Comparison of prevalence, clinical course, and pathological findings of left ventricular systolic impairment versus normal systolic function in patients with hypertrophic cardiomyopathy

Advanced Heart Failure Therapies for Hypertrophic Cardiomyopathy: State-of-the-Art Review and an Updated Analysis From UNOS

Hypertrophic cardiomyopathy (HCM) is most commonly associated with obstructive symptoms and sudden cardiac death; however, predominantly nonobstructive advanced heart failure in HCM, marked by medically refractory disease with severe functional impairment, occurs in 5% to 7% of patients with HCM. The diagnosis relies on the integration of imaging (echocardiography/cardiac magnetic resonance), hemodynamic data, and cardiopulmonary exercise testing to identify the patients who will benefit from advanced heart failure therapies. Most advanced heart failure therapies focus on systolic dysfunction and are not always applicable to this patient population. Left ventricular assist devices may be an option in a highly selected population with left ventricular dilation. Heart transplantation is often the best option for patients with advanced heart failure in HCM with excellent post-transplantation survival.

Hypertrophic Cardiomyopathy in a Latin American Center: A Single Center Observational Study

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a complex disorder that includes various phenotypes, leading to different manifestations. It also shares different disadvantages typical of rare diseases, including limited recognition, lack of prospective studies assessing treatment, and little or delayed access to advanced treatment options. Reliable data about the prevalence and natural history of cardiomyopathies in South America are lacking. This study summarizes the features and management of patients with HCM in a university hospital in Colombia.

METHODS

This was an observational retrospective cohort study of patients with HCM between January 2010 and December 2021. Patient data were analyzed from an institutional cardiomyopathy registry. Demographic, paraclinical, and outcome data were collected.

RESULTS

A total of 82 patients during the study period were enrolled. Of these, 67.1% were male, and the mean age at diagnosis was 49 years. Approximately 83% were in NYHA functional class I and II, and the most reported symptoms were dyspnea (38%), angina (20%), syncope (15%), and palpitations (11%). In addition, 89% had preserved left ventricular ejection fraction (LVEF) with an asymmetric septal pattern in 65%. Five patients (6%) had alcohol septal ablation and four (5%) had septal myectomy. One patient required heart transplantation during follow-up. Sudden cardiovascular death was observed in 2.6%. The overall mortality during follow-up was 7.3%.

CONCLUSIONS

HCM is a complex and heterogeneous disorder that presents with significant morbidity and mortality. Our registry provides comprehensive data on disease courses and management in a developing country.

Left Ventricular Systolic Dysfunction in Patients Diagnosed With Hypertrophic Cardiomyopathy During Childhood: Insights From the SHaRe Registry

BACKGROUND

The development of left ventricular systolic dysfunction (LVSD) in hypertrophic cardiomyopathy (HCM) is rare but serious and associated with poor outcomes in adults. Little is known about the prevalence, predictors, and prognosis of LVSD in patients diagnosed with HCM as children.

METHODS

Data from patients with HCM in the international, multicenter SHaRe (Sarcomeric Human Cardiomyopathy Registry) were analyzed. LVSD was defined as left ventricular ejection fraction <50% on echocardiographic reports. Prognosis was assessed by a composite of death, cardiac transplantation, and left ventricular assist device implantation. Predictors of developing incident LVSD and subsequent prognosis with LVSD were assessed using Cox proportional hazards models.

RESULTS

We studied 1010 patients diagnosed with HCM during childhood (<18 years of age) and compared them with 6741 patients with HCM diagnosed as adults. In the pediatric HCM cohort, median age at HCM diagnosis was 12.7 years (interquartile range, 8.0-15.3), and 393 (36%) patients were female. At initial SHaRe site evaluation, 56 (5.5%) patients with childhood-diagnosed HCM had prevalent LVSD, and 92 (9.1%) developed incident LVSD during a median follow-up of 5.5 years. Overall LVSD prevalence was 14.7% compared with 8.7% in patients with adult-diagnosed HCM. Median age at incident LVSD was 32.6 years (interquartile range, 21.3-41.6) for the pediatric cohort and 57.2 years (interquartile range, 47.3-66.5) for the adult cohort. Predictors of developing incident LVSD in childhood-diagnosed HCM included age <12 years at HCM diagnosis (hazard ratio [HR], 1.72 [CI, 1.13-2.62), male sex (HR, 3.1 [CI, 1.88-5.2), carrying a pathogenic sarcomere variant (HR, 2.19 [CI, 1.08-4.4]), previous septal reduction therapy (HR, 2.34 [CI, 1.42-3.9]), and lower initial left ventricular ejection fraction (HR, 1.53 [CI, 1.38-1.69] per 5% decrease). Forty percent of patients with LVSD and HCM diagnosed during childhood met the composite outcome, with higher rates in female participants (HR, 2.60 [CI, 1.41-4.78]) and patients with a left ventricular ejection fraction <35% (HR, 3.76 [2.16-6.52]).

