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Background: Rapamycin has been shown to reduce anatomical evidence of cardiac allograft vasculopathy, but its effect on coronary artery physiology is unknown., Methods: Twenty-seven patients without angiographic evidence of coronary artery disease underwent measurement of fractional flow reserve (FFR), coronary flow reserve (CFR), and the index of microcirculatory resistance (IMR) within 8 weeks and then 1 year after transplantation using a pressure sensor/thermistor-tipped guidewire. Measurements were compared between consecutive patients who were on rapamycin for at least 3 months during the first year after transplantation (rapamycin group, n = 9) and a comparable group on mycophenolate mofetil (MMF) instead (MMF group, n = 18)., Results: At baseline, there was no significant difference in FFR, CFR, or IMR between the 2 groups. At 1 year, FFR declined significantly in the MMF group (0.87 +/- 0.06 to 0.82 +/- 0.06, P = .009) but did not change in the rapamycin group (0.91 +/- 0.05 to 0.89 +/- 0.04, P = .33). Coronary flow reserve and IMR did not change significantly in the MMF group (3.1 +/- 1.7 to 3.2 +/- 1.0, P = .76; and 27.5 +/- 18.1 to 19.1 +/- 7.6, P = .10, respectively) but improved significantly in the rapamycin group (2.3 +/- 0.8 to 3.8 +/- 1.4, P < .03; and 27.0 +/- 11.5 to 17.6 +/- 7.5, P < .03, respectively). Multivariate regression analysis revealed that rapamycin therapy was an independent predictor of CFR and FFR at 1 year after transplantation., Conclusion: Early after cardiac transplantation, rapamycin therapy is associated with improved coronary artery physiology involving both the epicardial vessel and the microvasculature.

Cardiac allograft vasculopathy (CAV) is a progressive process involving the epicardial and microvascular coronary systems. The timing of the development of abnormalities in these 2 compartments and the correlation between changes in physiology and anatomy are undefined. The invasive evaluation of coronary artery anatomy and physiology with intravascular ultrasound, fractional flow reserve, coronary flow reserve, and the index of microcirculatory resistance (IMR) was performed in the left anterior descending coronary artery during 151 angiographic evaluations of asymptomatic heart transplant recipients from 0 to >5 years after heart transplantation (HT). There was no angiographic evidence of significant CAV, but during the first year after HT, fractional flow reserve decreased significantly (0.89 +/- 0.06 vs 0.85 +/- 0.07, p = 0.001), and percentage plaque volume derived by intravascular ultrasound increased significantly (15.6 +/- 7.7% to 22.5 +/- 12.3%, p = 0.0002), resulting in a significant inverse correlation between epicardial physiology and anatomy (r = -0.58, p <0.0001). The IMR was lower in these patients compared with those > or =2 years after HT (24.1 +/- 14.3 vs 29.4 +/- 18.8 units, p = 0.05), suggesting later spread of CAV to the microvasculature. As the IMR increased, fractional flow reserve increased (0.86 +/- 0.06 to 0.90 +/- 0.06, p = 0.0035 comparing recipients with IMRs < or =20 to those with IMRs > or =40), despite no difference in percentage plaque volume (21.0 +/- 11.2% vs 20.5 +/- 10.5%, p = NS). In conclusion, early after HT, anatomic and physiologic evidence of epicardial CAV was found. Later after HT, the physiologic effect of epicardial CAV may be less, because of increased microvascular dysfunction.

Background: Investigating changes in coronary physiology that occur after cardiac transplantation has been challenging. Simultaneous and independent assessment of the epicardial artery by measuring fractional flow reserve (FFR) and of the microvasculature by calculating the index of microvascular resistance (IMR) with a single coronary pressure wire may be useful., Methods: Twenty-five asymptomatic patients with normal coronary angiograms underwent FFR, thermodilution-derived IMR and coronary flow reserve (CFR) and intravascular ultrasound (IVUS) evaluation soon after cardiac transplantation and 1 year later., Results: FFR significantly worsened (0.90 +/- 0.05 at baseline to 0.85 +/- 0.06 at 1 year, p = 0.004). FFR correlated strongly with percent plaque volume as measured by IVUS (r = -0.58, p < 0.0001). IMR improved significantly (29.2 +/- 15.9 at baseline to 19.3 +/- 7.6 units at 1 year, p = 0.007). CFR increased, but not significantly (2.6 +/- 1.4 at baseline to 3.2 +/- 1.2 at 1 year, p = not significant). Diabetes and donor heart ischemic time independently predicted baseline IMR. Treatment with rapamycin independently predicted FFR at 1 year., Conclusions: New coronary physiologic measures, FFR and IMR, show that epicardial artery physiology worsens and correlates with anatomic changes, whereas microvascular physiology improves during the first year after cardiac transplantation. CFR, the traditional method for evaluating coronary circulatory physiology, did not identify these changes.

