Classical ECG Research Articles

Searching for the Best Machine Learning Algorithm for the Detection of Left Ventricular Hypertrophy from the ECG: A Review.

Background: Left ventricular hypertrophy (LVH) is a powerful predictor of future cardiovascular events. Objectives: The objectives of this study were to conduct a systematic review of machine learning (ML) algorithms for the identification of LVH and compare them with respect to the classical features of test sensitivity, specificity, accuracy, ROC and the traditional ECG criteria for LVH. Methods: A search string was constructed with the operators "left ventricular hypertrophy, electrocardiogram" AND machine learning; then, Medline and PubMed were systematically searched. Results: There were 14 studies that examined the detection of LVH utilizing the ECG and utilized at least one ML approach. ML approaches encompassed support vector machines, logistic regression, Random Forest, GLMNet, Gradient Boosting Machine, XGBoost, AdaBoost, ensemble neural networks, convolutional neural networks, deep neural networks and a back-propagation neural network. Sensitivity ranged from 0.29 to 0.966 and specificity ranged from 0.53 to 0.99. A comparison with the classical ECG criteria for LVH was performed in nine studies. ML algorithms were universally more sensitive than the Cornell voltage, Cornell product, Sokolow-Lyons or Romhilt-Estes criteria. However, none of the ML algorithms had meaningfully better specificity, and four were worse. Many of the ML algorithms included a large number of clinical (age, sex, height, weight), laboratory and detailed ECG waveform data (P, QRS and T wave), making them difficult to utilize in a clinical screening situation. Conclusions: There are over a dozen different ML algorithms for the detection of LVH on a 12-lead ECG that use various ECG signal analyses and/or the inclusion of clinical and laboratory variables. Most improved in terms of sensitivity, but most also failed to outperform specificity compared to the classic ECG criteria. ML algorithms should be compared or tested on the same (standard) database.

On-chip, non-invasive detection of all atrial arrhythmias for immediate and accurate characterization in adult rats

Abstract Background To monitor and record the occurrence and duration of cardiac arrhythmias in freely moving animals, ECG telemetry devices are often used. However, traditional telemetry devices require complex equipment unsuitable for on-site application in most animal housing facilities. Additionally, current atrial arrhythmias detection algorithms are mainly based on ECG R-R interval variability for atrial fibrillation (AF) detection. Such algorithms do not allow the detection of stable R-R interval atrial arrhythmias such as flutter. Thus there is currently a lack of non-invasive methods allowing automated detection of all atrial arrhythmias subtypes, thereby precluding in-depth research into general and subtype-specific mechanisms and treatment. Purpose Here we aim to create a non-invasive system allowing fast and accurate on-site detection and characterization of all atrial arrhythmias in rats. Methods Our atrial arrhythmia detector system was made of an on-skin ECG sensor, a low-power microprocessor unit, a large data storage unit and a battery. All components were assembled within a lightweight rat jacket. The filtered ECG signal was sent to the microprocessor allowing algorithm-based, real-time detection of atrial arrhythmias. The device allowed storage of ECG traces as well as arrhythmia characteristics (including type of arrhythmia and its duration). Atrial arrhythmias were induced by transesophageal atrial burst pacing in Wistar rats. These arrhythmia recordings were used to develop an AI detection method. Next, real-time detection algorithms based on R-R variability and AI were both integrated on-chip and compared using the same ECG data. Results ECG traces measured with our new system were similar to classical ECG measurements. Stored ECG traces provided the raw data for the development of an AI-based detection algorithm. The AI training was done using ECG data recorded from five different rats and reached 99.5% self-testing accuracy to detect all sub-types of atrial arrhythmias based on pre-categorized data. Using uncategorized data (n=25 from 5 rats) different from the training dataset, the AI algorithm could detect >80% of all types of atrial arrhythmias within 3s after initiation, while the rest could be detected within 10s. Though R-R interval based algorithm showed a high detection rate of 88% of AF within 10s, this method did not allow the detection of flutter or AF presenting regular R-R intervals within 1 minute after initiation. Conclusion Our atrial arrhythmia detection and analysis system provides a novel method for non-invasive investigation into atrial arrhythmias in rats and could easily be scaled for other species. It allows on-site fast and accurate detection and characterization of atrial arrhythmia subtypes without external equipment, thereby opening new possibilities for mechanistic studies and therapeutic testing, including closed-loop applications aiming for arrhythmia termination.

