Survival After Cardiac Transplantation in Patients With Hypertrophic Cardiomyopathy

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1 Survival After Cardiac Transplantation in Patients With Hypertrophic Cardiomyopathy Martin S. Maron, MD; Benjamin M. Kalsmith, MD; James E. Udelson, MD; Wenjun Li, PhD; David DeNofrio, MD Background Heart transplant is a treatment option for selected patients with hypertrophic cardiomyopathy (HCM). However, the prevalence, clinical profile, and outcome of this subgroup of HCM patients are uncertain. Therefore, we sought to determine the occurrence, clinical characteristics, and prognosis of HCM patients who underwent cardiac transplantation in the United States during a 15-year period. Methods and Results Demographic, clinical, and survival outcomes of adult (age 18 years), heart-only transplant recipients between January 1990 and December 2004 were acquired from the United Network of Organ Sharing Registry. Pretransplant diagnoses were classified as follows: HCM (n 303, 1%) and non-hcm (26 403, 99%), comprising 3 patient subgroups: (1) ischemic cardiomyopathy (n , 54%), (2) dilated cardiomyopathy (n , 44%), and (3) restrictive cardiomyopathy (n 335, 1%). Study follow-up began at the time of heart transplant and was months (mean SD) among survivors. The 1-, 5-, and 10-year overall transplant survival for HCM patients was 85%, 75%, and 61%, respectively, with a trend toward greater survival compared with that of non-hcm transplant patients (82%, 70%, and 49%, respectively; log-rank test, P 0.05). However, propensity-matched, covariate-adjusted, Cox regression model analysis showed better survival over time (P 0.01) among the HCM patients. When HCM posttransplant survival was compared with that in each of the non-hcm patient subgroups, HCM patients had more favorable survival than did those transplanted for ischemic cardiomyopathy (P 0.02). In contrast, HCM posttransplant survival did not differ from that of patients transplanted for restrictive (P 0.08) or dilated (P 0.25) cardiomyopathy. Conclusions HCM patients compose a small subset (1%) of the overall population of patients who undergo heart transplantation in the United States. Nonetheless, survival after transplant among HCM patients is comparable to that of patients transplanted for non-hcm cardiovascular diseases, with possible enhanced survival over time. (Circ Heart Fail. 2010;3: ) Key Words: hypertrophic cardiomyopathy heart transplantation heart failure Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease and is characterized by a diverse phenotypic expression and heterogeneous clinical course, including being a major cause of heart failure symptoms and death in patients of all ages. 1 6 Previous reports of cardiac transplantation in patients with HCM have largely been confined to small series or single-center experiences. 7,8 Consequently, the clinical profile and prognosis of HCM patients who undergo cardiac transplantation remain uncertain. Therefore, we sought to characterize the clinical characteristics and prognosis of HCM patients who underwent cardiac transplantation in the United States in a recent, 15-year period. Clinical Perspective on p 579 Methods Selection and Identification of Patients All transplant centers in the United States are required to report clinical and demographic data for pre- and posttransplant patients to the Organ Procurement and Transplantation Network registry, which is operated by the United Network of Organ Sharing (UNOS). 