased during sleep. Daytime periods of hypoglycaemia are characterized by shorter duration, increased awareness and a larger increase in catecholamines. The counterregulatory response is reduced during nightly episodes of hypoglycaemia, resulting in prolonged periods of hypoglycaemia with multiple nadirs. An initial sympathetic activity at plasma glucose nadir is replaced by increased vagal activity, which results in bradycardia. Here, we provide an overview of the existing literature exploring potential mechanisms for hypoglycaemia-induced cardiac arrhythmias and studies linking hypoglycaemia to cardiac arrhythmias in patients with diabetes.

P919Ventricular arrhythmias in patients with mitral valve prolapse and severe mitral regurgitation

Abstract Background Mitral valve prolapse (MVP) is known to be associated with ventricular arrhythmias (VA), from symptomatic premature ventricular contractions (PVCs) to malignant ventricular tachycardia (VT) and sudden cardiac death (SCD). Previous studies identified risk factors for VA in these patients such as young woman, bileaflet prolapse and inverted T-waves, but they included only specific cohort of patients who experienced SCD or who had only trivial or mild mitral regurgitation (MR). The prevalence of VA and their potential risk factors in a population of MVP patients with severe MR are unknown. Purpose The aim of our study was to describe the prevalence of VA in patients who underwent mitral valve surgery for moderate to severe MR due to MVP and to identify clinical, electrocardiographic and echocardiographic parameters associated with VA. Methods 797 patients (65±12 years, 65% male) who underwent surgery for MVP were included from 2000 until 2018. The presence of VA was defined as symptomatic and frequent PVCs (Lown grade ≥2), non-sustained ventricular tachycardia (nsVT), VT or ventricular fibrillation (VF) documented before surgery and without an ischemic cause. The echocardiogram and electrocardiogram (ECG) prior to operation were used for the specific analysis. ECGs were checked for rhythm, conduction times, QRS morphology and inferior T-wave inversion. The origin of the PVCs was derived from a 12-lead ECG when available and divided in 5 groups; mitral annulus, papillary muscle (PM), left ventricle (LV, including outflow tract), right ventricle (including outflow tract) and other. By echocardiography, several parameters such as LV thickness and volumes, LV ejection fraction (EF), global longitudinal strain (GLS) and MR grade were obtained. Results A total of 99 (12%) patients showed VA; 70% (69/99) of the patients had symptomatic PVCs, 36% (36/99) had nsVT, 12% (12/99) VT and 3% (3/99) VF. 21 patients had more than one type of VA, of which the combination PVCs and nsVT was the most common (19/99, 19%). In addition, 6 patients experienced an out of hospital cardiac arrest of a non-ischemic cause. When comparing the clinical characteristics (Table), patients with VA were significantly younger (and with better renal function), more frequently diagnosed with Barlow's disease and experienced more palpitations as compared to patients without VA. The ECG analysis showed that patients with VA more often had inferior T-wave inversions and that the PVCs predominantly originated from the PM whereas in patients without VA the PVCs originated from different regions. Echocardiography showed that patients with VA had a thinner posterior wall, reduced LV EF and worse GLS; more severe MR was not associated with VA. Conclusion In MVP patients with moderate to severe MR undergoing surgery, Barlow's disease, inferior T-wave inversions, thinner posterior wall and LV systolic dysfunction are associated with the presence and development of VA.

Correlations between arrhythmogenic substrate and noninvasive risk stratification in ischemic heart disease patients modifications by radiofrequency ablation.

Several noninvasive risk factors for ventricular arrhythmias have been described in postmyocardial infarction (MI) patients, whose relationships with scar characteristics and modifications by ablation are unknown. Twenty-two patients with previous MI referred for ventricular tachycardia ablation were prospectively included. ECG, heart rate variability (HRV), signal-averaged ECG (SA-ECG), and T wave alternans (TWA) were performed before and after radiofrequency ablation. Scar areas were correlated to preablation parameters. Pre and postablation parameters were furthermore compared. Left ventricular ejection fraction and some spectral and time-domain HRV parameters were significantly correlated to the scar areas. QRS duration was larger after vs before ablation (120 ± 29 vs 105 ± 22 msec, P = .01). No significant modification in time or spectral domain of HRV was observed. There was no significant change in TWA and SA-ECG before and after ablation. Borderline decreases in quantitative TWA parameters were noted in patients with positive TWA and successful ablation procedure. Some noninvasive risk factors were linked to the scar areas, but few were significantly modified after ablation. Larger populations are needed to demonstrate significant differences or correlations.