CONCLUSIONS

Patients with childhood-diagnosed HCM have a significantly higher lifetime risk of developing LVSD, and LVSD emerges earlier than for patients with adult-diagnosed HCM. Regardless of age at diagnosis with HCM or LVSD, the prognosis with LVSD is poor, warranting careful surveillance for LVSD, especially as children with HCM transition to adult care.

Insight into different phenotypic presentations of heart failure with preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) accounts for half of all HF diagnoses, and its prevalence is increasing at an alarming rate. Lately, it has been recognized as a clinical syndrome due to diverse underlying etiology and pathophysiological mechanisms. The classic echocardiographic features of HFpEF have been well described as preserved ejection fraction (≥50%), left ventricular hypertrophy, and left atrial enlargement. However, echocardiography can play a key role in identifying the principal underlying mechanism responsible for HFpEF in the individual patient. The recognition of different phenotypic presentations of HFpEF (infiltrative, metabolic, genetic, and inflammatory) can assist the clinician in tailoring the appropriate management, and offer prognostic information. The goal of this review is to highlight several key phenotypes of HFpEF and illustrate the classic clinical scenario and echocardiographic features of each phenotype with real patient cases.

Association of NT-proBNP and hs-cTnT with Imaging Markers of Diastolic Dysfunction and Focal Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Serum biomarkers such as N-terminal prohormone of the brain natriuretic peptide (NT-proBNP) and cardiac troponins are elevated in patients with hypertrophic cardiomyopathy (HCM). At present, it is not clear if these markers are associated with distinct clinical alterations in HCM, such as left ventricular hypertrophy, outflow tract obstruction, myocardial fibrosis and/or diastolic dysfunction (DD), which are associated with adverse cardiovascular outcome. Here we evaluate the association of NT-proBNP and high sensitivity cardiac troponin T (hs-cTnT) to a variety of cardiac imaging parameters in HCM patients in a multivariable regression analysis. This retrospective cross-sectional study included 366 HCM patients who underwent transthoracic echocardiography (TTE), 218 of whom also obtained cardiovascular magnetic resonance (CMR) to assess focal myocardial fibrosis by LGE. Multivariable regression analyses revealed the strongest association of the DD parameters E/E′ mean and E/E′ septal with NT-proBNP (b = 0.06, 95%-CI [0.05−0.07], p < 0.001, R2 = 0.28; b = 0.08, 95%-CI [0.06−0.1], p < 0.001, R2 = 0.25) and LGE size showed the strongest association with hs-cTnT (b = 0.20, 95%-CI [0.15−0.24], p < 0.001, R2 = 0.28). This study indicates that NT-proBNP and hs-cTnT are associated with structural and functional alterations in HCM. NT-proBNP is a stronger predictor for DD, while hs-cTnT is associated with the extent of focal myocardial fibrosis. Both biomarkers might be useful in the diagnostic procedure in addition to imaging parameters.

Hypertrophic Cardiomyopathy With Left Ventricular Systolic Dysfunction: Insights From the SHaRe Registry

BACKGROUND

The term "end stage" has been used to describe hypertrophic cardiomyopathy (HCM) with left ventricular systolic dysfunction (LVSD), defined as occurring when left ventricular ejection fraction is <50%. The prognosis of HCM-LVSD has reportedly been poor, but because of its relative rarity, the natural history remains incompletely characterized.

METHODS

Data from 11 high-volume HCM specialty centers making up the international SHaRe Registry (Sarcomeric Human Cardiomyopathy Registry) were used to describe the natural history of patients with HCM-LVSD. Cox proportional hazards models were used to identify predictors of prognosis and incident development.

