What's new in cardiovascular prevention?

This review is essentially a summary of the 2007 version of the European guidelines on cardiovascular disease prevention in clinical practice recently published by the 4th JointTask Force. New data from the guidelines in the fields of the general objectives in lifestyle modifications and drug therapies are emphasised. Recent studies on antioxydant vitamins, homocysteine-lowering vitamins and HDL-Cholesterol raising drugs are also being discussed.

Computer-assisted study of ECG indices of the dispersion of ventricular repolarization.

A new computer-assisted method for the quantitative assessment of the dispersion of ventricular repolarization (DVR) has been developed. Through interactive editing of an averaged QRS-T cycle from a 15-lead electrocardiographic (ECG) record (12-lead ECG + XYZ leads), five ECG indices of DVR are automatically computed: they represent the maximal interlead difference of QT and the intervals from the J point to the T wave end, from the J point to the T wave apex, and from the T wave apex to the T wave end. The standard limits of these indices were then established in six clinical groups, including normal subjects and patients with left ventricular hypertrophy, with myocardial infarction, and with intraventricular conduction defect, all subjects being without ventricular arrhythmias and without interacting drugs. The mean values and percentile ranges of all DVR indices were lower in the normal group than in all pathologic groups. The 97.5th percentiles of the QT end dispersion and the JT end dispersion were, respectively, 65 and 76 ms in normal subjects, 84 and 86 ms in patients with inferior MI; 89 and 100 ms in those with anterior MI; 90 and 98 ms in those with left ventricular hypertrophy; and 94 and 99 ms in those with intraventricular conduction defects. This suggests that increased DVR is associated with the varieties of heart disease represented in this study, even in the absence of ventricular arrhythmias, and also that individual measurements of DVR used as predictors of future arrhythmic events should be referred to the standard range of their own clinical group.

Evaluation of ECG interpretation results obtained by computer and cardiologists.

In an international project investigators from 25 institutes are trying to establish a common reference library and evaluation methods for testing the diagnostic performance of various ECG computer programs and of cardiologists, based on ECG-independent clinical information. A first set of 500 validated ECGs was collected and analyzed by fifteen different computer programs and nine cardiologists, seven of who analysed the ECG and five the VCG. A coding scheme was used to map individual diagnostic statements onto a common set. Combined program and referee results were obtained by weighted averaging. Preliminary results indicate that the classification accuracy of several programs can still be improved. However, it was also apparent that the results of the best 12-lead ECG computer programs proved to be almost as accurate as the best of seven cardiologists in classifying seven main disease categories, i.e., normal, left, right and biventricular hypertrophy, anterior, inferior and combined myocardial infarction. Evaluation of rhythm statements and conduction disturbances was not included in the study. The data collection is still being pursued in order to reach over 1,000 cases. In this way a common diagnostic database is being established for comparative testing of diagnostic computer programs. This should lead to consumer protection and improve the accuracy and reliability of computerized electrocardiography.

Methodology of ECG interpretation in the Louvain program.

The Louvain program performs the analysis and interpretation of the vectorcardiogram (VCG) to increase the clinical utility of ECG analysis. Among its original features, there are (1) a high-resolution vector-loop display for visual analysis, (2) quantitative analysis of the spatial VCG using age-sex stratified limits, (3) separate software for adult and pediatric series and (4) complementary deterministic and statistical methods of diagnostic classification. Using objective, ECG-independent evidence as a reference standard, the Louvain program has shown satisfactory levels of diagnostic accuracy in most basic categories. However, its usefulness is especially marked in "borderline" or "complex" situations, where the 12-lead ECG cannot provide a clear answer. It corresponds to the concept of "computer-assisted ECG interpretation" as opposed to "computer ECG analysis".

Non-invasive data provide independent prognostic information in patients with chest pain without previous myocardial infarction: findings in male patients who have had cardiac catheterization.