Early Ventricular Arrhythmias After LVAD Implantation Is the Strongest Predictor of 30-Day Post-Operative Mortality.

This study aimed to evaluate incidence, clinical significance, and predictors of early ventricular arrhythmias (VAs) in left ventricular assist device (LVAD) recipients. LVAD implantation is increasingly used in patients with end-stage heart failure. Early VAs may occur during the 30-day post-operative period, but many questions remain unanswered regarding their incidence and clinicalimpact. This observational study was conducted in 19 centers between 2006 and 2016. Early VAs were defined as sustained ventricular tachycardia and/or ventricular fibrillation occurring<30days post-LVAD implantation and requiring appropriate implantable cardioverter-defibrillator therapy, external electrical shock, or medical therapy. A total of 652 patients (median age: 59.8 years; left ventricular ejection fraction: 20.7 ± 7.4%; HeartMate 2: 72.8%; HeartWare: 19.5%; Jarvik 2000: 7.7%) were included in the analysis. Early VAs occurred in 162 patients (24.8%), most frequently during the first week after LVAD implantation. Multivariable analysis identified history of VAs prior to LVAD and any combined surgery with LVAD as 2 predictors of early VAs. The occurrence of early VAs with electrical storm was the strongest predictor of 30-day post-operative mortality, associated with a 7-fold increase of 30-day mortality. However, in patients discharged alive from hospital, occurrence of early VAs did not influence long-term survival. Early VAs are common after LVAD implantation and increase 30-day post-operative mortality, without affecting long-term survival. Further studies will be needed to analyze whether pre- or pre-operative ablation of VAs may improve post-operative outcomes. (Determination of Risk Factors of Ventricular Arrhythmias After Implantation of Continuous Flow Left Ventricular Assist Device With Continuous Flow Left Ventricular Assist Device [ASSIST-ICD]; NCT02873169).

Loss of MD1 increases vulnerability to ventricular arrhythmia in diet-induced obesity mice via enhanced activation of the TLR4/MyD88/CaMKII signaling pathway

Background and aimObesity is an important risk factor for ventricular arrhythmia (VA), and myeloid differentiation protein 1 (MD1) has been reported to decrease in obese hearts. Nevertheless, underlying mechanisms linking MD1 and VA have not been fully studied. This study aims to investigate the regulatory role of MD1 in VA caused by diet-induced obesity. Methods and resultsMD1 knock-out (KO) and wild type (WT) mice from experimental groups were fed with a high-fat diet (HFD) since the age of six weeks for 20 weeks. The body weight gain, fast glucose and serum lipid levels were measured and recorded. In addition, pathological analysis, echocardiography, electrocardiography, langendorff-perfused heart and molecular analysis were performed to detect HFD-induced vulnerability to VA and its underlying mechanisms. After a 20-week HFD feeding, the mice showed an increase in body weight, glycemic, lipid levels, QTc interval, LVEDd, LVEDs and LVFS. HFD feeding also increased vulnerability to VA, as shown by the prolonged action potential duration (APD), enhanced APD alternans threshold and greater incidence of VA. Moreover, HFD feeding caused LV hypertrophy and fibrosis, and decreased the protein expressions of Kv4.2, Kv4.3, Kv1.5, Kv2.1 and Cav1.2 channels. At last, the above-mentioned HFD-induced adverse effects were further exacerbated in KO mice compared with WT mice. Mechanistically, MD1 deletion markedly enhanced the activation of TLR4/MyD88/CaMKII signaling pathway in HFD-fed mice. ConclusionMD1 deficiency increased HFD-induced vulnerability to VA. This is mainly caused by the aggravated maladaptive LV hypertrophy, fibrosis and decreased protein expressions of ion channels, which are induced by the enhanced activation of the TLR4/MyD88/CaMKII signaling pathway.

