First description and validation of a new method for estimating aortic stenosis burden and predicting the functional response to TAVI.

Background: Up to one-fifth of patients continue to have poor quality of life after transcatheter aortic valve implantation (TAVI), with an additional similar proportion not surviving 1 year after the procedure. We aimed to assess the value of a new method based on an integrated analysis of left ventricular outflow tract flow velocity and aortic pressure to predict objective functional improvement and prognosis after TAVI. Methods: In a cohort of consecutive patients undergoing TAVI, flow velocity-pressure integrated analysis was obtained from simultaneous pressure recordings in the ascending aorta and flow velocity recordings in the left ventricular outflow tract by echocardiography. Objective functional improvement 6 months after TAVI was assessed through changes in a 6-min walk test and NT-proBNP levels. A clinical follow-up was conducted at 2 years. Results: Of the 102 patients studied, 82 (80.4%) showed objective functional improvement. The 2-year mortality of these patients was significantly lower (9% vs. 44%, p = 0.001). In multivariate analysis, parameter "(Pressure at Vmax - Pressure at Vo)/Vmax" was found to be an independent predictor for objective improvement. The C-statistic was 0.70 in the overall population and 0.78 in the low-gradient subgroup. All echocardiographic parameters and the valvuloarterial impedance showed a C-statistic of <0.6 for the overall and low-gradient patients. In a validation cohort of 119 patients, the C-statistic was 0.67 for the total cohort and 0.76 for the low-gradient subgroup. Conclusion: This new method allows predicting objective functional improvement after TAVI more precisely than the conventional parameters used to assess the severity of aortic stenosis, particularly in low-gradient patients.

A new integrative approach to assess aortic stenosis burden and predict objective functional improvement after TAVR.

Background: A non-negligible rate of patients undergoing transcatheter aortic valve replacement (TAVR) do not report symptomatic improvement or even die in the short-midterm. We sought to assess the degree of objective functional recovery after TAVR and its prognostic implications and to develop a predictive model. Methods: In a cohort of patients undergoing TAVR, a prospective evaluation of clinical, anatomical, and physiological parameters was conducted before and after the procedure. These parameters were derived from echocardiography, non-invasive analysis of arterial pulse waves, and cardiac tomography. Objective functional improvement 6 months after TAVR was assessed using a 6-min walk test and nitro-terminal pro-brain natriuretic peptide (NT-proBNP) levels. The derived predictive model was prospectively validated in a different cohort. A clinical follow-up was conducted at 2 years. Results: Among the 212 patients included, objective functional improvement was observed in 169 patients (80%) and subjective improvement in 187 (88%). Patients with objective functional improvement showed a much lower death rate at 2 years (9% vs. 31% p = 0.0002). Independent predictors of improvement were as follows: mean aortic gradient of ≥40 mmHg, augmentation index75 of ≥45%, the posterior wall thickness of ≤12 mm, and absence of atrial fibrillation. A simple integer-based point score was developed (GAPA score), which showed an area under the curve of 0.81 for the overall cohort and 0.78 for the low-gradient subgroup. In a validation cohort of 216 patients, these values were 0.75 and 0.76, respectively. Conclusion: A total of 80% of patients experienced objective functional improvement after TAVR, showing a significantly lower 2-year mortality rate. A predictive score was built that showed a good discriminative performance in overall and low-gradient populations.

Validation study to determine the accuracy of central blood pressure measurement using the SphygmoCor XCEL cuff device in patients with severe aortic stenosis undergoing transcatheter aortic valve replacement.

Central aortic blood pressure could be helpful in the evaluation of patients with aortic stenosis (AS). The SphygmoCor XCEL device estimates central blood pressure (BP) measurement with its easy-to-use, operator-independent procedure. However, this device has not been properly validated against invasive measurement in patients with severe AS. We evaluated the relationship between cuff-brachial BP, transfer function-estimated and invasively measured central aortic pressure in patients with severe AS before and after transcatheter aortic valve replacement (TAVR). Agreement between techniques was analyzed and, according to the ARTERY Society recommendations, the minimum acceptable error was a mean difference ± SD ≤5 ± ≤8 mm Hg. A total of 94 patients with AS undergoing TAVR had simultaneous non-invasive and invasive measurements of central BP before and after the procedure. Before TAVR central systolic BP was in average slightly underestimated, though with wide variability, when using the default calibration of brachial-cuff SBP (mean difference ± SD, -3 ± 15 mm Hg), and after TAVR the degree of underestimation increased (mean difference ± SD, -9 ± 13 mm Hg). The agreement tended to improve for those patients with low aortic gradient stenosis compared to those with high gradient at baseline (mean difference ± SD, -2 ± 11 mm Hg vs. -4 ± 17, respectively, p = .3). The cuff-brachial systolic BP yielded numerically lower degree of agreement and weaker correlation with invasive measurements than SphygmoCor XCEL. In patients with severe AS the SphygmoCor XCEL cuff device, despite showing strong correlation, does not meet the ARTERY Society accuracy criteria for non-invasive measurement of central SBP.

