Progression of Coronary Atherosclerosis After Heart Transplantation on Electron-beam Computed Tomography

Rationale and Objectives

Cardiac transplant vasculopathy is the most important long-term complication of heart transplantation, with overlapping features with conventional, atherosclerotic coronary artery disease. The aim of this study was to determine the progression of coronary artery disease after heart transplantation by measuring total coronary calcium load.

Materials and Methods

After heart transplantation, 185 patients were serially examined using electron-beam computed tomography for coronary calcium load for clinical reasons. The mean time between the initial examination and the follow-up scan was 566 days (range, 126–1,436). Coronary calcium load was measured by the Agatston method, and the total calcium scores at both examinations were compared between patients taking and those not taking lipid-lowering medications (statins).

Results

Patients not taking statins ( n = 94) displayed a median annualized percentage increase in total calcium score of 0 Agatston units, whereas patients taking at least the lowest recommended daily dose of a statin ( n = 84) displayed an annualized percentage decrease of 11 Agatston units. The difference was not statistically significant (Wilcoxon’s rank-sum test, P = .35). Only 17 patients had increases of > 24 Agatston units, and eight of them were taking statins (χ 2 test, P = .99).

Conclusion

The annual rate of progression of coronary calcium load after heart transplantation is low. In this investigation, no beneficial effects of statins could be detected.

Cardiac transplant vasculopathy (TVP) is the most important long-term complication of cardiac transplantation ( ). To diagnose TVP, intracoronary ultrasound (ICUS) has evolved as the reference technique, whereas coronary angiography fails to detect early disease ( ). Using ICUS, intimal thickening as the hallmark of TVP increases by 0.04 to 0.1 mm on average within the first year after transplantation, with important differences between medical regimens ( ). On ICUS, 75% of heart transplant recipients fulfill diagnostic criteria for TVP within the first 3 years after transplantation ( ). Although ICUS is the only clinically established method capable of detecting such subtle intimal changes, it remains an invasive method with associated risks, is costly, and is limited to the proximal coronary segments. Electron-beam computed tomography has been introduced for the noninvasive quantification of coronary calcium as a surrogate marker of coronary atherosclerosis (expressed as the total calcium score [TCS]), both in patients with conventional coronary artery disease ( ) and in heart transplant recipients ( ). Although there has been some debate about the occurrence of calcifications with TVP ( ), more recent evidence indicates that coronary calcifications do occur in TVP as well ( ).

Using electron-beam computed tomography, statins have been shown to significantly reduce the progression of coronary atherosclerosis in conventional coronary artery disease ( ). Statins reduce the progression of TVP assessed using ICUS ( ). Consequently, we hypothesized that electron-beam computed tomographic (EBCT) quantification of the coronary calcium burden in cardiac transplant recipients would reflect the progression of coronary disease and that the progression of the TCS would be less in transplant recipients treated with statins.

Materials and methods

Patients

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Table 1

Patient Characteristics

Characteristic Value Total no. of patients 185 No. of patients with 1 follow-up EBCT study 115 No. of patients with 2 follow-up EBCT studies 57 No. of patients with 3 follow-up EBCT studies 13 Observational period (mo), range (median) 4–70 (27) Time of transplantation 1985–2000 Age at transplantation (y), mean ± SD (range) 46 ± 14 (8–67) Age at study entry (y), mean ± SD 50 ± 14 Patient gender 42 female Donor gender 51 female, 16 unknown Donor age (y), median (range) 33 (9–66) Indication for transplantation Ischemic cardiomyopathy 30 Nonischemic dilated cardiomyopathy 155

EBCT, electron-beam computed tomographic; SD, standard deviation.

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Test Methods

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Statistical Analysis

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Results

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Discussion

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Study Limitations

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References

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Progression of Coronary Atherosclerosis After Heart Transplantation on Electron-beam Computed Tomography

Rationale and Objectives

Materials and Methods

Results

Conclusion

Materials and methods

Patients

Test Methods

Statistical Analysis

Results

Discussion

Study Limitations

References

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