RESULTS

From a cohort of 6793 patients with HCM, 553 (8%) met the criteria for HCM-LVSD. Overall, 75% of patients with HCM-LVSD experienced clinically relevant events, and 35% met the composite outcome (all-cause death [n=128], cardiac transplantation [n=55], or left ventricular assist device implantation [n=9]). After recognition of HCM-LVSD, the median time to composite outcome was 8.4 years. However, there was substantial individual variation in natural history. Significant predictors of the composite outcome included the presence of multiple pathogenic/likely pathogenic sarcomeric variants (hazard ratio [HR], 5.6 [95% CI, 2.3-13.5]), atrial fibrillation (HR, 2.6 [95% CI, 1.7-3.5]), and left ventricular ejection fraction <35% (HR, 2.0 [95% CI, 1.3-2.8]). The incidence of new HCM-LVSD was ≈7.5% over 15 years. Significant predictors of developing incident HCM-LVSD included greater left ventricular cavity size (HR, 1.1 [95% CI, 1.0-1.3] and wall thickness (HR, 1.3 [95% CI, 1.1-1.4]), left ventricular ejection fraction of 50% to 60% (HR, 1.8 [95% CI, 1.2, 2.8]-2.8 [95% CI, 1.8-4.2]) at baseline evaluation, the presence of late gadolinium enhancement on cardiac magnetic resonance imaging (HR, 2.3 [95% CI, 1.0-4.9]), and the presence of a pathogenic/likely pathogenic sarcomeric variant, particularly in thin filament genes (HR, 1.5 [95% CI, 1.0-2.1] and 2.5 [95% CI, 1.2-5.1], respectively).

CONCLUSIONS

HCM-LVSD affects ≈8% of patients with HCM. Although the natural history of HCM-LVSD was variable, 75% of patients experienced adverse events, including 35% experiencing a death equivalent an estimated median time of 8.4 years after developing systolic dysfunction. In addition to clinical features, genetic substrate appears to play a role in both prognosis (multiple sarcomeric variants) and the risk for incident development of HCM-LVSD (thin filament variants).

Validation of the 2014 European Society of Cardiology Sudden Cardiac Death Risk Prediction Model Among Various Phenotypes in Japanese Patients With Hypertrophic Cardiomyopathy

Risk stratification for sudden cardiac death (SCD) is essential in the management of hypertrophic cardiomyopathy (HC). The 2014 European Society of Cardiology SCD risk prediction model (Risk-SCD) is a novel risk scoring system; however, whether it can be applied to Japanese HC and its usefulness among various HC phenotypes remain unclear. The aim of this study was to validate the Risk-SCD model in Japanese HC, and to evaluate its usefulness among various HC phenotypes. We studied 370 consecutive Japanese HC patients evaluated for primary SCD prevention at our tertiary referral center. The Risk-SCD model was validated in 289 HC patients with ejection fraction (EF) ≥50% (including left ventricular outflow tract obstruction [LVOTO], mid ventricular obstruction [MVO], apical hypertrophy, and nonobstructive phenotypes), and 81 end-stage HC patients (EF <50%). The end point of the study was SCD or an equivalent event (appropriate implantable cardioverter defibrillator therapy or successful resuscitation after cardiac arrest). Thirty-one SCD events were observed during a median follow-up of 5.2 (interquartile range 3.5 to 6.9) years. The Risk-SCD model showed improved risk prediction in HC with EF ≥50% compared with the previous 2011 American College of Cardiology Foundation/American Heart Association and 2003 American College of Cardiology/European Society of Cardiology guideline approaches (number needed to treat = 3.8 at Risk-SCD >6%) regardless of phenotypes; LVOTO, MVO, apical, and nonobstructive, but misclassified SCD risk in end-stage HC. In the current external validation of the Risk-SCD model in Japanese HC, the model improved SCD prediction compared with previous approaches, and was also shown to be useful in LVOTO, MVO, apical, and nonobstructive phenotypes.

Advanced Heart Failure Management and Transplantation

Hypertrophic cardiomyopathy is a genetic heart disease with heterogeneous clinical features, including progression to advanced heart failure. The development of these symptoms can be related to outflow obstruction but in some patients reflects an underlying process of fibrosis and progressive ventricular dysfunction. For patients with end-stage disease, traditional heart failure therapies have not proved beneficial. As such, more advanced therapies, such as left ventricular assist device or cardiac transplantation, should be considered for these patients. Although left ventricular assist device support is used infrequently due to the restrictive physiology underlying hypertrophic cardiomyopathy, transplant represents an effective treatment, with encouraging long-term outcome data.