Genetic architecture of spatial electrical biomarkers for cardiac arrhythmia and relationship with cardiovascular disease

The 3-dimensional spatial and 2-dimensional frontal QRS-T angles are measures derived from the vectorcardiogram. They are independent risk predictors for arrhythmia, but the underlying biology is unknown. Using multi-ancestry genome-wide association studies we identify 61 (58 previously unreported) loci for the spatial QRS-T angle (N = 118,780) and 11 for the frontal QRS-T angle (N = 159,715). Seven out of the 61 spatial QRS-T angle loci have not been reported for other electrocardiographic measures. Enrichments are observed in pathways related to cardiac and vascular development, muscle contraction, and hypertrophy. Pairwise genome-wide association studies with classical ECG traits identify shared genetic influences with PR interval and QRS duration. Phenome-wide scanning indicate associations with atrial fibrillation, atrioventricular block and arterial embolism and genetically determined QRS-T angle measures are associated with fascicular and bundle branch block (and also atrioventricular block for the frontal QRS-T angle). We identify potential biology involved in the QRS-T angle and their genetic relationships with cardiovascular traits and diseases, may inform future research and risk prediction.

Extreme physical exhaustion leading to hypokalemic periodic paralysis- a case report

Sudden onset limb weakness in a young individual requires a thorough evaluation and prompt diagnosis. Delay in treatment awaiting CT scan reports or laboratory investigations can lead to complications. Our case report stresses upon the clinicians to consider hypokalemic periodic paralysis in the differential diagnosis in evaluating such patients. Classical ECG changes and blood gas analysis can effectively diagnose hypokalemia and institute gradual correction of the electrolyte abnormality. In a very rare incident, our patient developed hypokalemia after strenuous exercise.
 Key words: Hypokalemic periodic paralysis; Hypokalemia; Flaccid paralysis; Exhaustion
 Citation: Borkotokey M, Dutta K. Extreme physical exhaustion leading to hypokalemic periodic paralysis- a case report. Anaesth. pain intensive care 2022;26(1):123-125.
 DOI: 10.35975/apic.v26i1.1782
 Received: November 30, 2021, Reviewed: December 25, 2021,, Accepted December 27, 2021

199 Lower aortic valve calcium scores by computed tomography scan. A potential new red flag of concomitant cardiac amyloidosis in patients with severe aortic stenosis

