Bharath Ambale Venkatesh

Association of Fitness in Young Adulthood With Survival and Cardiovascular Risk: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

IMPORTANCE Although cardiorespiratory fitness (CRF) is prognostic in older adults, the effect of CRF during early adulthood on long-term cardiovascular structure, function, and prognosis is less clear. OBJECTIVE To examine whether CRF in young adults is associated with long-term clinical outcome and subclinical cardiovascular disease (CVD). DESIGN, SETTING, AND PARTICIPANTS Prospective study of 4872 US adults aged 18 to 30 years who underwent treadmill exercise testing at a baseline study visit from March 25, 1985, to June 7, 1986, and 2472 individuals who underwent a second treadmill test 7 years later. Median follow-up was 26.9 years, with assessment of obesity, left ventricular mass and strain, coronary artery calcification (CAC), and vital status and incident CVD. Follow-up was complete on August 31, 2011, and data were analyzed from recruitment through the end of follow-up. MAIN OUTCOMES AND MEASURES The presence of CAC was assessed by computed tomography at years 15 (2000-2001), 20 (2005-2006), and 25 (2010-2011), and left ventricular mass was assessed at years 5 (1990-1991) and 25 (with global longitudinal strain). Incident CVD and all-cause mortality were adjudicated. RESULTS Of the 4872 individuals, 273 (5.6%) died and 193 (4.0%) experienced CVD events during follow-up. After comprehensive adjustment, each additional minute of baseline exercise test duration was associated with a 15% lower hazard of death (hazard ratio [HR], 0.85; 95% CI, 0.80-0.91; P < .001) and a 12% lower hazard of CVD (HR, 0.88; 95% CI, 0.81-0.96; P = .002). Higher levels of baseline CRF were associated with significantly lower left ventricular mass index (β = -0.24; 95% CI, -0.45 to -0.03; P = .02) and significantly better lobal longitudinal strain (β = -0.09; 95% CI, -0.14 to -0.05; P < .001) at year 25. Fitness was not associated with CAC. A 1-minute reduction in fitness by year 7 was associated with 21% and 20% increased hazards of death (HR, 1.21; 95% CI, 1.07-1.37; P = .002) and CVD (HR, 1.20; 95% CI, 1.06-1.37; P = .006), respectively, along with a more impaired strain (β = 0.15; 95% CI, 0.08-0.23; P < .001). No association between change in fitness and CAC was found. CONCLUSIONS AND RELEVANCE Higher levels of fitness at baseline and improvement in fitness early in adulthood are favorably associated with lower risks for CVD and mortality. Fitness and changes in fitness are associated with myocardial hypertrophy and dysfunction but not CAC. Regular efforts to ascertain and improve CRF in young adulthood may play a critical role in promoting cardiovascular health and interrupting early CVD pathogenesis.

Interstitial fibrosis, left ventricular remodeling, and myocardial mechanical behavior in a population-based multiethnic cohort: the Multi-Ethnic Study of Atherosclerosis (MESA) study.

Background—Tagged cardiac magnetic resonance provides detailed information on regional myocardial function and mechanical behavior. T1 mapping by cardiac magnetic resonance allows noninvasive quantification of myocardial extracellular expansion (ECE), which has been related to interstitial fibrosis in previous clinical and subclinical studies. We assessed sex-associated differences in the relation of ECE to left ventricular (LV) remodeling and myocardial systolic and diastolic deformation in a large community-based multiethnic population. Methods and Results—Midventricular midwall peak circumferential shortening and early diastolic strain rate and LV torsion and torsional recoil rate were determined using cardiac magnetic resonance tagging. Midventricular short-axis T1 maps were acquired in the same examination pre- and postcontrast injection using Modified Look-Locker Inversion-Recovery sequence. Multivariable linear regression (estimated regression coefficient, B) was used to adjust for risk factors and subclinical disease measures. Of 1230 participants, 114 had a visible myocardial scar by late gadolinium enhancement. Participants without a visible myocardial scar (n=1116) had no history of previous clinical events. In the latter group, multivariable linear regression demonstrated that lower postcontrast T1 times, reflecting greater ECE, were associated with lower circumferential shortening (B=−0.1; P=0.0001), lower LV end-diastolic volume index (B=0.6; P=0.0001), and lower LV end-diastolic mass index (B=0.4; P=0.0001). In addition, lower postcontrast T1 times were associated with lower early diastolic strain rate (B=0.01; P=0.03) in women only and lower LV torsion (B=0.005; P=0.03) and lower LV ejection fraction (B=0.2, P=0.01) in men only. Conclusions—Greater ECE is associated with reduced LV end-diastolic volume index and LV end-diastolic mass index in a large multiethnic population without history of previous cardiovascular events. In addition, greater ECE is associated with reduced circumferential shortening, lower early diastolic strain rate, and a preserved ejection fraction in women, whereas in men, greater ECE is associated with greater LV dysfunction manifested as reduced circumferential shortening, reduced LV torsion, and reduced ejection fraction.

