External validation of a deep learning electrocardiogram algorithm to detect ventricular dysfunction

Objective - To validate a novel artificial-intelligence electrocardiogram algorithm (AI-ECG) to detect left ventricular systolic dysfunction (LVSD) in an external population. Background - LVSD, even when asymptomatic, confers increased morbidity and mortality. We recently derived AI-ECG to detect LVSD using ECGs based on a large sample of patients treated at the Mayo Clinic. Methods - We performed an external validation study with subjects from the Know Your Heart Study, a cross-sectional study of adults aged 35–69 years residing in two cities in Russia, who had undergone both ECG and transthoracic echocardiography. LVSD was defined as left ventricular ejection fraction ≤ 35%. We assessed the performance of the AI-ECG to identify LVSD in this distinct patient population. Results - Among 4277 subjects in this external population-based validation study, 0.6% had LVSD (compared to 7.8% of the original clinical derivation study). The overall performance of the AI-ECG to detect LVSD was robust with an area under the receiver operating curve of 0.82. When using the LVSD probability cut-off of 0.256 from the original derivation study, the sensitivity, specificity, and accuracy in this population were 26.9%, 97.4%, 97.0%, respectively. Other probability cut-offs were analysed for different sensitivity values. Conclusions - The AI-ECG detected LVSD with robust test performance in a population that was very different from that used to develop the algorithm. Population-specific cut-offs may be necessary for clinical implementation. Differences in population characteristics, ECG and echocardiographic data quality may affect test performance

Prevalence of left ventricular diastolic dysfunction in European populations based on cross-validated diagnostic thresholds

BACKGROUND: Different diagnostic criteria limit comparisons between populations in the prevalence of diastolic left ventricular (LV) dysfunction. We aimed to compare across populations age-specific echocardiographic criteria for diastolic LV dysfunction as well as their correlates and prevalence. METHODS: We measured the E and A peaks of transmitral blood flow by pulsed wave Doppler and the e' and a' peaks of mitral annular velocities by tissue Doppler imaging (TDI) in 2 cohorts randomly recruited in Belgium (n = 782; 51.4% women; mean age, 51.1 years) and in Italy, Poland and Russia (n = 476; 55.7%; 44.5 years). RESULTS: In stepwise regression, the multivariable-adjusted correlates of the transmitral and TDI diastolic indexes were similar in the 2 cohorts and included sex, age, body mass index, blood pressure and heart rate. Similarly, cut-off limits for the E/A ratio (2.5th percentile) and E/e' ratio (97.5th percentile) in 338 and 185 reference subjects free from cardiovascular risk factors respectively selected from both cohorts were consistent within 0.02 and 0.26 units (median across 5 age groups). The rounded 2.5th percentile of the E/A ratio decreased by ~0.10 per age decade in these apparently healthy subjects. The reference subsample provided age-specific cut-off limits for normal E/A and E/e' ratios. In the 2 cohorts combined, diastolic dysfunction groups 1 (impaired relaxation), 2 (possible elevated LV filling pressure) and 3 (elevated E/e' and abnormally low E/A) encompassed 114 (9.1%), 135 (10.7%), and 40 (3.2%) subjects, respectively. CONCLUSIONS: The age-specific criteria for diastolic LV dysfunction were highly consistent across the study populations with an age-standardized prevalence of 22.4% vs. 25.1%

Prevalence of left ventricular diastolic dysfunction in European populations based on cross-validated diagnostic thresholds

BACKGROUND: Different diagnostic criteria limit comparisons between populations in the prevalence of diastolic left ventricular (LV) dysfunction. We aimed to compare across populations age-specific echocardiographic criteria for diastolic LV dysfunction as well as their correlates and prevalence. METHODS: We measured the E and A peaks of transmitral blood flow by pulsed wave Doppler and the e' and a' peaks of mitral annular velocities by tissue Doppler imaging (TDI) in 2 cohorts randomly recruited in Belgium (n = 782; 51.4% women; mean age, 51.1 years) and in Italy, Poland and Russia (n = 476; 55.7%; 44.5 years). RESULTS: In stepwise regression, the multivariable-adjusted correlates of the transmitral and TDI diastolic indexes were similar in the 2 cohorts and included sex, age, body mass index, blood pressure and heart rate. Similarly, cut-off limits for the E/A ratio (2.5th percentile) and E/e' ratio (97.5th percentile) in 338 and 185 reference subjects free from cardiovascular risk factors respectively selected from both cohorts were consistent within 0.02 and 0.26 units (median across 5 age groups). The rounded 2.5th percentile of the E/A ratio decreased by ~0.10 per age decade in these apparently healthy subjects. The reference subsample provided age-specific cut-off limits for normal E/A and E/e' ratios. In the 2 cohorts combined, diastolic dysfunction groups 1 (impaired relaxation), 2 (possible elevated LV filling pressure) and 3 (elevated E/e' and abnormally low E/A) encompassed 114 (9.1%), 135 (10.7%), and 40 (3.2%) subjects, respectively. CONCLUSIONS: The age-specific criteria for diastolic LV dysfunction were highly consistent across the study populations with an age-standardized prevalence of 22.4% vs. 25.1%