9 We limited our analysis to patients in the UNOS Thoracic Registry who were 18 years of age and who underwent cardiac transplantation between January 1990 and December The analysis was limited to first-time, single-organ, heart-only transplant recipients. Patients with multiorgan transplants, pediatric transplants, and repeated cardiac transplants were excluded from the study. Baseline clinical characteristics of the study population were obtained from the Heart Transplant Candidate Registration Form (uniform collection of data, which is contained in the comprehensive Organ Procurement and Transplantation Network registry database). The Received January 11, 2009; accepted July 7, From the Hypertrophic Cardiomyopathy Center (M.S.M., B.M.K., J.E.U., D.D.), Division of Cardiology, Tufts Medical Center, Boston, and the Biostatistics Research Group (W.L.), Division of Preventive and Behavioral Medicine, University of Massachusetts Medical School, Worcester, Mass. The data reported here have been supplied by the United Network for Organ Sharing as the contractor for the Organ Procurement and Transplantation Network. The interpretation and reporting of these data are the responsibility of the author(s) and in no way should be seen as an official policy of or interpretation by the Organ Procurement and Transplantation Network or the US Government. Guest Editor for this article was Daniel I. Simon, MD. Correspondence to Martin S. Maron, MD, Tufts Medical Center, 800 Washington St, No. 70, Boston, MA mmaron@tuftsmedicalcenter.org 2010 American Heart Association, Inc. Circ Heart Fail is available at DOI: /CIRCHEARTFAILURE

2 Maron et al Cardiac Transplantation in HCM 575 Table 1. Baseline Demographics and Clinical Data for HCM and Non-HCM Heart-Only Transplant Recipients Before Propensity Score Matching Before Propensity Score Matching Recipient Characteristics Overall (N )* HCM (n 303) Non-HCM (n )* P Value Age, mean SD, y Sex, No. of males (%) (79%) 146 (48%) (79%) Race, No. white (%) (81%) 261 (86%) (81%) Diabetes mellitus 98 (0.34%) 0 (0%) 98 (0.34%) COPD 595 (2.2%) 3 (1.0%) 592 (2.2%) History of smoking 8382 (31%) 50 (17%) 8332 (32%) History of prior cardiac surgery 632 (2.4%) 10 (3.3%) 622 (2.4%) Dialysis 1686 (6.3%) 25 (8.3%) 1661 (6.3%) Circulatory support (54%) 149 (49%) (54%) BMI, mean SD, kg/m Ischemic time, h (19%) 44 (16%) 4648 (19%) (36%) 106 (39%) 8954 (36%) (32%) 87 (32%) 7824 (32%) (13%) 38 (13%) 3233 (13%) Life support at transplant (54%) 149 (49%) (54%) IABP 1480 (6%) 8 (3.0%) 1472 (6%) LVAD 4,940 (19%) 66 (22%) 4874 (19%) Ventilator (54%) 149 (49%) (54%) UNOS status (67%) 184 (61%) (67%) (33%) 117 (39%) 8560 (33%) Days waited for transplant Median Mean SD Serum creatinine, mean SD, mg/dl Peak VO 2, mean SD, ml/kg per min PAP, mean SD, mm Hg PCWP, mean SD, mm Hg COPD indicates chronic obstructive pulmonary disease; BMI, body mass index; IABP, intra-aortic balloon pump; LVAD, left ventricular assist device; PAP, pulmonary artery pressure; and PCWP, pulmonary capillary wedge pressure. *Excluding unknowns. cohort was then divided into HCM and non-hcm groups according to the pretransplant diagnostic code listed in the Heart Transplant Recipient Registration Form. The non-hcm group comprised 3 subgroups of patients: (1) ischemic cardiomyopathy (ie, predominant etiology of heart failure due to coronary artery disease); (2) dilated cardiomyopathy (ie, adriamycin, familial, myocarditis, postpartum, viral, and idiopathic); and (3) restrictive cardiomyopathy (ie, amyloidosis, endocardial fibrosis, idiopathic, and sarcoidosis). Cases were excluded when they could not classified into these groups owing to missing data (n 2048). Statistical Analyses Patient demographic and clinical characteristics of the whole cohort were first compared by status of HCM, ischemic, dilated, or restrictive sympathy. For continuous variables, the mean and SD were calculated, and for categorical variables, proportions or percentages were calculated. For unadjusted comparison between groups, the Kruskal-Wallis rank test was used for continuous variables, and the 2 test was used for categorical variables. A multivariable logistic-regression model was used to quantify the association of HCM versus non HCM status with patient demographic and clinical characteristics at transplant and to estimate the propensity scores for HCM status for each subject included in the analysis. A backward stepwise elimination method was used to identify the final multiple variable logistic-regression model by considering a set of patient attributes that were thought to be predictive of HCM. Potential nonlinear associations with several predictor variables