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Adrenergic Receptor Polymorphism and Maximal Exercise Capacity after Orthotopic Heart Transplantation

View Article: PubMed Central - PubMed

ABSTRACT

Background: Maximal exercise capacity after heart transplantion (HTx) is reduced to the 50–70% level of healthy controls when assessed by cardiopulmonary exercise testing (CPET) despite of normal left ventricular function of the donor heart. This study investigates the role of donor heart β1 and β2- adrenergic receptor (AR) polymorphisms for maximal exercise capacity after orthotopic HTx.

Methods: CPET measured peak VO2 as outcome parameter for maximal exercise in HTx recipients ≥9 months and ≤4 years post-transplant (n = 41; mean peak VO2: 57±15% of predicted value). Donor hearts were genotyped for polymorphisms of the β1-AR (Ser49Gly, Arg389Gly) and the β2-AR (Arg16Gly, Gln27Glu). Circumferential shortening of the left ventricle was measured using magnetic resonance based CSPAMM tagging.

Results: Peak VO2 was higher in donor hearts expressing the β1-Ser49Ser alleles when compared with β1-Gly49 carriers (60±15% vs. 47±10% of the predicted value; p = 0.015), and by trend in cardiac allografts with the β1-AR Gly389Gly vs. β1-Arg389 (61±15% vs. 54±14%, p = 0.093). Peak VO2 was highest for the haplotype Ser49Ser-Gly389, and decreased progressively for Ser49Ser-Arg389Arg > 49Gly-389Gly > 49Gly-Arg389Arg (adjusted R2 = 0.56, p = 0.003). Peak VO2 was not different for the tested β2-AR polymorphisms. Independent predictors of peak VO2 (adjusted R2 = 0.55) were β1-AR Ser49Gly SNP (p = 0.005), heart rate increase (p = 0.016), and peak systolic blood pressure (p = 0.031). Left ventricular (LV) motion kinetics as measured by cardiac MRI CSPAMM tagging at rest was not different between carriers and non-carriers of the β1-AR Gly49allele.

Conclusion: Similar LV cardiac motion kinetics at rest in donor hearts carrying either β1-AR Gly49 or β1-Ser49Ser variant suggests exercise-induced desensitization and down-regulation of the β1-AR Gly49 variant as relevant pathomechanism for reduced peak VO2 in β1-AR Gly49 carriers.

No MeSH data available.


Related in: MedlinePlus

Mean circumferential strain at basal, mid-ventricular and apical slices of the left ventricle comparing β1-AR Ser49Ser and β1-Gly49 carriers along the cardiac cycle.The strain values were obtained using HARP analysis on tagged images acquired with a SF bSSFP CSPAMM tagging technique. All measurements were adapted to the systole duration of each exam. No statistically significant difference could be found between the two groups.
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pone.0163475.g004: Mean circumferential strain at basal, mid-ventricular and apical slices of the left ventricle comparing β1-AR Ser49Ser and β1-Gly49 carriers along the cardiac cycle.The strain values were obtained using HARP analysis on tagged images acquired with a SF bSSFP CSPAMM tagging technique. All measurements were adapted to the systole duration of each exam. No statistically significant difference could be found between the two groups.

Mentions: Nine patients (3 women; age 46±14 y) were scanned. Circumferential strain measurements were obtained as described above; one slice with artifact was not included in the analysis (n = 1/27 slices). Patients were grouped into carriers of the β1-AR Gly49 variant (n = 4) and patients with the β1-AR Ser49Ser variant (n = 5). Groups were without significant difference at any time of the cardiac cycle as assessed at the time point of largest difference (Fig 4A base: -12.7±4.2 vs. -9.6±4.5% at 130% of systole duration, p = 0.32; Fig 4B mid-ventricular: -14.6±4.3 vs. -13.0±4.2% at 80% of systole duration, p = 0.60; Fig 4C apical: -9.4±10.2% vs. -12.7±3.4% at 80% of systole duration, p = 0.58).


