Ventricular Repolarization Abnormalities Research Articles

Magnetocardiographic imaging of Tpeak-Tend magnetic field dynamics discriminates between ventricular repolarization disorders due to mitral valve prolapse and to ischemic heart disease

Abstract Background Several etiopathogenetic mechanisms, including ischemia of the papillary muscles, abnormal catecholamine regulation, baroreflex modulation, and activation of atrial natriuretic peptide induced by abnormal stretch of the prolapsing mitral leaflets, have been suggested as possible causes of ventricular repolarization abnormalities (VRab) in patients (pts) with mitral valve prolapse (MVP) [1-3], especially in those with chest pain (CP). Purpose Since magnetocardiography (MCG) is a sensitive alternative to improve the detection of VRab, this study aimed to evaluate its discrimination accuracy to differentiate VRab due to MVP from those due to ischemic heart disease (IHD). Methods MCG recordings of 32 female patients (age 40.3±13.3 years) with MVP (at echocardiography), 20 of them with CP and/or palpitations, were retrospectively compared with those of 35 pts with IHD (at least one vessel stenosis >70%) (age 66.2±10.6 years), and with those of 32 age-matched (age 40.8±11.5 years) healthy females (HF) without MVP. The cardiac magnetic field (MF) component perpendicular to the anterior chest wall (Bz) was recorded with a 36-channel DC-SQUID MCG system (sensitivity ~30 fT/VHz). Thirteen MCG parameters, five derived from the analysis of the T-wave MF extrema dynamics, and eight from the effective magnetic vector (EMV) dynamics, were automatically calculated with proprietary software during the Tpeak-Tend interval (T3-T4 in Figure 1). Discriminant analysis (DA) was applied to separate groups. Results At univariate analysis, 11 MCG parameters were significantly different (p< 0.05) between MVP and IHD pts (Table 1). After multivariate analysis, 9 parameters (AzimuthMeanA, TrajectoryLengthRangeD, AngleDerivativeRangeD, AzimuthdiffAD, Q2AnalysisScore, AngleMinimum, AngleDynamics, DistanceDynamics, RatioDynamics) differentiated MVP and IHD pts’ VRab with 80% accuracy (cross-correlated), at DA. Moreover, in IHD pts abnormality of EMV dynamics extended also along the whole T-wave [4]. Three EMV parameters of the Tpeak-Tend interval (TrajectoryLengthRangeD, AzimuthdiffAD, Q2AnalysisScore), and three T-wave MF extrema parameters (AngleMinimum, Distance Dynamics, and Ratio Dynamics) were abnormal in 11 MVP pts, 10 of them with CP but normal ECG, and only one asymptomatic. Discussion: MCG EMV and MF dynamics calculated from rest-MCG data are reliable to identify VRab in pts with MVP and with IHD, differentiating them with a good discrimination accuracy. MCG VRa abnormality was mostly confined in the Tpeak-Tend interval in pts with MVP (in agreement with previous ECG findings [5]), while extended to the whole ST interval in IHD pts. Rest MCG is more sensitive than ECG in detecting VRab in pts with MVP and CP. Due to the limited number of investigated cases, the potential arrhythmogenicity of MVP-related VRab detected with MCG was not evaluated.Figure 1.MCG imaging of Tpeak-Tend MFTable 1

Electrocardiographic abnormalities are frequently detected in healthy adult Borzoi with a normal echocardiogram.

Borzoi reportedly experience sudden death. The objective of this study was to report ECG intervals, amplitudes, and frequency of ECG abnormalities in clinically healthy Borzoi. 98 clinically healthy Borzoi were prospectively recruited and underwent echocardiogram, ECG, and cardiac troponin I testing between October 2020 and December 2022. Standard ECG measurements were obtained. Early repolarization notches and slurs were recorded. Of 82 Borzoi with a structurally normal echocardiogram, ventricular arrhythmias were documented in 8 (10%) dogs, all of which had normal cardiac troponin I concentrations. Median P wave duration was 55 milliseconds (range, 45 to 70 milliseconds). Median PR interval was 125 milliseconds (range, 80 to 175 milliseconds). Thirty-one (38%) Borzoi had first-degree atrioventricular block (PR interval > 130 milliseconds). Median QRS duration was 65 milliseconds (range, 48 to 90 milliseconds). Median QT interval was 235 milliseconds (range, 185 to 275 milliseconds). Twenty-nine (35%) and 15 (18%) of 82 Borzoi had QT intervals > 240 or > 250 milliseconds, respectively. Sixty-seven of 82 (82%) Borzoi had early repolarization notches or slurs. Seventeen of 82 (21%) Borzoi had an abnormality of the ST segment, most commonly convexity/doming. Convexity of the ST segment was intermittent (n = 9) or persistent (4). Ventricular arrhythmias, early repolarization, prolonged QT intervals, and ST segment abnormalities are not infrequent in clinically healthy Borzoi. P, PR, and QRS durations are commonly prolonged compared to general canine reference intervals. Future study into heritable channelopathies in Borzoi is warranted given the frequency of ventricular arrhythmias, repolarization abnormalities, and sudden death in the breed. Breed-specific ECG reference intervals are needed.