Impact of Advanced Therapies for Improving Survival to Heart Transplant in Patients with Hypertrophic Cardiomyopathy

Heart transplant has become an increasingly important option for patients with end-stage nonobstructive hypertrophic cardiomyopathy (HC). However, clinical details related specifically to the overall HC transplant experience remain sparse. We assessed outcomes of HC heart transplants, from 2002 to 2016, at Tufts Medical Center. Fifty-two nonobstructive severely symptomatic patients underwent evaluation at 47 ± 13 years; 11 (21%) declined or failed to qualify, most commonly because of co-morbidities (n = 7). Of the remaining 41 patients ultimately listed, 6 (15%) died of heart failure awaiting transplant (11%/year), 26 underwent transplant, and 9 remained active on the list. Survival rates on the waiting list depended on ≥1 treatment intervention: inotropic medications (n = 20), ventricular assist devices (n = 7), or implantable defibrillators terminating ventricular tachyarrhythmias (n = 7). Of the 26 transplanted patients, 24 survived for 4.8 ± 3.4 years (up to 12), including 23 who are currently alive. The survival rate 5 years post transplant is 92%. Compared with heart transplants for other cardiomyopathies, patients with HC had similar mortality while wait-listed and post transplant (p = 0.77 and 0.13, respectively). In conclusion, a large proportion of patients with HC considered for transplant ultimately received hearts and experienced excellent short- and long-term survival rates. The survival rate on the waiting list was directly attributable to major interventions: implantable cardioverter-defibrillators, inotropic drugs, and ventricular assist devices, and the perception that patients with HC have low wait-list mortality risk does not appear justified. Neither normal ejection fraction nor peak oxygen consumption > 14 ml/kg/min should exclude drug refractory severely symptomatic patients with HC from heart transplant consideration.

Ineffective and prolonged apical contraction is associated with chest pain and ischaemia in apical hypertrophic cardiomyopathy

OBJECTIVES

To investigate the hypothesis that persistence of apical contraction into diastole is linked to reduced myocardial perfusion and chest pain.

BACKGROUND

Apical hypertrophic cardiomyopathy (HCM) is defined by left ventricular (LV) hypertrophy predominantly of the apex. Hyperdynamic contractility resulting in obliteration of the apical cavity is often present. Apical HCM can lead to drug-refractory chest pain.

METHODS

We retrospectively studied 126 subjects; 76 with apical HCM and 50 controls (31 with asymmetrical septal hypertrophy (ASH) and 19 with non-cardiac chest pain and culprit free angiograms and structurally normal hearts). Perfusion cardiac magnetic resonance imaging (CMR) scans were assessed for myocardial perfusion reserve index (MPRi), late gadolinium enhancement (LGE), LV volumes (muscle and cavity) and regional contractile persistence (apex, mid and basal LV).

RESULTS

In apical HCM, apical MPRi was lower than in normal and ASH controls (p<0.05). In apical HCM, duration of contractile persistence was associated with lower MPRi (p<0.01) and chest pain (p<0.05). In multivariate regression, contractile persistence was independently associated with chest pain (p<0.01) and reduced MPRi (p<0.001).

CONCLUSION

In apical HCM, regional contractile persistence is associated with impaired myocardial perfusion and chest pain. As apical myocardium makes limited contributions to stroke volume, apical contractility is also largely ineffective. Interventions to reduce apical contraction and/or muscle mass are potential therapies for improving symptoms without reducing cardiac output.