Spanish Heart Transplant Registry. 31th Official Report of the Heart Failure Association of the Spanish Society of Cardiology.

INTRODUCTION AND OBJECTIVES: The present report describes the clinical characteristics and outcomes of heart transplants in Spain and updates the data to 2019. METHODS: We describe the clinical characteristics and outcomes of heart transplants performed in Spain in 2019, as well as trends in this procedure from 2010 to 2018. RESULTS: In 2019, 300 transplants were performed (8794 since 1984; 2745 between 2010 and 2019). Compared with previous years, the most notable findings were the decreasing rate of urgent transplants (38%), and the consolidation of the type of circulatory support prior to transplant, with an almost complete disappearance of counterpulsation balloon (0.7%), stabilization in the use of extracorporeal membrane oxygenation (9.6%), and an increase in the use of ventricular assist devices (29.0%). Survival from 2016 to 2018 was similar to that from 2013 to 2015 (P=.34). Survival in both these periods was better than that from 2010 to 2012 (P=.002 and P=.01, respectively). CONCLUSIONS: Heart transplant activity has remained stable during the last few years, as have outcomes (in terms of survival). There has been a trend to a lower rate of urgent transplants and to a higher use of ventricular assist devices prior to transplant.

Eficacia y seguridad del uso de novo y precoz de tacrolimus de liberación prolongada en el trasplante cardiaco / Efficacy and safety of de novo and early use of extended-release tacrolimus in heart transplantation

Introducción y objetivos: El tacrolimus de liberación prolongada (TLP) permite una dosificación única diaria, lo que simplifica el régimen inmunosupresor. El presente estudio describe la eficacia y la seguridad del uso de TLP de novo y precoz para el trasplante cardiaco. Métodos: Se realizó un estudio observacional, retrospectivo y multicéntrico para comparar el uso de novode TLP (grupo de TLP; n = 94), tacrolimus de liberación estándar (grupo de TLE; n = 42) y la conversión precoz (CP) de TLP a TLE (grupo de CP; n = 44). El TLP se usó entre 2007 y 2012. Se analizaron la tasa de incidencia de rechazo agudo, infección e infección por citomegalovirus al primer año tras el trasplante, así como parámetros de seguridad. Resultados: Entre los grupos no hubo diferencias significativas en la dosis diaria y las concentraciones séricas de tacrolimus durante el primer año tras el trasplante. La incidencia de rechazo fue de 1,05 (IC95%, 0,51-1,54), 1,39 (IC95%, 1,00-1,78) y 1,11 (IC95%, 0,58-1,65) eventos/pacientes-años en los grupos de TLE, TLP y CP respectivamente (p = 0,48). La incidencia de infección fue de 0,75 (IC95%, 0,60-0,86), 0,62 (IC95%, 0,52-0,71) y 0,55 (IC95%, 0,40-0,68) en los grupos de TLE, TLP y CP respectivamente (p = 0,46). Se produjo infección por citomegalovirus en el 23,8, el 20,2 y el 18,2% respectivamente (p = 0,86). No hubo diferencias significativas entre los grupos en los parámetros de seguridad o la función del injerto. Falleció 1 paciente del grupo de TLE y 2 del grupo de TLP. Conclusiones: Parece que el uso de novo de TLP o la CP de TLP a TLE tienen similares eficacia y seguridad que el TLE en el trasplante cardiaco (AU)