From 1978 to 1985, 470 consecutive male patients with complaints of chest pain underwent a maximal exercise test with a thallium scan and coronary angiography (CA). Patients with a history of myocardial infarction (MI) were excluded. During the follow-up (from 12 to 96 months), 32 patients died and 30 had a non-fatal MI. Survival (SR) and event-free rates (EFR) were estimated by actuarial methods; the influence of non-invasive and invasive variables were examined in univariate and multivariate models using Cox analysis. The five-year SR was 89% and EFR was 81%. Among historical data, age (less than 0.001), type of complaints (less than 0.01) and pretest likelihood of CAD (less than 0.01) were univariate predictors of EFR; by multivariate analysis, age was the only significant predictor (less than 0.001). Most of the maximal-exercise (MEX) test data were good univariate predictors; by multivariate analysis, workload (less than 0.001) and the maximal-exercise test score (less than 0.001) were the significant predictors. From history and maximal-exercise test data, multivariate analysis indicated that the prognostic information was given by age (less than 0.05) and maximal-exercise test score (less than 0.001). Among the invasive data, the number of diseased vessels (less than 0.001) and ejection fraction were the predictors. The combination of invasive and non-invasive data indicated that age, MEX score, number of diseased vessels and ejection fraction contributed significantly and independently to the estimation of prognosis. Among 242 patients with two or three diseased vessels, the prognosis was determined by the maximal workload (less than 0.01); ejection fraction (less than 0.07) was no longer significant.(ABSTRACT TRUNCATED AT 250 WORDS)

[Left ventricle in Noonan's syndrome. Electro-vecto-echo and angiocardiographic aspects]. / Le ventricule gauche dans le syndrome de Noonan. Aspects électro-vecto-écho et angio-cardiographiques.

The electrocardiographic features of Noonan's syndrome have been known for several years, but the discordance between these electrical findings and the underlying haemodynamic disorders remains unexplained. In an attempt to elucidate the genesis of electrical abnormalities, we present here a retrospective study of 14 children with Noonan's disease, aged from a few days to 16 years and evaluated by electrocardiography, vectography, one- or two-dimensional echocardiography, angiography and His bundle electrophysiology. The electrocardiographic abnormalities observed concerned ventricular depolarization and intracardiac electric conduction with, notably, a QRS axis directed towards the right upper part of the electric field and a first degree infra-hisian atrioventricular block (His bundle potentials). Vectography showed in some cases an image of inferior pseudo-necrosis due to the absence of initial inferior forces; this image is highly characteristic. In other cases the QRS loop showed an image of left segmental block which is unusual in this type or cardiac pathology (pulmonary stenosis with or without atrial septal defect of the ostium secundum type).

The normal pediatric Frank orthogonal electrocardiogram: variations according to age and sex.

Quantitative computerized analysis of QRS and ST-T parameters of the Frank orthogonal electrocardiogram and vectorcardiogram was undertaken in a large series of 1317 normal infants, children and adolescents stratified according to age and sex. This study confirms the influence of these two constitutional variables, age and sex, over the normal VCG in the whole time span between birth and late adolescence. As children mature, the mid-portion of the spatial QRS loop shifts leftward and posteriorly with relatively little change in the initial and terminal vectors. The spatial T loop shifts anteriorly but at a different rate in males and in females. Unidirectional changes in many amplitude parameters are observed until age 19 in males whereas in females these changes stop earlier or even show a reverse trend around puberty, leading to more important differences between adolescent males and females. Sex-related differences are the most marked for parameters representing the repolarization process. Infants under six months of age form a distinct group with larger dispersions and more disparate variations in the values of vectorcardiographic parameters than in older children. In the newborn period larger sample size might be necessary in order to reduce the normal ranges of vectorcardiographic parameters.

The normal pediatric Frank orthogonal electrocardiogram: influence of weight, height and chest circumference.