Echocardiographic predictors of elevated left ventricular end diastolic pressure in adolescent and adult patients with repaired tetralogy of Fallot.

Elevated left ventricular end diastolic pressure is a risk factor for ventricular arrhythmias in patients with tetralogy of Fallot. The objective of this retrospective study was to identify echocardiographic measures associated with left ventricular end diastolic pressure >12 mmHg in this population. Repaired tetralogy of Fallot patients age ≥13 years, who underwent a left heart catheterisation within 7 days of having an echocardiogram were evaluated. Univariate comparison was made in echocardiographic and clinical variables between patients with left ventricular end diastolic pressure >12 versus ≤12 mmHg. Ninety-four patients (54% male) with a median age of 24.6 years were included. Thirty-four (36%) had left ventricular end diastolic pressure >12 mmHg. Patients with left ventricular end diastolic pressure >12mmHg were older (median 32.9 versus 24.0 years, p = 0.02), more likely to have a history of an aortopulmonary shunt (62% versus 38%, p = 0.03), and have a diagnosis of hypertension (24% versus 7%, p = 0.03) compared to those with left ventricular end diastolic pressure ≤12 mmHg. There were no significant differences in mitral valve E/A ratio, annular e' velocity, or E/e' ratio between patients with left ventricular end diastolic pressure >12 versus ≤12 mmHg. Patients with left ventricular end diastolic pressure >12mmHg had larger left atrial area (mean 17.7 versus 14.0 cm2, p = 0.03) and larger left atrium anterior-posterior diameter (mean 36.0 versus 30.6 mm, p = 0.004). In conclusion, typical echocardiographic measures of left ventricular diastolic dysfunction may not be reliable in tetralogy of Fallot patients. Prospective studies with the use of novel echocardiographic measures are needed.

Predictive value of gamma-glutamyltransferase for ventricular arrhythmias and cardiovascular mortality in implantable cardioverter-defibrillator patients

BackgroundGamma-glutamyltransferase (GGT) is a new predictor of cardiovascular diseases. In this study, we aimed to determine its association with ventricular arrhythmias (VAs) in implantable cardioverter-defibrillator (ICD) patients.MethodsOne hundred and forty patients implanted with ICD or cardiac resynchronization therapy defibrillator with home monitoring were studied retrospectively. The primary endpoint was appropriate ICD treatment of VAs, secondary endpoint was cardiac death.ResultsDuring a mean follow-up period of 44 ± 17 months, 78 patients (55.7%) experienced VAs, 50 patients (35.7%) were treated with appropriate ICD shocks and 16 patients (11.4%) died due to cardiovascular diseases. GGT was positively correlated with high sensitivity C reactive protein (r = 0.482, P < 0.001), left ventricular end-diastolic dimension (r = 0.175, P = 0.039), New York Heart Association class (r = 0.199, P = 0.018), fasting blood glucose (r = 0.233, P = 0.006) and negatively with left ventricular ejection fraction (r = − 0.181, P = 0.032) and high-density lipoprotein (r = − 0.313, P < 0.001). Based on receiver operating characteristics curve, the cut-off value of GGT = 56 U/L was identified to predict VAs. In Kaplan-Meier survival analysis, GGT ≥56 U/L was associated with increased VAs (P<0.001), ICD shock events (P = 0.006) and cardiovascular mortality (P = 0.003). In multivariate COX regression models, GGT ≥56 U/L was an independent risk factor for VAs (HR 2.253, 95%CI:1.383–3.671, P = 0.001), ICD shocks (HR 2.256, 95%CI:1.219–4.176, P = 0.010) and cardiac death (HR 3.555, 95%CI:1.215–10.404, P = 0.021).ConclusionsIn this ICD population, GGT ≥56 U/L was independently associated with VAs and cardiac death.

