Heart rate variability: reference values and role for clinical profile and mortality in individuals with heart failure

AIMS

To establish reference values and clinically relevant determinants for measures of heart rate variability (HRV) and to assess their relevance for clinical outcome prediction in individuals with heart failure.

METHODS

Data from the MyoVasc study (NCT04064450; N = 3289), a prospective cohort on chronic heart failure with a highly standardized, 5 h examination, and Holter ECG recording were investigated. HRV markers were selected using a systematic literature screen and a data-driven approach. Reference values were determined from a healthy subsample. Clinical determinants of HRV were investigated via multivariable linear regression analyses, while their relationship with mortality was investigated by multivariable Cox regression analyses.

RESULTS

Holter ECG recordings were available for analysis in 1001 study participants (mean age 64.5 ± 10.5 years; female sex 35.4%). While the most frequently reported HRV markers in literature were from time and frequency domains, the data-driven approach revealed predominantly non-linear HRV measures. Age, sex, dyslipidemia, family history of myocardial infarction or stroke, peripheral artery disease, and heart failure were strongly related to HRV in multivariable models. In a follow-up period of 6.5 years, acceleration capacity [HR_perSD 1.53 (95% CI 1.21/1.93), p = 0.0004], deceleration capacity [HR_perSD: 0.70 (95% CI 0.55/0.88), p = 0.002], and time lag [HR_perSD 1.22 (95% CI 1.03/1.44), p = 0.018] were the strongest predictors of all-cause mortality in individuals with heart failure independently of cardiovascular risk factors, comorbidities, and medication.

CONCLUSION

HRV markers are associated with the cardiovascular clinical profile and are strong and independent predictors of survival in heart failure. This underscores clinical relevance and interventional potential for individuals with heart failure.

CLINICALTRIALS

GOV IDENTIFIER

NCT04064450.

Effects of empagliflozin on left ventricular diastolic function in addition to usual care in individuals with type 2 diabetes mellitus-results from the randomized, double-blind, placebo-controlled EmDia trial

BACKGROUND

The sodium-glucose co-transporter 2 inhibitor empagliflozin improves cardiovascular outcome in patients with type 2 diabetes mellitus (T2DM) and heart failure. Experimental studies suggest a direct cardiac effect of empagliflozin associated with an improvement in left ventricular diastolic function.

METHODS

In the randomized, double-blind, two-armed, placebo-controlled, parallel group trial EmDia, patients with T2DM and elevated left ventricular E/E´ ratio were enrolled and randomized 1:1 to receive empagliflozin 10 mg/day versus placebo. The primary endpoint was the change of left ventricular E/E´ ratio after 12 weeks of intervention.

RESULTS

A total of 144 patients with T2DM and an elevated left ventricular E/e´ ratio (age 68.9 ± 7.7 years; 14.1% women; E/e´ ratio 9.61[8.24/11.14], left ventricular ejection fraction 58.9% ± 5.6%). After 12 weeks of intervention, empagliflozin resulted in a significant higher decrease in the primary endpoint E/e´ ratio by - 1.18 ([95% confidence interval (CI) - 1.72/- 0.65]; P < 0.0001) compared with placebo. The beneficial effect of empagliflozin was consistent across all subgroups and also occurred in subjects with heart failure and preserved ejection fraction (n = 30). Additional effects of empagliflozin on body weight, HbA1c, uric acid, red blood cell count, hemoglobin, mean corpuscular hemoglobin, and hematocrit were detected (all P < 0.001). Approximately one-third of the reduction in E/e´ by empagliflozin could be explained by the variables examined.

CONCLUSIONS

Empagliflozin improves diastolic function in patients with T2DM and elevated end-diastolic pressure. Since the positive effects were consistent in patients with and without heart failure with preserved ejection fraction, the data add a mechanistic insight for the beneficial cardiovascular effect of empagliflozin.

TRIAL REGISTRATION

Clinicaltrials.gov, unique identifier: NCT02932436.

Sex-Specific Relationship Between Parathyroid Hormone and Platelet Indices in Phenotypes of Heart Failure-Results From the MyoVasc Study

Background: Heart failure (HF) is a multifactorial syndrome with pathophysiological complexities still not fully understood. Higher mean platelet volume (MPV), a potential marker of platelet activation, and high concentrations of parathyroid hormone (PTH) have been implicated in the pathogenesis of HF.