Interaction of Adverse Disease Related Pathways in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HC) has been characterized as a generally progressive genetic heart disease, creating an ominous perspective for patients and managing cardiologists. We explored the HC disease burden and interaction of adverse clinical pathways to clarify patient expectations over long time periods in the contemporary therapeutic era. We studied 1,000 consecutive HC patients (52 ± 17 years) at Tufts Medical Center, followed 9.3 ± 8 years from diagnosis, employing a novel disease pathway model: 46% experienced a benign course free of adverse pathways, but 42% of patients progressed along 1 major pathway, most commonly refractory heart failure to New York Heart Association class III or IV requiring surgical myectomy (or alcohol ablation) or heart transplant; repetitive or permanent atrial fibrillation; and least commonly arrhythmic sudden death events. Eleven percent experienced 2 of these therapeutic end points at different times in their clinical course, most frequently the combination of advanced heart failure and atrial fibrillation, whereas only 1% incurred all 3 pathways. Freedom of progression from 1 to 2 disease pathways, or from 2 to 3 was 80% and 93% at 5 years, respectively. Annual HC-related mortality did not differ according to the number of pathways: 1 (0.8%), 2 (0.8%), or 3 (2.4%) (p = 0.56), and 93% of patients were in New York Heart Association classes I or II at follow-up. In conclusion, it is uncommon for HC patients to experience multiple adverse (but treatable) disease pathways, underscoring the principle that HC is not a uniformly progressive disease. These observations provide a measure of clarity and/or reassurance to patients regarding the true long-term disease burden of HC.

Contemporary Natural History and Management of Nonobstructive Hypertrophic Cardiomyopathy

BACKGROUND

Left ventricular outflow tract gradients are absent in an important proportion of patients with hypertrophic cardiomyopathy (HCM). However, the natural course of this important patient subgroup remains largely unresolved.

OBJECTIVES

The authors systematically employed exercise (stress) echocardiography to define those patients without obstruction to left ventricular outflow at rest and/or under physiological exercise and to examine their natural history and clinical course to create a more robust understanding of this complex disease.

METHODS

We prospectively studied 573 consecutive HCM patients in 3 centers (44 ± 17 years; 66% male) with New York Heart Association functional class I/II symptoms at study entry, including 249 in whom left ventricular outflow tract obstruction was absent both at rest and following physiological exercise (<30 mm Hg; nonobstructive HCM) and retrospectively assembled clinical follow-up data.

RESULTS

Over a median follow-up of 6.5 years, 225 of 249 nonobstructive patients (90%) remained in classes I/II, whereas 24 (10%) developed progressive heart failure to New York Heart Association functional classes III/IV. Nonobstructive HCM patients were less likely to experience advanced limiting class III/IV symptoms than the 324 patients with outflow obstruction (1.6%/year vs. 7.4%/year rest obstruction vs. 3.2%/year provocable obstruction; p < 0.001). However, 7 nonobstructive patients (2.8%) did require heart transplantation for progression to end stage versus none of the obstructive patients. HCM-related mortality among nonobstructive patients was low (n = 8; 0.5%/year), with 5- and 10-year survival rates of 99% and 97%, respectively, which is not different from expected all-cause mortality in an age- and sex-matched U.S. population (p = 0.15).

CONCLUSIONS

HCM patients with nonobstructive disease appear to experience a relatively benign clinical course, associated with a low risk for advanced heart failure symptoms, other disease complications, and HCM-related mortality, and largely without the requirement for major treatment interventions. A small minority of nonobstructive HCM patients progress to heart transplant.

Validation of the 2014 European Society of Cardiology Sudden Cardiac Death Risk Prediction Model in Hypertrophic Cardiomyopathy in a Reference Center in South America

Sudden cardiac death (SCD) is a common cause of death in hypertrophic cardiomyopathy (HC). Our aim was to conduct an external and independent validation in South America of the 2014 European Society of Cardiology (ESC) SCD risk prediction model to identify patients requiring an implantable cardioverter defibrillator. This study included 502 consecutive patients with HC followed from March, 1993 to December, 2014. A combined end point of SCD or appropriate implantable cardioverter defibrillator therapy was assessed. For the quantitative estimation of individual 5-year SCD risk, we used the formula: 1 - 0.998(exp(Prognostic index)). Our database also included the abnormal blood pressure response to exercise as a risk marker. We analyzed the 3 categories of 5-year risk proposed by the ESC: low risk (LR) <4%; intermediate risk (IR) ≥4% to <6%, and high risk (HR) ≥6%. The LR group included 387 patients (77%); the IR group 39 (8%); and the HR group 76 (15%). Fourteen patients (3%) had SCD/appropriate implantable cardioverter defibrillator therapy (LR: 0%; IR: 2 of 39 [5%]; and HR: 12 of 76 [16%]). In a receiver-operating characteristic curve, the new model proved to be an excellent predictor because the area under the curve for the estimated risk is 0.925 (statistical C: 0.925; 95% CI 0.8884 to 0.9539, p <0.0001). In conclusion, the SCD risk prediction model in HC proposed by the 2014 ESC guidelines was validated in our population and represents an improvement compared with previous approaches. A larger multicenter, independent and external validation of the model with long-term follow-up would be advisable.