were evaluated by lowess curves as well as fractional polynomial regression models while adjusting for other covariables in the models. For nonlinear associations, we transformed the data either by using a logarithmic function (ie, months waited for transplant) or by categorization. The final identified model fit the data well, with an area under the receiver operating characteristic curve of 0.806, and P 0.67 for the Hosmer- Lemeshow goodness-of-fit test. To select the matching controls, we used radius matching within a caliper distance of in propensity (probability) scores in the common support region. Subjects with nonoverlapping (n 1010) or nonmatching (n 5712) propensity scores were excluded from further analysis involving propensity scores. After propensity matching, there were no statistically significant differences among the covariates between HCM and non-hcm patients. For mortality analysis, follow-up time was censored at 12 years (144 months) after transplant. Most recent follow-up was determined as the last clinic visit entered into the database and was defined as time from transplantation to death or last clinic visit. For descriptive purposes, crude cumulative mortality rates were estimated and plotted with the Kaplan Meier method and compared between groups based by the log-rank test. Using Cox proportional-hazards regression models, we

3 576 Circ Heart Fail September 2010 Table 2. Multivariable-Adjusted Associations Between HCM and Patient Characteristics at Cardiac Transplant Patient Characteristics Unit Odds Ratio 95% CI P Value Sex Male Referent... Female 3.67 (2.82, 4.78) Age (centered at 50 years) 1 year for men 0.94 (0.93, 0.95) year for women 0.97* (0.96, 0.98) Race/ethnicity Non-Hispanic white Referent... Black 0.32 (0.20, 0.49) Hispanic 0.36 (0.19, 0.69) Asian, American Indian, and Pacific Islander 0.66 (0.31, 1.43) Log 10 (months waited for transplant) 1-unit increase 1.32 (1.10, 1.57) Year of transplant Referent (1.15, 2.63) (2.35, 5.18) History of cigarette smoking No Referent... Yes 0.48 (0.34, 0.66) BMI, kg/m 2 1-unit increase 0.97 (0.95, 1.00) PA systolic pressure, mm Hg 30 Referent (1.05, 2.18) Unknown 0.84 (0.47, 1.49) Life support None Referent... Any 0.75 (0.59, 0.96) Most recent PRA 20% Referent... 20% 0.39 (0.20, 0.77) Unknown 1.01 (0.71, 1.43) Most recent hemodynamics, CO 4 L/min Referent... 4 L/min 0.65 (0.49, 0.86) Unknown 0.65 (0.38, 1.10) BMI indicates body mass index; PA, pulmonary artery; PRA, peak panel reactive antibody; and CO, cardiac output. The area under the receiver operating characteristics curve was Hosmer-Lemeshow goodness-of-fit test, P *Significant sex age interaction, P estimated associations of HCM with mortality for several scenarios, including (1) without any adjustment and consideration of time-varying effect of HCM, (2) considering time-varying effect only, (3) adjusting for propensity score only, (4) adjusting for both time-varying effect and propensity score for HCM, and (5) adjusting for time-varying effect and a set of covariates and propensity score for HCM. In these analyses, propensity score was adjusted by the inverse probability weighting method. A number of previously established pre- and posttransplant risk factors were adjusted in the Cox regression models. Pretransplant variables included recipient sex, recipient age, body mass index, principal diagnosis, years of heart failure treatment, duration on the transplant waiting list, UNOS status, serum creatinine, serum bilirubin, peak panel reactive antibody, amiodarone use, and need for life support, including pretransplant balloon pump, ventilator, and/or mechanical ventricular-assist device. Transplantation variables were donor age, a Cytomegalovirus status of donor-positive to recipientnegative, female donor to male recipient, and ischemic time. For risk factors (ie, amiodarone use, donor/recipient sex match, pretransplant ventilator and ventricular-assist device, serum creatinine, serum bilirubin, and peak panel reactive antibody) exhibiting a nonproportional hazard over time, the hazard was modeled as a logarithmic