Blunted cardiac output response to exercise in adolescents born preterm

Elevated pulmonary capillary wedge pressure, higher blood pressure, and lower cardiac index in infants with bronchopulmonary dysplasia

BACKGROUND

Left ventricular diastolic dysfunction indicated by elevated pulmonary capillary wedge pressure (ePCWP) may worsen cardiorespiratory status in bronchopulmonary dysplasia (BPD), but the scope of ePCWP by cardiac catheterization is not well described.

METHODS

This single-center retrospective cohort study included infants with BPD without congenital heart disease, significant intracardiac shunts, or pulmonary vein stenosis who underwent cardiac catheterization from 2010 to 2021. ePCWP was defined as >10 mmHg. Quantitative measures of ventricular systolic and diastolic function were performed on existing echocardiograms. Patients with and without ePCWP were compared using the Chi-squared or Wilcoxon rank-sum tests. Associations between catheterization hemodynamics and echocardiographic parameters were assessed by simple linear regression.

RESULTS

Seventy-one infants (93% Grade 2 or 3 BPD) met inclusion criteria, and 30 (42%) had ePCWP. Patients with ePCWP were older at catheterization (6.7 vs. 4.5 months, p < 0.001), more commonly underwent tracheostomy (66.7% vs. 29.3%, p = 0.003), and had higher mean systemic blood pressure [64.5 (56.0, 75.0) vs. 47.0 (43.0, 55.0) mm Hg, p < 0.001], higher systemic vascular resistance [11.9 (10.4, 15.6) vs. 8.7 (6.7, 11.2) WU*m2, p < 0.001), and lower cardiac index [3.9 (3.8, 4.9) vs. 4.7 (4.0, 6.3) L/min/m2, p = 0.03] at catheterization. Mean pulmonary artery pressure, pulmonary vascular resistance, and mortality were similar between the groups. Echocardiographic indices of left ventricular diastolic dysfunction did not correlate with PCWP.

CONCLUSIONS

ePCWP was common in infants with severe BPD who underwent cardiac catheterization in this cohort. The association between ePCWP and higher systemic blood pressure supports further study of afterload reduction in this population.

Influence of Preterm Birth and Low Birthweight on Physical Fitness: A Systematic Review, Meta-Analysis, and Meta-Regression

BACKGROUND

Preterm birth and low birthweight (LBW) might be associated with reduced physical fitness, although evidence remains inconclusive.

OBJECTIVE

To examine the influence of preterm birth and LBW on physical fitness, as well as to assess whether variables such as gestational age, birthweight, or age at assessment moderate these effects.

METHODS

PubMed, Scopus, and PsycINFO were systematically searched from inception to 7 December 2023 for case-control and cohort studies analyzing the association between preterm birth or LBW (or gestational age or birthweight as continuous variables) with at least one physical fitness-related outcome (i.e., cardiorespiratory fitness (CRF), muscle strength, flexibility, speed, agility). Random-effects meta-analysis and meta-regression models were used to estimate the pooled effect size, as well as to examine potential associations between the magnitude of the effect and gestational age, birthweight, or age at assessment.

RESULTS

Fifty-two studies (n = 920,603 participants, average age ranging from 4.7 to 34.4 years) were included. Preterm birth was associated with reduced CRF (standardized mean difference (SMD) = -0.38, 95% confidence interval (CI) = -0.51 to -0.25) and muscle strength (SMD = -0.44, 95% CI = -0.79 to -0.08). LBW was associated with reduced CRF (SMD = -0.40, 95% CI = -0.64 to -0.17), muscle strength (SMD = -0.18, 95% CI = -0.24 to -0.13), flexibility (SMD = -0.11, 95% CI = -0.22 to -0.01), and agility (SMD = -0.99, 95% CI = -1.91 to -0.07). Meta-regression analyses showed that a lower gestational age or birthweight were associated with larger reductions in physical fitness, whereas no consistent association was found for the age at assessment.

CONCLUSION

Both preterm birth and LBW seem associated with reduced physical fitness regardless of age, with larger reductions overall observed in individuals with lower gestational age or birthweight. These findings might support the implementation of preventive strategies (e.g., fitness monitoring and physical exercise interventions) in these populations through the life course. PROSPERO registration: CRD42021231845.