Congenital Apical Left Ventricular Aneurysm.

A 17-year-old male was referred for evaluation by Pediatric Cardiology following a pre-sports medical screening, which revealed abnormal ventricular repolarization (negative T wave from V3-V6) on a 12-lead ECG. For 8 years, he has been a competitive football player. There was no relevant personal or family medical history, and he denied any prior cardiovascular symptoms. His cardiovascular physical examination was normal. In the initial assessment, a transthoracic echocardiogram was conducted, revealing an apical aneurysm of the left ventricle (LV) with regional dyskinesia, accompanied by mild mitral regurgitation. The examination also demonstrated globally preserved left ventricular systolic function, with no images suggestive of vegetations or intracardiac thrombi found. For further anatomical and myocardial characterization, a cardiac magnetic resonance (CMR) was performed. The results revealed a wide apical aneurysm of the LV, predominantly lateral, with thin walls, ridges within the outpouching, and local dyskinesia. No areas of late gadolinium enhancement (LGE) were found, suggestive of fibrosis, anomalous infiltration, or scar from a previous infarction. After excluding other etiologies, the diagnosis of a congenital ventricular aneurysm was determined. This is a very rare condition (0.12%) with a wide and variable clinical presentation, ranging from benign arrhythmias to sudden death. Various imaging techniques aid in its diagnosis, with CMR being particularly useful for excluding inflammation and cardiomyopathies, identifying LGE, and evaluating left ventricular volumes and function. There is no standard treatment, and controversy surrounds indications for surgical intervention. If a conservative approach is adopted, measures aimed at preventing endocarditis and embolism must be considered.

Early Screening for Long QT Syndrome and Cardiac Anomalies in Infants: A Comprehensive Study.

(1) Background: Sudden Infant Death Syndrome (SIDS) represents sudden and unexplained deaths during the sleep of infants under one year of age, despite thorough investigation. Screening for a prolonged QTc interval, a marker for Long QT Syndrome (LQTS), should be conducted on all newborns to reduce the incidence of SIDS. Neonatal electrocardiograms (ECGs) could identify congenital heart defects (CHDs) early, especially those not detected at birth. Infants with prolonged QTc intervals typically undergo genetic analysis for Long QT Syndrome. (2) Methods: The study involved infants aged 20-40 days, born with no apparent clinical signs of heart disease, with initial ECG screening. Infants with prenatal diagnoses or signs/symptoms of CHDs identified immediately after birth, as well as infants who had previously had an ECG or echocardiogram for other medical reasons, were excluded from the study. We used statistical software (SPSS version 22.0) to analyze the data. (3) Results: Of the 42,200 infants involved, 2245 were enrolled, with 39.9% being males. Following this initial screening, 164 children (37.8% males) with prolonged QTc intervals underwent further evaluation. Out of these 164 children, 27 children were confirmed to have LQTS. However, only 18 children were finally investigated for genetic mutations, and mutations were identified in 11 tests. The most common mutations were LQT1 (54.5%), LQT2 (36.4%), and LQT3 (1 patient). Treatment options included propranolol (39.8%), nadolol (22.2%), inderal (11.1%), metoprolol (11.1%), and no treatment (16.7%). The most common abnormalities were focal right bundle branch block (54.5%), left axis deviation (9.2%), and nonspecific ventricular repolarization abnormalities (7.1%). Multiple anomalies were found in 0.47% of children with focal right bundle branch block. Structural abnormalities were associated with specific features in 267 patients (11.9%), primarily isolated patent foramen ovale (PFO) at 61.4%. (4) Conclusions: This screening approach has demonstrated effectiveness in the early identification of LQTS and other cardiac rhythm anomalies, with additional identification of mutations and/or prolonged QTc intervals in family members. Identifying other ECG abnormalities and congenital heart malformations further enhances the benefits of the screening.