Objectives: We sought to document whether a physiologic change in gender has any effect on coronary arterial size., Background: The coronary arteries are smaller in women, even after correction for body surface area (BSA). These differences may contribute to adverse clinical outcomes after coronary artery bypass graft surgery and myocardial infarction in women. In male and female transsexuals, pharmacologic doses of estrogens and androgens significantly influence vascular diameter. Thus, gender differences in the coronary vasculature may be a reflection of the hormonal environment., Methods: In 86 patients who had undergone orthotopic heart transplantation, serial intravascular ultrasound studies of the proximal left anterior descending coronary artery (LAD) were analyzed. Changes in vessel area (VA) over the first or second post-transplant year were recorded, and comparisons were made between donor hearts that were transplanted in a patient of the same gender and those that were transplanted in a patient of the opposite gender., Results: Vessel area of the proximal LAD increased over time in all patient groups. In hearts transplanted within the same gender and in male donor hearts transplanted to female recipients, the change was small and not significant. However, in hearts transplanted from female donors to male recipients, there was a substantial and highly significant increase in LAD VA (median 16.13 to 17.88 mm(2); p = 0.01). This increase was not explained by confounding due to changes in BSA or left ventricular wall thickness., Conclusions: This pattern of arterial remodeling early after heart transplantation supports a link between host gender and coronary arterial size.

Background: Although intracoronary ultrasound (ICUS) has been validated for the early detection of transplant coronary artery disease (TxCAD), the prognostic importance of findings detected by this new imaging technique is unknown., Methods and Results: This study examined the relation of clinical outcome in 145 heart transplant recipients (mean age, 45.1 +/- 11.1 years) with the amount of intimal thickness measured by ICUS during routine annual coronary angiography 1 to 10 years (mean, 3.1 +/- 2.2 years) after transplantation. From published autopsy data, a mean intimal thickness of > 0.3 mm was considered significant. During a mean follow-up time of 48.2 +/- 10.2 months, 23 deaths (12 cardiac) occurred, and 6 patients required retransplantation. Angiographic TxCAD developed in 22 of 125 patients (17.6%) in the subgroup with normal angiograms at the time of ICUS and a follow-up annual angiographic study. In the total population and the subgroup, mean intimal thicknesses of > 0.3 and < or = 0.3 mm, respectively, were associated with significantly inferior 4-year actuarial overall survival (73% versus 96%, P = .005; 72% versus 92%, P = .05), cardiac survival (79% versus 96%, P = .005; 80% versus 98%, P = .04), and freedom from cardiac death and retransplantation (74% versus 98%, P < .0001; 70% versus 96%, P = .001). In addition, ICUS predicted freedom from development of subsequent angiographic TxCAD in the subgroup that was initially normal (26% versus 72%, P = .02). A mean intimal thickness by ICUS of > 0.3 mm was associated with inferior clinical outcome regardless of the presence of angiographic TxCAD and predicted the development of subsequent angiographic TxCAD. Despite significantly longer duration after transplantation, higher rejection incidence, and lower average daily cyclosporine dose, none of these covariates were independent risk factors for outcome., Conclusions: These findings confirm the prognostic importance of mean intimal thickening of > 0.3 mm in heart transplant recipients and suggest that these patients should be candidates for early interventional strategies.