Impact of preterm birth on muscle mass and function: a systematic review and meta-analysis

Individuals born preterm present lower exercise capacity. Along with the cardiopulmonary responses and activity level, muscle strength is a key determinant of exercise capacity. This systematic review aimed to summarize the current knowledge on the impact of preterm birth on skeletal muscle mass and function across the lifespan. The databases PubMed, MEDLINE, EBM, Embase, CINAHL Plus, Global Index Medicus, and Google Scholar were searched using keywords and MeSH terms related to skeletal muscle, preterm birth, and low birth weight. Two independent reviewers undertook study selection, data extraction, and quality appraisal using Covidence review management. Data were pooled to estimate the prematurity effect on muscle mass and function using the R software. From 4378 studies retrieved, 132 were full-text reviewed and 25 met the inclusion/exclusion criteria. Five studies presented a low risk of bias, and 5 had a higher risk of bias due to a lack of adjustment for confounding factors and presenting incomplete outcomes. Meta-analyses of pooled data from homogenous studies indicated a significant reduction in muscle thickness and jump test (muscle power) in individuals born preterm versus full-term with standardized mean difference and confidence interval of - 0.58 (0.27, 0.89) and - 0.45 (0.21, 0.69), respectively.    Conclusion: Overall, this systematic review summarizing the existing literature on the impact of preterm birth on skeletal muscle indicates emerging evidence that individuals born preterm, display alteration in the development of their skeletal muscle mass and function. This work also highlights a clear knowledge gap in understanding the effect of preterm birth on skeletal muscle development. What is Known: • Preterm birth, which occurs at a critical time of skeletal muscle development and maturation, impairs the development of different organs and tissues leading to a higher risk of comorbidities such as cardiovascular diseases. • Preterm birth is associated with reduced exercise capacity. What is New: • Individuals born preterm display alterations in muscle mass and function compared to individuals born at term from infancy to adulthood. • There is a need to develop preventive or curative interventions to improve skeletal muscle health in preterm-born individuals.

Influence of preterm birth on physical fitness in early childhood

Evidence suggests that preterm birth is associated with an impaired physical fitness later in life, but whether these effects are already visible since early childhood remains unknown. We aimed to compare the physical fitness of preterm preschoolers with that of children born at term. Children aged three to six years and born preterm (<35 weeks) were recruited from a Neonatal Intensive Care Unit, and children born at term (>37 weeks) were included as controls. A variety of physical fitness indicators (strength, cardiorespiratory fitness, agility, flexibility and balance) were assessed with the PREFIT battery and the adapted sit and reach test. Physical activity levels were measured through the PrePAQ questionnaire. A total of 98 preterm children (gestational age 32.4 ± 2.3 weeks, age 5.1 ± 0.8 years) and 74 controls (gestational age 39.9 ± 1.0 weeks, age 4.8 ± 0.9 years) were analysed. Despite no significant differences in physical activity levels (p > 0.05), preterm children showed an overall poorer physical fitness compared to controls. Specifically, preterm children had an impaired handgrip strength (-13.95%, p < 0.001), lower-limb muscle strength (-12.67%, p = 0.003), agility (-14.9%, p = 0.001), cardiorespiratory fitness (-12.73% p = 0.005) and flexibility (-17.04%, p = 0.001) compared to controls. An inverse dose-response association was observed between the level of prematurity and physical fitness, with very preterm children (gestational age ≤32 weeks) presenting the poorest fitness levels. In summary, prematurity seems to impair physical fitness since early childhood, which might support the need for promoting preventive strategies (e.g. fitness monitoring and applying exercise interventions).Highlights Preterm children present an impaired physical fitness compared with peers born at term since early childhood (3-6 years), as reflected by lower muscle strength, agility, flexibility and cardiorespiratory fitness.A greater impairment of physical fitness in observed in children born very preterm (≤32 weeks of gestation).These findings might support the implementation of preventive strategies (e.g. fitness monitoring and exercise training) in preterm children since early childhood.