Cumulative blood pressure in early adulthood and cardiac dysfunction in middle age: The CARDIA study

BACKGROUND Cumulative blood pressure (BP) exposure may adversely influence myocardial function, predisposing individuals to heart failure later in life. OBJECTIVES This study sought to investigate how cumulative exposure to higher BP influences left ventricular (LV) function during young to middle adulthood. METHODS The CARDIA (Coronary Artery Risk Development in Young Adults) study prospectively enrolled 5,115 healthy African Americans and whites in 1985 and 1986 (baseline). At the year 25 examination, LV function was measured by 2-dimensional echocardiography; cardiac deformation was assessed in detail by speckle-tracking echocardiography. We used cumulative exposure of BP through baseline and up to the year 25 examination (millimeters of mercury × year) to represent long-term exposure to BP levels. Linear regression and logistic regression were used to quantify the association of BP measured repeatedly through early adulthood (18 to 30 years of age) up to middle age (43 to 55 years). RESULTS Among 2,479 participants, cumulative BP measures were not related to LV ejection fraction; however, high cumulative exposure to systolic blood pressure (SBP) and diastolic blood pressure (DBP) were associated with lower longitudinal strain rate (both p < 0.001). For diastolic function, higher cumulative exposures to SBP and DBP were associated with low early diastolic longitudinal peak strain rate. Of note, higher DBP (per SD increment) had a stronger association with diastolic dysfunction compared with SBP. CONCLUSIONS Higher cumulative exposure to BP over 25 years from young adulthood to middle age is associated with incipient LV systolic and diastolic dysfunction in middle age.

Multi-Ethnic Study of Atherosclerosis: Association between Left Atrial Function Using Tissue Tracking from Cine MR Imaging and Myocardial Fibrosis

PURPOSE To investigate the association between left atrial ( LA left atrium ) function and left ventricular myocardial fibrosis using cardiac magnetic resonance (MR) imaging in a multi-ethnic population. MATERIALS AND METHODS For this HIPAA-compliant study, the institutional review board at each participating center approved the study protocol, and all participants provided informed consent. Of 2839 participants who had undergone cardiac MR in 2010-2012, 143 participants with myocardial scar determined with late gadolinium enhancement and 286 age-, sex-, and ethnicity-matched control participants were identified. LA left atrium volume, strain, and strain rate were analyzed by using multimodality tissue tracking from cine MR imaging. T1 mapping was applied to assess diffuse myocardial fibrosis. The association between LA left atrium parameters and myocardial fibrosis was evaluated with the Student t test and multivariable regression analysis. RESULTS The scar group had significantly higher minimum LA left atrium volume than the control group (mean, 22.0 ± 10.5 [standard deviation] vs 19.0 ± 7.8, P = .002) and lower LA left atrium ejection fraction (45.9 ± 10.7 vs 51.3 ± 8.7, P < .001), maximal LA left atrium strain ( Smax maximum LA strain ) (25.4 ± 10.7 vs 30.6 ± 10.6, P < .001) and maximum LA left atrium strain rate ( SRmax maximum LA strain rate ) (1.08 ± 0.45 vs 1.29 ± 0.51, P < .001), and lower absolute LA left atrium strain rate at early diastolic peak ( SRE LA strain rate at early diastolic peak ) (-0.77 ± 0.42 vs -1.01 ± 0.48, P < .001) and LA left atrium strain rate at atrial contraction peak ( SRA LA strain rate at atrial contraction peak ) (-1.50 ± 0.62 vs -1.78 ± 0.69, P < .001) than the control group. T1 time 12 minutes after contrast material injection was significantly associated with Smax maximum LA strain (β coefficient = 0.043, P = .013), SRmax maximum LA strain rate (β coefficient = 0.0025, P = .001), SRE LA strain rate at early diastolic peak (β coefficient = -0.0016, P = .027), and SRA LA strain rate at atrial contraction peak LA strain rate at atrial contraction peak (β coefficient -0.0028, P = .01) in the regression model. T1 time 25 minutes after contrast material injection was significantly associated with SRmax maximum LA strain rate (β coefficient = 0.0019, P = .016) and SRA LA strain rate at atrial contraction peak (β coefficient = -0.0022, P = .034). CONCLUSION Reduced LA left atrium regional and global function are related to both replacement and diffuse myocardial fibrosis processes. Clinical trial registration no.: NCT00005487

Association of Longitudinal Changes in Left Ventricular Structure and Function With Myocardial Fibrosis: The Multi-Ethnic Study of Atherosclerosis Study

