Novel electrocardiographic criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy.

AIMS: In order to improve the electrocardiographic (ECG) diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC), we evaluated novel quantitative parameters of the QRS complex and the value of bipolar chest leads (CF leads) computed from the standard 12 leads. METHODS AND RESULTS: We analysed digital 12-lead ECGs in 44 patients with ARVC, 276 healthy subjects including 44 age and sex-matched with the patients and 36 genotyped members of ARVC families. The length and area of the terminal S wave in V1 to V3 were measured automatically using a common for all 12 leads QRS end. T wave negativity was assessed in V1 to V6 and in the bipolar CF leads computed from the standard 12 leads. The length and area of the terminal S wave were significantly shorter, whereas the S wave duration was significantly longer in ARVC patients compared with matched controls. Among members of ARVC families, those with mutations (n = 15) had shorter QRS length in V2 and V3 and smaller QRS area in lead V2 compared with those without mutations (n = 20). In ARVC patients, the CF leads were diagnostically superior to the standard unipolar precordial leads. Terminal S wave duration in V1 >48 ms or major T wave negativity in CF leads separated ARVC patients from matched controls with 90% sensitivity and 86% specificity. CONCLUSION: The terminal S wave length and area in the right precordial leads are diagnostically useful and suitable for automatic analysis in ARVC. The CF leads are diagnostically superior to the unipolar precordial leads.

Resting heart rate, heart rate variability and functional decline in old age.

BACKGROUND: Heart rate and heart rate variability, markers of cardiac autonomic function, have been linked with cardiovascular disease. We investigated whether heart rate and heart rate variability are associated with functional status in older adults, independent of cardiovascular disease. METHODS: We obtained data from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER). A total of 5042 participants were included in the present study, and mean follow-up was 3.2 years. Heart rate and heart rate variability were derived from baseline 10-second electrocardiograms. Heart rate variability was defined as the standard deviation of normal-to-normal RR intervals (SDNN). Functional status in basic (ADL) and instrumental (IADL) activities of daily living was measured using Barthel and Lawton scales, at baseline and during follow-up. RESULTS: The mean age of the study population was 75.3 years. At baseline, higher heart rate was associated with worse ADL and IADL, and lower SDNN was related to worse IADL (all p values < 0.05). Participants in the highest tertile of heart rate (range 71-117 beats/min) had a 1.79-fold (95% confidence interval [CI] 1.45-2.22) and 1.35-fold (95% CI 1.12-1.63) higher risk of decline in ADL and IADL, respectively (p for trend < 0.001 and 0.001, respectively). Participants in the lowest tertile of SDNN (range 1.70-13.30 ms) had 1.21-fold (95% CI 1.00-1.46) and 1.25-fold (95% CI 1.05-1.48) higher risk of decline in ADL and IADL, respectively (both p for trends < 0.05). All associations were independent of sex, medications, cardiovascular risk factors and comorbidities. INTERPRETATION: Higher resting heart rate and lower heart rate variability were associated with worse functional status and with higher risk of future functional decline in older adults, independent of cardiovascular disease. This study provides insight into the role of cardiac autonomic function in the development of functional decline.

Automatic detection of end QRS notching or slurring.

The purpose of this study was to define criteria suited to automated detection of end QRS notching and slurring and to evaluate their accuracy. One hundred resting 12 lead ECGs from young adult men, split randomly into equal training and test sets, were examined independently by two reviewers for the presence of such notching or slurring. Consensus was reached by re-examination. Logic was added to the Glasgow resting ECG program to automate the detection of the phenomenon. After training, the automated detection had a sensitivity (SE) of 92.1% and a specificity (SP) of 96.6%. For the test set, SE was 90.5%, SP 96.5%. Two populations of healthy subjects--one Caucasian, one Nigerian--were analysed using the automated method. The prevalence of notching/slurring with peak/onset amplitude respectively ≥ 0.1 mV in two contiguous inferolateral leads was 23% and 29% respectively. In conclusion, the detection of end QRS notching or slurring can be automated with a high degree of accuracy.

J wave patterns--morphology, prevalence and nomenclature.

The recent resurgence of interest in early repolarization has demonstrated a variation in the definition of the term and a consequent variation in the prevalence of the pattern in different studies. This can vary from 35% in males and 21.5% in females if ST elevation is not considered part of the definition, to 3.3% and 0.5% in females with the inclusion of ST elevation. In contrast, the prevalence of the Brugada Syndrome is in the order of 0.1%-0.2% in Japan for example and has been found to be significantly lower in Denmark. Standardisation of measurement definitions, particularly for early repolarisation, is required.