Machine learning in drug development: Characterizing the effect of 30 drugs on the QT interval using Gaussian process regression, sensitivity analysis, and uncertainty quantification

Prolonged QT intervals are a major risk factor for ventricular arrhythmias and a leading cause of sudden cardiac death. Various drugs are known to trigger QT interval prolongation and increase the proarrhythmic potential. Yet, how precisely the action of drugs on the cellular level translates into QT interval prolongation on the whole organ level remains insufficiently understood. Here we use machine learning techniques to systematically characterize the effect of 30 common drugs on the QT interval. We combine information from high fidelity three-dimensional human heart simulations with low fidelity one-dimensional cable simulations to build a surrogate model for the QT interval using multi-fidelity Gaussian process regression. Once trained and cross-validated, we apply our surrogate model to perform sensitivity analysis and uncertainty quantification. Our sensitivity analysis suggests that compounds that block the rapid delayed rectifier potassium current IKr have the greatest prolonging effect of the QT interval, and that blocking the L-type calcium current ICaL and late sodium current INaL shortens the QT interval. Our uncertainty quantification allows us to propagate the experimental variability from individual block-concentration measurements into the QT interval and reveals that QT interval uncertainty is mainly driven by the variability in IKr block. In a final validation study, we demonstrate an excellent agreement between our predicted QT interval changes and the changes observed in a randomized clinical trial for the drugs dofetilide, quinidine, ranolazine, and verapamil. We anticipate that both the machine learning methods and the results of this study will have great potential in the efficient development of safer drugs.

Surgical ablation of ventricular tachycardia in patients with repaired tetralogy of Fallot†.

Life expectancy of patients with repaired tetralogy of Fallot is normal until adulthood, when it becomes burdened by major complications such as cardiac arrhythmias and heart failure. Ventricular tachycardia (VT), associated with electrical conduction abnormalities in anatomical isthmuses, is the most common complication and is refractory to medical therapy. The arrhythmogenic sources can be surgically ablated during reoperations for pulmonary valve incompetence. The purpose of our study is to evaluate the safety and effectiveness of surgical radiofrequency ablation during PVR and its long-term impact on the occurrence of cardiac events. A total of 118 patients with repaired tetralogy of Fallot underwent reoperation for pulmonary valve regurgitation in IRCCS-Policlinico San Donato between January 2002 and February 2016. Twenty patients with risk factors for ventricular arrhythmia underwent EP testing and were found positive. The mean QRS duration was 178 ms. Right ventricular dysfunction was present in all the patients, and 20% had associated tricuspid regurgitation. The cohort (N = 20), with positive EP study, underwent pulmonary valve replacement and concomitant intraoperative ventricular surgical radiofrequency ablation, targeting the slow conducting isthmuses identified during preoperative electroanatomical mapping. All patients were reviewed at 1 month, 3 months and 6 months with clinical evaluation, echocardiography, ECG and implantable cardioverter-defibrillator interrogation. At 6 months, a postoperative electrophysiological study was performed in all patients, and a cardioverter defibrillator was implanted as primary preventive measure in patients with residual inducible VT. Pulmonary valve replacement and surgical ventricular radiofrequency ablation were performed in all cases. One patient died while on V-V extracorporeal membrane oxygenation (ECMO) due to respiratory failure. There was no late mortality. Follow-up was complete with a median of 6.5 years. During the postoperative EPS study, inducible VT was found in 15.7% of patients who received an implantable cardioverter-defibrillator, whereas VT could no longer be induced in the remaining patients. No procedure-related complication was observed, and freedom from ventricular arrhythmia was 94% and 89.5% at 1 year and 5 years, respectively. Pulmonary regurgitation and right ventricular dysfunction correlate with VT and SCD, but valve replacement alone does not reduce the risk of ventricular tachyarrhythmias. Intraoperative ventricular ablation during reoperation for pulmonary regurgitation prevents the occurrence of ventricular arrhythmias in the early and medium term. Accordingly, this technique may be proposed as a safe associated procedure in selected patients.