The influence of body weight, height and chest circumference on the pediatric Frank vectorcardiogram (VCG) was investigated in a population of 1317 normal infants, children and adolescents. Simple linear regression analysis showed that 94, 96 and 57 VCG variables were significantly correlated with weight, height and chest circumference, respectively. These numbers were reduced to 10, 18 and 6 VCG variables after a stepwise multiple correlation analysis. The relationship between the VCG and the somatic variables was also studied in ten different age/sex subgroups. Simple regression analysis showed a residual significant correlation between the VCG and all three somatic variables in each group. The multiple correlation analysis allowed us to define a minimum set of VCG variables, from one to six, which could explain all the variation produced by the somatic variables. The coefficient of multiple correlation between VCG and weight was the highest in babies 0 to 6 months old (R = 0.73). For height, the strongest correlation was found in females two to five years old (R = 0.76). In subjects older than two years of age, the correlation between chest circumference and VCG (R = 0.30 to 0.69) was weaker than between VCG and pediatric VCG after stratification for age and sex, especially in the youngest groups.

Diagnostic value of computerized exercise testing in men without previous myocardial infarction. A multivariate, compartmental and probabilistic approach.

The value of exercise testing for the diagnosis of coronary artery disease is disputed but very few studies have taken advantage of all recent improvements, namely computer averaging of the ECG signals, multivariate analysis of the data, a compartmental diagnostic approach and probabilistic interpretation of the results. These methods were tested in a group of 387 men who had a computer-assisted multistage maximal exercise test; none had a history of myocardial infarction. In 284 symptomatic patients, the diagnosis was made by arteriography; 103 ostensibly healthy men were also included. The computer-averaged ECG signals (X, Y, Z) recorded at maximal exercise, maximal heart rate, blood pressure and workload, and the onset of angina pectoris during exercise were submitted to a multivariate stepwise discriminant analysis. The pretest likelihood for CAD was calculated from age and history; the post-test likelihood was calculated from Bayes' theorem and the average information content of several diagnostic methods was assessed in categorical and compartmental models. By multivariate analysis, 5 variables collected at maximal exercise were selected, namely the heart-rate, the ST60 segment level, the onset of angina during the test, the workload and the slope of the ST segment in lead X. The average information content of the analysis using 5 variables was 44% in a categorical model versus 55% in a compartmental model (P less than 0.001). For comparison, the information content of the analysis using the ST60 segment level alone was only 16% in the categorical model and 27% in the compartmental model. The clinical value of these diagnostic methods (categorical versus compartmental, univariate versus multivariate) was assessed by a probabilistic classification of the patients. The classification provided by the analysis of the ST60 segment changes was barely better than that one provided by the simple history. The probabilistic use of a multivariate and compartmental analysis of the data led to a significantly better and more accurate classification of the patients (83% of correct classification).

Computer interpretation of pediatric orthogonal electrocardiograms: statistical and deterministic classification methods.

Statistical multivariate and conventional deterministic methods of computerized interpretation of the electrocardiogram (ECG) were compared in the analysis of 1711 pediatric orthogonal ECGs validated by nonelectrocardiographic criteria on the basis of clinical and anatomic diagnoses. Among 642 children catheterized for the evaluation of congenital heart disease, there were 140 patients with left ventricular hypertrophy, 299 with right ventricular hypertrophy, and 203 with biventricular hypertrophy. A group of 1069 obviously healthy school children was studied as a control. The overall accuracy of multigroup ECG diagnosis was 85% and 79% for the statistical and deterministic methods, respectively. The diagnostic performances of both methods expressed in terms of sensitivity and predictive value were the highest for normal children and those with right ventricular hypertrophy and lowest for children with biventricular hypertrophy. The statistical method was more sensitive in the diagnosis of left ventricular hypertrophy (74% vs 64%), right ventricular hypertrophy (86% vs 83%), and biventricular hypertrophy (62% vs 50%). Mutual agreement for a correct diagnosis by the two methods was 83% for normal children and 82% for those with right ventricular hypertrophy but only 61% for children with left ventricular hypertrophy and 39% for those with biventricular hypertrophy. In conclusion, better classification results are obtained with statistical multivariate techniques as compared with conventional deterministic analysis, but both methods of ECG interpretation are complementary and their combination in the same electrocardiographic computer program can improve diagnostic accuracy.

Normal limits of pediatric Frank lead electrocardiograms. Differences in data obtained in 4th or 5th intercostal spaces.