Cardiac repolarization abnormalities and neurally mediated syncope: overlooked aspects in the diagnosis of pheochromocytoma

BackgroundPheochromocytoma is a rare catecholamine-producing tumour originating from adrenal chromaffin cells. Classic clinical presentation includes headache, diaphoresis and palpitation. Syncope is uncommon and may result from hypotension or arrhythmia. We report a case of neurally mediated syncope in pheochromocytoma associated with cardiac repolarization abnormalities, a unique presentation of the disease.Case presentationThis case report presents a 28 year-old woman, describing recurrent syncope usually preceded by prodromes such as headache, visual blurring, heart palpitations and psychomotor agitation. Firstly she was diagnosed with anxiety and depression, but there was no improvement of symptoms with psychiatric treatment. Previous Holter revealed long QT interval. Echocardiogram showed normal dimensions, preserved left ventricular function and no valvopathies. The patient was referred for a Head-up tilt test (HUTT) in order to investigate reflex syncope. The electrocardiogram (ECG) exhibited normal sinus rhythm and diffuse cardiac repolarisation abnormalities. HUTT was positive for vasodepressor type neurally mediated syncope and ECG showed U waves after a syncope episode. This electrocardiographic finding motivated further clinical investigation. The patient also described abdominal pain, increased abdominal volume, weight loss and blood pressure instability. Based on clinical history and ventricular repolarisation abnormalities uncovered by HUTT, pheochromocytoma was suspected. Urinary test was positive for catecholamines and the abdominal imaging revelead expansive lesion. She underwent surgery to remove the pheochromocytoma, confirmed by immunohistochemistry.ConclusionsAfter surgery she had no recurrency of symptoms, remaining asymptomatic after six years of follow-up, suggesting a cause-effect relationship between neurally mediated syncope and pheochromocytoma.

Impact of Smokeless Tobacco on Cardiovascular Disease Risk in a Nigerian Metropolitan City.

The use of smokeless tobacco products (STP) as a substitute for tobacco smoking is driving increasing consumption of these products especially in developing countries. The study sought to make comparison of cardiovascular risk profile between chronic STP users and suitably matched tobacco-naïve controls. This is a preliminary report from the cross sectional part of a two-arm prospective study of Smokeless Tobacco Products Composition and Exposure Outcome in Enugu metropolis, Nigeria. Consecutively recruited current Smokeless tobacco users, who had no history of cigarette smoking, aged 18years and above, residing in selected communities in Enugu metropolis, Nigeria were recruited for the study from October 2022 to July 2023. Age and sex matched non-tobacco users from same localities as the study subjects served as controls. Written informed consent to participate in the study was obtained from all study participants. All participants were screened by the investigators, using the study case report forms, to obtain data on medical history, demographic, clinical, laboratory, and electrocardiographic evaluation. Data from 54 STP-users and 54 non-STP-users (mean age 56.58 ± 8.15years) were analyzed. Anthropometric parameters were similar in both groups. Smokeless tobacco users had higher erect and supine blood pressure indices as well asgreater postural drop in systolic blood pressure. The occurrence of diabetes mellitus (20.37% versus 5.56%) and hypertension (25.93%; 11.11%) was significantly higher in the STP-users than in the non-user population, (p = 0.02192 and 0.04751 respectively). Electrocardiographic evaluation showed significantly increased QTc and dispersions of P-wave, QRS and QT intervals as well as reduced PR interval in STP users. Electrocardiographic abnormalities observed in STP users include left ventricular hypertrophy, left atrial enlargement, ST-segment elevation, short PR interval and long QTc. Use of smokeless tobacco products is associated with increased risk burden of diabetes mellitus and hypertensive heart disease. Electrocardiographic findings linked to STP-use in this study are features consistent with arrhythmia, ventricular repolarization abnormality, myocardial hypertrophy and ischaemia, suggesting that smokeless tobacco products are not safe substitutes for tobacco smoking.