Abstract Aims Cardiac amyloidosis (CA) and degenerative aortic stenosis (AS) are two diseases often combined but the diagnosis of both these conditions is challenging because these two illnesses share common echocardiographic characteristics. Different predictors have been proposed in the last few years, including clinical, ECG-graphic, and echocardiographic features. To identify a new marker of concomitant CA in patients with severe AS using computed tomography scan (CT). Methods and results Fifty-five patients with severe AS and suspicion of concomitant CA were retrospectively enrolled. Patients with a bicuspid aortic valve, previous aortic valve replacement, or an incomplete diagnostic workup for CA were excluded. Thirty-three patients underwent CT-scan and were included in the final analysis. None of the patients had at laboratory tests suspicion for AL amyloidosis; 12 patients (AS-CA) had positive 99 m Tc-DPD bone scintigraphy (two with visual score 1, eight score 2 and two score 3), 21 patients (AS-alone) had negative bone scintigraphy (visual score 0). AS-CA patients had a median age of 85.5 years (vs. 82) with only one female patient (vs. 8 in the AS-alone group). AVA indexed were almost comparable between AS-CA and AS-alone groups (0.4 vs. 0.3 mm2/m2, P = 0.25). Stroke volume evaluated by pulsed Doppler, maximum and mean gradient were significatively lower in AS-CA group (respectively 30 vs. 41 ml/m2, P = 0.017, 62 vs. 74 mmHg, 0.038 and 33 vs. 46 mmHg, P = 0.022) with a higher percentage of paradoxical low flow-low gradient aortic stenosis in AS-CA group (7 patients, 58% vs. 3 patients in AS-alone 14%, P = 0.027), in line with the literature. ECG at first presentation in AS-CA group showed atrial fibrillation in eight patients (67%), vs. two patients in the AS-alone group (10%), and lower QRS voltages (peripheral QRS score 40 mV vs. 51 mV, P-value = 0.017; total QRS score 113 mV vs. 155 mV, P-value = 0.005). The echocardiogram showed a more thickened IVS and PW in AS-CA patients (17 vs. 15 mm, P = 0.05 and 15 vs. 14 mm, P = 0.013), an increased left ventricular mass (441 vs. 356 g, P = 0.036) with a reduction of longitudinal systolic function (septal S wave at TDI 4.4 vs. 5.2 cm/s, P = 0.026, lateral S wave 4.1 vs. 5.6 cm/s, P = 0.024) and a lower myocardial contraction fraction (12% vs. 14%, P = 0.036). CT-aortic valve calcium was valued and quantified by an experienced operator. A statistically significant difference between AS-CA and AS-alone groups was observed in calcium score (3345 vs. 4785 Hounsfield units, P = 0.037) calcium volume (2411 vs. 3626 mm2, P = 0.03) and calcium mass (687 vs. 1147 g, P = 0.023). Conclusions This study is the first to our knowledge to use relative aortic valve calcium score evaluation from CT imaging to define patients with severe AS with or without concomitant CA in addition to the classical clinical, ECG graphic, and echocardiographic features. CT-aortic valve calcium burner was significatively lower in patients with concomitant CA.

Effect of habitual cigarette smoking on the index of cardiac electrophysiological balance in apparently healthy individuals

Background and aimChronic cigarette smoking has been suggested to portend risk for cardiac arrhythmia generation. Index of cardiac electrophysiological balance (iCEB) is a relatively new ECG parameter indicating balance between ventricular depolarization and repolarization, thereby providing more insight concerning ventricular arrhythmogenesis (VA) than other classical ECG parameters such as QT and corrected QT (QTc) intervals. The present study aimed to assess the status of iCEB in healthy habitual smokers. MethodsThis retrospective study included a total of 80 apparently healthy subjects (45% female, mean age 39.4 ± 8.1 years) with smoking habit and 82 healthy non-smoking subjects (40% female, mean age 37.0 ± 8.6 years) were included between January–September 2019. Demographic, clinical and ECG characteristics were obtained from medical records. iCEB and corrected iCEB values were calculated by dividing respective QT and QTc intervals by QRS duration. ResultsMean PR, QRS and QT intervals were similar between the groups, whereas mean heart rate and QTc interval were greater in the smoker group compared with the non-smokers [(82.0 ± 8.9 bpm vs 77.8 ± 12.4 bpm, respectively, p = 0.016) and (427.05 ± 22.6 msec vs 399.9 ± 12.8 msec, respectively, p < 0.001)]. Subject with smoking habit had greater iCEBc than the controls (5.10 ± 0.49 vs 4.68 ± 0.39, respectively, p < 0.001). However, there was no significant difference in regard of iCEB between the groups (4.37 ± 0.46 vs 4.32 ± 0.42, respectively, p = 0.456). ConclusioniCEBc increases significantly in healthy smokers compared with non-smokers. This may suggest an increased predisposition to Torsades de Pointes-mediated VA in healthy smokers, or in chronic smokers with inherent QT-prolonging genetic variations or those on QT-prolonging drug therapy.

