Missense Genetic Variation of ICAM1 and Incident Heart Failure.

BACKGROUND: Intercellular adhesion molecule-1 (ICAM-1) is a cell surface protein that participates in endothelial activation and is hypothesized to play a central role in heart failure (HF). We evaluated associations of ICAM1 missense genetic variants with circulating ICAM-1 levels and with incident HF. METHODS AND RESULTS: We identified 3 missense variants within ICAM1 (rs5491, rs5498 and rs1799969) and evaluated their associations with ICAM-1 levels in the Coronary Artery Risk Development in Young Adults Study and the Multi-Ethnic Study of Atherosclerosis (MESA). We determined the association among these 3 variants and incident HF in MESA. We separately evaluated significant associations in the Atherosclerosis Risk in Communities (ARIC) study. Of the 3 missense variants, rs5491 was common in Black participants (minor allele frequency [MAF] > 20%) and rare in other race/ethnic groups (MAF < 5%). In Black participants, the presence of rs5491 was associated with higher levels of circulating ICAM-1 at 2 timepoints separated by 8 years. Among Black participants in MESA (n = 1600), the presence of rs5491 was associated with an increased risk of incident HF with preserved ejection fraction (HFpEF; HR = 2.30; [95% CI 1.25-4.21; P = 0.007]). The other ICAM1 missense variants (rs5498 and rs1799969) were associated with ICAM-1 levels, but there were no associations with HF. In ARIC, rs5491 was significantly associated with incident HF (HR = 1.24 [95% CI 1.02 - 1.51]; P = 0.03), with a similar direction of effect for HFpEF that was not statistically significant. CONCLUSIONS: A common ICAM1 missense variant among Black individuals may be associated with increased risk of HF, which may be HFpEF-specific.

Immune cell profiling of the ICAM1 p.K56M heart failure with preserved ejection fraction risk variant.

AIMS: Intercellular adhesion molecule-1 (ICAM-1) facilitates inflammation via leucocyte recruitment and has been implicated in heart failure with preserved ejection fraction (HFpEF). Approximately 35% of African American individuals carry a copy of an ICAM1 missense variant (rs5491; p.K56M), which is associated with an increased risk of HFpEF. The pathways by which rs5491 increases HFpEF risk are not well defined. We evaluated the circulating immune cell profile of rs5491. METHODS: Among African American individuals in the Multi-Ethnic Study of Atherosclerosis, we evaluated the associations of rs5491 with 29 circulating peripheral blood mononuclear cell subsets. The top immune cells were then related to echocardiographic measures of structure and function. RESULTS: Among 502 individuals with immune cell profiling (mean age 63 years, 51% female), 191 individuals (38%) had at least one copy of rs5491. Each additional rs5491 allele was significantly associated with higher proportions of Tc17 CD8+ cytotoxic T cells (ß = 1.34, SE = 0.45, P = 9.5 × 10-5) and Tc2 CD8+ cytotoxic T cells (ß = 1.19, SE = 0.44, P = 0.00012). There were no other associations noted between rs5491 and the remaining immune cells. A higher proportion of Tc17 cells was significantly associated with a higher left ventricular ejection fraction, E/e' average and right ventricular systolic pressure (RVSP), while a higher proportion of Tc2 cells was significantly associated with a higher RVSP. CONCLUSIONS: The ICAM1 p.K56M variant (rs5491) carries a distinct and inflammatory T-cell subset profile. These cytotoxic T cells are in turn associated with alterations in cardiac function and adverse haemodynamics later in life, thus providing insight into pathways by which rs5491 may increase the risk of HFpEF.

Heart Failure Risk Among African-American Women With an ICAM1 Missense Variant.

BACKGROUND: A common genetic variant of ICAM1 among African-American individuals (rs5491; p.K56M) is associated with heart failure (HF) hospitalization, but whether this risk is specific to heart failure with preserved ejection fraction (HFpEF) remains unclear. Older women are at high risk for HFpEF, and the relationship between rs5491 and HFpEF across the age spectrum is unknown. OBJECTIVES: This study assessed risk of HF and its subtypes conferred by ICAM1 p.K56M (rs5491). METHODS: Associations of rs5491 with risk of HF and its subtypes were estimated among African American individuals in WHI (Women's Health Initiative). The study evaluated whether the association between rs5491 and HF hospitalizations was modified by baseline age. Subsequently, African-American women in WHI and MESA (Multi-Ethnic Study of Atherosclerosis) were pooled and analyses were repeated. RESULTS: Among 8,401 women in WHI, the minor allele frequency of rs5491 was 20.7%, and 731 HF hospitalizations occurred over 19.2 years. The rs5491 variant was not associated with HF or its subtypes across WHI. Interaction analyses suggested that age as a continuous variable modified the association of rs5491 with HFpEF hospitalization (interaction P = 0.04). Upon categorizing women into age decades, rs5491 conferred increased risk of HFpEF among women ≥70 years (HR per additional rs5491 allele: 1.82 [95% CI: 1.25-2.65]; P = 0.002) but was not associated with HFpEF risk among women <70 years. Pooling African-American women in WHI (n = 8,401) and MESA (n = 856) demonstrated that the effect modification by age on the association of rs5491 with HFpEF became more significant (interaction P = 0.009), with consistent HFpEF risk effect estimates among women ≥70 years. CONCLUSIONS: ICAM1 p.K56M (rs5491) is associated with HFpEF among African-American women ≥70 years.

Metabolomic profiling identifies novel metabolites associated with cardiac dysfunction.