Intrafamilial correlations of carotid intima-media thickness and flow-mediated dilation in a Siberian population

BACKGROUND: Intima-media thickening and impaired endothelium-dependent vasodilation are complex phenotypes determined by genetic and environmental factors. Few studies assessed these phenotypes in the same subjects. The goal of our study was to assess the sex-specific intrafamilial aggregation of ultrasonographic carotid intima-media thickness (IMT) and brachial flow-mediated vasodilation (FMD) in a Siberian population. METHODS: We randomly recruited 81 nuclear families of Caucasian ancestry (129 parents and 157 offspring, mean age 52.4 and 26.3 years) in Novosibirsk, Russia. Carotid artery IMT and brachial artery FMD were assessed by ultrasound. Intraclass correlation coefficients were calculated between first-degree relatives and between unrelated spouse pairs for IMT and FMD in age- adjusted, sex-adjusted, and multivariate-adjusted models. RESULTS: Multivariate-adjusted correlation coefficients in sib-sib pairs were 0.27 (P = .042) for IMT and 0.29 (P = .049) for FMD with heritabilities (h(2)= 2r) of 0.54 and 0.58, respectively. For IMT, the mother-offspring (r = 0.17, P = .051) and mother-daughter correlations (r = 0.28, P = .025) were significant, whereas the father-offspring correlation did not differ from zero (r = 0.11, P = .33). For FMD the father-offspring (r = 0.24, P = .042) and father-son correlations (r = 0.40, P = .051) were significant, whereas the mother-offspring correlation was only -0.09 (P = .39). The P value for the difference in familial aggregation of FMD between father-offspring and mother-offspring pairs was .018. CONCLUSIONS: Our findings confirm that a substantial proportion of the variability of carotid IMT and brachial FMD is attributable to genetic variation. They also suggest that offspring share more genetic or environmental determinants of FMD with fathers than their mothers.status: publishe

Maternal and paternal influences on left ventricular mass of offspring

Significant intrafamilial correlations of left ventricular mass exist in first-degree relatives. However, the specific maternal and paternal influences on left ventricular mass of offspring remain unknown. We therefore evaluated familial aggregation of left ventricular mass by type of familial relation in two European populations. A random sample of 159 nuclear families (250 parents and 321 offspring) was investigated in Cracow, Poland, and Novosibirsk, Russia. The mean age of parents and offspring was 51.4 years and 25.1 years, respectively. Two-dimensionally guided M-mode echocardiography was performed, and left ventricular mass was calculated. As a measure of concordance, we computed correlation coefficients for left ventricular mass between first-degree relatives and between spouse pairs. After adjustment for center, gender, age, height, body weight, systolic blood pressure, antihypertensive treatment, smoking, alcohol intake, and physical activity, the intrafamilial correlations for left ventricular mass were 0.06 (P=0.57) in 91 spouse-spouse pairs, 0.14 (P=0.002) in 500 parent-offspring pairs, and 0.32 (P<0.001) in 179 sib-sib pairs. Across the four parent-offspring relations, the intrafamilial correlations of left ventricular mass differed. The mother-son (n=140, r=0.27, P<0.001) and mother-daughter (n=161, r=0.28, P<0.001) correlations were significant, whereas the father-son (n=101, r=0.04, P=0.69) and father-daughter (n=98, r=-0.09, P=0.38) correlations were not different from zero. Overall, the mother-offspring correlation coefficient was significantly higher than the father-offspring correlation (r=0.28 versus r=-0.04; P=0.005). Thus, maternal factors appear to have more impact on left ventricular mass of offspring than do paternal influences. Further studies are required to elucidate the genetic, epigenetic, and ecogenetic mechanisms underlying these divergent parent-offspring correlations.status: publishe

The Relationship between Epigenetic Age and Myocardial Infarction/Acute Coronary Syndrome in a Population-Based Nested Case-Control Study

We investigated the relationship between &lsquo;epigenetic age&rsquo; (EA) derived from DNA methylation (DNAm) and myocardial infarction (MI)/acute coronary syndrome (ACS). A random population sample was examined in 2003/2005 (n = 9360, 45&ndash;69, the HAPIEE project) and followed up for 15 years. From this cohort, incident MI/ACS (cases, n = 129) and age- and sex-stratified controls (n = 177) were selected for a nested case-control study. Baseline EA (Horvath&rsquo;s, Hannum&rsquo;s, PhenoAge, Skin and Blood) and the differences between EA and chronological age (CA) were calculated (&Delta;AHr, &Delta;AHn, &Delta;APh, &Delta;ASB). EAs by Horvath&rsquo;s, Hannum&rsquo;s and Skin and Blood were close to CA (median absolute difference, MAD, of 1.08, &ndash;1.91 and &ndash;2.03 years); PhenoAge had MAD of &minus;9.29 years vs. CA. The adjusted odds ratios (ORs) of MI/ACS per 1&ndash;year increments of &Delta;AHr, &Delta;AHn, &Delta;ASB and &Delta;APh were 1.01 (95% CI 0.95&ndash;1.07), 1.01 (95% CI 0.95&ndash;1.08), 1.02 (95% CI 0.97&ndash;1.06) and 1.01 (0.93&ndash;1.09), respectively. When classified into tertiles, only the highest tertile of &Delta;APh showed a suggestion of increased risk of MI/ACS with OR 2.09 (1.11&ndash;3.94) independent of age and 1.84 (0.99&ndash;3.52) in the age- and sex-adjusted model. Metabolic modulation may be the likely mechanism of this association. In conclusion, this case-control study nested in a prospective population-based cohort did not find strong associations between accelerated epigenetic age markers and risk of MI/ACS. Larger cohort studies are needed to re-examine this important research question

