Sex- and age-related cardiac remodelling and its association with risk factors - Results from Cardiovascular Magnetic Resonance Imaging in the German National Cohort (NAKO)

This study utilizing data from the German National Cohort reveals that while postmenopausal women exhibit more adverse cardiac remodeling, this is primarily driven by a higher burden of cardiometabolic risk factors rather than stronger risk-factor associations, with distinct sex- and age-specific patterns identified for BMI, triglycerides, and sleep problems.

The Gist

Imagine your heart as a high-performance engine in a car. Over time, this engine changes shape and size depending on how hard you drive it, the quality of the fuel you put in, and the wear and tear of the road. This process is called cardiac remodelling.

This study, conducted on over 20,000 people in Germany using super-precise heart cameras (MRI), looked at how this "engine" changes as we age, and how it differs between men and women—especially around the time women go through menopause.

Here is the breakdown in simple terms, using some everyday analogies:

1. The "Menopause Shift" (The Great Reset)

Think of a woman's body before menopause as a car running on a very efficient, protective fuel system (thanks to estrogen). After menopause, that protective fuel system runs out.

• What happened: The study found that after menopause, women's hearts start to change shape faster than men's. They get "stiffer" and more "round" (concentric), rather than just getting bigger.
• The Big Question: Is this because women's hearts suddenly become more fragile? Or is it because their bodies are carrying more "heavy cargo" (risk factors like high blood pressure and weight) at this stage?
• The Answer: It's the cargo. The study concluded that postmenopausal women don't necessarily have hearts that are more sensitive to damage; rather, they are carrying a heavier load of risk factors (like higher blood pressure and belly fat) that force the heart to work harder and change shape.

2. The "Fuel" Differences (Risk Factors)

The researchers looked at different types of "fuel" (risk factors) and how they affect the heart engine.

• Body Weight (BMI):

  • Younger Women: Being heavier was like adding a bigger gas tank. The heart got bigger to handle the extra weight, but it still pumped efficiently.
  • Older Women: Being heavier became like putting heavy rocks in the trunk. The heart didn't just get bigger; it got thick and stiff (concentric), which is less efficient.
  • Men: Men generally showed a stronger link between weight and heart size (getting bigger) rather than just stiffness.

• Triglycerides (Blood Fats):

  • The Surprise: In women before menopause, high triglycerides were surprisingly bad for the heart's size and function. It was like a small clog in a high-performance engine causing big problems.
  • The Comparison: This effect was actually stronger in young women than in young men. Once women hit menopause, this specific link weakened a bit, but the overall risk from other factors (like blood pressure) took over.

• Sleep Problems:

  • The Gender Gap: If a man has trouble sleeping, his heart seems to suffer more than a woman's does. It's as if men's hearts are more sensitive to the "stress" of a bad night's sleep. The study suggests this might be linked to hormones like testosterone, which can drop when sleep is poor.

3. The "Engine" Changes Over Time

• Volume: As people get older, the "gas tank" (heart chamber volume) gets smaller in everyone. But in women, this shrinking happens much faster after menopause, like a balloon deflating quickly once the knot is untied.
• Stiffness: The heart walls get thicker with age for everyone, but women's walls thicken faster in midlife.

4. Lifestyle: Smoking and Exercise

• Smoking: It turns out that how much you smoked over your whole life matters more than whether you are currently smoking. Older people who quit smoking had more "wear and tear" on their hearts than younger smokers, simply because they had smoked for longer.
• Exercise: Young men who exercise seem to build the biggest, strongest heart muscles (like bodybuilders). This is usually a good thing (physiological adaptation), but it highlights that men and women respond to exercise slightly differently.

The Bottom Line

Think of the heart as a tire.

• Men tend to get wider tires as they age and gain weight.
• Women tend to get thicker, stiffer tires, especially after menopause.

The study's main takeaway is that postmenopausal women aren't "broken" by nature. Instead, they are facing a "perfect storm" of risk factors (higher blood pressure, weight gain, metabolic changes) that pile up at this life stage.

The Good News: Since the problem is the load (the risk factors) and not a fundamental flaw in the heart itself, managing those risk factors—keeping blood pressure down, maintaining a healthy weight, and sleeping well—is the key to keeping the heart engine running smoothly for both men and women at any age.

Technical Summary

1. Problem Statement

Cardiac remodelling is a structural and functional adaptation to stressors that precedes heart failure. While it is well-established that aging and the postmenopausal period are associated with adverse cardiometabolic profiles and unfavorable cardiac changes, several critical gaps remain:

• Sex-Specific Differences: It is unclear whether the associations between modifiable risk factors (e.g., BMI, blood pressure, lipids) and subclinical cardiac remodelling differ between pre- and postmenopausal women compared to men of similar ages.
• Right Ventricle (RV) Neglect: Historically, research has focused on the Left Ventricle (LV), leaving sex- and age-related patterns of RV remodelling poorly described.
• Mechanism of Menopause: It is debated whether the adverse cardiac remodelling seen in postmenopausal women is driven by a higher burden of risk factors or by an increased intrinsic susceptibility of the myocardium to these factors after menopause.

2. Methodology

Study Design & Population:

• Cohort: Cross-sectional analysis of the baseline examination of the German National Cohort (NAKO), a large population-based study.
• Sample: 20,152 participants (40% women, mean age 47 ± 12 years) from the MRI subsample.
• Exclusions: Participants with poor-quality CMR images, prevalent cardiovascular disease (CVD), or missing data on menopausal status/lifestyle/metabolic factors were excluded.

