Early Growth Patterns and Cardiac Structure and Function at Midlife: Northern Finland 1966 Birth Cohort Study.

OBJECTIVES: To evaluate the influence of early growth patterns that have previously been associated with later cardiometabolic risk on cardiac left ventricular (LV) structure and function in midlife. STUDY DESIGN: A subpopulation of the Northern Finland Birth Cohort 1966 took part in follow-up, including echocardiography (n = 1155) at the age of 46 years. Body mass index (BMI) growth curves were modeled based on frequent anthropometric measurements in childhood. Age and BMI at adiposity peak (n = 482, mean age 9.0 months) and at adiposity rebound (n = 586, mean age 5.8 years) were determined. Results are reported as unstandardized beta (ß) or OR with 95% CIs for 1 SD increase in early growth variable. RESULTS: Earlier adiposity rebound was associated with increased LV mass index (ß = -4.10 g/m2 (-6.9, -1.3); P = .004) and LV end-diastolic volume index (ß = -2.36 mL/m2 (-3.9, -0.84); P = .002) as well as with eccentric LV hypertrophy (OR 0.54 [0.38, 0.77]; P = .001) in adulthood in males. BMI at adiposity rebound was directly associated with LV mass index (ß = 2.33 g/m2 [0.80, 3.9]; P = .003). Higher BMI at both adiposity peak and at adiposity rebound were associated with greater LV end-diastolic volume index (ß = 1.47 mL/m2; [0.51, 2.4], ß = 1.28 mL/m2 [0.41, 2.2], respectively) and also with eccentric LV hypertrophy (OR 1.41 [1.10, 1.82], OR 1.53 [1.23, 1.91], respectively) and LV concentric remodeling (OR 1.38 [1.02, 1.87], OR 1.40 [1.06, 1.83], respectively) in adulthood (P < .05 for all). These relationships were only partly mediated by adult BMI. CONCLUSIONS: Early growth patterns in infancy and childhood contribute to cardiac structure at midlife.

Postexercise Heart Rate Recovery in Adults Born Preterm.

OBJECTIVE: To evaluate postexercise heart rate recovery (HRR) in adults born preterm. STUDY DESIGN: We studied the association between preterm birth and postexercise HRR in 545 adults (267 women) at 23.3 years of age (range 19.9-26.3 years). One hundred three participants were born early preterm (<34 completed weeks), 178 late preterm (34-36), and 264 were full term (control group). HRR was calculated as change in heart rate (HR) 30 seconds and 60 seconds after cessation of submaximal step test and maximum HR slope during the first minute after. RESULTS: Mean peak HR was 159.5 bpm in the early preterm (P = .16 with controls), 157.8 bpm in the late preterm (P = .56), and 157.0 bpm in the control group. Mean HRR 30 seconds after exercise was 3.2 bpm (95% CI 1.1-5.2) lower in the early preterm group and 2.1 bpm (0.3-3.8) lower in the late preterm group than the full term controls. Mean 60s HRR was 2.5 (-0.1 to 5.1) lower in the early preterm group and 2.8 bpm (0.6-4.9) lower in the late preterm group. Mean maximum slope after exercise was 0.10 beats/s (0.02-0.17) lower in the early preterm group and 0.06 beats/s (0.00-0.12) lower in the late preterm group. CONCLUSIONS: Our results suggest reduced HRR after exercise in adults born preterm, including those born late preterm. This suggests altered reactivation of the parasympathetic nervous system, which may contribute to cardiovascular risk among adults born preterm.

Cardiac Autonomic Function in Adults Born Preterm.

OBJECTIVE: To evaluate cardiac autonomic function in adults born preterm. STUDY DESIGN: We studied the association between prematurity and cardiac autonomic function using heart rate variability measurements in 600 adults (mean age of 23.3 years) from a geographically based cohort in Northern Finland. There were 117 young adults born early preterm (<34 weeks), 207 born late preterm (34-36 weeks), and 276 born at term (≥37 weeks, controls). Autonomic function was analyzed by calculating time and frequency domain heart rate variability measurements using linear regression. RESULTS: Compared with controls, the mean difference in root mean square of successive differences (indicating cardiac vagal activity) was -12.0% (95% CI -22.2%, -0.5%, adjusted for sex, age, source cohort, and season P = .04) for the early preterm group and -7.8% (-16.8%, 2.0%, P = .12) for the late preterm group. Mean differences with controls in low frequency power (indicating cardiac vagal activity, including some sympathetic- and baroreflex-mediated effects) were -13.6% (-26.7%, 1.8%, P = .08) for the early preterm group and -16.4% (-27.0%, -4.3%, P = .01) for the late preterm group. Mean differences in high frequency power (quantifying cardiac vagal modulation in respiratory frequency) were -19.2% (-36.6%, 2.9%, P = .09) for the early preterm group and -13.8% (-29.4%, 5.3%, P = .15) for the late preterm group. Differences were attenuated when controlled for body mass index and physical activity. CONCLUSIONS: Our results suggest altered autonomic regulatory control in adults born preterm, including those born late preterm. Altered autonomic regulatory control may contribute to increased cardiovascular risk in adults born preterm.

Linear and nonlinear analysis of heart rate variability in coronary disease.

OBJECTIVE: Coronary artery disease (CAD) and acute myocardial infarction (AMI) are associated with a reduction of heart rate variability (HRV). The aim of this study was to compare the HRV of CAD patients with and without AMI (CAD-AMI) with health-matched controls by linear (spectral analysis) and nonlinear [Shannon entropy (SE), conditional entropy (CE) and symbolic analysis (SA)] analysis. METHODS: Fifty-eight men were divided into three groups: healthy (n = 19, 57 ± 4 years), CAD (n = 20, 56 ± 10 years) and CAD-AMI (n = 19, 54 ± 12 years). The RR intervals were recorded at rest in the supine position for 10 min with an HR monitor (Polar(®)S810i). A series of 250 beats was selected to analyze variance, spectral analysis, SE, CE [complexity index (CI), normalized CI (NCI)] and SA (0V, 1V, 2LV and 2ULV patterns), as well as 0V (no significant variation) and 2ULV (two significant unlike variations), which reflect sympathetic and vagal modulation, respectively. One-way ANOVA (or the Kruskal-Wallis test when appropriate) and Pearson correlation were used. RESULTS: The CAD group had higher body mass index and weight than the CAD-AMI group, but no differences were found between the healthy and AMI groups. There were no differences between the groups regarding linear and nonlinear analysis. The 0V and 2ULV patterns were significantly correlated with the SE, CI and NCI of the three groups. INTERPRETATION: There was no difference between the groups regarding cardiac autonomic modulation by linear and nonlinear methods, which may be due to beta-blocker use, coronary angioplasty and the exercise capacity of healthy subjects.