Clinical Spectrum, Therapeutic Options, and Outcome of Advanced Heart Failure in Hypertrophic Cardiomyopathy

BACKGROUND

The clinical course of patients with hypertrophic cardiomyopathy and advanced heart failure (HF) subtended by progressive left ventricular dysfunction has received limited attention. Our aim was to assess the outcome of HF and impact of treatment options including the implantable cardioverter-defibrillator and heart transplantation (HT) in patients with hypertrophic cardiomyopathy evaluated at 2 Italian referral centers >3 decades.

METHODS AND RESULTS

All-cause mortality and a combined end point including death, HT, or appropriate implantable cardioverter-defibrillator shock were assessed in 71 consecutive patients with HF not related to outflow obstruction (7% of the entire hypertrophic cardiomyopathy cohort) followed up for 6.1±6.9 years after development of New York Heart Association class III to IV symptoms. At enrollment, left ventricular ejection fraction was <50% in 55 patients and >50% in 16; all had restrictive left ventricular filling. During follow-up, 35 patients died (49%%; 5-year rate, 49%) and 53 met the combined end point (75%; 5-year rate, 62%). Most events occurred in the 3 years after HF onset (17% per year compared with only 3% per year subsequently). Appropriate implantable cardioverter-defibrillator shocks occurred in 11 of 34 implanted patients. Of 37 patients evaluated for HT, 14 were transplanted, 10 listed, and 13 excluded; 2 early post-HT deaths occurred in patients with elevated pulmonary vascular resistance. Eleven of the 14 HT patients were alive at 10±8 years.

CONCLUSIONS

In hypertrophic cardiomyopathy, advanced HF not associated with outflow obstruction portends a severely unfavorable prognosis, particularly in the first 3 years after onset of symptoms, despite frequently preserved systolic function in about one quarter of the patients. Outcome of HT is favorable but requires early consideration, as the window of opportunity may be short.

Advanced Heart Failure With Preserved Systolic Function in Nonobstructive Hypertrophic Cardiomyopathy

Background—

In hypertrophic cardiomyopathy (HCM), heart transplant has been predominantly confined to patients with systolic dysfunction. An underappreciated HCM subset comprises patients with preserved left ventricular (LV) systolic function who may also require consideration for transplantation. Therefore, we sought to define the clinical profile and occurrence of advanced heart failure among patients with nonobstructive HCM and preserved systolic function.

Methods and Results—

Databases from 2 referral centers comprising 2100 HCM patients were interrogated. Forty-six nonobstructive HCM patients (2.2%) either received or were listed for heart transplant, including 20 with normal systolic function (ejection fraction ≥50%). At transplant listing, these 20 patients were 42±13 years old, each in New York Heart Association functional class III/IV with ejection fraction of 62±7%. LV was hypertrophied with maximum wall thickness of 22±4 mm and nondilated (end-diastolic dimension, 39±7 mm). Cardiovascular magnetic resonance in 10 (of 15) patients showed no or minimal fibrosis (≤5% LV mass). Elevated LV end-diastolic or pulmonary capillary wedge pressure, consistent with diastolic dysfunction, was present in 15 patients (75%). LV filling was impaired by echocardiographic measures in all patients, including a restrictive inflow pattern in 8 (40%). In 2 patients, traditional criteria for transplant were absent, including peak V O 2 >14 mL/kg/min. Heart transplantation was performed in 12 patients with each alive and without cardiovascular symptoms, 2.3±1.7 years later.

Conclusions—

A previously under-recognized segment of the broad HCM clinical spectrum consists of nonobstructive patients with advanced heart failure, in the presence of preserved systolic function, for whom heart transplant is the sole definitive therapeutic option.

Presence of antigen-experienced T cells with low grade of differentiation and proliferative potential in chronic Chagas disease myocarditis

BACKGROUND

The main consequence of chronic Trypanosoma cruzi infection is the development of myocarditis in approximately 20-30% of infected individuals but not until 10-20 years after the initial infection. We have previously shown that circulating interferon-γ-secreting T cells responsive to Trypanosoma cruzi antigens in chronic Chagas disease patients display a low grade of differentiation and the frequency of these T lymphocytes decreases along with the severity of heart disease. This study thought to explore the expression of inhibitory receptors, transcription factors of type 1 or regulatory T cells, and markers of T cell differentiation, immunosenescence or active cell cycle in cardiac explants from patients with advanced Chagas disease myocarditis.