Normal limits of the electrocardiogram in Nigerians.

BACKGROUND: There has been no large study of ECG measures derived by automated methods in an apparently healthy indigenous West African population. METHODS: ECGs were recorded from apparently healthy Nigerians and analysed using automated methods. Age and sex based normal ranges were then established. RESULTS: A total of 782 males and 479 females aged between 20 and 87years were studied. Mean QRS duration in males was 87.9±9.4ms and 83.4±7.6ms in females (P<.0001). Mean QTc (Hodges) was 393±16ms in males and 406±16ms in females (P<.0001). The Cornell index (SV3+RaVL) was higher in males and decreased with increasing age in males though the reverse was true in females (P<.0001). STj amplitude was lower in older compared to younger males and higher in males. CONCLUSION: This is the first large study of automated ECG measurements from healthy blacks living in West Africa which allows the determination of ECG normal limits in such a population.

Spatial QRS-T Angle and Cognitive Decline in Older Subjects.

BACKGROUND: An abnormally wide spatial QRS-T angle on an ECG is a marker of heterogeneity in electrical activity of cardiac ventricles and is linked with cardiovascular events. Growing evidence suggests that cardiac dysfunction might signal future cognitive decline. OBJECTIVE: In this study, we investigated whether spatial QRS-T angle associates with future cognitive decline in older subjects at high cardiovascular risk. METHODS: We included 4,172 men and women (mean age 75.2±3.3 years) free of cardiac arrhythmias from the PROSPER cohort. Spatial QRS-T angle was calculated from baseline 12-lead ECGs using a matrix transformation method. Cognitive function was assessed using 4 neuropsychological tests including Stroop test, letter-digit coding test, immediate and delayed picture word learning tests. Cognitive function was assessed at baseline and repeatedly during a mean follow-up time of 3.2 years. Using linear mixed models, we calculated the annual changes of cognitive scores in sex-specific thirds of spatial QRS-T angle. RESULTS: Participants with wider spatial QRS-T angle had a steeper decline in letter-digit coding test (ß= -0.0106, p = 0.004), immediate picture-word learning test (ß= -0.0049, p = 0.001), and delayed picture-word learning test (ß= -0.0055, p = 0.013). All associations were independent of arrhythmias, cardiovascular risk factors, comorbidities, medication use, cardiovascular events, and other ECG abnormalities including QRS duration, QTc interval, T wave abnormalities, and left ventricular hypertrophy. CONCLUSION: Abnormal cardiac electrical activity characterized by wide spatial QRS-T angle associates with accelerated cognitive decline independent of conventional cardiovascular factors. These findings suggest a link between a non-traditional ECG measure of pre-clinical cardiac pathology and future cognitive decline.

Left Ventricular Hypertrophy and Cognitive Decline in Old Age.

BACKGROUND: Patients with advanced heart failure run a greater risk of dementia. Whether early cardiac structural changes also associate with cognitive decline is yet to be determined. OBJECTIVE: We tested whether left ventricular hypertrophy (LVH) derived from electrocardiogram associates with cognitive decline in older subjects at risk of cardiovascular disease. METHODS: We included 4,233 participants (mean age 75.2 years, 47.8% male) from PROSPER (PROspective Study of Pravastatin in the Elderly at Risk). LVH was assessed from baseline electrocardiograms by measuring the Sokolow-Lyon index. Higher levels of Sokolow-Lyon index indicate higher degrees of LVH. Cognitive domains involving selective attention, processing speed, and immediate and delayed memory were measured at baseline and repeated during a mean follow-up of 3.2 years. RESULTS: At baseline, LVH was not associated with worse cognitive function. During follow-up, participants with higher levels of LVH had a steeper decline in cognitive function including in selective attention (p = 0.009), processing speed (p = 0.010), immediate memory (p < 0.001), and delayed memory (p = 0.002). These associations were independent of cardiovascular risk factors, co-morbidities, and medications. CONCLUSION: LVH assessed by electrocardiogram associates with steeper decline in cognitive function of older subjects independent of cardiovascular risk factors and co-morbidities. This study provides further evidence on the link between subclinical cardiac structural changes and cognitive decline in older subjects.

10-Second heart rate variability and cognitive function in old age.