function of time. A backward stepwise elimination procedure was used to identify the final multivariable models, starting with a set of potential covariates known to be associated with posttransplant mortality from our previous analysis. Variables were included when their significance level was On the basis of the final multivariable Cox regression models, we estimated and plotted the mortality rates by HCM status by median risk score methods. Results Occurrence During the 15-year study period, patients underwent cardiac transplantation, including 303 (1%) HCM patients and (99%) non-hcm patients (ischemic cardiomyopathy n , 54%; dilated cardiomyopathyn , 44%, and restrictive cardiomyopathy n 335, 1%). For the patients included in the analysis, mean SD follow-up time for the study was months. Clinical and Demographic Profile of the Study Group The clinical and demographic characteristics of the overall study population are shown in Table 1. Compared with non-hcm transplant patients, HCM transplant patients were younger (43 13 vs years, P 0.001), were less likely to be male (48% vs 79%, P 0.001) or cigarette smokers (17% vs 32%, P 0.001), and had a lower body mass index (25 vs 26 kg/m 2, P 0.001). Clinical and Demographic Factors Associated With HCM A number of patient characteristics were associated with HCM (Table 2). There was a higher likelihood of being

4 Maron et al Cardiac Transplantation in HCM 577 Figure 1. Kaplan Meier curves for all-cause mortality after cardiac transplantation in patients with HCM, ischemic cardiomyopathy (coronary artery disease), dilated cardiomyopathy, and restrictive cardiomyopathy. diagnosed with HCM if the patient was female, had a history of cigarette smoking, had a longer wait time for transplant, was transplanted in later years (1995 to 2004 vs 1990 to 1994), and had a higher mean pulmonary artery pressure ( 30 vs 30 mm Hg). There was also a significant sex age interaction (P 0.001), with men having a stronger association of HCM with age (odds ratio 0.94; 95% CI, 0.93 to 0.95) than women (odds ratio 0.97; 95% CI, 0.96 to 0.98). Survival After Cardiac Transplantation During the follow-up period, 84 (28%) HCM patients died. The mean age at death was years (range, 18 to 84 years), occurring years (range, 0 to 12 years) after transplant. The cause of death for the HCM patients was noncardiovascular (n 70, 83%) and cardiovascular (n 14, 17%). HCM patients were more likely to die from noncardiovascular causes compared with non-hcm patients (17% vs 10%, P 0.04). The crude 1-, 5-, and 10-year overall transplant survival for HCM patients was 85%, 75%, and 61%, respectively, with a trend toward greater survival compared with non-hcm transplant patients (82%, 70%, and 49%, respectively; log-rank test, P 0.05). However, crude 1-, 5-, and 10-year survival was greater among HCM patients compared with that of patients transplanted for ischemic cardiomyopathy (82%, 69%, and 48%, respectively; log rank P 0.02) but was not different compared with that of patients transplanted for dilated (87%, 71%, and 52%, respectively; log rank P 0.08) or restrictive cardiomyopathy (84%, 70%, and 67%, respectively; log rank P 0.25) (Figure 1). The overall crude hazard ratios (95% CIs) of HCM versus non-hcm for all-cause mortality were 0.79 (0.64, 0.99) and 0.83 (0.67, 1.04) before and after adjusting for propensity score, respectively. However, the difference in posttransplant survival in HCM versus non-hcm patients appeared time dependent, based on both the crude and the propensity analysis, with HCM patients having slightly higher mortalities initially after transplant but lower long-term mortality. Therefore, we assessed time-varying effects on all-cause mortality rates after transplant while adjusting propensity scores and a set of covariates. The estimated time-varying hazard ratios of HCM at selected time points are summarized in Table 3. When we divided the posttransplant period into 3 time segments ( 3, 4 12, and 12 months), the hazard ratios for HCM versus non-hcm were 1.27 (0.90, 1.79), 1.06 (0.59, 1.86), and 0.65 (0.46, 0.92), respectively, which decreased over time (trend, P 0.006). Except for the initial several months after transplantation, risk for all-cause mortality among HCM patients was progressively lower than for non-hcm patients, after adjusting for both propensity score and a set of covariables (P 0.01; Figure 2). Discussion HCM is the most common genetic heart disease and a major cause of heart failure symptoms and death at all ages. 2 6,10 12 For HCM patients who develop end-stage heart failure symptoms