The mechanisms responsible for transplant coronary artery disease (CAD) and its predisposing factors remain incompletely understood. The influence of donor characteristics as predisposing factors has not been studied systematically. We examined the correlation of donor demographic, clinical, and immunologic parameters with transplant CAD assessed by both intracoronary ultrasound (ICUS) and coronary angiography in 116 heart transplant recipients (age 44.7 +/- 12.0 years) studied 3.4 years (range 1.0 to 14.6) after transplantation. Quantitative ultrasound data were obtained by calculating mean intimal thickness from several distinct coronary sites. Coronary angiograms were categorized visually as normal or showing any transplant CAD. By multivariate regression analysis, donor undersize of > 20% of recipient weight (p < 0.02) and duration after transplantation (p < 0.005) were independently correlated with the amount of ICUS intimal thickness (r = 0.36, p = 0.0007), and older donor age with angiographic evidence for the disease (r = 0.34, p < 0.006). In a subgroup analysis of the 39 patients studied 1 year after transplantation, white donor race (p < 0.05), fewer human leukocyte antigen-DR mismatches (p < 0.002), shorter ischemic time (p < 0.04), and donor smoking history (p < 0.02) were independent predictors for severity of ICUS intimal thickening (r = 0.92, p = 0.0009); higher donor age (p < 0.006) and higher arterial partial pressure of oxygen (p < 0.003) were independent predictors for angiographic disease (r = 0.67, p < 0.002). In conclusion, donor characteristics may contribute to the probably multifactorial pathogenesis of transplant CAD.

To assess survival after the development of transplant coronary artery disease, annual angiography reports from 353 heart transplant recipients were reviewed. Fifty-four patients who survived beyond 1 year and in whom moderate-to-severe proximal or midvessel coronary artery disease developed were identified. Moderate-to-severe proximal or midvessel coronary disease was defined for this study as a 40% or more stenosis in 1 or more primary or secondary epicardial arteries. Actuarial survival (Kaplan-Meier) from the time of disease detection in those 54 patients was 67% at 1 year, 44% at 2 years, and 17% at 5 years. Actuarial survival was reduced proportionate to disease severity. Survival for single-vessel disease (> or = 40% stenosis) was 64% at 1 year, 36% at 2 years, and 22% at 5 years. Survival was significantly worse with triple-vessel disease (13% at 2 years; p = 0.01) and intermediate for double-vessel disease (41% at 2 years; p = 0.01). Of 19 patients who underwent retransplantation for coronary artery disease, 13 patients (68%) died at a mean of 24 +/- 20 months (range, 1 to 59), and of 15 patients from whom postmortem or angiographic data were available, 11 patients (73%) showed recurrence of significant coronary artery disease in the new graft. Identification of moderate or severe proximal or midvessel coronary disease at angiography predicts an overall mortality rate of more than 50% at 2 years. The poor survival rate in those who underwent retransplantation (around 50% at 4 years) and the high rate of redevelopment of coronary disease suggest that retransplantation should be reserved for selected candidates with angiographically severe disease, if used at all.

Accelerated coronary disease is a major factor limiting long-term survival in cardiac transplant recipients. Coronary angiography was obtained a mean of 5.1 weeks posttransplantation and annually thereafter. Replicate projections recorded after nitroglycerine administration were quantitated using computer-assisted edge detection. Five hundred and fifteen coronary segments in 25 patients having 1-year follow-up and 353 segments in 18 patients reaching 2-year follow-up were compared with baseline angiograms. Significant change was defined as +/- 0.10 mm, equal to 3.8% change in diameter based on three standard deviations obtained from estimation of measurement error. Mean coronary diameter fell from 2.44 +/- 0.26 mm at baseline to 2.21 +/- 0.34 mm (p less than 0.001) at 1-year follow-up. This rate of diameter decline was 20-fold more rapid during the initial posttransplantation year than the rate of change of visually normal segments in nontransplant patients with coronary atherosclerosis elsewhere. There was no significant drop in mean diameter between the first and second year in those patients who had second-year studies. Decrease in absolute diameter for vessels greater than 2.9 mm significantly exceeded diameter reduction for smaller vessels but did not differ when considered as a ratio of vessel diameter. In 21 of 25 patients, mean coronary diameter reduction exceeded the three-standard deviation threshold at their last angiogram, but only two of these patients had visually detectable transplant coronary disease.