Myocardial injury in dogs: a retrospective analysis on etiological, echocardiographic, electrocardiographic, therapeutic, and outcome findings in 102 cases

IntroductionIn dogs, myocardial injury (MI) is a poorly characterized clinical entity; therefore, this study aimed to provide a detailed description of dogs affected by this condition. Animals, materials, and methodsDogs diagnosed with MI according to the concentration of cardiac troponin I (cTnI) were retrospectively searched. Signalment, diagnostic, therapeutic, and outcome data were retrieved. Dogs were divided into six echocardiographic (dilated cardiomyopathy phenotype; hypertrophic cardiomyopathy phenotype; hypertrophic cardiomyopathy phenotype with systolic dysfunction; abnormal echogenicity only; endocarditis; and no echocardiographic abnormalities suggestive of MI), four electrocardiographic (abnormalities of impulse formation; abnormalities of impulse conduction; abnormalities of ventricular repolarization; and no electrocardiographic abnormalities suggestive of MI), and nine etiological (infective; inflammatory; neoplastic; metabolic; toxic; nutritional; immune-mediated; traumatic/mechanical; and unknown) categories. Statistical analysis was performed to compare cTnI values among different categories and analyze survival. ResultsOne hundred two dogs were included. The median cTnI value was 3.71 ng/mL (0.2–180 ng/mL). Echocardiographic and electrocardiographic abnormalities were documented in 86 of 102 and 89 of 102 dogs, respectively. Among echocardiographic and electrocardiographic categories, the dilated cardiomyopathy phenotype (n = 52) and abnormalities of impulse formation (n = 67) were overrepresented, respectively. Among dogs in which a suspected etiological trigger was identified (68/102), the infective category was overrepresented (n = 20). Among dogs belonging to different echocardiographic, electrocardiographic, and etiological categories, cTnI did not differ significantly. The median survival time was 603 days; only eight of 102 dogs died due to MI. ConclusionsDogs with MI often have an identifiable suspected trigger, show various echocardiographic and electrocardiographic abnormalities, and frequently survive to MI-related complications.

Does vitamin D deficiency affect ventricular repolarization in the elderly?

Introduction: The aim of the current study is to establish whether vitamin D deficiency interacts with the electrocardiographic indices of abnormal ventricular repolarization in elderly patients. Material and Methods: 138 patients were divided into three groups: patients with vitamin D deficiency, patients with vitamin D insufficiency, and patients with adequate vitamin D levels. 12-lead electrocardiography and laboratory data were collected. Results: The resting heart rate, PR interval, QRS duration, QTd, and Tp-e dispersion were similar among the groups. However, the QTc interval was significantly prolonged in patients with vitamin D deficiency, when compared to patients with sufficient vitamin D levels. Vitamin D level was found as the only independent predictor of the QTc interval. The cut-off value of Vitamin D level determining the significant prolongation of QTc interval was found to be 20 ng/ml on ROC analysis (Area Under Curve: 0,629±0.051 (95% CI: 0,530-0.728, p=0.013). Conclusion: Low vitamin D levels are associated with QTc prolongation in the elderly. Vitamin D-deficient elderly patients may benefit from routine ECG screening. Timely diagnosis and treatment of vitamin D deficiency may aid in reducing the rate of arrhythmias in this patient population.

Are the Exacerbations of Chronic Obstructive Pulmonary Disease a Risk Factor for Cardiac Arrhythmia?