Introduction and objectives: The extended-release formulation of tacrolimus (ERT) allows once-daily dosage, thus simplifying the immunosuppressive regimen. This study aimed to describe the safety and efficacy of the de novo and early use of ERT in heart transplantation. Methods: This was an observational, retrospective, multicenter study comparing the safety and efficacy of the de novo use of ERT (ERT group [n = 94]), standard-release tacrolimus (SRT group [n = 42]) and early conversion (EC) from SRT to ERT (EC group [n = 44]). Extended-release tacrolimus was used between 2007 and 2012. One-year incidence rates of acute rejection, infection, and cytomegalovirus infection were analyzed. Safety parameters were also evaluated. Results: There were no significant between-group differences in the daily dose or trough levels of tacrolimus during the first year after transplantation. The rejection incidence rates were 1.05 (95%CI, 0.51-1.54), 1.39 (95%CI, 1.00-1.78), and 1.11 (95%CI, 0.58-1.65) episodes per patient-years in the SRT group, ERT group, and EC group, respectively (P = .48). The infection incidence rates were 0.75 (95%CI, 0.60-0.86), 0.62 (95%CI, 0.52-0.71), and 0.55 (95%CI, 0.40-0.68) in the SRT group, ERT group, and EC group, respectively (P = .46). Cytomegalovirus infection occurred in 23.8%, 20.2%, and 18.2% of the patients, respectively (P = .86). No significant between-group differences were found in laboratory tests or in allograft function. There was 1 death in the SRT group and 2 in the ERT group. Conclusions: Both de novo and early use of ERT seem to have similar safety and efficacy profiles to conventional SRT-based immunosuppression (AU)

Efficacy and Safety of de Novo and Early Use of Extended-release Tacrolimus in Heart Transplantation.

INTRODUCTION AND OBJECTIVES: The extended-release formulation of tacrolimus (ERT) allows once-daily dosage, thus simplifying the immunosuppressive regimen. This study aimed to describe the safety and efficacy of the de novo and early use of ERT in heart transplantation. METHODS: This was an observational, retrospective, multicenter study comparing the safety and efficacy of the de novo use of ERT (ERT group [n=94]), standard-release tacrolimus (SRT group [n=42]) and early conversion (EC) from SRT to ERT (EC group [n=44]). Extended-release tacrolimus was used between 2007 and 2012. One-year incidence rates of acute rejection, infection, and cytomegalovirus infection were analyzed. Safety parameters were also evaluated. RESULTS: There were no significant between-group differences in the daily dose or trough levels of tacrolimus during the first year after transplantation. The rejection incidence rates were 1.05 (95%CI, 0.51-1.54), 1.39 (95%CI, 1.00-1.78), and 1.11 (95%CI, 0.58-1.65) episodes per patient-years in the SRT group, ERT group, and EC group, respectively (P=.48). The infection incidence rates were 0.75 (95%CI, 0.60-0.86), 0.62 (95%CI, 0.52-0.71), and 0.55 (95%CI, 0.40-0.68) in the SRT group, ERT group, and EC group, respectively (P=.46). Cytomegalovirus infection occurred in 23.8%, 20.2%, and 18.2% of the patients, respectively (P=.86). No significant between-group differences were found in laboratory tests or in allograft function. There was 1 death in the SRT group and 2 in the ERT group. CONCLUSIONS: Both de novo and early use of ERT seem to have similar safety and efficacy profiles to conventional SRT-based immunosuppression.

Registro Español de Trasplante Cardiaco. Una visión histórica / The Spanish heart transplantation registry. a historical perspective

El Registro Español de Trasplante Cardiaco cumple 24 años de actividad. En el presente artículo se hace referencia histórica a su evolución hasta el presente, incluyendo su organización, los resultados de su actividad y sus potencialidades (AU)

The Spanish Heart Transplantation Registry has been in existence for 24 years. This article provides a historical perspective on the development of the Registry up to the present day and discusses its organization, achievements and future potential (AU)

Rejection after conversion to a proliferation signal inhibitor in chronic heart transplantation.

We sought to determine the incidence, risk factors, and consequences of acute rejection (AR) after conversion from a calcineurin inhibitor (CNI) to a proliferation signal inhibitor (PSI) in maintenance heart transplantation. Relevant clinical data were retrospectively obtained for 284 long-term heart transplant recipients from nine centers in whom CNIs were replaced with a PSI (sirolimus or everolimus) between October 2001 and March 2009. The rejection rate at one yr was 8.3%, stabilizing to 2% per year thereafter. The incidence rate after conversion (4.9 per 100 patient-years) was significantly higher than that observed on CNI therapy in the pre-conversion period (2.2 per 100 patient-years). By multivariate analysis, rejection risk was associated with a history of late AR prior to PSI conversion, early conversion (<5 yr) after transplantation and age <50 yr at the time of conversion. Use of mycophenolate mofetil was a protective factor. Post-conversion rejection did not significantly influence the evolution of left ventricular ejection fraction, renal function, or mortality during further follow-up. Conversion to a CNI-free immunosuppression based on a PSI results in an increased risk of AR. Awareness of the clinical determinants of post-conversion rejection could help to refine the current PSI conversion strategies.