Exercise Capacity in Very Low Birth Weight Adults: A Systematic Review and Meta-Analysis

There is an association between very low birth weight (VLBW) and cardiovascular morbidity and mortality in adulthood. Aerobic fitness, measured as the maximal oxygen consumption (VO2 max), is a good indicator of cardiopulmonary health and predictor of cardiovascular mortality. Our aim was to determine the effect of birth weight on aerobic exercise capacity and physical activity. We systematically identified studies reporting exercise capacity (VO2 max and VO2 peak) and physical activity levels in participants born at VLBW aged eighteen years or older compared to term-born controls from six databases (MEDLINE, OVID, EMBASE, CI NAHL, CENTRAL, and Google Scholar). Meta-analysis of eligible studies was conducted using a random effect model. We screened 6202 articles and identified 15 relevant studies, 10 of which were eligible for meta-analysis. VLBW participants had a lower VO2 max compared to their term counterparts (-3.35, 95% CI: -5.23 to -1.47, p = 0.0005), as did VLBW adults who had developed bronchopulmonary dysplasia (-6.08, 95% CI -11.26 to -0.90, p = 0.02). Five of nine studies reported significantly reduced self-reported physical activity levels. Our systematic review and meta-analysis demonstrated reduced maximal aerobic exercise capacity in adults born at VLBW compared to term-born controls.

Impact of premature birth on cardiopulmonary function in later life

Pulmonary function is reduced in children after preterm birth. The variety of subgroups ranges from early to late preterm births. Limitations in pulmonary function can be observed even after late preterm birth without signs of bronchopulmonary dysplasia and/or history of mechanical ventilation. Whether this reduction in lung function is reflected in the cardiopulmonary capacity of these children is unclear. This study aims to investigate the impact of moderate to late premature birth on cardiopulmonary function. Cardiopulmonary exercise testing on a treadmill was performed by 33 former preterm infants between 8 and 10 years of age who were born between 32 + 0 and 36 + 6 weeks of gestation and compared with a control group of 19 children born in term of comparable age and sex. The former preterm children achieved comparable results to the term-born controls with respect to most of the cardiopulmonary exercise parameters [Formula: see text]. The only differences were in a slightly higher oxygen uptake efficiency slope [Formula: see text] and higher peak minute ventilation [Formula: see text] in the group of children born preterm. With respect to heart rate recovery [Formula: see text] and breathing efficiency [Formula: see text], there were no significant differences.

CONCLUSION

 Children born preterm did not show limitations in cardiopulmonary function in comparison with matched controls.

WHAT IS KNOWN

• Preterm birth is associated with reduced pulmonary function in later life, this is also true for former late preterms. • As a consequence of being born premature, the lungs have not finished their important embryological development. Cardiopulmonary fitness is an important parameter for overall mortality and morbidity in children and adults and a good pulmonary function is therefore paramount.

WHAT IS NEW

• Children born prematurely were comparable to an age- and sex-matched control group with regards to almost all cardiopulmonary exercise variables. • A significantly higher OUES, a surrogate parameter for VO₂peak was found for the group of former preterm children, most likely reflecting on more physical exercise in this group. Importantly, there were no signs of impaired cardiopulmonary function in the group of former preterm children.

Aerobic Exercise Training Response in Preterm-Born Young Adults with Elevated Blood Pressure and Stage 1 Hypertension: A Randomized Clinical Trial

Rationale: Premature birth is an independent predictor of long-term cardiovascular risk. Individuals affected are reported to have a lower rate of [Formula: see text]o2 at peak exercise intensity ([Formula: see text]o2PEAK) and at the ventilatory anaerobic threshold ([Formula: see text]o2VAT), but little is known about their response to exercise training. Objectives: The primary objective was to determine whether the [Formula: see text]o2PEAK response to exercise training differed between preterm-born and term-born individuals; the secondary objective was to quantify group differences in [Formula: see text]o2VAT response. Methods: Fifty-two preterm-born and 151 term-born participants were randomly assigned (1:1) to 16 weeks of aerobic exercise training (n = 102) or a control group (n = 101). Cardiopulmonary exercise tests were conducted before and after the intervention to measure [Formula: see text]o2PEAK and the [Formula: see text]o2VAT. A prespecified subgroup analysis was conducted by fitting an interaction term for preterm and term birth histories and exercise group allocation. Measurements and Main Results: For term-born participants, [Formula: see text]o2PEAK increased by 3.1 ml/kg/min (95% confidence interval [CI], 1.7 to 4.4), and the [Formula: see text]o2VAT increased by 2.3 ml/kg/min (95% CI, 0.7 to 3.8) in the intervention group versus controls. For preterm-born participants, [Formula: see text]o2PEAK increased by 1.8 ml/kg/min (95% CI, -0.4 to 3.9), and the [Formula: see text]o2VAT increased by 4.6 ml/kg/min (95% CI, 2.1 to 7.0) in the intervention group versus controls. No significant interaction was observed with birth history for [Formula: see text]o2PEAK (P = 0.32) or the [Formula: see text]o2VAT (P = 0.12). Conclusions: The training intervention led to significant improvements in [Formula: see text]o2PEAK and [Formula: see text]o2VAT, with no evidence of a statistically different response based on birth history. Clinical trial registered with www.clinicaltrials.gov (NCT02723552).