Aim: Hypoxemia, hypercapnia, and automaticity—which are dependent on exacerbation—increase the risk of arrhythmia by causing abnormal atrial and ventricular repolarization in chronic obstructive pulmonary disease (COPD). This study aimed to foresee the possibility of arrhythmia by evaluating the electrocardiograms (ECG) of patients having COPD attacks. Material and Method: In total, 120 patients (66 in the COPD group and 54 in the control group) were included. The differences between the two groups were statistically examined by determining (in milliseconds) QT and QTc interval maximum (max), minimum (min), and dispersion (disp); T-wave peak to end (Tp-e) max, min, and disp; Tp-e max/QT max, Tp-e max/QTc max proportions; and P wave max, min, and disp duration in the ECG parameters of the patients. Results: Forty-eight (64%) of the males included in the study were in the COPD group and 27 (36%) in the control group, whereas 18 (40%) of the females were in the COPD group and 27 (60%) in the control group. There was no significant difference between the ages of the patients and the levels of sodium and potassium (p = 0.189, 0.353, and 0.071). There was a significant difference between QT max and min in the groups, whereas there was no difference in terms of QT disp (p < 0.001, p < 0.001, and p = 0.490). There was a significant difference between the Tp-e max, min, and disp values in the COPD and control groups (p = 0.041, p < 0.001, and p = 0.001, respectively). There was no significant difference between the groups in terms of the P max duration (p = 0.442), but significant differences between the two groups in P min and disp durations were determined (p = 0.003 and p < 0.001, respectively). In receiver operating characteristic analysis made for P disp and Tp-e disp values in which a firm difference was made, 30 ms was determined as the cutoff for both parameters. Conclusion: To our knowledge, this is the first study that the rise of the dispersions of P wave and Tp-e intervals (without rise of QTc disp.) is detected on the evaluation of atrial and ventricular arrhythmia risks on COPD acute attacks.

Electrocardiographic T Wave Abnormality and Associated Factors Among Type 2 Diabetic Patients: Multicenter Institution-Based Cross-Sectional Study

Introduction: T wave abnormalities are usually found on ECG and show abnormal ventricular repolarization. The presence and magnitude of T wave abnormality are often associated with cardiovascular disease and mortality in diabetes. However, there is no study about the electrocardiographic T wave abnormalities among type 2 DM patients in Ethiopia. Therefore, this study determined the overall prevalence and the associated factors of T wave abnormalities among people living with T2DM in Amhara National Regional State referral hospitals, Ethiopia. Methods: A multicenter institution-based cross-sectional study was conducted from 01 January to 30 March 2022. Simple random sampling and systematic sampling techniques were employed to select the referral hospitals and study participants, respectively. A digital electrocardiograph was used to measure the T wave patterns, and an interviewer-administered questionnaire to collect sociodemographic and some clinical factors. Epi-data version-4.6 and Stata-14 were used for data entry and statistical analysis, respectively. The descriptive statistics were presented with tables and graphs. A binary logistic regression model was fitted to identify associated factors of T wave abnormality. In the final model, statistical significance was decided at p<0.05, and the strength of association was indicated using an adjusted odds ratio with 95% CI. Results: Two hundred and fifty-eight participants (response rate=99.6%) were included in the analysis. The prevalence of overall T wave abnormality was 21.7% (95% CI: 19, 29.2%). Higher monthly income (>90$) (AOR=0.16 [0.06, 0.46]), hypertension 5.55 (AOR=5.55 [2.12, 14.49]), fasting blood sugar of >130mg/dl 6.38 (AOR=6.38 [1.94, 20.94]), were statistically significant factors of T wave abnormality. Conclusions: Higher income, hypertension, and higher fasting blood sugar were significantly associated with ECG abnormality. The findings of this study suggest the need to institute routine ECG screening for all T2DM patients to reduce silent myocardial ischemia and further complications.

Action potential morphology affects T-wave symmetry (simulation study)

BackgroundAssessing T-wave symmetry in addition to QT subintervals measurements can provide novel independent data about ventricular repolarization abnormalities linked with arrhythmogenesis. However, the causes of the changes of T-wave symmetry are not completely understood. In silico studies showed that the more symmetrical T-waves were associated with shorter action potential duration (APD) and larger dispersion of ventricular repolarization (DOR). The aim of present simulation was to study the association between T-wave symmetry and action potential (AP) shape. MethodsECGs were simulated using a cellular automata model shaped as a ventricular wall segment, and two biophysically-detailed models of ventricular AP – the rabbit and the human. The symmetry ratio (SR) was calculated as a T-wave onset-peak to peak-end area ratio. The individual and combined effects of APD, DOR and AP shape on SR were simulated. To study the effect of AP shape, different APs from triangulated to rectangular were simulated. ResultsThe simulations showed that AP shape along with APD and DOR contributes much to T-wave symmetry. APs with a flat phase 3 (triangulated) produced asymmetrical T-waves (SR ≥ 1.5) in all simulations, except the shortest APD range. APs with a rapid phase 3 (rectangular) were associated with more symmetrical T-waves (SR ≤ =1) both at the short and the long APDs. ConclusionSR marker in combination with the standard ECG parameters (QT interval, Tpeak-Tend interval) may be useful to identify the proarrhythmic triangulated AP shape.