Avaliação da capacidade cardiorrespiratória (vo2máx) em policiais militares, com testes indiretos / Assessment of cardiorespiratory fitness (VO2máx) in the military police of, with indirect tests

O objetivo deste estudo foi avaliar o (VO2máx) de militares com testes indiretos de 1600m (ALMEIDA et al., 2010) e 12min (COOPER,1968). Participaram 49 militares masculinos, aptos fisicamente, média de idade de 25,6 ±3,10 anos, IMC 23 ±1,4 Kg.m2, selecionados aleatoriamente. O (VO2máx) foi mensurado através das equações de Cooper e Almeida após os testes; coletados e analisados os parâmetros fisiológicos: frequência cardíaca, glicemia e lactato pré e pós-testes e percepção subjetiva do esforço ao final. Observou-se grande fidedignidade entre eles, sendo o valor do (VO2máx) de 1600m (43,63±3,21) superior ao de 12min (39,42±4,18), mostrando aumento significativo (p<0,0001), atribuída à potência de exercício desenvolvida durante o teste, que pode ser observada nos valores de lactato no de 1600m. A prova de 1600m, mostrou-se como uma alternativa eficaz na mensuração do (VO2máx) em militares, portanto sendo uma medida indireta de baixo custo e fácil uso e de grande valia sua aplicabilidade nas Instituições Militares.

The objective of this research was to evaluate the (VO2máx), in indirect tests of 1600m (Almeida et al., 2010) and 12 min (Cooper, 1968). 49 physically fit military aged 25.6±3.10 years, BMI23±1.4 kg.m2, where randomly chosen according to the inclusion criteria of the research took part of it. The (VO2máx) was measured through COOPER and Almeida equations after the tests of 1600m and 12min run, collected and analyzed physiological parameters of cardiac frequency glycemia and lactate were collected before and after the tests. Besides, the subjective perception of effort at the end of each test was evaluated. Through the physiological parameters, it could be observed a great reliability between the 1600m and 12min run tests, in which the (vo2máx) value in the former (43.63±3.21) was higher than in the latter test (39.42±4.18), showing a significant incriase (p<0.0001), attributed to the power developedduring the exercise test, which can be observed for lactate in the 1600m. The 1600m test, proved to be an effective alternative in measuring (vo2máx) in milytary, being an indirect measure of cost and ease of use and great value for their applicability in the military institutions.

Papillary muscle rupture: first report of this complication in a retrograde transfemoral aortic valve implantation.

We report a not previously described complication in a retrograde transcatheter aortic valve implantation procedure: A fatal rupture of a papillary muscle producing massive regurgitation. We found papillary muscle head calcification as an anatomical substrate that could facilitate this complication.

Predictors of long-term renal function after conversion to proliferation signal inhibitors in long-term heart transplant recipients.

BACKGROUND: The purpose of this study was to evaluate the change in renal function and its determinants after replacement of calcineurin inhibitors with a proliferation signal inhibitor (sirolimus or everolimus) in long-term heart transplant recipients. METHODS: We studied 49 consecutive patients in whom a switch to a proliferation signal inhibitor was carried out 9 ± 4 years after transplantation. Evolutive glomerular filtration rate was assessed at a mean of 28 months after conversion by the simplified MDRD equation. RESULTS: Pre-conversion glomerular filtration rate (40 ± 22 ml/min/1.73 m(2)) remained stable at 1 year after conversion (41 ± 22 ml/min/1.73 m(2)), but decreased significantly by the end of follow-up (35 ± 22 ml/min/1.73 m(2); p = 0.008 and p = 0.002 vs pre-conversion and 1-year values, respectively). In a multivariate model, including age, time from transplantation to conversion, pre-conversion glomerular filtration rate, presence of diabetes and use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB) therapy, the rate of decline in renal function was related only to the presence of diabetes (p = 0.017) and inversely related to the use of ACEI/ARB therapy (p = 0.003). There were no significant differences with respect to age, time between transplantation and replacement and baseline glomerular filtration rate. CONCLUSION: In long-term heart transplant recipients, late substitution of a calcineurin inhibitor for a proliferation signal inhibitor does not preclude a decrease in renal function in the long-term setting. We identified the presence of diabetes as the main clinical predictor of renal function deterioration. In contrast, we found that the use of ACEI/ARB therapy could exert a protective effect.