Data Acquisition:

• Imaging: 3.0-T MRI scanners were used to acquire standard short-axis cine balanced steady-state free precession (bSSFP) images.
• Parameters: Morphofunctional data were derived for both ventricles, including:
  • Volumes/Mass: End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), cardiac output (CO), and mass (LVM), indexed to height$^{1.7}$.
  • Function: Ejection fraction (EF).
  • Structure: Concentricity index (LVCI = LVM/LVEDV) and wall thickness (LVWT).
• Risk Factors: Standardized measurements included BMI, blood pressure (SBP/DBP), lipid profiles (LDL-C, HDL-C, triglycerides), HbA1c, smoking status, alcohol use, physical activity (MET-hours), and sleep metrics (duration and problems).

Stratification:

• Women: Stratified by menopausal status (Pre-menopause vs. Post-menopause). Post-menopause was defined as no menstruation >6 months (age ≥45), surgical cessation, or age >60.
• Men: Stratified by age groups corresponding to the women's groups: <50 years (younger) and ≥50 years (older).

Statistical Analysis:

• Models: Multivariable linear regression models were used to assess associations between risk factors and cardiac parameters.
• Adjustments: Models were adjusted for HDL-C, medication use (antihypertensive, antidiabetic, lipid-lowering), and other exposures entered simultaneously.
• Comparisons: Differences in regression coefficients ($\beta$) between groups were tested using z-tests. Significance was determined using False Discovery Rate (FDR) correction ($p < 0.05$).
• Visualization: Generalized Additive Models (GAMs) with thin plate regression splines were used to visualize continuous trends across age.

3. Key Contributions

• Comprehensive RV Assessment: This study provides one of the largest population-based descriptions of Right Ventricle (RV) remodelling patterns across the adult lifespan, a domain historically under-researched compared to the LV.
• Menopause-Specific Analysis: By stratifying women by menopausal status and men by corresponding age, the study isolates the specific impact of the menopausal transition on risk factor-cardiac associations.
• Mechanistic Insight: The study distinguishes between the burden of risk factors (prevalence/severity) and the susceptibility (strength of association) of the heart to those factors in postmenopausal women.

4. Key Results

Baseline Characteristics & Trends:

• Risk Factors: Women showed steeper increases in SBP, LDL-C, and triglycerides during midlife compared to men. BMI increased steadily in women, while in men it stabilized or declined after age 60.
• Cardiac Remodelling:
  • Volumes: Ventricular volumes declined with age in both sexes, but the decline accelerated in women during midlife.
  • Structure: LVWT and LVCI increased with age. The rate of increase was steeper in women, particularly post-menopause, indicating a shift toward concentric remodelling.
  • EF: LVEF remained higher in women than men across all age groups.

Associations with Risk Factors:

• BMI:
  • Women: In premenopausal women, higher BMI was associated with larger volumes (compensatory). In postmenopausal women, higher BMI was strongly associated with increased LVCI (concentricity) and lower LVEF, indicating adverse remodelling.
  • Men: BMI showed stronger associations with LV mass and concentricity in men than in women, but the pattern of adverse remodelling (lower EF) was more distinct in postmenopausal women.
• Triglycerides:
  • Associations were strongest in premenopausal women. Higher triglycerides were linked to lower volumes and higher LVCI.
  • The association between triglycerides and RV volumes was significantly stronger in premenopausal women than in men <50 years (e.g., RVEDV: $\beta$ -0.173 vs. -0.064).
• Blood Pressure:
  • Higher SBP was associated with larger volumes and mass in men (eccentric pattern), while associations with concentricity were similar across sexes.
• Sleep:
  • Sleep problems were more strongly associated with adverse cardiac parameters in men (particularly older men) compared to postmenopausal women. For example, sleep problems were negatively associated with LVEDV in older men but positively in postmenopausal women.
• Smoking:
  • Adverse associations of smoking with cardiac structure were largely driven by cumulative exposure (pack-years) rather than age or menopausal status alone.

5. Significance and Conclusion

Primary Conclusion:
The less favorable cardiac remodelling observed in postmenopausal women (specifically increased concentricity and reduced EF) is primarily driven by a higher burden of cardiometabolic risk factors (elevated BP, adiposity, metabolic dysfunction) rather than an increased intrinsic susceptibility of the myocardium to these factors.

Clinical and Public Health Implications:

• Risk Factor Control: Effective management of cardiometabolic risk factors (BP, lipids, BMI) is crucial across the entire adult lifespan, with specific attention needed during the menopausal transition.
• Sex-Specific Nuances:
  • Women: Triglyceride levels may be a critical early marker of cardiac risk in premenopausal women, while BMI and BP become dominant drivers of adverse concentric remodelling post-menopause.
  • Men: Sleep disturbances appear to be a more potent predictor of adverse cardiac structural changes in men than in women.
• RV Importance: The findings highlight the necessity of including RV assessment in cardiovascular risk stratification, as RV volumes and function also exhibit distinct sex- and age-related patterns.

This study underscores the need for sex-specific prevention strategies and the importance of early intervention to mitigate the accelerated cardiac aging observed in postmenopausal women.