Evaluation of the effects of insulin resistance on ECG parameters in obese children.

Obese people are at increased risk of arrhythmia and sudden death, even in the absence of heart dysfunction. Increased insulin resistance, neurohumoral and autonomic changes in obesity can cause atrial and ventricular repolarization abnormalities. This study aimed to investigate the effect on ventricular repolarization parameters and to show the increased risk of ventricular arrhythmia in obese children. The data of 50 obese children aged 2-18 who applied to the Pediatric Endocrinology Outpatient Clinic were evaluated prospectively. In 12-lead ECGs, heart rate, Pmax, Pmin, P-wave dispersion (Pwdisp), QTmax, QTmin, QT dispersion (QTd), QTcmax, QTcmin, QTc interval dispersion (QTcd), Tpeak-Tend interval (Tp-e), Tp-e/QT, Tp-e/QTc were calculated electronically. Tp-e time (0.041 ± 0.004/0.049 ± 0.015/p=0.018) and Tp parameters were measured in obese children with and without insulin resistance. Tp-e/QT ratio was also found to be high (p=0.035). There is a negative correlation between BMI SDS values and QTcmax and QTcmin values in patients with insulin resistance (p=0.015). In our study, the Tp-e interval and Tp-e/QT ratios, which had been revealed in literature to be more sensitive in demonstrating ventricular arrhythmias, were found to be higher in obese individuals with insulin resistance than in those without insulin resistance. Obese individuals with or without insulin resistance should be carefully evaluated in terms of atrial and ventricular depolarization and repolarization parameters with 12-lead ECG during their outpatient controls, and annual 24-hour Holter control should be performed to detect arrhythmias.

Non-Invasive Risk Assessment and Prediction of Mortality in Patients Undergoing Coronary Artery Bypass Graft Surgery.

Objectives: Heart rate turbulence (HRT) and T-wave alternans (TWA), non-invasive markers of cardiac autonomic dysfunction, and ventricular repolarization abnormality, reportedly, predict the risk of cardiovascular death after myocardial infarction. We investigated whether pre-operative assessment of HRT and/or TWA could predict long-term mortality following coronary artery bypass graft (CABG) surgery. Methods: From May 2010 to December 2017, patients undergoing elective CABG and receiving 24 h ambulatory electrocardiogram monitoring 1 to 5 days prior to CABG surgery were prospectively enrolled. Pre-operative HRT and TWA were measured using a 24 h ambulatory electrocardiogram. The relative risk of cardiac or overall death was assessed according to abnormalities of HRT, TWA, or left ventricular ejection fraction (LV EF). Results: During the mean follow-up period of 4.6 ± 3.9 years, 40 adjudicated overall (5.9%/yr) and 5 cardiac deaths (0.9%/yr) occurred in 146 enrolled patients (64.9 ± 9.3 years; 108 males). Patients with abnormal HRT exhibited significantly higher relative risks of cardiac death (adjusted hazard ratio [HR] 24.9, 95% confidence interval [CI] 1.46-427) and all-cause death (adjusted HR 5.77, 95% CI 2.34-14.2) compared to those with normal HRT. Moreover, abnormal HRT plus abnormal TWA and LV EF < 50% was associated with a greater elevation in cardiac and overall mortality risk. The predictive role of abnormal HRT with/without abnormal TWA for all-cause death was likely more prominent in patients with mildly reduced (35 to 50%) or preserved (≥50%) LV EF. Abnormal HRT plus abnormal TWA and LV EF < 50% showed high negative predictive value in cardiac and overall mortality risk. Conclusions: Assessment of pre-operative HRT and/or TWA predicted mortality risk in patients undergoing elective CABG. Combined analysis of HRT, TWA, and LVEF enhanced the prognostic power. In particular, the predictive value of HRT was enhanced in patients with preserved or mid-range LV EF.

Ventricular Arrhythmia in Cancer Patients: Mechanisms, Treatment Strategies and Future Avenues.

