Mary J. Roman

Assessment of left ventricular function by meridional and circumferential endsystolic stress/minor-axis shortening relations in dilated cardiomyopathy

Echocardiographic meridional wall stress-endocardial shortening relations provide estimates of left ventricular (LV) contractility that do not uniformly detect myocardial dysfunction despite severe symptoms in dilated cardiomyopathy. To improve detection of myocardial dysfunction in patients with congestive heart failure (CHF) due to dilated cardiomyopathy, echocardiographic meridional and circumferential end-systolic stress were related to endocardial and midwall shortening in 42 patients (95% dead within a mean of 22 months) with dilated cardiomyopathy and 140 normal subjects. A method to estimate LV long-axis dimension from M-mode minor-axis epicardial measurements was developed in a separate series of 115 subjects. Endocardial shortening to meridional wall stress relation identified 31 of 42 CHF patients falling below the 95% normal confidence interval of the reference population; use of midwall shortening decreased this number to 26 (p = NS). The use of circumferential wall stress identified 39 of 42 patients with subnormal endocardial LV shortening and 41 of 42 patients with depressed midwall performance (p < 0.01 vs use of meridional stress). The circumferential/meridional wall stress ratio was 2.6 +/- 0.5 in normal subjects and 1.3 +/- 0.2 in CHF patients (p < 0.0001). Thus, use of circumferential end-systolic stress as the measure of afterload improves the detection of myocardial dysfunction by stress/shortening relations in patients with CHF. The ratio between the 2 stresses decreases with more spherical LV shape. Midwall and endocardial shortening measurements are equivalent in the setting of thin LV walls as occurs in dilated cardiomyopathy.

ASSOCIATION OF INSULIN RESISTANCE WITH PRECLINICAL CARDIOVASCULAR DISEASE IN ADOLESCENTS AND YOUNG ADULTS: THE STRONG HEART STUDY: 1C.01

Background: Insulin resistance is associated with unfavorable cardiovascular (CV) phenotype, but it is unclear whether this association is already recognizable in adolescents and young adults independently of significant confounders. Methods: We analyzed clinical characteristics, hemodynamic parameters, echocardiographic left ventricular (LV) geometry and function in 1688, 14 to 39 year-old non-diabetic participants in the 4th Strong Heart Study exam (mean age 26 ± 7.6, 57% female), without prevalent valvular or CV disease, divided into tertiles of insulin resistance, estimated by Homeostasis Model Assessment (HOMA). Comparison among the groups was obtained by ANCOVA, adjusting for major covariates. Multiple linear regression analysis was performed to evaluate factors associated with log HOMA. Results: Age, BMI, waist girth, waist-hip ratio (WHR), and systolic and diastolic BP progressively increased with tertiles of HOMA (all p < 0.0001). Compared to participants in the 2 lower HOMA tertiles, those in the 3rd tertile were more often obese (85% vs. 57% in the 2nd and 19% in the 1st tertile), more commonly had hypertension (21% vs. 12% and 12%), dyslipidemia (80% vs. 70% and 45%) and albuminuria (20% vs. 14% and 10, all p < 0.0001). After adjustment for age, gender, WHR, systolic BP and presence of hypertension, participants with higher level of HOMA index showed, compared to lower tertiles, progressively higher left atrial dimension, LV mass index (LVMi) and stroke volume (all p for trend < 0.05). In multiple linear regression logHOMA was independently related to age (β = 0.13), female gender (β = 0.28), WHR (β = 0.30), triglycerides (β = 0.18), HDL cholesterol (β = −0.18), systolic BP (β = 0.11) and LVMi (β = 0.17, all p < 0.0001) without significant relation to albumin/creatinine ratio. Compared to the 1st HOMA tertile, LV hypertrophy was associated with the higher HOMA tertiles (OR=3.15, CI:1.15–6,51 for the 2nd tertile; OR = 4.24, CI:2.04–8.81 for the 3rd tertile), independent of age, sex, WHR, systolic BP, hypertension and dyslipidemia. Conclusions: Despite the young age of participants, in a population with high prevalence of obesity, insulin resistance is associated with early metabolic abnormalities and preclinical CV disease.

