Determinants of Lumen Loss Between Years 1 and 2 After Cardiac Transplantation

PET assessment of myocardial perfusion reserve inversely correlates with intravascular ultrasound findings in angiographically normal cardiac transplant recipients

Cardiac allograft vasculopathy (CAV) is the major determinant of long-term survival after heart transplantation. We aimed to evaluate the efficacy of PET as a noninvasive way to assess the early stages of CAV.

METHODS

Twenty-seven consecutive patients (20 men and 7 women; mean age +/- SD, 46 +/- 12 y) who had normal results on coronary angiography and normal left ventricular systolic function (ejection fraction >or= 60%) were enrolled at 2.5 +/- 2.1 y after transplantation. Myocardial blood flow (MBF) was assessed using dynamic (13)N-ammonia PET at rest and during adenosine-induced hyperemia, and myocardial perfusion reserve (MPR) was calculated as the ratio of hyperemic MBF to resting MBF. Regional (13)N-ammonia PET was assessed using a 5-point scoring system. The intravascular ultrasound (IVUS) measurements for the extent of intimal hyperplasia, including plaque volume index (calculated as [total plaque volume/total vessel volume] x 100%) and maximum area of stenosis, were compared with MPR by linear regression analysis.

RESULTS

In 27 angiographically normal cardiac transplant recipients, MBF at rest and during adenosine stress and MPR of the left anterior descending artery distribution correlated strongly with the other 2 coronary artery distribution territories (r >or= 0.97, P < 0.0001). Summed stress score and summed difference score showed a moderate inverse correlation with MPR (r = -0.41 and -0.49, respectively; P < 0.05) but not with IVUS measurements. MPR correlated inversely with plaque volume index (r = -0.40, P < 0.05) but not with maximal luminal stenosis as assessed by IVUS. In addition, MPR and IVUS measurements gradually inversely changed after heart transplantation (all P < 0.05).

CONCLUSION

This study confirms that CAV is a progressive process, diffusely involving the epicardial and microvascular coronary system. Plaque burden as determined by IVUS agrees well with MPR as assessed by PET in recipients with normal coronary angiography results. This finding suggests that dynamic (13)N-ammonia PET is clinically feasible for the early detection of CAV and can be used as a reliable marker of disease progression.

Effect of diabetes on progression of coronary atherosclerosis and arterial remodeling: a pooled analysis of 5 intravascular ultrasound trials

OBJECTIVES

Our goal was to characterize coronary atherosclerosis progression and arterial remodeling in diabetic patients.

BACKGROUND

The mechanisms that underlie adverse cardiovascular outcomes in diabetic patients have not been well characterized.

METHODS

A systematic analysis was performed in 2,237 subjects in randomized controlled studies of atherosclerosis progression. The pattern of arterial remodeling, extent of coronary atherosclerosis, and disease progression was compared in subjects with and without diabetes.

RESULTS

In association with more risk factors, diabetic patients demonstrated a greater percent atheroma volume (PAV) (40.2 +/- 0.9% vs. 37.5 +/- 0.8%, p < 0.0001) and total atheroma volume (TAV) (199.4 +/- 7.9 mm(3) vs. 189.4 +/- 7.1 mm(3), p = 0.03) on multivariate analysis. A stronger correlation was observed between PAV and glycated hemoglobin (r = 0.22, p = 0.0003) than fasting glucose (r = 0.09, p < 0.0001), although the difference just failed to meet statistical significance after controlling for study. Diabetic patients exhibited a smaller lumen (291.1 +/- 104.8 mm(3) vs. 306.5 +/- 108.2 mm(3), p = 0.005) but no difference in external elastic membrane (494.9 +/- 166.9 mm(3) vs. 498.8 +/- 167.2 mm(3), p = 0.61) volumes. More rapid progression of PAV (0.6 +/- 0.4% vs. 0.05 +/- 0.3%, p = 0.0001) and TAV (-0.6 +/- 2.5 mm(3) vs. -2.7 +/- 2.4 mm(3), p = 0.03) was observed in diabetic patients on multivariate analysis. Smaller external elastic membrane (482.5 +/- 160.7 mm(3) vs. 519.9 +/- 166.9 mm(3), p = 0.03) and lumen (276.0 +/- 100.3 mm(3) vs. 310.1 +/- 105.6 mm(3), p = 0.001) volumes were observed in diabetic patients treated with insulin despite the presence of a similar TAV (206.5 +/- 88.6 mm(3) vs. 209.9 +/- 90.2 mm(3), p = 0.84). Intensive low-density lipoprotein cholesterol lowering in patients improved the rate of plaque progression, but only to the level observed in nondiabetic patients with suboptimal lipid control.

CONCLUSIONS

Diabetes is accompanied by more extensive atherosclerosis and inadequate compensatory remodeling. Accelerated plaque progression, despite use of medical therapies, supports the need to develop new antiatherosclerotic strategies in diabetic patients.