Prematurity blunts protein synthesis in skeletal muscle independently of body weight in neonatal pigs

BACKGROUND

Postnatal growth failure in premature infants is associated with reduced lean mass accretion. Prematurity impairs the feeding-induced stimulation of translation initiation and protein synthesis in the skeletal muscle of neonatal pigs. The objective was to determine whether body weight independently contributes to the blunted postprandial protein synthesis.

METHODS

Preterm and term pigs that were either fasted or fed were stratified into quartiles according to birth weight to yield preterm and term groups of similar body weight; first and second quartiles of preterm pigs and third and fourth quartiles of term pigs were compared (preterm-fasted, n = 23; preterm-fed, n = 25; term-fasted, n = 21; term-fed, n = 21). Protein synthesis rates and mechanistic target of rapamycin complex 1 (mTORC1) activation in skeletal muscle were determined.

RESULTS

Relative body weight gain was lower in preterm compared to term pigs. Prematurity attenuated the feeding-induced increase in mTORC1 activation in longissimus dorsi and gastrocnemius muscles (P < 0.05). Protein synthesis in gastrocnemius (P < 0.01), but not in longissimus dorsi muscle, was blunted by preterm birth.

CONCLUSION

A lower capacity of skeletal muscle to respond adequately to feeding may contribute to reduced body weight gain and lean mass accretion in preterm infants.

IMPACT

This study has shown that the feeding-induced increase in protein synthesis of skeletal and cardiac muscle is blunted in neonatal pigs born preterm compared to pigs born at term independently of birth weight. These findings support the notion that preterm birth, and not low birth weight, impairs the capacity of skeletal and cardiac muscle to upregulate mechanistic target of rapamycin-dependent anabolic signaling pathways and protein synthesis in response to the postprandial increase in insulin and amino acids. These observations suggest that a blunted anabolic response to feeding contributes to reduced lean mass accretion and altered body composition in preterm infants.

A new cardiovascular disease risk factor for young adults: Preterm birth

ABSTRACT

Adults born preterm (birth <37 weeks' gestation) have a two-fold increased risk of early cardiovascular mortality. With 10% of the U.S. population born prematurely and perinatal advancements dramatically improving survival rates, millions of survivors are now reaching adulthood. This phenomenon has introduced a whole new population of individuals with a history of preterm birth. Although the prevailing notion has been that preterm birth is a condition confined only to infancy and early childhood, we now know preterm birth is a risk for lifelong chronic health conditions. Despite almost a decade of epidemiological evidence showing increased cardiovascular risk for those born preterm, this has not yet been translated into clinical practice. As a result, clinicians are caring for adults born prematurely without screening and treatment guidelines for this at-risk population and few inquire about birth history during clinical encounters. This brief report presents growing evidence about disrupted cardiogenesis and consequential structural and functional modifications. By asking the question "Were you born preterm?," nurse practitioners can take the first step of increasing their awareness of this at-risk population and mitigate adverse cardiovascular outcomes by using preterm birth as a risk factor when determining health promotion and treatment decisions.

The Effect of Preterm Birth on Maximal Aerobic Exercise Capacity and Lung Function in Healthy Adults: A Systematic Review and Meta-analysis

BACKGROUND

A negative impact of premature birth on health in adulthood is well established. However, it is not clear whether healthy adults who were born prematurely but have similar physical activity levels compared to adults born at term have a reduced maximal aerobic exercise capacity (maximum oxygen consumption [VO2max]).

OBJECTIVE

We aimed to determine the effect of premature birth on aerobic exercise capacity and lung function in otherwise healthy, physically active individuals.