Analysis of risk factors of ventricular arrhythmia in patients with Brugada syndrome

Objective: To investigate the risk factors of ventricular arrhythmias in patients with Brugada syndrome. Methods: Clinical data of 60 Brugada syndrome patients admitted in the department of cardiology of the First Affiliated Hospital of Nanjing Medical University from March 2003 to December 2016 were collected and retrospectively analyzed. The age at diagnosis was (43.2±13.1) years (0.6-83.0 years), 98.3% were males (n=59), and the patients were followed up to (92±41) months (12-169 months). The 12-lead surface electrocardiogram (ECG) recorded at the time of diagnosis and showing the highest type 1 ST elevation, either spontaneously or after provocative drug test, was used for the analysis. Patients were divided into ventricular arrhythmia (VA, n=12) group and non-ventricular arrhythmia (non-VA, n=48) group depending on the presence or absence of clinical VA event. The demographic data and ECG data of the 2 groups were compared, and the independent risk factors of VA events were analyzed by stepwise logistic regression. Results: Incidence of family history of sudden death (7/12 vs. 22.9% (11/48)) and percentage of type 1 ST elevation in the peripheral ECG leads (6/12 vs. 16.67% (8/48)) were significantly higher in VA group than in non-VA group (both P<0.05). Max Tpeak-Tend (Max-Tpe) interval ((144±53)ms vs. (110±16)ms) and dispersion of Tpe ((74±50)ms vs. (43±17)ms) were significantly higher in VA group than in non-VA group (both P<0.05). The area under receiver operating characteristic (ROC) curves for the Max-Tpe interval was 0.693 and Max-Tpe interval ≥140 ms was determined as an optimized cutoff point with increased risk of VA event, which had a sensitivity of 50.0%, a specificity of 98.0%, a positive predictive value of 85.7%, and a negative predictive value of 88.7% for predicting VA event. The ROC curves for the dispersion of Tpe was 0.775 and dispersion of Tpe ≥45 ms was determined as an optimized cutoff point for predicting VA event, which had a sensitivity of 91.7%, a specificity of 64.6%, a positive predictive value of 39.3%, and a negative predictive value of 96.9% for predicting VA event. In multivariate analysis, Max-Tpe interval ≥140 ms (OR=27.53, 95%CI 1.07-706.77, P=0.045) and family history of sudden death (OR=24.63, 95%CI 2.05-295.38, P=0.011) were found to be the independent risk factors of arrhythmic events. Conclusions: Max-Tpe interval ≥140 ms and family history of sudden death are risk factors of VA event in included patients with Brugada syndrome.

An African loss-of-function CACNA1C variant p.T1787M associated with a risk of ventricular fibrillation

Calcium regulation plays a central role in cardiac function. Several variants in the calcium channel Cav1.2 have been implicated in arrhythmic syndromes. We screened patients with Brugada syndrome, short QT syndrome, early repolarisation syndrome, and idiopathic ventricular fibrillation to determine the frequency and pathogenicity of Cav1.2 variants. Cav1.2 related genes, CACNA1C, CACNB2 and CACNA2D1, were screened in 65 probands. Missense variants were introduced in the Cav1.2 alpha subunit plasmid by mutagenesis to assess their pathogenicity using patch clamp approaches. Six missense variants were identified in CACNA1C in five individuals. Five of them, A1648T, A1689T, G1795R, R1973Q, C1992F, showed no major alterations of the channel function. The sixth C-terminal variant, Cavα1c-T1787M, present mostly in the African population, was identified in two patients with resuscitated cardiac arrest. The first patient originated from Cameroon and the second was an inhabitant of La Reunion Island with idiopathic ventricular fibrillation originating from Purkinje tissues. Patch-clamp analysis revealed that Cavα1c-T1787M reduces the calcium and barium currents by increasing the auto-inhibition mediated by the C-terminal part and increases the voltage-dependent inhibition. We identified a loss-of-function variant, Cavα1c-T1787M, present in 0.8% of the African population, as a new risk factor for ventricular arrhythmia.