A comparative study of serum uric acid level in various acute coronary syndromes and its short term prognostic significance using KILLIP classification

Background: Serum uric acid is increased in ischemic conditions and is significantly higher in patients with acute myocardial infarction. The aim of study was to correlate serum uric acid level with KILLIP class in respect of mortality and morbidity profile of patients with acute coronary syndromes..Methods: 100 patients fulfilling the standard diagnostic criteria for acute coronary syndromes on the basis of classical history, clinical signs, ECG changes and biomarkers were included in the study. Age and sex matched 50 normal healthy subjects were also included as control group after obtaining informed consent. Serum uric acid level was measured on day 0, 3 and 7 of various ACS.Results: There was statistically significant higher level of serum uric acid concentration in patients of AMI on day of admission as compared to controls and unstable angina patients. On all three days of serum uric acid estimation, the serum uric acid levels were higher in AMI patients who were in higher KILLIP class as compared to lower KILLIP class group. Smokers had significantly higher baseline serum uric acid but age, sex, dyslipidemia, hypertension and diabetes mellitus did not significantly affect serum uric acid level at any stage in various ACS patients. Five patients who died during hospital stay, had serum uric acid level more than 7.0 mg/dL and all of them were in KILLIP class III and IV.Conclusions: serum uric acid level is a strong and independent risk factor in predicting mortality and morbidity profile of patients of acute myocardial infarction. Also, serum uric acid level correlates well with KILLIP class.

Correction to: Differentiating Right- and Left-Sided Outflow Tract Ventricular Arrhythmias: Classical ECG Signatures and Prediction Algorithms

Correction to: Differentiating Right- and Left-Sided Outflow Tract Ventricular Arrhythmias: Classical ECG Signatures and Prediction Algorithms

Prevalence of cardiac amyloidosis among elderly patients with systolic heart failure or conduction disorders

Objective: Cardiac amyloid infiltration can lead to systolic heart failure (HF) or to conduction disorders (CD). Patients with transthyretin (ATTR) amyloidosis are particularly exposed. We sought to determine the prevalence of ATTR and AL among patients >60 years admitted with CD or unexplained systolic HF and increased wall thickness.Materials and Methods: We studied 143 patients (57% males, 79 ± 9 years) with HF (N = 28) or CD requiring pacemaker implantation (N = 115). In total, 139 (97%) patients (28 with HF and 111 with CD) underwent 99mTc-DPD scintigraphy to detect ATTR, and 105 (73%; 19 HF and 86 CD) underwent AL screening.Results: Five patients (4%; 95%CI:0–7%) exhibited wild-type ATTR (ATTRwt) amyloidosis, 2 (2%; 95%CI:0–4%) had CD and 3 (11%; 95%CI:0–23%) HF. No patient showed AL. The 2 ATTRwt patients with CD were previously asymptomatic, did not show classical ECG signs and exhibited mild LV hypertrophy with preserved LVEF. By contrast, all ATTRwt patients with HF had ECG and echocardiographic signs of amyloid. During a mean follow-up of 18 ± 11 months, 3(60%) patients with ATTRwt amyloidosis (1 CD and 2 HF) and 14(10.4%) without died.Conclusion: Prevalence of ATTRwt amyloidosis in patients with CD requiring pacemaker is low. Although, additional studies are needed, prevalence seems to be higher in elderly patients with systolic HF.

Leads Selection of Body Surface Potential Mapping During Atrial Fibrillation: A Sequential Selection Based on Adapted Botteron’s Approach

Atrial fibrillation (AF) is a common clinical arrhythmia with a lifetime risk and has become an attractive topic of clinical research and health management. Although the 12-lead classical ECG configuration is adequate for the detection of AF, its configuration is suboptimal for constructing surface potential mapping or extracting other diagnostic features during AF. Body surface potential mapping (BSPM) has a broad application prospect in AF study, but the electrode wiring is complicated and the hardware cost is high. This paper proposes a method to improve the performance of leads selection algorithm from a 128-lead BSPM system with equidistantly spaced electrodes. 128-lead BSPM data obtained from 8 AF patients were used in the study. Leads selection was performed by a sequential selection based on an adapted Botteron’s approach and multiple linear regression. The result showed that the proposed method has significant improvement on the performance of the accurate reconstruction of dominant frequency on the patient-specific dataset. The proposed method may not only improve the performance on the spectrum characteristic but also effectively improve the performance of time domain criteria when the number of selected leads is above 12.