The association of longitudinal changes in left ventricular (LV) structure and function with myocardial fibrosis is unclear. We relate temporal changes in body size–indexed LV mass (LVMi) and end-diastolic volume indexed to body surface area, LV mass-to-volume ratio, and LV ejection fraction (LVEF) from cine cardiac magnetic resonance for 10 years, with replacement scar assessed from late gadolinium enhancement, and lower postcontrast T1 times reflecting greater diffuse myocardial fibrosis measured at the end of the follow-up period. All participants (n=1813) who underwent cardiac magnetic resonance twice as part of the Multi-Ethnic Study of Atherosclerosis 10 years apart were included. Multivariable logistic and linear regression models adjusted for cardiovascular risk factors measured the association of 10-year changes in LV structure and function, with fibrosis measured at follow-up. The presence of LV scar at year 10 was cross-sectionally associated with higher LVMi (≈10 g/m2), higher mass-to-volume ratio (0.1–0.2 g/mL), but lower LVEF (≈4%) and longitudinally with 3% decrease in LVEF and 0.7% greater end-diastolic volume indexed to body surface area in men for 10 years. Lower postcontrast T1 times at year 10 were associated cross-sectionally with lower LVMi (r=0.33), end-diastolic volume indexed to body surface area (r=0.25), and LVEF (in men only: r=0.14) and longitudinally with a decrease in LVMi (r=0.20) and reduction in LVEF (in men only: r=0.15). Sustained hypertension for 10 years was associated with increased LVMi and higher diffuse and replacement fibrosis at follow-up. During a 10-year period, increased concentric hypertrophy in women and LV dilatation in men were associated with replacement fibrosis, whereas decreasing LVMi was associated with diffuse fibrosis. Hypertension-induced remodeling was related to enhanced replacement and diffuse fibrosis, as well as hypertrophy.

Race–Ethnic and Sex Differences in Left Ventricular Structure and Function: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

Background We investigated race–ethnic and sex‐specific relationships of left ventricular (LV) structure and LV function in African American and white men and women at 43 to 55 years of age. Methods and Results The Coronary Artery Risk Development in Young Adults (CARDIA) Study enrolled African American and white adults, age 18 to 30 years, from 4 US field centers in 1985–1986 (Year‐0) who have been followed prospectively. We included participants with echocardiographic assessment at the Year‐25 examination (n=3320; 44% men, 46% African American). The end points of LV structure and function were assessed using conventional echocardiography and speckle‐tracking echocardiography. In the multivariable models, we used, in addition to race–ethnic and gender terms, demographic (age, physical activity, and educational level) and cardiovascular risk variables (body mass index, systolic blood pressure, diastolic blood pressure, heart rate, presence of diabetes, use of antihypertensive medications, number of cigarettes/day) at Year‐0 and ‐25 examinations as independent predictors of echocardiographic outcomes at the Year‐25 examination (LV end‐diastolic volume [LVEDV]/height, LV end‐systolic volume [LVESV]/height, LV mass [LVM]/height, and LVM/LVEDV ratio for LV structural indices; LV ejection fraction [LVEF], Ell, and Ecc for systolic indices; and early diastolic and atrial ratio, mitral annulus early peak velocity, ratio of mitral early peak velocity/mitral annulus early peak velocity; ratio, left atrial volume/height, longitudinal peak early diastolic strain rate, and circumferential peak early diastolic strain rate for diastolic indices). Compared with women, African American and white men had greater LV volume and LV mass (P<0.05). For LV systolic function, African American men had the lowest LVEF as well as longitudinal (Ell) and circumferential (Ecc) strain indices among the 4 sex/race–ethnic groups (P<0.05). For LV diastolic function, African American men and women had larger left atrial volumes; African American men had the lowest values of Ell and Ecc for diastolic strain rate (P<0.05). These race/sex differences in LV structure and LV function persisted after adjustment. Conclusions African American men have greater LV size and lower LV systolic and diastolic function compared to African American women and to white men and women. The reasons for these racial‐ethnic differences are partially but not completely explained by established cardiovascular risk factors.

Associations of electrocardiographic P-wave characteristics with left atrial function, and diffuse left ventricular fibrosis defined by cardiac magnetic resonance: The PRIMERI Study

