Key result
Lower resting heart rate linked to ~48% higher prevalence of transplant CAD.
Why the study?
The relevance of changes in heart rate to the development of transplant coronary artery disease remains unclear due to conflicting prior findings.
Does a lower resting heart rate predict the presence of transplant coronary artery disease in heart transplant recipients?
Observational (n=130)
Does a lower resting heart rate predict the presence of transplant coronary artery disease in heart transplant recipients?
In heart transplant recipients, a lower resting heart rate is associated with a higher prevalence of transplant coronary artery disease, contrary to findings in non-transplant populations.
Studies in animals and humans have demonstrated that an increased heart rate is a predictor for the development of coronary atherosclerosis and overall cardiovascular mortality. In contrast, we have previously reported that the need for pacemaker implantation because of bradycardia in heart transplant recipients is associated with an increased prevalence of transplant coronary artery disease (TxCAD). Hence, the relevance of changes in heart rate to the development of TxCAD remains unclear. Intra-coronary ultrasound examinations (ICUS) were therefore analyzed in 130 heart transplant recipients (age 50 +/- 11 yr) studied at annual evaluations (3.7 +/- 3.0 yr after transplantation). Quantitative ultrasound measurements were obtained by calculating mean coronary artery intimal thickness (MIT) obtained by examination of the left anterior descending artery. The presence of TxCAD was defined as MIT > 0.3 mm. Resting heart rates (HR) were recorded with the patients in the supine position during routine echocardiography. Based on HR recordings, two groups were defined: group 1, HR below; or group 2, HR above the median. TxCAD was detected in 40% of the ICUS studies overall. The prevalence of TxCAD was higher in group 1 (49%) compared with group 2 (33%), p < 0.05. There was no significant difference in donor ischemic time or donor gender, recipient age, gender, body weight, CMV status, creatinine, total cholesterol, use of lipid lowering drugs or diltiazem. Donor age and use of beta-blockers were higher in group 1 compared with group 2 (29 +/- 10 vs. 25 +/- 9 yr, and 15% vs. 5%, for donor age and beta-blocker use, respectively). By multivariate regression analysis only donor age and years after transplantation were independently correlated with TxCAD. After excluding patients taking beta-blockers and diltiazem, the prevalence of CAD was still higher in group 1 (50%) vs. group 2 (34%). In conclusion, transplant coronary artery disease is more prevalent in patients with lower, rather than higher, heart rates. The reason for this is unclear, but may reflect impaired blood flow to the sinoatrial node.
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Gullestad et al. (1997) conducted an observational in Transplant coronary artery disease (n=130). Lower resting heart rate (below median) vs. Higher resting heart rate (above median) was evaluated on Presence of transplant coronary artery disease (mean intimal thickness > 0.3 mm) (p=<0.05). Lower resting heart rate was associated with a higher prevalence of transplant coronary artery disease compared to higher heart rate (49% vs 33%, p<0.05).
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