METHODS

A broad literature search was conducted in the PubMed database. Search terms included 'preterm/premature birth' and 'aerobic exercise capacity'. Maximal oxygen consumption (mL/kg/min) was the main variable required for inclusion, and amongst those investigations forced expiratory volume in 1 s (FEV1, % predicted) was evaluated as a secondary parameter. For the systematic review, 29 eligible articles were identified. Importantly, for the meta-analysis, only studies which reported similar activity levels between healthy controls and the preterm group/s were included, resulting in 11 articles for the VO2max analysis (total n = 688, n = 333 preterm and n = 355 controls) and six articles for the FEV1 analysis (total n = 296, n = 147 preterm and n = 149 controls). Data were analysed using Review Manager ( Review Manager. RevMan version 5.4 software. The Cochrane Collaboration; 2020.).

RESULTS

The systematic review highlighted the broad biological impact of premature birth. While the current literature tends to suggest that there may be a negative impact of premature birth on both VO2max and FEV1, several studies did not control for the potential influence of differing physical activity levels between study groups, thus justifying a focused meta-analysis of selected studies. Our meta-analysis strongly suggests that prematurely born humans who are otherwise healthy do have a reduced VO2max (mean difference: - 4.40 [95% confidence interval - 6.02, - 2.78] mL/kg/min, p < 0.00001, test for overall effect: Z = 5.32) and FEV1 (mean difference - 9.22 [95% confidence interval - 13.54, - 4.89] % predicted, p < 0.0001, test for overall effect: Z = 4.18) independent of physical activity levels.

CONCLUSIONS

Whilst the current literature contains mixed findings on the effects of premature birth on VO2max and FEV1, our focused meta-analysis suggests that even when physical activity levels are similar, there is a clear reduction in VO2max and FEV1 in adults born prematurely. Therefore, future studies should carefully investigate the underlying determinants of the reduced VO2max and FEV1 in humans born preterm, and develop strategies to improve their maximal aerobic capacity and lung function beyond physical activity interventions.

Understanding the Preterm Human Heart: What do We Know So Far?

Globally, preterm birth affects more than one in every 10 live births. Although the short‐term cardiopulmonary complications of prematurity are well known, long‐term health effects are only now becoming apparent. Indeed, preterm birth has been associated with elevated cardiovascular morbidity and mortality in adulthood. Experimental animal models and observational human studies point toward changes in heart morphology and function from birth to adulthood in people born preterm that may contribute to known long‐term risks. Moreover, recent data support the notion of a heterogeneous cardiac phenotype of prematurity, which is likely driven by various maternal, early, and late life factors. This review aims to describe the early fetal‐to‐neonatal transition in preterm birth, the different structural and functional changes of the preterm human heart across developmental stages, as well as potential factors contributing to the cardiac phenotype of prematurity.

Motor outcomes of children born extremely preterm; from early childhood to adolescence

Children and adolescents born extremely preterm (EP; <28 weeks' gestation) are at greater risk of motor impairment, including cerebral palsy and developmental coordination disorder, than their term born peers. Importantly, motor impairment has implications beyond performing motor skills; it negatively affects outcomes as diverse as school success, emotional wellbeing, physical health, and physical activity (PA) participation. This review will outline what is known about PA participation across childhood and adolescence for children born EP and term, recognising that PA may improve physical, social, and mental health outcomes. Critically, PA participation occurs in the context of children's and adolescents' daily lives, and is influenced by the family, social and physical environment, as well as by the child's personal factors, such as motor impairment. Further research is needed to better understand PA participation levels and correlates for children and adolescents born preterm, to better inform effective and sustainable interventions.

Exercise-induced irregular right heart flow dynamics in adolescents and young adults born preterm

BACKGROUND

Preterm birth has been linked to an elevated risk of heart failure and cardiopulmonary disease later in life. With improved neonatal care and survival, most infants born preterm are now reaching adulthood. In this study, we used 4D flow cardiovascular magnetic resonance (CMR) coupled with an exercise challenge to assess the impact of preterm birth on right heart flow dynamics in otherwise healthy adolescents and young adults who were born preterm.

METHODS

Eleven young adults and 17 adolescents born preterm (< 32 weeks of gestation and < 1500 g birth weight) were compared to 11 young adult and 18 adolescent age-matched controls born at term. Stroke volume, cardiac output, and flow in the main pulmonary artery were quantified with 4D flow CMR. Kinetic energy and vorticity were measured in the right ventricle. All parameters were measured at rest and during exercise at a power corresponding to 70% VO2max for each subject. Multivariate linear regression was used to perform age-adjusted term-preterm comparisons.