BACKGROUND Abnormal P-terminal force in lead V1 (PTFV1) is associated with an increased risk of heart failure, stroke, atrial fibrillation, and death. OBJECTIVE Our goal was to explore associations of left ventricular (LV) diffuse fibrosis with left atrial (LA) function and electrocardiographic (ECG) measures of LA electrical activity. METHODS Patients without atrial fibrillation (n = 91; mean age 59.5 years; 61.5% men; 65.9% white) with structural heart disease (spatial QRS-T angle ≥105° and/or Selvester QRS score ≥5 on ECG) but LV ejection fraction >35% underwent clinical evaluation, cardiac magnetic resonance, and resting ECG. LA function indices were obtained by multimodality tissue tracking using 2- and 4-chamber long-axis images. T1 mapping and late gadolinium enhancement were used to assess diffuse LV fibrosis and presence of scar. P-prime in V1 amplitude (PPaV1) and duration (PPdV1), averaged P-wave-duration, PR interval, and P-wave axis were automatically measured using 12 SLTM algorithm. PTFV1 was calculated as a product of PPaV1 and PPdV1. RESULTS In linear regression after adjustment for demographic characteristics, body mass index, maximum LA volume index, presence of scar, and LV mass index, each decile increase in LV interstitial fibrosis was associated with 0.76 mV*ms increase in negative abnormal PTFV1 (95% confidence interval [CI] -1.42 to -0.09; P = .025), 15.3 ms prolongation of PPdV1 (95% CI 6.9 to 23.8; P = .001) and 5.4 ms prolongation of averaged P-duration (95% CI 0.9-10.0; P = .020). LV fibrosis did not affect LA function. PPaV1 and PTFV1 were associated with an increase in LA volumes and decrease in LA emptying fraction and LA reservoir function. CONCLUSION LV interstitial fibrosis is associated with abnormal PTFV1, prolonged PPdV1, and P-duration, but does not affect LA function.

Rationale and Design for PACE: Patients with Intermittent Claudication Injected with ALDH Bright Cells

Peripheral artery disease (PAD) is recognized as a public health issue because of its prevalence, functional limitations, and increased risk of systemic ischemic events. Current treatments for claudication, the primary symptom in patients with PAD, have limitations. Cells identified using cytosolic enzyme aldehyde dehydrogenase (ALDH) may benefit patients with severe PAD but has not been studied in patients with claudication. PACE is a randomized, double-blind, placebo-controlled clinical trial conducted by the Cardiovascular Cell Therapy Research Network to assess the safety and efficacy of autologous bone marrow-derived ALDH(br) cells delivered by direct intramuscular injections in 80 patients with symptom-limiting intermittent claudication. Eligible patients will have a significant stenosis or occlusion of infrainguinal arteries and a resting ankle-brachial index less than 0.90 and will be randomized 1:1 to cell or placebo treatment with a 1-year follow-up. The primary end points are the change in peak walking time and leg collateral arterial anatomy, calf muscle blood flow, and tissue perfusion as determined by magnetic resonance imaging at 6 months compared with baseline. The latter 3 measurements are new physiologic lower extremity tissue perfusion and PAD imaging-based end points that may help to quantify the biologic and mechanistic effects of cell therapy. This trial will collect important mechanistic and clinical information on the safety and efficacy of ALDH(br) cells in patients with claudication and provide valuable insight into the utility of advanced magnetic resonance imaging end points.

Quantitative Tissue‐Tracking Cardiac Magnetic Resonance (CMR) of Left Atrial Deformation and the Risk of Stroke in Patients With Atrial Fibrillation

Background Recent evidence suggests that left atrial (LA) dysfunction may be mechanistically contributing to cerebrovascular events in patients with atrial fibrillation (AF). We investigated the association between regional LA function and a prior history of stroke during sinus rhythm in patients referred for catheter ablation of AF. Methods and Results A total of 169 patients (59±10 years, 74% male, 29% persistent AF) with a history of AF in sinus rhythm at the time of pre‐ablation cardiac magnetic resonance (CMR) were analyzed. The LA volume, emptying fraction, strain (S), and strain rate (SR) were assessed by tissue‐tracking cardiac magnetic resonance. The patients with a history of stroke or transient ischemic attack (n=18) had greater LA volumes (Vmax and Vmin; P=0.02 and P<0.001, respectively), lower LA total emptying fraction (P<0.001), lower LA maximum and pre‐atrial contraction strains (Smax and SpreA; P<0.001 and P=0.01, respectively), and lower absolute values of LA SR during left ventricular (LV) systole and early diastole (SRs and SRe; P=0.005 and 0.03, respectively) than those without stroke/transient ischemic attack (n=151). Multivariable analysis demonstrated that the LA reservoir function, including total emptying fraction, Smax, and SRs, was associated with stroke/transient ischemic attack (odds ratio 0.94, 0.91, and 0.17; P=0.03, 0.02, and 0.04, respectively) after adjusting for the CHA2DS2‐VASc score and LA Vmin. Conclusions Depressed LA reservoir function assessed by tissue‐tracking cardiac magnetic resonance is significantly associated with a prior history of stroke/transient ischemic attack in patients with AF. Our findings suggest that assessment of LA reservoir function can improve the risk stratification of cerebrovascular events in AF patients.

MR proton spectroscopy for myocardial lipid deposition quantification: A quantitative comparison between 1.5T and 3T

To evaluate 3T magnetic resonance spectroscopy (MRS)‐derived myocardial fat‐signal fractions in comparison with those from 1.5T MRS.