LEFT VENTRICULAR MASS, PUMP PERFORMANCE AND CARDIOVASCULAR EVENTS: THE STRONG HEART STUDY: PP.22.374

Background: Ejection-phase indices of LV function such as ejection fraction (EF) are strong prognostic indicators. However, at given level of EF, LV pump performance (stroke volume [SV]) may differ, depending on LV size. but, it is unknown whether low SV is a prognostic marker independent of its strong biological collinearity with high LV mass (LVM). We assessed the associations of EF, SV and LVM with cardiovascular (CV) events in a large population free of CV disease. Method: After the 2nd SHS exam, we examined 8-year outcome of quintiles of EF, SV (z-derived method) and LVM in 2323 participants (58 ± 7 yrs; 62% women) without prevalent coronary heart disease, stroke or heart failure (hypertension in 39%, diabetes in 45% and obesity in 54%). Results: In univariate Cox models, risk of composite fatal or non-fatal cardiovascular (CV) events increased across lower quintiles of EF (log rank = 21.7; p = 0.0002) and higher quintiles of LVM (log rank = 40.8; p < 0.00001). In contrast SV did not show significant predictive value. LVM was negatively related to EF (r = −0.37), but was positively correlated with SV (r = 0.66), (both p < 0.0001). Thus, the level of LVM, could confound evaluation of the association of SV with subsequent CV events. Thus, we evaluated LV pump performance per gram of LVM (SV/LVM). Kaplan Meier curves revealed a progressively higher rate of CV events with lower quintiles of SV/LVM (log Rank = 36.3; p < 0.0001). Cox regression, adjusting for age and sex and including EF, SV and LVM showed that hazard of incident CV events increased with higher LVM (HR = 1.1/10 g, CI = 1.05–1. 12, p < 0.0001) and lower SV (HR = 0.90/10 mL, CI = 0.80–0.98; p < 0.01), with no independent effect of EF (HR = 0.90/10%, CI = 0.70–1.03, p = 0.11). Conclusion: Evaluation of LV pump performance is influenced by the amount of myocardial muscle pumping blood into the arterial tree. When LV mass is taken into consideration, indices of LV pump performance may be at least as good as ejection-phase indices of LV function for identification of subjects at risk of incident CV events.

AORTIC DILATATION IN NORMOTENSIVE OR HYPERTENSIVE ADOLESCENTS AND YOUNG ADULTS: THE STRONG HEART STUDY: 8A.04

Background: Aortic root diameter (Ao) is related to body size, gender and age and may be influenced by arterial hypertension (HTN). Few data on clinical correlates of Ao dilatation (AoD) are available in adolescents and young adults in population-based samples. Methods: We analyzed clinical and echocardiographic characteristics of 327 hypertensive and 1595 normotensive, 15 to 39 year-old participants in the 4th Strong Heart Study exam (58% female, 56% obese). AoD was defined as measured sinuses of Valsalva diameter exceeding the 97.5th percentile of the confidence interval of predicted diameter for age, gender and height (ht) or body surface area (BSA). Results: Using ht-based definition, 239 (12%) of total population had AoD and 81 (4.2%) of population had AoD based on BSA-definition. Using both definitions criteria, prevalence of -AoD was higher in men and in participants with HTN and aortic regurgitation(AR) was more common in participants with (all p < 0.05) Independently of gender and measure of body size, AoD was associated with older age, higher BMI and blood pressure (BP)(all p < 0.05). After adjusting for age, gender, BP and BMI, participants with AoD had greater left ventricular mass (LVM), stroke volume and stroke index/pulse pressure ratio (all p < 0.05). AoD independently related to older age, male gender height, weight, diastolic BP, LVM, stroke volume and AR (all p < 0.05). In multivariate analysis, odds of AR increased significantly with female gender (OR = 4.36, 95% CI: 1.42–13), higher systolic BP (OR = 1.07/mmHg, 1.04–1.11), larger Ao (OR = 13/cm, 3.2–50), lower BMI (OR = 0.93/ kg/m2, 0.87–0.98), and lower diastolic BP (OR = 0.95/mmHg, 0.91–0.99, all p < 0.05), independently of age. Conclusion: In a population-based sample of adolescents and young adults, AoD is more common in participants with HTN and is associated with higher LVM, stroke volume and total arterial compliance, and higher prevalence of AR, independently of major confounders.

Left Ventricular Mass as a Measure of Preclinical Disease in Patients with Hypertension

Although hypertension is diagnosed based on elevation of arterial blood pressure, its clinical significance derives from morbid events affecting the heart, brain, and kidneys. However, the morbid events that most commonly complicate hypertension-myocardial infarction, sudden cardiac death and atherothrombotic brain infarction—are not directly due to blood pressure elevation, but rather to hypertension-induced cardiac and vascular damage. These structural abnormalities constitute preclinical hypertensive disease, among which the manifestation that has been best studied in patients is cardiac hypertrophy, detected by echocardiographic measurement of left ventricular (LV) mass (8).