Meta‐Analysis of Cardiorespiratory Fitness Impairment in Pediatric Heart Transplant Recipients
Nadeen Wu, Stephen J. Foulkes, Nathan R. Weeldreyer, Calvin Kruger, Corey R. Tomczak, Michael Khoury, Jennifer L. Conway, Mark J. HaykowskyABSTRACT
Pediatric heart transplant (PHTR) recipients have reduced cardiorespiratory fitness (VO 2 peak); however, the magnitude of this impairment and its underlying central hemodynamic mechanisms remain poorly characterized. This systematic review and meta‐analysis quantified differences in VO 2 peak and peak exercise central hemodynamics between PHTR recipients and age‐matched healthy controls (CON). MEDLINE (PubMed) was searched for studies comparing VO 2 peak in PHTR recipients and CON. Pooled effect sizes were expressed as weighted mean differences (WMD) using a DerSimonian–Laird random‐effects model, and weighted least‐squares meta‐regression assessed the moderating effects of age and time post‐transplant. Seven unique studies (PHTR n = 90; CON n = 118) reported VO 2 peak and peak HR. PHTR had significantly lower VO 2 peak (WMD = −9.5 mL/kg/min), peak HR (WMD: −30 bpm), and CO ( n = 3 studies, WMD: −2.5 L/min), with no difference in peak SBP ( n = 3 studies). Meta‐regression revealed no significant moderating effect of age or time post‐transplant on the VO 2 peak deficit. The markedly reduced VO 2 peak in PHTR recipients is driven primarily by impaired peak CO and persistent chronotropic incompetence, consistent with cardiac allograft sympathetic denervation.