5 578 Circ Heart Fail September 2010 Table 3. Crude and Adjusted Time-Varying Hazard Ratios (95% CIs) of HCM Patients With All-Cause Mortality After Cardiac Transplant* Time Crude Propensity Score Adjusted Propensity Score and Covariate Adjusted Propensity Score and Covariate Adjusted 0 months 1.21 (0.83, 1.75) 1.51 (0.72, 3.17) 1.61 (0.79, 3.26) 1.57 (0.81, 3.05) 3 months 0.80 (0.64, 0.99) 0.82 (0.56, 1.19) 0.85 (0.58, 1.24) 0.86 (0.59, 1.24) 6 months 0.75 (0.60, 0.94) 0.75 (0.51, 1.09) 0.77 (0.53, 1.13) 0.78 (0.54, 1.14) 9 months 0.72 (0.57, 0.91) 0.71 (0.48, 1.04) 0.73 (0.49, 1.08) 0.74 (0.50, 1.09) 1 year 0.70 (0.55, 0.90) 0.68 (0.46, 1.02) 0.70 (0.47, 1.05) 0.71 (0.48, 1.07) 3 years 0.64 (0.48, 0.85) 0.59 (0.37, 0.94) 0.60 (0.38, 0.97) 0.62 (0.39, 0.99) 5 years 0.61 (0.45, 0.83) 0.55 (0.33, 0.92) 0.56 (0.34, 0.94) 0.58 (0.35, 0.96) 10 years 0.57 (0.41, 0.81) 0.50 (0.28, 0.89) 0.51 (0.29, 0.91) 0.53 (0.30, 0.93) P value# *The time-varying hazard for HCM was parametrically modeled as a logarithmic function of time since transplant. Propensity score was adjusted by using inverse probability weights. Covariates include recipient sex, recipient age, sex age interaction, body mass index, principal diagnosis, years of heart failure treatment, duration on the transplant waiting list, UNOS status, serum creatinine, serum bilirubin, peak panel reactive antibody, amiodarone use, and need for life support, including pretransplant balloon pump, ventilator, and/or mechanical ventricular-assist device. Transplantation variables were donor age, a Cytomegalovirus status of donor-positive to recipient-negative, female donor to male recipient, and ischemic time. Adjusted for all of the covariates listed in the preceding paragraph and the potential time-varying effects of sex, serum creatinine, serum bilirubin, peak panel reactive antibody, amiodarone use, need for life support, female donor to male recipient, and ischemic time. #P value for testing trend of time-varying effect of HCM. despite medical and/or invasive septal reduction therapy, heart transplantation may be the only viable therapeutic option. 2,7,8,10,12,13 The previous literature with regard to heart transplantation in HCM has been limited to small series of patients or single-center experiences. 7,8 Therefore, our aim was to characterize the prevalence, clinical characteristics, and prognosis among a large cohort of HCM patients who underwent cardiac transplantation in the United States during a recent 15-year period. These data demonstrate that within this large US heart transplant cohort, the prevalence of transplantation due to HCM was 1% per year. This frequency is similar to that of patients transplanted for restrictive cardiomyopathy but is significantly less than that for patients transplanted for ischemic or dilated cardiomyopathy. However, this reported prevalence of cardiac transplantation in HCM likely represents an underestimation of the actual number of patients with this disease transplanted each year in the United States. In this regard, it is likely that some HCM patients who have already achieved substantial left ventricular remodeling (including left ventricular wall thinning, cavity enlargement, and systolic dysfunction) at the time of their initial cardiovascular evaluation may have been inadvertently identified with a pretransplant diagnosis of dilated cardiomyopathy. 