Frank lead electrocardiograms (VCGs) were recorded from 970 young subjects in order to establish normal limits for pediatric VCGs. In 245 children and 231 adolescents, the thoracic electrodes were located at the levels of the 4th and of the 5th intercostal space with subjects in supine position. Pairwise comparisons of 211 linear and angular parameters were made, using the 4th interspace as the reference. In children, there were 155 parameters with statistically significant differences and 56 parameters without significant differences between levels 4 and 5. In adolescents, corresponding figures were 158 parameters with significant differences and 53 without. Results for selected measurements showed an increase of the amplitude of Q and R waves in leads X and Y, a decrease of Q and R waves in lead Z and an increase of maximal spatial and planar QRS vectors, with the QRS loop being more anteriorly oriented by shifting the electrodes from level 4 to level 5. The mean differences in amplitude and orientation were generally small and of little practical value. However, the percentile distribution of the differences indicated that substantial changes in either direction can occur in some subjects. Thus, quantitative analysis of the pediatric Frank VCGs can be critically affected by modification of electrode placement. It is suggested that normal limits should be determined for each recording level and that criteria for analysis should be applied only to VCGs recorded at the same specified level.

[Evaluation of tolerance of a modified protein diet in obese subjects]. / Evaluation de la tolérance d'une diète protidique modifiée chez les sujets obèses.

The purpose of this investigation was to evaluate the benefits and the potential risks of a very low calorie protein-diet in obese patients with metabolic abnormalities and at increased cardiovascular risk. To this end, the 420 kcal diet (with 50% of energy as protein) was administered for 10 days to 10 grossly obese subjects with glucose intolerance, hyperlipemia, arterial hypertension, ischemic cardiopathy and thrombotic risk related to high levels of fibrinogen factor VIII and reduced fibrinolytic activity. Weights loss averaged 360 g/day with a mean protein loss of 17 g/day occurring essentially during the very early phase of the diet. There was a rapid normalisation of blood pressure, plasma lipids and glycaemia. With the exception of a slightly negative potassium balance other ion remained in balance. There was no change in electrocardiogram, in parameters of blood coagulation or in hepatic and renal function. There was only a moderate increase in ketonaemia and plasma urate. It appears therefore, that an 8 to 10 day very low calorie protein-diet is well tolerated even in obese patients with increased cardiovascular risk, and that it corrects of several metabolic abnormalities without alteration in cardiac, hepatic or renal function.

Computer interpretation of pediatric Frank vectorcardiograms in the evaluation of congenital heart disease.

The evaluation of a new computer program for analysis and interpretation of pediatric Frank vectorcardiograms is reported. The program includes extensive age- and sex-dependent criteria based on tables of limits for numerous vectorcardiographic parameters. In 728 catheterized patients, the diagnostic performance for type A statements was tested against independent and objective evidence obtained from hemodynamic and angiographic data. The overall diagnostic accuracy ranged from 75 to 89% without difference between children less than 2 years of age and those greater than or equal to 2 years of age. Sensitivities and specificities of the various diagnoses did not differ much between the 2 age groups. In the younger children, the accuracy of a positive diagnosis of left ventricular hypertrophy, right ventricular hypertrophy, and biventricular hypertrophy was 20, 15, and 32% higher, respectively, than in the older children. The accuracy of the diagnosis "normal" was 28% lower in the younger children. These differences were explained by the higher proportion of pathologic findings in the younger children: 93% versus 74% in the older children. Given the strict methods of the evaluation, the diagnostic accuracy of this pediatric program was considered clinically satisfactory. Program performance appears to be dependent not on patient age but on prevalence of abnormalities in the population analyzed. Further improvement can be expected by making the criteria more adaptable to the composition of the population.

Reassessment of the relation between QRS forces of the orthogonal electrocardiogram and left ventricular ejection fraction.