Risk factors associated with moderate-to-severe renal dysfunction among heart transplant patients: results from the CAPRI study.

The longer survival of patients with heart transplantation (HT) favors calcineurin inhibitor-related chronic kidney disease (CKD). It behoves to identify risk factors. At 14 Spanish centers, data on 1062 adult patients with HT (age 59.2 ± 12.3 yr, 82.5% men) were collected at routine follow-up examinations. Glomerular filtration rate, GFR, was estimated using the four-variable MDRD equation, and moderate-or-severe renal dysfunction (MSRD) was defined as K/DOQI stage 3 CKD or worse. Time since transplant ranged from one month to 22 yr (mean 6.7 yr). At assessment, 26.6% of patients were diabetic and 63.9% hypertensive; 53.9% were taking cyclosporine and 33.1% tacrolimus; and 61.4% had MSRD. Among patients on cyclosporine or tacrolimus at assessment, multivariate logistic regression identified male sex (OR 0.44), pre- and post-HT creatinine (2.73 and 3.13 per mg/dL), age at transplant (1.06 per yr), time since transplant (1.05 per yr), and tacrolimus (0.65) as independent positive or negative predictors of MSRD. It is concluded that female sex, pre- and one-month post-HT serum creatinine, age at transplant, time since transplant, and immunosuppression with cyclosporine rather than tacrolimus may all be risk factors for development of CKD ≥ stage 3 by patients with HT.

Prevalence and severity of renal dysfunction among 1062 heart transplant patients according to criteria based on serum creatinine and estimated glomerular filtration rate: results from the CAPRI study.

Chronic kidney disease (CKD) is staged on the basis of glomerular filtration rate; generally, the MDRD study estimate, eGFR, is used. Renal dysfunction (RD) in heart transplant (HT) patients is often evaluated solely in terms of serum creatinine (SCr). In a cross-sectional, 14-center study of 1062 stable adult HT patients aged 59.1±12.5 yr (82.3% men), RD was graded as absent-or-mild (AoM), moderate, or severe (this last including dialysis and kidney graft) by two classifications: SCr-RD (SCr cutoffs 1.6 and 2.5 mg/dL) and eGFR-RD (eGFR cutoffs 60 and 30 mL/min/1.73 m2). SCr-RD was AoM in 68.5% of patients, moderate in 24.9%, and severe in 6.7%; eGFR-RD, AoM in 38.6%, moderate in 52.2%, severe in 9.2%. Among patients evaluated <2.7, 2.7-6.2, 6.2-9.5 and >9.5 yr post-HT (the periods defined by time-since-transplant quartiles), AoM/moderate/severe RD prevalences were <2.7, SCr-RD 74/21/5%, eGFR-RD 47/47/6%; 2.7-6.2, SCr-RD 73/22/5%, eGFR-RD 37/56/7%; 6.2-9.5, SCr-RD 69/24/7%, eGFR-RD 37/54/9%; >9.5, SCr-RD 58/32/10%, eGFR-RD 32/52/16%. The prevalence of severe RD increases with time since transplant. If the usual CKD stages are appropriate for HT patients, the need for less nephrotoxic immunosuppressants and other renoprotective measures is greater than is suggested by direct SCr-based grading, which should be abandoned as excessively insensitive.

Virtual histology intravascular ultrasound assessment of cardiac allograft vasculopathy from 1 to 20 years after heart transplantation.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is the main cause of graft loss and death in heart transplant (HTx) recipients surviving >1 year. There is a dual etiology for coronary disease in HTx: classic atherosclerosis and an immunologically mediated disease. Intravascular ultrasound (IVUS) is highly sensitive for CAV detection; however, gray-scale IVUS is of limited value for identification of specific plaque components. We sought to characterize graft coronary artery disease by means of IVUS-virtual histology (IVUS-VH) at different time-points of follow-up and to correlate plaque composition with clinical factors. METHODS: In our study we included 67 patients, who were 7.6 +/- 5.7 years post-HTx. IVUS gray-scale evaluation was performed on all patients. IVUS-VH analysis was done in those patients showing intimal thickening >0.5 mm at the three more significant lesions (three cross-sections for each) of the left anterior descending artery. RESULTS: IVUS-VH analysis was obtained done on 58 patients (86.5%). We found a significant correlation between time of HTx and IVUS gray-scale parameters (plaque area and plaque burden), with both increasing over time. We also found a significant correlation between time and IVUS-VH-derived plaque components, necrotic core and calcium, which increased with time, and fibrous and fibrofatty components, both decreased at follow-up. IVUS-VH results were also related to donor age and cardiovascular risk factors. CONCLUSIONS: We observed a time-related change in IVUS-VH-derived plaque composition. Necrotic core and calcium, typical atheromatous components, become more prevalent with time after HTx, especially when influenced by cardiovascular risk factors. The presence of a necrotic core in the early stages was linked to older donor age.