Cardiovascular disease and cancer are the leading causes of morbidity and mortality in the US. Despite the significant progress made in cancer treatment leading to improved prognosis and survival, ventricular arrhythmias (VA) remain a known cardiovascular complication either exacerbated or induced by the direct and indirect effects of both traditional and novel cancer treatments. Although interruption of cancer treatment because of VA is rarely required, knowledge surrounding this issue is essential for optimising the overall care of patients with cancer. The mechanisms of cancer-therapeutic-induced VA are poorly understood. This review will discuss the ventricular conduction (QRS) and repolarisation abnormalities (QTc prolongation), and VAs associated with cancer therapies, as well as existing strategies for the identification, prevention and management of cancer-treatment-induced VAs.

P204 CARDIAC INVOLVEMENT IN NEUTRAL LIPID STORAGE DISEASE (NLSD): A CASE REPORT

Abstract Introduction Neutral Lipid Storage Diseases (NLSDs) are rare diseases with autosomal recessive transmission characterized by a defect in the metabolism of triglycerides that accumulate in many tissues. Vacuoles containing lipids in white blood cells (Jordans anomaly) are considered a diagnostic marker. In particular, NLSD–M (NLSD–myopathy) is caused by mutations in the PNPLA2 gene (Patatin Like Phospholipase Domain Containing 2, chromosome 11p15.5) that codes for an enzyme involved in the first phase of triglyceride hydrolysis in adipose tissue. In this patient the mutation of the PNPLA2 gene is c.542delCA, truncating the protein with loss of the hydrophobic domain. This mutation is associated with more severe infiltrative and arrhythmic cardiac involvement than those known in the literature. Case Report 52–year–old man with NLSD–M. The first symptoms of the disease appeared when he turned 35: weakness and atrophy of axial and proximal muscles, increased CK, scoliosis, fatty liver, electromyographic changes, arterial hypertension, dyslipidemia, renal failure and hypertransaminasemia. At 49, ECG revealed sinus rhythm, absence of ventricular repolarization abnormalities and echocardiogram revealed wall hypertrophy with a trabecular appearance of the left ventricle, sigmoid interventricular septum, preserved EF (58%), moderate diastolic dysfunction, left atrial enlargement, absence of significant valvulopathies. Cardiac MRI revealed lipid infiltration. An ICD was implanted for sustained ventricular tachycardia. At 50, atrial fibrillation was detected. EF was 53% and there was a small partially organized circumferential pericardial effusion. The last medical check, performed at 52 during hospitalization for atrial fibrillation with high ventricular response associated with hypokalemia and hypomagnesaemia, revealed ST–T alterations on ECG and a further reduction of EF to 46% on echocardiogram. Conclusions There is currently no medical treatment. A dietary supplement with medium–chain fatty acids (CNT–02) can be used to slow down the accumulation of lipids. The search for specific mutation is important to stratify cardiac risk.

Relationship of the T-wave Tpeak-Tend interval with conduction system disorders in arterial hypertension.

The Tpeak-Tend interval of the T wave has emerged as a new electrocardiographic marker of increased transmural dispersion of ventricular repolarization. We aimed to determine the presence of cardiac conduction system disorders in patients with systemic arterial hypertension (SAH) who have altered Tpeak-Tend interval of the T wave. The 67 patients with SAH were divided into two groups. Those with prolonged (≥ 77 ms) Tpeak-Tend intervals, 21 (31%) patients were in the study group. Those with normal (< 77 ms) Tpeak-Tend intervals, 46 (69%) patients were in the control group. Alteration of ventricular repolarization manifested as a prolongation of the Tpeak-Tend interval was detected by computerized electrocardiographic analysis tools. The median value of QRS complex duration was significantly wider in the study group as compared to the control group (110 ± 12 ms vs. 94 ± 8 ms p < 0.001). There was a significantly greater incidence of left anterior hemiblock in the study group (14% vs. 0% p < 0.04). The median value of the QTc interval was significantly greater in the study group (440 ± 26 vs. 422 ± 15 p < 0.01). There was a significantly greater incidence of patients with prolonged QTc interval in the study group (33% vs. 11% p < 0.02). The median value of the Tpeak-Tend interval was significantly greater in the study group (84 ± 5 ms vs. 65 ± 4 ms p < 0.001), as well as, the Tpeak-Tend/QTc ratio in the study group (0.19 ± 0.1 vs. 0.16 ± 0.1 p < 0.001). There is a significantly greater ventricular repolarization disorders and abnormalities of the cardiac conduction system in SAH patients who possess altered Tpeak-Tend interval of the T wave.