Mechanisms of ECG signs in chronic obstructive pulmonary disease

ObjectivePatients with chronic obstructive pulmonary disease (COPD) often have abnormal ECGs. Our aim was to separate the effects on ECG by airway obstruction, emphysema and right ventricular (RV) afterload in...

ECG Features that suggest a potentially life-threatening arrhythmia as the cause for syncope

Syncope is a risk factor for sudden cardiac death (SCD) in many conditions associated with structural heart disease as well as inherited heart disease. The ECG in patients with syncope should be examined carefully for signs of structural heart disease, such as myocardial infarction or cardiomyopathy; signs of conduction system disease, such as bundle branch block or atrioventricular block; and signs of primary electrical disease. Important forms of cardiomyopathy accompanied by ECG changes include hypertrophic cardiomyopathy (HCM), and arrhythmogenic right ventricular dysplasia (ARVD/C). Common ECG findings in HCM include left ventricular hypertrophy by voltage, repolarization abnormalities, QRS widening, pseudoinfarction patterns, and slurred QRS upstroke mimicking delta waves. Classical ECG findings of ARVD/C include T-wave inversions and epsilon waves in the right precordial leads (V1–V3). Important forms of primary electrical disease which may result in syncope include Wolff–Parkinson–White syndrome, long QT syndrome, and Brugada syndrome, which is characterized by coved ST-segments in the right precordial leads, associated with a history of syncope, ventricular arrhythmia, or sudden cardiac death in probands or family member. There are three Brugada ECG patterns; however, only type I (spontaneous or induced) is considered diagnostic. Recently, studies have suggested that patients with J-point elevation or early repolarization pattern on ECG are at elevated risk of SCD. The clinical significance of finding early repolarization in a patient with syncope is unknown and should be a subject of future research.

Changes in spatial ventricular gradient and QRS-T angle induced by strict 5-days immobilization, and effects of exercise countermeasure

Purpose: The spatial QRS-T angle (SA) and ventricular gradient (SVG) are classical ECG parameters that provide information on cardiac conduction system function and on ventricular action potential duration heterogeneity. Wide SA and reduced SVG are related to pathological conditions. Our aims were: 1) to assess the effects of 5 days immobilization (-6 degrees bed-rest, BR) on SA and SVG; 2) to evaluate the effectiveness of 25 min/day standing exercise (unilateral and bilateral heel raise, bilateral squatting (60°, 90° and 120°), bilateral and cross-hopping) as possible countermeasure. Methods: 10 healthy men (mean age 30±6) were enrolled in a cross-over design (wash out period: 2 months; control, CTRL, and exercise, EXE, groups) at DLR (Cologne, Germany) as part of the European Space Agency BR studies. High fidelity (1000 Hz) Holter ECG (12-leads, Mortara Instrument) was acquired before (PRE), the last day of BR (HDT5), and four days after the BR conclusion (POST). The night period (23:00-06:30) was selected for the analysis. X,Y,Z leads were derived (inverse Dower matrix) and vectorcardiogram computed. Selective beat averaging was used to obtain averages of P-QRS-T complexes preceded by the same stable heart rate (10 msec bin amplitude, in the range 900-1200 msec). For each averaged waveform (i.e., one for each bin), Twave maximum amplitude (Tmax), VG and SVG were computed. Results: Compared to PRE, a reduction in SVG (11%±3% and 9%±1%) and corresponding widening in SA (27%±9% and 21%±5%) were found at HDT5 in both CTRL and EXE, respectively. The EXE countermeasure significantly reduced both SVG and SA changes compared to CTRL. Tmax presented the same changes, being reduced of 8%±3% in CTRL and only of 4%±2% in EXE. At POST, in both groups SA was restored to PRE values; conversely, while in EXE the SVG returned to PRE values, in CTRL it was found still reduced by 3%. Also, while Tmax was back to PRE values in EXE, it was increased by 5% in CTRL. Conclusions: Despite the short-term -6° BR immobilization, cardiac adaptation to this deconditioning condition affected ventricular repolarization during the night period, thus widening SA and reducing SVG as result of increased heterogeneity, thus increasing the risk of arrhythmia development. Selective beat averaging allowed quantifying these changes. Application of 25 min/day standing exercise reduced, but not canceled, these effects. This should be taken into account in patients with cardiovascular diseases, when immobilized in bed, to proper adjust the pharmacological therapy or set the rehabilitation training, in order to avoid further complications.