Adrenergic Receptor Polymorphism and Maximal Exercise Capacity after Orthotopic Heart Transplantation
Mean circumferential strain at basal, mid-ventricular and apical slices of the left ventricle comparing β1-AR Ser49Ser and β1-Gly49 carriers along the cardiac cycle.The strain values were obtained using HARP analysis on tagged images acquired with a SF bSSFP CSPAMM tagging technique. All measurements were adapted to the systole duration of each exam. No statistically significant difference could be found between the two groups.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036840&req=5

pone.0163475.g004: Mean circumferential strain at basal, mid-ventricular and apical slices of the left ventricle comparing β1-AR Ser49Ser and β1-Gly49 carriers along the cardiac cycle.The strain values were obtained using HARP analysis on tagged images acquired with a SF bSSFP CSPAMM tagging technique. All measurements were adapted to the systole duration of each exam. No statistically significant difference could be found between the two groups.
Mentions: Nine patients (3 women; age 46±14 y) were scanned. Circumferential strain measurements were obtained as described above; one slice with artifact was not included in the analysis (n = 1/27 slices). Patients were grouped into carriers of the β1-AR Gly49 variant (n = 4) and patients with the β1-AR Ser49Ser variant (n = 5). Groups were without significant difference at any time of the cardiac cycle as assessed at the time point of largest difference (Fig 4A base: -12.7±4.2 vs. -9.6±4.5% at 130% of systole duration, p = 0.32; Fig 4B mid-ventricular: -14.6±4.3 vs. -13.0±4.2% at 80% of systole duration, p = 0.60; Fig 4C apical: -9.4±10.2% vs. -12.7±3.4% at 80% of systole duration, p = 0.58).

View Article: PubMed Central - PubMed

ABSTRACT

Background: Maximal exercise capacity after heart transplantion (HTx) is reduced to the 50–70% level of healthy controls when assessed by cardiopulmonary exercise testing (CPET) despite of normal left ventricular function of the donor heart. This study investigates the role of donor heart β1 and β2- adrenergic receptor (AR) polymorphisms for maximal exercise capacity after orthotopic HTx.

Methods: CPET measured peak VO2 as outcome parameter for maximal exercise in HTx recipients ≥9 months and ≤4 years post-transplant (n = 41; mean peak VO2: 57±15% of predicted value). Donor hearts were genotyped for polymorphisms of the β1-AR (Ser49Gly, Arg389Gly) and the β2-AR (Arg16Gly, Gln27Glu). Circumferential shortening of the left ventricle was measured using magnetic resonance based CSPAMM tagging.

Results: Peak VO2 was higher in donor hearts expressing the β1-Ser49Ser alleles when compared with β1-Gly49 carriers (60±15% vs. 47±10% of the predicted value; p = 0.015), and by trend in cardiac allografts with the β1-AR Gly389Gly vs. β1-Arg389 (61±15% vs. 54±14%, p = 0.093). Peak VO2 was highest for the haplotype Ser49Ser-Gly389, and decreased progressively for Ser49Ser-Arg389Arg > 49Gly-389Gly > 49Gly-Arg389Arg (adjusted R2 = 0.56, p = 0.003). Peak VO2 was not different for the tested β2-AR polymorphisms. Independent predictors of peak VO2 (adjusted R2 = 0.55) were β1-AR Ser49Gly SNP (p = 0.005), heart rate increase (p = 0.016), and peak systolic blood pressure (p = 0.031). Left ventricular (LV) motion kinetics as measured by cardiac MRI CSPAMM tagging at rest was not different between carriers and non-carriers of the β1-AR Gly49allele.

Conclusion: Similar LV cardiac motion kinetics at rest in donor hearts carrying either β1-AR Gly49 or β1-Ser49Ser variant suggests exercise-induced desensitization and down-regulation of the β1-AR Gly49 variant as relevant pathomechanism for reduced peak VO2 in β1-AR Gly49 carriers.

No MeSH data available.


Related in: MedlinePlus