A bony fish immunological receptor of the NITR multigene family mediates allogeneic recognition.

Novel immune-type receptors (NITRs) comprise an exceptionally large, diversified family of activating and inhibitory receptors that has been identified in bony fish. Here, we characterized the structure of an activating NITR that is expressed by a cytotoxic natural killer (NK)-like cell line and that specifically binds an allogeneic B cell target. A single amino acid residue within the NITR immunoglobulin variable (V)-type domain accounts for specificity of the interaction. Structures solved by X-ray crystallography revealed that the V-type domains of NITRs form homodimers resembling rearranging antigen-binding receptor heterodimers. CDR1 elements of both subunits of NITR dimers form ligand-binding surfaces that determine specificity for the nonself target. In the evolution of immune function, it appears that a specific NK type of innate recognition may be mediated by a complex germline multigene family of V structures resembling those that are somatically diversified in adaptive immunological responses.

Crystallization of the focal adhesion kinase targeting (FAT) domain in a primitive orthorhombic space group.

X-ray diffraction data from the targeting (FAT) domain of focal adhesion kinase (FAK) were collected from a single crystal that diffracted to 1.99 A resolution and reduced to the primitive orthorhombic lattice. A single molecule was predicted to be present in the asymmetric unit based on the Matthews coefficient. The data were phased using molecular-replacement methods using an existing model of the FAK FAT domain. All structures of human focal adhesion kinase FAT domains solved to date have been solved in a C-centered orthorhombic space group.

Everolimus-related pulmonary toxicity in heart transplant recipients.

Pulmonary toxicity (PT) is emerging as a frequent and serious complication of sirolimus, a proliferation signal inhibitor (PSI) used in solid-organ transplantation. Everolimus is a more recently developed PSI with molecular structure very similar to that of sirolimus. Surprisingly, although experience with everolimus is increasing and becoming substantial, there remains very little information about everolimus-related PT. Herein we report 2 heart transplant recipients who developed a non-infectious pulmonary syndrome after everolimus treatment was started. Transbronchial pulmonary biopsy specimens showed typical interstitial pneumonitis, and everolimus discontinuation resulted in rapid clinical and radiological improvement. Although PT seems to be more common after sirolimus exposure, everolimus is by no means spared from this potentially lethal complication and should always be suspected in the relevant clinical setting.

Structure-based identification of small-molecule angiotensin-converting enzyme 2 activators as novel antihypertensive agents.

Angiotensin-converting enzyme 2 (ACE2) is a key renin-angiotensin system enzyme involved in balancing the adverse effects of angiotensin II on the cardiovascular system, and its overexpression by gene transfer is beneficial in cardiovascular disease. Therefore, our objectives were 2-fold: to identify compounds that enhance ACE2 activity using a novel conformation-based rational drug discovery strategy and to evaluate whether such compounds reverse hypertension-induced pathophysiologies. We used a unique virtual screening approach. In vitro assays revealed 2 compounds (a xanthenone and resorcinolnaphthalein) that enhanced ACE2 activity in a dose-dependent manner. Acute in vivo administration of the xanthenone resulted in a dose-dependent transient and robust decrease in blood pressure (at 10 mg/kg, spontaneously hypertensive rats decreased 71+/-9 mm Hg and Wistar-Kyoto rats decreased 21+/-8 mm Hg; P<0.05). Chronic infusion of the xanthenone (120 microg/day) resulted in a modest decrease in the spontaneously hypertensive rat blood pressure (17 mm Hg; 2-way ANOVA; P<0.05), whereas it had no effect in Wistar-Kyoto rats. Strikingly, the decrease in blood pressure was also associated with improvements in cardiac function and reversal of myocardial, perivascular, and renal fibrosis in the spontaneously hypertensive rats. We conclude that structure-based screening can help identify compounds that activate ACE2, decrease blood pressure, and reverse tissue remodeling. Administration of ACE2 activators may be a valid strategy for antihypertensive therapy.