METHODOLOGY/PRINCIPAL FINDINGS

The expression of different markers for T and B cells as well as for macrophages was evaluated by immunohistochemistry and immunofluorescence techniques in cardiac explants from patients with advanced chronic Chagas disease submitted to heart transplantation. Most infiltrating cells displayed markers of antigen-experienced T cells (CD3(+), CD4(+), CD8(+), CD45RO(+)) with a low grade of differentiation (CD27(+), CD57(-), CD45RA(-), PD(-)1(-)). A skewed T helper1/T cytotoxic 1 profile was supported by the expression of T-bet; whereas FOXP3(+) cells were scarce and located only in areas of severe myocarditis. In addition, a significant proliferative capacity of CD3(+) T cells, assessed by Ki67 staining, was found.

CONCLUSIONS/SIGNIFICANCE

The quality of T cell responses and immunoregulatory mechanisms might determine the pattern of the cellular response and the severity of disease in chronic Trypanosoma cruzi infection.

Risk stratification at diagnosis for children with hypertrophic cardiomyopathy: an analysis of data from the Pediatric Cardiomyopathy Registry

BACKGROUND

Treatment of children with hypertrophic cardiomyopathy might be improved if the risk of death or heart transplantation could be predicted by risk factors present at the time of diagnosis.

METHODS

We analysed data from the Pediatric Cardiomyopathy Registry, which collected longitudinal data for 1085 children with hypertrophic cardiomyopathy from 1990 to 2009. Our goal was to understand how patient factors measured at diagnosis predicted the subsequent risk of the primary outcome of death or heart transplantation. The Kaplan-Meier method was used to calculate time-to-event rates from time of diagnosis to the earlier of heart transplantation or death for children in each subgroup. Cox proportional-hazards regression was used to identify univariable and multivariable predictors of death or heart transplantation within each causal subgroup.

FINDINGS

The poorest outcomes were recorded for the 69 children with pure hypertrophic cardiomyopathy with inborn errors of metabolism, for whom the estimated rate of death or heart transplantation was 57% (95% CI 44-69) at 2 years. Children with mixed functional phenotypes also did poorly, with rates of death or heart transplantation of 45% (95% CI 32-58) at 2 years for the 69 children with mixed hypertrophic and dilated cardiomyopathy and 38% (95% CI 25-51) at 2 years for the 58 children with mixed hypertrophic and restrictive cardiomyopathy. For children diagnosed with hypertrophic cardiomyopathy at younger than 1 year, the rate of death or transplantation was 21% (95% CI 16-27) at 2 years. For children diagnosed with hypertrophic cardiomyopathy and a malformation syndrome, the rate of death or transplantation was 23% (95% CI 12-34) at 2 years. Excellent outcomes were reported for the 407 children who were diagnosed with idiopathic hypertrophic cardiomyopathy at age 1 year or older, with a rate of death or heart transplantation of 3% (95% CI 1-5) at 2 years. The risk factors for poor outcomes varied according to hypertrophic cardiomyopathy subgroup, but they generally included young age, low weight, presence of congestive heart failure, lower left ventricular fractional shortening, or higher left ventricular end-diastolic posterior wall thickness or end-diastolic ventricular septal thickness at the time of cardiomyopathy diagnosis. For all hypertrophic cardiomyopathy subgroups, the risk of death or heart transplantation was significantly increased when two or more risk factors were present and also as the number of risk factors increased.

INTERPRETATION

In children with hypertrophic cardiomyopathy, the risk of death or heart transplantation was greatest for those who presented as infants or with inborn errors of metabolism or with mixed hypertrophic and dilated or restrictive cardiomyopathy. Risk stratification by subgroup of cardiomyopathy, by characteristics such as low weight, congestive heart failure, or abnormal echocardiographic findings, and by the presence of multiple risk factors allows for more informed clinical decision making and prognosis at the time of diagnosis.

FUNDING

US National Institutes of Health and Children's Cardiomyopathy Foundation.