Evaluation of the Corrected QT Interval with Bazett’s Method in Cavalier King Charles Spaniel Dogs with Myxomatous Mitral Valve Disease

Abstract Myxomatous mitral valve disease (MMVD) is one of the most common heart diseases in dogs. The disease progresses faster in Cavalier King Charles Spaniel (CKCS) dogs and occurs at an earlier age. QT interval length reflects abnormalities in ventricular repolarization which may predispose to the formation of fatal arrhythmias such as torsades de pointes. A fast and accurate assessment is therefore essential. The study aimed to examine the changes in QT duration in MMVD cases of CKCS and to calculate the corrected QT durations with Bazett’s formula in various stages of the disease. The study included 20 CKCS dogs of both genders, various ages and weights, and different stages of MMVD (n=6 in B1 stage, n=6 in B2 stage, and n=8 in C stage), and 5 healthy CKCS which were included in the control group. Clinical, radiological, hematological, biochemical, echocardiographic, and electrocardiographic examinations were performed. The corrected QT interval duration in the MMVD group was longer than the control (p&lt;0.05). However, there was no significant difference between B1, B2, and C. It was concluded that the corrected QT interval can give a significant distinction between healthy and MMVD CKCS dogs.

Electrocardiogram markers of atrial and ventricular repolarization abnormalities and their association with symptom severity in antipsychotic-free patients with schizophrenia

Electrocardiogram markers of atrial and ventricular repolarization abnormalities and their association with symptom severity in antipsychotic-free patients with schizophrenia

High risk of ventricular repolarization abnormalities among hemodialytic end-stage renal disease patients.

Patients with chronic renal disease (CKD) are at a significantly elevated risk for ventricular arrhythmia. Several electrocardiographic (ECG) methods can be used to assess the ventricular arrhythmia risk on the standard 12-lead ECG.

Abstract 12538: Intermittent Hypoxemia Progressively Destabilizes Ventricular Repolarization in Healthy Awake Subjects

Introduction : Obstructive sleep apnea (OSA) is highly prevalent in the general population. OSA is associated with adverse cardiovascular events, including sudden cardiac death, but the mechanism is unclear. Intermittent hypoxemia, a pathognomonic feature of OSA, could increase the propensity for abnormal ventricular repolarization. We previously found that short-term exposure of awake healthy subjects to recurrent hypoxic episodes increased their heart rate (HR) and HR variability. Hypothesis: Exposure to intermittent hypoxia increases ventricular repolarization instability in awake healthy subjects. Methods: Healthy adults (N = 19) were exposed to either intermittent hypoxia or air for 4 hours on two different days in a randomized order. Intermittent hypoxia was induced with exposure to hypoxic gas (95% N 2 and 5% O 2 ) or ambient air in an alternative fashion at a frequency of ⁓ 25 times/hour, mimicking moderate to severe OSA. Repolarization stability was assessed using the QT variability index (QTVI), a validated predictor of cardiac arrhythmias and mortality. HR and QTVI were measured from one-lead ECG over consecutive 5-min epochs. Paired sample t - test was used to assess statistical associations. Results: Mean oxygen saturation levels were lower during exposure to intermittent hypoxia (90.86 ± 0.19%) versus normoxia (97.37 ± 0.20%, P &lt; 10 -13 ). Electrocardiographic measures at baseline were similar between the two conditions. No changes in these measures were noted during the conditions of normoxia. However, with intermittent hypoxia, mean HR and QTVI steadily increased (HR: 63.31 ± 1.51 initial, 69.21 ± 2.14 final, P &lt; 0.001; QTVI: -1.85 ± 0.04 initial, -1.64 ± 0.07 final, P = 0.016). By the end of the 4-hour experiment, QTVI was greater in hypoxia vs. normoxia (final QTVI in hypoxia: -1.64 ± 0.07, in normoxia: -1.86 ± 0.06, P = 0.021). Conclusion: Four hours of intermittent hypoxia in awake normal healthy subjects progressively destabilized ventricular repolarization. Chronic exposure to recurrent periods of intermittent hypoxemia in OSA can increase ventricular repolarization and contribute to the OSA-associated adverse cardiovascular events, including sudden cardiac death.