055: Improved screening for silent AF during the acute phase of myocardial infarction

Although silent Atrial Fibrillation (AF) has been suggested to be common in Acute myocardial infarction (AMI), the true incidence and characteristics of silent AF in AMI remains unknown. We aim to assess silent AF incidence and determinants, including left atrium parameters. 581 consecutive AMI were prospectively analyzed by Continuous ECG Scope Monitoring (CSM) for 48H after hospital admission. New onset AF was defined as at least 1 episode >30 sec, absence of p waves, and irregular RR intervals on CSM or absence of p waves or irregular RR intervals on 12-lead ECG, without any duration criterion. Left Atrial (LA) dimensions and Left Ventricular Ejection Fraction (LVEF) were determined on admission by echocardiography. We analyzed the study population into 3 groups: No AF, silent AF (defined as asymptomatic episodes of AF lasting at least >30 sec) and symptomatic AF (defined as symptomatic episodes of AF that lasted ≥12hours). Ninety-five (16.4%) patients had AF on CSM, of whom 76 (80%) developed silent AF. Compared with No AF group, patients with silent AF were older (80 vs 62 y; p < 0.001), more frequently women (45 vs 27%; p = 0.006), hypertensive (76% vs 52%; p < 0.001) but less smoker (18% vs 38%; p < 0.001). Moreover, they had significant LA enlargement based on indexed LA diameter (24.4 vs 20.3 mm/m 2 ; p < 0.001), and indexed left atrial volume (LAVI) (36.12 vs 26.95 ml/ m 2 ; p = 0.002). They also had impaired LVEF (46 vs 54%; p < 0.001). By multivariate analysis, age (OR (95%CI): 1.06 (1.03–1.09), CRP (OR (95%CI): 1.01(1.00–1.02) and indexed LA diameter (OR (95%CI): 2.37 (1.31–4.25) were predictors of silent AF. By ROC curve analysis, LAVI at 26.88 ml/m 2 was the best cutoff value to predict silent AF occurrence after AMI, with sensibility at 73% and specificity at 50%. In this prospective study in routine clinical practice, silent AF in AMI is very common and is mostly underdiagnosed by classical discontinued serial ECG monitoring. Left atrial parameters assessed by echocardiography, including indexed diameter and LAVI, should be evaluated on admission to predict silent AF occurrence.

The role of ST-segment elevation in lead aVR in the risk assessment of patients with acute pulmonary embolism

BACKGROUD AND AIM: Patients with acute pulmonary embolism (APE) present with highly variable symptoms and ECG abnormalities. As ST-elevation in lead aVR has recently been described to predict right ventricular dysfunction (RVD), we aimed to correlate this sign to the severity of APE. Three-hundred ninety-six consecutive patients (in centers a and b) with proven APE were retrospectively analysed with respect to 12-lead-ECG, symptoms, thrombus location, echocardiograpy, troponin T, initial therapy and outcome. Data were then compared between patients with and without aVR-ST-elevation. On admission aVR-ST-elevation was present in 34.3% (n=136). Presence of aVR-ST-elevation was assossiated with more severe clinical presentation (dyspnoea at rest 44.9 vs. 29.2%; p=0.002, hypotension 17.0 vs. 6.5%; p=0.001, syncope 16.2 vs. 6.5%; p=0.002), higher median troponin T levels (0.035 [0.01-0.2] versus 0.01 [0.01-0.02]; p<0.001), more frequent RVD (74.5 vs. 46.6%; p<0.001) and central located thrombi (50.8 vs. 29.2; p<0.001). Thrombolysis was used more frequently (29.1 vs. 7.5%; p<0.001) and in-hospital-mortality was increased (10.3 vs. 5.4%; p=0.07) when compared to patients without that sign. Mortality in intermediate-risk APE patients with aVR-ST-elevation was 8.9% compared to 0% in those without (p=0.04). In contrast, the presence of other classical ECG pattern of APE did not further increase mortality in intermediate-risk patients. ST-elevation in lead aVR is associated with a more severe course of APE, especially in patients with intermediate-risk. Therefore, aVR-ST-elevation might be useful in risk stratification of APE.