Metabolic comorbidities, such as obesity and diabetes, are associated with subclinical alterations in both cardiac structure/function and natriuretic peptides prior to the onset of heart failure (HF). Despite this, the exact metabolic pathways of cardiac dysfunction which precede HF are not well-defined. Among older individuals without HF in the Multi-Ethnic Study of Atherosclerosis (MESA), we evaluated the associations of 47 circulating metabolites measured by 1H-NMR with echocardiographic measures of cardiac structure and function. We then evaluated associations of significant metabolites with circulating N-terminal pro-B-type natriuretic peptide (NT-proBNP). In a separate cohort, we evaluated differences between top metabolites in patients with HF with preserved ejection fraction (HFpEF) and comorbidity-matched controls. Genetic variants associated with top metabolites (mQTLs) were then related to echocardiographic measures and NT-proBNP. Among 3440 individuals with metabolic and echocardiographic data in MESA (62 ± 10 years, 52% female, 38% White), 10 metabolites broadly reflective of glucose and amino acid metabolism were associated with at least 1 measure of cardiac structure or function. Of these 10 metabolites, 4 (myo-inositol, glucose, dimethylsulfone, carnitine) were associated with higher NT-proBNP and 2 (d-mannose, acetone) were associated with lower NT-proBNP. In a separate cohort, patients with HFpEF had higher circulating myo-inositol levels compared with comorbidity-matched controls. Genetic analyses revealed that 1 of 6 known myo-inositol mQTLs conferred risk of higher NT-proBNP. In conclusion, metabolomic profiling identifies several novel metabolites associated with cardiac dysfunction in a cohort at high risk for HF, revealing pathways potentially relevant to future HF risk.

Proteomic Profile of the ICAM1 p.K56M HFpEF Risk Variant.

A common missense variant in ICAM1 among African American individuals (rs5491; pK56M) has been associated with risk of heart failure with preserved ejection fraction (HFpEF), but the pathways that lead to HFpEF among those with this variant are not clear. In this analysis of 92 circulating proteins and their associated networks, we identified 7 circulating inflammatory proteins associated with rs5491 among >600 African American individuals. Using weighted coexpression network analysis, 3 protein networks were identified, one of which was associated with rs5491. This protein network was most highly represented by members of the tumor necrosis receptor superfamily. The rs5491 variant demonstrated an inflammatory proteomic profile in a separate cohort of African American individuals. This analysis identifies inflammatory pathways that may drive HFpEF among African American individuals with the ICAM1 pK56M (rs5491) variant.

The pK56M ICAM1 HFpEF risk variant and inflammatory biomarkers.

Introduction: The ICAM1 variant rs5491 (p.K56M) is common among Black individuals and has been associated with risk of heart failure with preserved ejection fraction (HFpEF). The pathways by which rs5491 leads to HFpEF are not known. Methods: Among Black individuals within the Multi-Ethnic Study of Atherosclerosis, we evaluated associations of rs5491 with 3 inflammatory biomarkers (high-sensitivity C-reactive protein [hsCRP], interleukin-6 [IL-6], and tumor necrosis factor-α receptor 1 [TNFR-1]). Results: Among 1558 Black participants (mean age 62 ± 10 y, 47 % female), each additional rs5491 allele was associated with higher hsCRP after covariate adjustment (ß: 0.15, SE: 0.07, P = 0.02). Each additional rs5491 allele was associated with higher TNFR-1 (ß: 0.06, SE: 0.02, P = 0.02), but not IL-6 (ß: 0.04, SE: 0.04, P = 0.29). The association between rs5491 and HFpEF remained significant after adjustment for hsCRP. Conclusion: In Black individuals, rs5491 (p.K56M) is associated with higher hsCRP and higher TNFR-1, but not IL-6.

Impairments in Blood Pressure Regulation and Cardiac Baroreceptor Sensitivity Among Patients With Heart Failure Supported With Continuous-Flow Left Ventricular Assist Devices.

BACKGROUND: Continuous-flow (CF) left ventricular assist devices (LVADs) improve outcomes for patients with advanced heart failure (HF). However, the lack of a physiological pulse predisposes to side-effects including uncontrolled blood pressure (BP), and there are little data regarding the impact of CF-LVADs on BP regulation. METHODS: Twelve patients (10 males, 60±11 years) with advanced heart failure completed hemodynamic assessment 2.7±4.1 months before, and 4.3±1.3 months following CF-LVAD implantation. Heart rate and systolic BP via arterial catheterization were monitored during Valsalva maneuver, spontaneous breathing, and a 0.05 Hz repetitive squat-stand maneuver to characterize cardiac baroreceptor sensitivity. Plasma norepinephrine levels were assessed during head-up tilt at supine, 30o and 60o. Heart rate and BP were monitored during cardiopulmonary exercise testing. RESULTS: Cardiac baroreceptor sensitivity, determined by Valsalva as well as Fourier transformation and transfer function gain of Heart rate and systolic BP during spontaneous breathing and squat-stand maneuver, was impaired before and following LVAD implantation. Norepinephrine levels were markedly elevated pre-LVAD and improved-but remained elevated post-LVAD (supine norepinephrine pre-LVAD versus post-LVAD: 654±437 versus 323±164 pg/mL). BP increased during cardiopulmonary exercise testing post-LVAD, but the magnitude of change was modest and comparable to the changes observed during the pre-LVAD cardiopulmonary exercise testing. CONCLUSIONS: Among patients with advanced heart failure with reduced ejection fraction, CF-LVAD implantation is associated with modest improvements in autonomic tone, but persistent reductions in cardiac baroreceptor sensitivity. Exercise-induced increases in BP are blunted. These findings shed new light on mechanisms for adverse events such as stroke, and persistent reductions in functional capacity, among patients supported by CF-LVADs. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03078972.