Aim: This study aims to investigate sex-specifically the association between PTH concentrations and platelet indices in phenotypes of HF.

Methods and Results: PTH and platelet indices (MPV and platelet count) were available in 1,896 participants from the MyoVasc study in Mainz, Germany. Multivariable linear regression models, adjusted for age, sex, season, vitamin D status, cardiovascular risk factors, comorbidities, estimated glomerular filtration rate, and medication, were used to assess the associations between platelet indices and PTH. The results showed distinct sex-specific associations between PTH and platelet indices. A positive association between PTH and MPV was found in females with symptomatic HF with reduced ejection fraction (HFrEF) only [β = 0.60 (0.19; 1.00)]. Platelet count was inversely associated with PTH in male HFrEF individuals [β = −7.6 (−15; −0.30)] and in both males and females with HF with preserved ejection fraction (HFpEF).

Conclusion: This study reports differential, sex-specific relationships between PTH and platelet indices in HF individuals independent of vitamin D status and clinical profile. Particularly in phenotypes of symptomatic HF, distinct associations were observed, suggesting a sex-specific mechanism involved in the interaction between PTH and platelets.

Association of Global Longitudinal Strain With Clinical Status and Mortality in Patients With Chronic Heart Failure

Importance

Global longitudinal strain (GLS) is an emerging echocardiographic biomarker of cardiac function in heart failure (HF). Evidence from large-scale studies comprehensively investigating GLS for its association with clinical phenotypes and mortality in asymptomatic and symptomatic chronic HF is limited.

Objective

To assess the factors associated with GLS and its prognostic value in patients with chronic HF.

Design, Setting, and Participants

The observational, prospective MyoVasc cohort study enrolled 3289 individuals with asymptomatic to symptomatic HF between January 17, 2013, and April 27, 2018. The median follow-up was 3.2 years (interquartile range, 2.0-4.0 years). Participants with stages A to D HF according to American Heart Association (AHA) criteria were examined at a dedicated study center. Echocardiography was performed with GLS measurement by independent reviewers. Data were analyzed from September 2, 2019, to January 15, 2020.

Main Outcomes and Measures

All-cause and cardiac mortality were recorded by structured follow-up and validated via death certificates.

Results

In the study sample, data on GLS were available on 2440 individuals, of whom 2186 (mean [SD] age, 65.0 [10.5] years; 1418 [64.9%] men) were classified as having AHA HF stages A to D. Mean (SD) GLS worsened across AHA stages from stage A (n = 434; -19.44 [3.15%]) to stage B (n = 629; -18.01 [3.46%]) to stages C/D (n = 1123; -15.52 [4.64%]). Age (β = -0.27; 95% CI, -0.47 to -0.067; per decade, P = .009), female sex (β = -1.2; 95% CI, -1.6 to -0.77; per decade, P < .001), obesity (β = 0.64; 95% CI, 0.25-1.0; P = .001), atrial fibrillation (β = 1.2; 95% CI, 0.69-1.6; P < .001), myocardial infarction (β = 1.5; 95% CI, 1.00-2.1; P < .001), and estimated glomerular filtration rate (β = -0.53; 95% CI, -0.73 to -0.32; per SD, P < .001) were independently associated with GLS in multivariable regression analysis. Global longitudinal strain was associated with the severity of HF as reflected by N-terminal prohormone B-type natriuretic protein (NT-proBNP) levels after additionally adjusting for cardiac structure and function (P < .001). During follow-up, GLS was associated with all-cause mortality (hazard ratio [HR] per SD, 1.55; 95% CI, 1.19-2.01; P < .001) and cardiac death (HR per SD, 2.32; 95% CI, 1.57-3.42; P < .001) independent of image quality, observer variability, clinical profile, HF medications, NYHA class, and cardiac structure and function. After further adjustment for the NT-proBNP level, GLS remained associated with cardiac death (HR per SD, 1.60; 95% CI, 1.07-2.41; P = .02) but not all-cause mortality (HR per SD, 1.26; 95% CI, 0.95-1.66; P = .11).

Conclusions and Relevance

In patients with chronic HF, GLS was associated with clinical and cardiac status, reflected neurohormonal activation, and was associated with cardiac mortality independent of clinical and cardiac status. These findings suggest that GLS may serve as a useful tool to improve risk stratification in patients with HF.