2,3,10,12,13 Unfortunately, detailed clinical (ie, family history of HCM) or previous echocardiographic information that might have provided additional insight with regard to this issue is not part of the data in the Heart Transplant Candidate Registration Forms. After cardiac transplantation, HCM patients experienced a 10-year survival rate of 60%. In this regard, long-term survival after cardiac transplantation showed a trend toward greater survival for HCM patients compared with patients transplanted for non-hcm related cardiovascular diseases. Indeed, after adjusting for time-varying effects on all-cause mortality rates after transplant, HCM patients demonstrated higher mortality only after the initial first several months after transplantation but overall lower long-term mortality. When survival after cardiac transplant was compared for each of the patient subgroups in the non-hcm group, HCM patients demonstrated better survival than did patients transplanted for ischemic cardiomyopathy, but survival was not different from that of patients transplanted for restrictive or dilated cardiomyopathies. Because HCM patients who undergo cardiac transplantation are significantly younger compared with those transplanted for non-hcm cardiovascular diseases, these survival data have implications for patient management. In this regard, HCM patients who develop advanced heart failure symptoms despite medical and/or invasive treatment strategies should be reassured that cardiac transplantation represents a practical therapeutic Figure 2. Propensity score and covariate-adjusted all-cause mortality after cardiac transplantation for HCM and non-hcm patients.

6 Maron et al Cardiac Transplantation in HCM 579 option associated with survival rates equivalent to (and maybe even better) than those in patients transplanted with other forms of heart disease. Finally, although somewhat speculative, the observation that HCM patients were significantly more likely to die from noncardiovascular causes suggests that it is unlikely that a phenotype of HCM recurs in the HCM transplant recipient. A limitation to the this study was that detailed clinical (ie, family history of HCM) or previous echocardiographic information was not part of the data in the Heart Transplant Candidate Registration Forms, nor are uniform guidelines provided with regard to diagnostic criteria for cardiomyopathies. As a result, these limitations of the UNOS database may have resulted in some HCM patients being improperly categorized. Also, owing to the limited posttransplant echocardiographic information, it was not feasible to determine with certainty whether HCM can recur in the transplanted heart. In addition, owing to the small number of HCM patients transplanted, it was not possible to identify clinical or demographic predictors responsible for the trend toward enhanced survival among HCM patients compared with non-hcm transplant patients. Finally, in this analysis, a number of covariates obtained from the UNOS database had missing values. As a result, we elected to code missing values as a distinct category and included them in the regression analysis. The results are robust with regard to whether subjects were excluded from analysis because of missing covariates. It would be optimal to use multiple imputation method to impute the missing values for those covariates. However, this type of analysis would require more information about the associations of these covariates with other potential predictors and significant modeling efforts, which was beyond the scope of the current analysis. In conclusion, the prevalence of cardiac transplantation in the United States due to HCM is low (1% per year) but similar to that of patients transplanted for restrictive cardiomyopathy. For HCM patients, long-term survival after cardiac transplantation showed a trend toward greater survival over time than in patients transplanted for non-hcm cardiovascular diseases and may be greater than in patients transplanted for ischemic cardiomyopathy. These data suggest that patients with HCM who are candidates for cardiac transplantation should be reassured of reasonable long-term survival rates. None. Disclosures References 1. Elliott PM, Gimeno JR, Thaman R, Shah J, Ward D, Dickie S, Tome Esteban MT, McKenna WJ. Historical trends in reported survival rates in patients with hypertrophic cardiomyopathy. Heart. 