217 Six-hour holter recording of microvolt T-wave alternans and heart rate turbulence in the CCU compared to classical 24-hour ambulatory ECG

T-wave alternans (TWA) and heart rate turbulence (HRT) measured during 24 hour-ECG recordings are 2 powerful non-invasive tools to risk-stratify cardiovascular patients. The aim of our study is to assess whether a fast ECG-holter scan yields different information from classical 24-hour ambulatory ECG regarding TWA and HRT measurements. All consecutive 21 patients with a non-ST-elevated myocardial infarction and admitted in intensive care unit of cardiology, have been monitored with an ECG-holter for classical, TWA and HRT analysis over 24 hours. TWA has been measured with the modified moving average method. Routine reading of the holters has been followed by a specific analysis. Each 24-hour period has been divided into four equal periods. Maximal TWA, T-onset and T-slope for HRT over those four 6-hour periods have been analyzed and compared with full day results using a repeated measures analysis of variance (ANOVA). 16 men and 5 women aged between 31 and 90 (mean 57.5 +/− 24.8) have been included. Mean maximal TWA was 73 ± 25 μV. 6-hour maximal TWA was 59 +/− 23 μV, 55 +/− 26 μV, 56 +/− 30.01 and 48 +/− 23.27 μV (p = 0.11). HRT as assessed by T onset and T slope were −0.00619% +/− 0.02, 0.00333% +/− 0.04, 0.00571% +/− 0.03, −0.00952% +/− 0.03 (p = 0.46) and 3.75 +/− 3.99, 5.46 +/− 7.29, 6.32 +/− 9.13, 5.96 +/− 10.85 (p = 0.46) respectively for each time period. This preliminary study suggests that a 6-hour ECG-Holter recording could be a reliable and feasible method to assess cardiovascular mortality and risk of SCD in patients admitted for an acute coronary syndrome in intensive care unit by studying TWA and HRT. Faster risk stratification could thus be done during hospitalization in order to optimize therapeutics and better identify candidate for fast ICU discharge.

Valor pronóstico del electrocardiograma en pacientes con diabetes tipo 2 sin enfermedad cardiovascular conocida

The predictive value of ECG abnormalities in patients with type-2 diabetes mellitus (DM2) has not been fully studied. Our objective was to assess the prognostic value of ECG abnormalities in patients with DM2 but without known cardiovascular disease. Overall, 412 patients with DM2 were identified at two primary care centers in the same city. Two hundred and twenty one patients younger 80 years without known cardiovascular disease were included in the study. An ECG was recorded at baseline and annually during follow-up. The ECGs were evaluated using a system based on the Minnesota code. The main study end-point during follow-up was the occurrence of a cardiovascular event, as defined in the Framingham study. The mean follow-up duration was 5.9 years (1.1-8.5 years). At the beginning of the study, 24.9% of patients had ECG abnormalities; at the end, 44.3% had abnormalities. Cardiovascular events occurred in 65 patients (29.4%). The relative risk (RR) of a cardiovascular event in a patient with an ECG abnormality was 8.28 (95% confidence interval [CI], 3.36-20.42). Only hypertension (RR = 2.29; 95% CI, 1.24-4.22) and age were significantly related to the occurrence of a cardiovascular event. Multiple regression analysis that included classical risk factors and ECG findings showed that an ECG abnormality was a significant independent predictor, with adjusted RR = 5.95 (95% CI, 2.29-15.47). The presence of an ECG abnormality can predict the occurrence of a future cardiovascular event in patients with DM2 more accurately than risk factors alone. This finding could be helpful in selecting subgroups of high-risk diabetic patients.