Previous studies have demonstrated the existence of a strong positive correlation between the amplitude of QRS forces of the orthogonal electrocardiogram and the angiographically determined left ventricular ejection fraction. In a large group of patients evaluated for chest pain, we examined the relationship between the arithmetic summation of RX + RY + QZ (sigma R), the maximal and mean spatial QRS vectors and the ejection fraction (EF). In a total of 252 patients, there was a statistically significant correlation between sigma R and EF but a low correlation coefficient value (r:0.22, P less than 0.001). This relationship was essentially due to the group of patients with coronary artery disease and myocardial infarction (r:0.24, P less than 0.015) whereas there was no correlation in the group of normal subjects or in patients with coronary artery disease without myocardial infarction. In the group with myocardial infarction, a significant correlation between sigma R and EF existed only in patients with anterior myocardial infarction (r:0.41, P less than 0.025). In conclusion, both ejection fraction and amplitude of QRS forces decrease in coronary artery disease especially when an anterior myocardial infarction is present. However, despite the positive association between these angiographic and electrocardiographic indices, the low value of the correlation coefficient indicates that it is not possible to predict ejection fraction from the value of sigma R in individual patients.

Clinical evaluation of automated processing of electrocardiograms by the Veterans Administration program (AVA 3.4).

Automated processing of electrocardiograms by the Veterans Administration program was evaluated for both agreement with physician interpretation and interpretative accuracy as assessed with nonelectrocardiographic criteria. One thousand unselected electrocardiograms were analyzed by two reviewer groups, one familiar and the other unfamiliar with the computer program. A significant number of measurement errors involving repolarization changes and left axis deviation occurred; however, interpretative disagreements related to statistical decision were largely language-related. Use of a printout with a more traditional format resulted in agreement with physician interpretation by both reviewer groups in more than 80 percent of cases. Overall sensitivity based on agreement with nonelectrocardiographic criteria was significantly greater with use of the computer program than with use of the conventional criteria utilized by the reviewers. This difference was particularly evident in the subgroup analysis of myocardial infarction and left ventricular hypertrophy. The degree of overdiagnosis of left ventricular hypertrophy and posteroinferior infarction was initially unacceptable, but this difficulty was corrected by adjustment of probabilities. Clinical acceptability of the Veterans Administration program appears to require greater physician education than that needed for other computer programs of electrocardiographic analysis; the flexibility of interpretation by statistical decision offers the potential for better diagnostic accuracy.

Vectorcardiographic diagnosis of right ventricular hypertrophy in the presence of right bundle branch block in young subjects.

Two groups of young patients, one with right bundle branch block complicated by right ventricular hypertrophy due to congenital heart disease, the other with right bundle branch block and no right ventricular hypertrophy, could be separated on the basis of a few quantitative vectorcardiographic and electrocardiographic criteria. Vectorcardiographic criteria proved better than electrocardiographic criteria in detecting right ventricular hypertropy in individual patients with complete right bundle branch block. Criteria based on the configuration of the QRS loop were also specific but much less sensitive for the diagnosis of this association. In a similar population, that is, young patients with postoperative right bundle branch block, the existence of a residual right ventricular overload would be strongly suggested by the presence of any one of the following criteria: (1) a clockwise rotation of the QRS loop in the horizontal plane, (2) a ratio of the magnitude of the R wave to that of the S wave (R/S ratio) in lead X at less than 2.0, (3) a mean QRS vector in lead X more negative than--10 mv.msec, or (4) a maximal QRS vector located between 90 degrees and 270 degrees in the horizontal plane. In contrast, an R/S ratio in lead X that was equal or superior to 2.0 or an azimuth angle of the mean spatial QRS vector that was not between 90 degrees and 180 degrees would indicate that the right ventricular conduction defect is probably uncomplicated.

A computer system automatic analysis of vectorcardiograms.

This computer system performs the analysis of orthogonal electrocardiograms for vectorcardiographic (VCG) display and classification. The data acquisition can be performed 'on-line' with the complete analysis in 'real-time', or off-line by processing a magnetic tape. The original computational methods for beat averaging and wave recognition are described. Some features, such as the quality of the visual display of the VCG traces, the availability of a measurement matrix allowing the quantitative analysis of the VCG and the use of a data bank for storage, retrieval and statistical studies make this system very efficient for clinical purposes, introducing the concept of 'Computer Assisted Vectorcardiography'.