2006;92: Harris KM, Spirito P, Maron MS, Zenovich AG, Formisano F, Lesser JR, Mackey-Bojack S, Manning WJ, Udelson JE, Maron BJ. Prevalence, clinical profile, and significance of left ventricular remodeling in the end-stage phase of hypertrophic cardiomyopathy. Circulation. 2006;114: Maron BJ. Hypertrophic cardiomyopathy: a systematic review. JAmMed Assoc. 2002;287: Maron BJ, McKenna WJ, Danielson GK, Kappenberger LJ, Kuhn HJ, Seidman CE, Shah PM, Spencer WH III, Spirito P, Ten Cate FJ, Wigle ED. American College of Cardiology/European Society of Cardiology clinical expert consensus document on hypertrophic cardiomyopathy. A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines. J Am Coll Cardiol. 2003;42: Spirito P, Seidman CE, McKenna WJ, Maron BJ. The management of hypertrophic cardiomyopathy. N Engl J Med. 1997;336: Wigle ED, Rakowski H, Kimball BP, Williams WG. Hypertrophic cardiomyopathy: clinical spectrum and treatment. Circulation. 1995;92: Biagini E, Spirito P, Leone O, Picchio FM, Coccolo F, Ragni L, Lofiego C, Grigioni F, Potena L, Rocchi G, Bacchi-Reggiani L, Boriani G, Prandstraller D, Arbustini E, Branzi A, Rapezzi C. Heart transplantation in hypertrophic cardiomyopathy. Am J Cardiol. 2008;101: Coutu M, Perrault LP, White M, Pelletier GB, Racine N, Poirier NC, Carrier M. Cardiac transplantation for hypertrophic cardiomyopathy: a valid therapeutic option. J Heart Lung Transplant. 2004;23: Lietz K, Miller LW. Improved survival of patients with end-stage heart failure listed for heart transplantation: analysis of organ procurement and transplantation network/u.s. United Network of Organ Sharing data, 1990 to J Am Coll Cardiol. 2007;50: Biagini E, Coccolo F, Ferlito M, Perugini E, Rocchi G, Bacchi-Reggiani L, Lofiego C, Boriani G, Prandstraller D, Picchio FM, Branzi A, Rapezzi C. Dilated hypokinetic evolution of hypertrophic cardiomyopathy: prevalence, incidence, risk factors, and prognostic implications in pediatric and adult patients. J Am Coll Cardiol. 2005;46: Maron BJ, Olivotto I, Spirito P, Casey SA, Bellone P, Gohman TE, Graham KJ, Burton DA, Cecchi F. Epidemiology of hypertrophic cardiomyopathy-related death: revisited in a large non-referral-based patient population. Circulation. 2000;102: Thaman R, Gimeno JR, Murphy RT, Kubo T, Sachdev B, Mogensen J, Elliott PM, McKenna WJ. Prevalence and clinical significance of systolic impairment in hypertrophic cardiomyopathy. Heart. 2005;91: Spirito P, Maron BJ, Bonow RO, Epstein SE. Occurrence and significance of progressive left ventricular wall thinning and relative cavity dilatation in hypertrophic cardiomyopathy. Am J Cardiol. 1987;60: CLINICAL PERSPECTIVE Heart transplantation is a treatment option for a select subset of patients with hypertrophic cardiomyopathy (HCM). However, the prevalence of and outcome for HCM patients who undergo transplantation in the United States are unknown. We acquired demographic, clinical, and survival outcome data for heart-only transplant recipients from the United Network of Organ Sharing Registry for a retrospective 15-year period. HCM patients composed 1% of patients transplanted during this time, with the remainder comprising 3 non-hcm patient subgroups, including ischemic cardiomyopathy (54%), dilated cardiomyopathy (44%), and restrictive cardiomyopathy (1%). The 1-, 5-, and 10-year overall transplant survival for HCM patients was 85%, 75%, and 61%, respectively, with a trend toward greater survival over time compared with non-hcm transplant patients (P 0.05). When compared with patients transplanted for ischemic cardiomyopathy, HCM patients had more favorable survival (P 0.02) but no difference compared with patients transplanted for restrictive (P 0.08) or dilated (P 0.25) cardiomyopathy. HCM patients compose a small portion of the US heart transplant population (1%) but have a trend toward better survival over time after transplantation, compared with that of patients transplanted for non-hcm cardiovascular diseases.