Desmoglein-2 mutations in arrhythmogenic right ventricular cardiomyopathy: a genotype-phenotype characterization of familial disease

Mutations in the desmoglein-2 (DSG2) gene have been reported in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) but clinical information regarding the associated phenotype is at present limited. In this study, we aimed to clinically characterize probands and family members carrying a DSG2 mutation. We investigated 86 Caucasian ARVC patients for mutations in DSG2 by direct sequencing and detected eight novel mutations in nine probands. Clinical evaluation of family members with DSG2 mutations demonstrated penetrance of 58% using Task Force criteria, or 75% using proposed modified criteria. Morphological abnormalities of the right ventricle were evident in 66% of gene carriers, left ventricular (LV) involvement in 25%, and classical right precordial T-wave inversion only in 26%. Sustained ventricular arrhythmia was present in 8% and a family history of sudden death/aborted sudden death in 66%. Mutations in DSG2 display a high degree of penetrance. Disease expression was of variable severity with LV involvement a prominent feature. The low prevalence of classical ECG changes highlights the need to expand current diagnostic criteria to take account of LV disease, childhood disease expression, and incomplete penetrance.

Cardiac troponin in the general adult critical care unit: solution or problem

Cardiac troponin T (cTnT) and troponin I (cTnI) are the most sensitive and specific biochemical markers of myocardial injury available, but do not indicate the mechanism of such injury [1]. There are many problems with their interpretation in the critical care setting. A recent editorial has highlighted that frequent determination of troponin in the ICU patient can lead to 'troponinitis'! [2]. The editorial quotes various studies, including those showing association between elevated cTnI levels and mortality. After analysis of 346 samples measured over 22 months from our general adult ICU (annual admissions 850), we also found a statistical relationship between levels of elevated cTnI and both ICU and hospital mortality (Table ​(Table1)1) using chi-square testing. However, we have not found this to be clinically significant. A hospital mortality of 51.2% may be high, but not so high as to precipitate the withdrawal of intensive care treatment. Table 1 Due to the low specificity and positive predictive value of cTnI in mixed adult general critical care patients, it is difficult for us as intensivists to place elevated troponin levels in their clinical context. We also have difficulty in using elevated troponin levels to influence patient management in the absence of a classical history and ECG changes. Thrombolysis, ACE-inhibitors and β-blockers can be doubled-edged swords in the critically ill; echocardiography in the resting patient provides scant meaningful information; a pulmonary artery catheter is invasive – and all this before we consider the risks associated with coronary angiography. We therefore believe that cardiac troponins in a mixed adult ICU should only be requested when it could confirm an acute coronary syndrome. In the ICU setting, this would almost always entail obtaining new ECG changes before requesting a cTnI level.

Electrocardiographic Changes during Hemodiafiltration with Different Potassium Removal Rates

Background/Aims: Sudden K removal is thought to be implicated in ECG alterations observed during hemodialysis (HD). The effects of the K removal rate on ECG-derived parameters have been investigated. Methods: Two different hemodiafiltration (HDF) schedules were used for 10 HD patients: the dialysate K concentration was kept constant in HDF_st, while in HDF_K it was decreased during the session in order to maintain a uniform plasma-dialysate K gradient. A 12-lead Holter monitor was used to acquire the ECG in the course of the treatments. Classical ECG parameters and overall indices for quantifying ventricular repolarization abnormalities were evaluated. Results: Several ECG parameters were affected by both HD therapies (ST depression, QRS amplitude and QT dispersion), but only indices of the homogeneity of repolarization (PCA-T, E1-T) were significantly affected by the K removal rate. Conclusion: The present study confirms the large impact of HD therapy on ECG. The analysis of the spatial T wave complexity points out the intrinsic arrhythmogenic implications of the K removal rate.