RESULTS

With exercise, stroke volume increased 10 ± 21% in term controls and decreased 4 ± 18% in preterm born subjects (p = 0.007). This resulted in significantly reduced capacity to increase cardiac output in response to exercise stress for the preterm group (58 ± 26% increase in controls, 36 ± 27% increase in preterm, p = 0.004). Elevated kinetic energy (KEterm = 71 ± 22 nJ, KEpreterm = 87 ± 38 nJ, p = 0.03) and vorticity (ωterm = 79 ± 16 s-1, ωpreterm = 94 ± 32 s-1, p = 0.01) during diastole in the right ventricle (RV) suggested altered RV flow dynamics in the preterm subjects. Streamline visualizations showed altered structure to the diastolic filling vortices in those born preterm.

CONCLUSIONS

For the participants examined here, preterm birth appeared to result in altered right-heart flow dynamics as early as adolescence, especially during diastole. Future studies should evaluate whether the altered dynamics identified here evolves into cardiopulmonary disease later in life. Trial registration None.

Decreased ventricular size and mass mediate the reduced exercise capacity in adolescents and adults born premature

BACKGROUND

Premature birth is associated with lower levels of cardiorespiratory fitness (CRF) but the underlying mechanisms responsible remain unclear. This study assessed whether differences in cardiac morphology or function mediate differences in CRF among adolescents and young adults born preterm.

METHODS

Adolescents and young adults born moderately to extremely premature (gestational age ≤ 32 weeks or birth weight < 1500 g) and age-matched term born participants underwent resting cardiac MRI and maximal exercise testing. Mediation analysis assessed whether individual cardiovascular variables accounted for a significant proportion of the difference in maximal aerobic capacity between groups.

RESULTS

Individuals born preterm had lower VO2max than those born term (41.7 ± 8.6 v 47.5 ± 8.7, p < 0.01). Several variables differed between term and preterm born subjects, including systolic and diastolic blood pressure, mean pulmonary artery pressure, indexed left ventricular end-diastolic volume (LVEDVi), right ventricular end-diastolic volume (RVEDVi), LV mass (LVMi), LV stroke volume index (LVSVi), and LV strain (p < 0.05 for all). Of these variables, LVEDVi, RVEDVi, LVSVi, LVMi, and LV longitudinal strain were significantly related to VO2max (p < 0.05 for all). Significant portions of the difference in VO2max between term and preterm born subjects were mediated by LVEDVi (74.3%, p = 0.010), RVEDVi (50.6%, p = 0.016), and LVMi (43.0%, p = 0.036).

CONCLUSIONS

Lower levels of CRF in adolescents and young adults born preterm are mediated by differences in LVEDVi, RVEDVi, and LVMi. This may represent greater risk for long-term cardiac morbidity and mortality in preterm born individuals.

Association of Systolic Blood Pressure Elevation With Disproportionate Left Ventricular Remodeling in Very Preterm-Born Young Adults: The Preterm Heart and Elevated Blood Pressure

Question

Are left ventricular structure and function in preterm-born adults more susceptible to remodeling in association with blood pressure elevation?

Findings

In this cross-sectional cohort study of 468 adults with cardiac magnetic resonance imaging, left ventricular mass index and mass to end-diastolic volume ratio were greater for each 1–mm Hg elevation in systolic blood pressure in preterm-born adults than in term-born adults, with the greatest rise in those born very and extremely preterm (<32 weeks’ gestation).

Meaning

The findings of this study show that adults born preterm demonstrate greater remodeling in response to systolic blood pressure elevation and may require earlier interventions to prevent cardiovascular disease progression.

Importance

Preterm-born individuals have higher blood pressure with an increased risk of hypertension by young adulthood, as well as potentially adverse cardiac remodeling even when normotensive. To what extent blood pressure elevation affects left ventricular (LV) structure and function in adults born preterm is currently unknown.

Objective

To investigate whether changes observed in LV structure and function in preterm-born adults make them more susceptible to cardiac remodeling in association with blood pressure elevation.

Design, Setting, and Participants

This cross-sectional cohort study, conducted at the Oxford Cardiovascular Clinical Research Facility and Oxford Centre for Clinical Magnetic Resonance Research, included 468 adults aged 18 to 40 years. Of these, 200 were born preterm (<37 weeks’ gestation) and 268 were born at term (≥37 weeks’ gestation). Cardiac magnetic resonance imaging was used to characterize LV structure and function, with clinical blood pressure readings measured to assess hypertension status. Demographic and anthropometric data, as well as birth history and family medical history information, were collected. Data were analyzed between January 2012 and February 2021.