Relationship between left ventricular mass and the ACE D/I polymorphism varies according to sodium intake

BACKGROUND: In the European Project on Genes in Hypertension (EPOGH), we investigated to what extent left ventricular mass (LVM) in populations and families relates to the angiotensin-converting enzyme (ACE D/I) and aldosterone synthase (CYP11B2 -344C/T) polymorphisms and urinary sodium excretion. METHODS: We recruited 219 nuclear families (382 parents and 436 offspring) randomly in Cracow (Poland), Novosibirsk (Russia) and Mirano (Italy). Echocardiographical LVM was indexed to body surface area, adjusted for covariables, and subjected to multivariate analyses using generalized estimating equations and quantitative transmission disequilibrium tests, in a population-based and family-based approach, respectively. RESULTS: We found significant differences between the two Slavic centres and Mirano in left ventricular mass index (LVMI) (94.9 versus 80.3 g/m2), sodium excretion (229 versus 186 mmol/day), and the prevalence of the ACE D allele (52.1 versus 58.5%). There was significant heterogeneity between Slavic and Italian subjects in the phenotype-genotype relationships with the ACE gene, but not with the aldosterone synthase gene. In the two Slavic centres, ACE II homozygosity was significantly associated with higher LVMI, in population-based as well as in family-based analyses. By contrast, in Mirano, LVMI was slightly higher in DD homozygotes (P = 0.05), but only in the population-based approach. LVMI increased with higher sodium excretion in ACE II homozygous offspring of both Slavic and Italian extraction (+4.2 +/- 2.1 g/m2 per 100 mmol; P = 0.04) and in Slavic (+2.6 +/- 1.1 g/m2 per 100 mmol; P = 0.02), but not Italian (-3.3 +/- 3.2 g/m2 per 100 mmol; P = 0.29) D allele carriers. We did not find any association between LVMI and the aldosterone synthase -344C/T polymorphism. CONCLUSIONS: The relationship between LVMI and the ACE D/I polymorphism differs across populations, possibly as a consequence of intermediate regulatory mechanisms responsive to varying levels of salt intake.status: publishe

Left ventricular mass in relation to genetic variation in angiotensin II receptors, renin system genes, and sodium excretion

BACKGROUND: In the European Project On Genes in Hypertension (EPOGH), we investigated in 3 populations to what extent left ventricular mass (LVM) was associated with genetic variation in the angiotensin II receptors type 1 (AGTR1 A1166C) and type 2 (AGTR2 G1675A) while accounting for possible gene-gene interactions with the angiotensin-converting enzyme (ACE D/I) and angiotensinogen (AGT -532C/T) polymorphisms. METHODS AND RESULTS: We randomly recruited 221 nuclear families (384 parents, 431 offspring) in Cracow (Poland), Novosibirsk (Russia), and Mirano (Italy). Echocardiographic LVM was indexed to body surface area, adjusted for covariates, and subjected to multivariate analyses using generalized estimating equations and quantitative transmission disequilibrium tests in a population-based and family-based approach, respectively. For AGTR1 and AGTR2, there was no heterogeneity in the phenotype-genotype relations across populations. LVM index was unrelated to the AGTR1 A1166C polymorphism. In men, in the population- and family-based analyses, the allelic effects of the AGTR2 polymorphism on LVM index differed (P=0.01) according to sodium excretion. In women, this gene-environment interaction did not reach statistical significance. In untreated men, LVM index (4.2 g/m2 per 100 mmol) and left ventricular internal diameter (0.73 mm/100 mmol) increased (P<0.02) with higher sodium excretion in the presence of the G allele with an opposite tendency in A allele carriers. The ACE D/I polymorphism, together with the ACE genotype-by-sodium interaction term, significantly and independently improved the models relating LVM index to the AGTR2 polymorphism and the AGTR2 genotype-by-sodium interaction. CONCLUSIONS: The present findings support the hypothesis that in men the AGTR2 G1675A and the ACE D/I polymorphisms independently influence LVM and that salt intake modulates these genetic effects.status: publishe

Impact and pitfalls of scaling of left ventricular and atrial structure in population-based studies

Several allometric methods for indexing cardiac structures to body size have been proposed but the optimal way for normalization of cardiac structures is still controversial. We aimed to estimate the allometric exponents that best describe the relationships between cardiac dimensions and body size, propose normative values, and analyze how the different scaling metrics influence the prevalence of left ventricular hypertrophy (LVH) and chambers enlargement as well as predictive models for cardiovascular outcome in the community.status: publishe