OBJECTIVE: To investigate the cross-sectional and longitudinal associations of 10-second heart rate variability (HRV) with various domains of cognitive function in older participants at risk of cardiovascular disease. METHODS: We studied 3,583 participants, mean age of 75.0 years, who were enrolled in the Prospective Study of Pravastatin in the Elderly at Risk. From baseline 10-second ECGs, standard deviation of normal-to-normal intervals was calculated as the index of HRV. Four cognitive domains were assessed at baseline and repeated during a mean follow-up period of 3.2 years. RESULTS: Lower HRV at baseline was associated with worse performance in reaction time (mean difference between low third vs high third of HRV = 1.96 seconds, 95% confidence interval [CI] 0.20 to 3.71) and processing speed (-0.57 digits coded, 95% CI -1.09 to -0.05). During follow-up, participants with lower HRV had a steeper decline in processing speed (mean annual change between low third vs high third of HRV = -0.16 digits coded, 95% CI -0.28 to -0.04). There was no difference in annual changes of reaction time or immediate and delayed memory among HRV thirds during follow-up. All these associations remained unchanged after adjustment for medications, cardiovascular risk factors, and comorbidities. CONCLUSIONS: Participants with lower 10-second HRV have worse performance in reaction time and processing speed and experience steeper decline in their processing speed, independent of medications, cardiovascular risk factors, and comorbidities.

Automated electrocardiogram interpretation programs versus cardiologists' triage decision making based on teletransmitted data in patients with suspected acute coronary syndrome.

The aims of this study were to assess the effectiveness of 2 automated electrocardiogram interpretation programs in patients with suspected acute coronary syndrome transported to hospital by ambulance in 1 rural region of Denmark with hospital discharge diagnosis used as the gold standard and to assess the effectiveness of cardiologists' triage decisions for these patients based on initial electrocardiogram. Twelve-lead electrocardiograms were recorded in ambulances using a LIFEPAK 12 monitor/defibrillator (Physio-Control, Inc., Redmond, Washington) and transmitted digitally to an attending cardiologist. If a diagnosis of ST elevation myocardial infarction was made, a patient was taken to a regional interventional center for primary percutaneous coronary intervention or to a local hospital. One thousand consecutive digital electrocardiograms and corresponding interpretations from LIFEPAK 12 were available, and these were subsequently interpreted by the University of Glasgow program. Electrocardiogram interpretations and cardiologists' decisions were compared to hospital discharge diagnoses. The sensitivity, specificity, and positive predictive values for a report of ST elevation myocardial infarction with respect to discharge diagnosis were 78%, 91%, and 81% for LIFEPAK 12 and 78%, 94%, and 87% for the Glasgow program. Corresponding data for attending cardiologists were 85%, 90%, and 81%. In conclusion, the Glasgow program had significantly higher specificity than the LIFEPAK 12 program (p = 0.02) and the cardiologists (p = 0.004). Triage decisions were effective, with good agreement between cardiologists' decisions and discharge diagnoses.

Diagnosis of acute myocardial ischaemia using probabilistic methods.

BACKGROUND: The present study was undertaken to test the effectiveness of an established equation for estimating the probability of acute cardiac ischaemia, but in an environment different from that in which it was developed. METHODS AND RESULTS: A total of 255 patients who presented to the accident and emergency department of Glasgow Royal Infirmary with symptoms suggesting acute ischaemic heart disease were enrolled in the study. Their clinical data and ECG measurements were used as input to the Time-Insensitive Predictive Instrument (TIPI) equation to calculate the probability of acute myocardial ischaemia being present. Receiver operating characteristic (ROC) curves were derived to evaluate the usefulness of the equation in diagnosing acute myocardial infarction versus nonmyocardial infarction and acute cardiac ischaemia verses nonischaemic chest pain. For the diagnosis of acute cardiac ischaemia versus noncardiac chest pain, the area under the ROC curve was 0.61 (95% CI 0.55-0.67). For the diagnosis of acute myocardial infarction versus nonmyocardial infarction, there was increased performance with the area under the ROC curve being 0.71 (95% CI 0.65-0.76). This compares with the originally published findings of a value of 0.88 for the area under the curve for the diagnosis of acute myocardial ischaemia versus noncardiac chest pain. CONCLUSION: The study suggests that equations for the diagnosis of acute cardiac ischaemia developed in one centre may not readily translate elsewhere, possibly due to varying interpretations of the clinical and ECG criteria used.