Main Outcomes and Measures

Cardiac magnetic resonance measures of LV structure and function in response to systolic blood pressure elevation.

Results

The cohort was primarily White (>95%) with a balanced sex distribution (51.5% women and 48.5% men). Preterm-born adults with and without hypertension had higher LV mass index, reduced LV function, and smaller LV volumes compared with term-born individuals both with and without hypertension. In regression analyses of systolic blood pressure with LV mass index and LV mass to end-diastolic volume ratio, there was a leftward shift in the slopes in preterm-born compared with term-born adults. Compared with term-born adults, there was a 2.5-fold greater LV mass index per 1–mm Hg elevation in systolic blood pressure in very and extremely preterm-born adults (<32 weeks’ gestation) (0.394 g/m² vs 0.157 g/m² per 1 mm Hg; P < .001) and a 1.6-fold greater LV mass index per 1–mm Hg elevation in systolic blood pressure in moderately preterm-born adults (32 to 36 weeks’ gestation) (0.250 g/m² vs 0.157 g/m² per 1 mm Hg; P < .001). The LV mass to end-diastolic volume ratio per 1–mm Hg elevation in systolic blood pressure in the very and extremely preterm-born adults was 3.4-fold greater compared with those born moderately preterm (3.56 × 10⁻³ vs 1.04 × 10⁻³ g/mL per 1 mm Hg; P < .001) and 3.3-fold greater compared with those born at term (3.56 × 10⁻³ vs 1.08 × 10⁻³ g/mL per 1 mm Hg; P < .001).

Conclusions and Relevance

Preterm-born adults have a unique LV structure and function that worsens with systolic blood pressure elevation. Additional primary prevention strategies specifically targeting cardiovascular risk reduction in this population may be warranted.

The Preterm Heart-Brain Axis in Young Adulthood: The Impact of Birth History and Modifiable Risk Factors

People born preterm are at risk of developing both cardiac and brain abnormalities. We aimed to investigate whether cardiovascular physiology may directly affect brain structure in young adulthood and whether cardiac changes are associated with modifiable biomarkers. Forty-eight people born preterm, followed since birth, underwent cardiac MRI at age 25.1 ± 1.4 years and brain MRI at age 33.4 ± 1.0 years. Term born controls were recruited at both time points for comparison. Cardiac left and right ventricular stroke volume, left and right ventricular end diastolic volume and right ventricular ejection fraction were significantly different between preterm and term born controls and associated with subcortical brain volumes and fractional anisotropy in the corpus callosum in the preterm group. This suggests that cardiovascular abnormalities in young adults born preterm are associated with potentially adverse future brain health. Associations between left ventricular stroke volume indexed to body surface area and right putamen volumes, as well as left ventricular end diastolic length and left thalamus volumes, remained significant when adjusting for early life factors related to prematurity. Although no significant associations were found between modifiable biomarkers and cardiac physiology, this highlights that cardiovascular health interventions may also be important for brain health in preterm born adults.

Exaggerated Cardiac Contractile Response to Hypoxia in Adults Born Preterm

Individuals born prematurely have smaller hearts, cardiac limitations to exercise, and increased overall cardiometabolic risk. The cardiac effects of acute hypoxia exposure as another physiologic stressor remain under explored. The purpose of this study was to determine the effects of hypoxia on ventricular function in adults born preterm. Adults born moderately to extremely preterm (≤32 weeks gestation or <1500 g, N = 32) and born at term (N = 18) underwent cardiac magnetic resonance imaging under normoxic (21% O₂) and hypoxic (12% O₂) conditions to assess cardiovascular function. In normoxia, cardiac function parameters were similar between groups. During hypoxia, the right ventricular (RV) contractile response was significantly greater in participants born premature, demonstrated by greater increases in RV ejection fraction (EF) (p = 0.002), ventricular-vascular coupling (VVC) (p = 0.004), and strain (p < 0.0001) measures compared to term-born participants, respectively. Left ventricular contractile reserve was similar to term-born participants. Adults born preterm exhibit an exaggerated contractile response to acute hypoxia, particularly in the RV. This suggests that adults born preterm may have contractile reserve, despite the lack of volume reserve identified in previous exercise studies. However, this exaggerated and hyper-adapted response may also increase their risk for late RV failure.