Kinetics of generic tacrolimus in heart transplantation: A cautionary note

Tacrolimus is a core component of immunosuppressive regimens. This study compared active pharmaceutical ingredient (API) and dissolution kinetics of branded tacrolimus and formulations from three generic manufacturers (Mylan, Dr. Reddy's, Intas) including samples from patients who suffered acute cardiac allograft rejection. Generic samples showed similar API content compared to branded samples with no major impurities. Capsules that underwent uniformity testing had consistent capsule-to-capsule API. Dissolution testing showed similar profiles between branded tacrolimus and Mylan, but notable differences with Dr. Reddy's and Intas. The approximate maximal inhibitory concentration (IC₅₀) was highest in branded tacrolimus (29 minutes), followed by Mylan (26 minutes), Dr. Reddy's (19 minutes), and Intas (14 minutes) (Student-Newman-Keuls Multiple Comparisons Test; overall ANOVA: p = 0.0199, F = 6.469). This study suggests that the bioavailability of certain generic tacrolimus formulations peak significantly earlier than branded tacrolimus. Further study is needed to determine whether these differences are clinically relevant.

Diastolic stress test echocardiography in patients with hypertrophy cardiomyopathy: association with exercise capacity

Background

Diastolic dysfunction (DD) is a frequent occurrence in hypertrophic cardiomyopathy (HCM) patients. Symptoms of DD are often unmasked only during exercise, as left ventricular (LV) filling pressure is normal at rest.

Purpose

We sought to establish if abnormal DST parameters are associated with reduced exercise capacity in HCM patients.

Methods

We examined 590 asymptomatic/minimally symptomatic HCM patients (54±14 years, 57% men, body mass index 30±6 kg/m2, 84% on beta-blockers) with HCM by echocardiography at rest & maximal exercise. Septal and lateral [e'] mitral annular velocity, peak early [E] and late [A] mitral inflow velocity, Mitral E/e' and left atrial volume index (LAVI) was recorded. Exercise functional capacity was stablished as age-gender predicted metabolic equivalents (AGP-METs).

Results

Echocardiography at rest had LVEF of 62±6, wall thickness of 16.7±0.5 mm, LVMI of 111±43 g m–2, LVOT gradient of 26±33 mmHg, LAVI 34.5±17 mm, E/A ratio of 1.2±0.6, and average E/e' ratio 12.7±0.6. Following maximal exercise had a mean LVOT gradient of 61±59 mmHg, E/A ratio of 1.2±1.0 and average E/e' ratio 12.7±1.0. Only 42% had >85% of age-sex predicted METs. Logistic regression analysis testing the association between various predictors and 85% AGP-METs are shown in table 1.

Conclusion

There is a significant association between abnormal diastolic response to exercise and reduced exercise capacity in patients with HCM.

Funding Acknowledgement

Type of funding source: None

Exercise capacity is associated with rest and peak-exercise left ventricular global longitudinal strain in patients with hypertrophic cardiomyopathy

Background

Patients with hypertrophic cardiomyopathy (HCM) frequently have reduced exercise capacity, which can be associated with subclinical cardiac dysfunction. Left ventricle global myocardial strain (LV-GLS) is a sensitive index to detect subclinical myocardial dysfunction. However, the clinical utility of LV-GLS during exercise test remains uncertain.

Purpose

We assessed the association of functional capacity with LV-GLS at rest and at the peak of stress in HCM patients.

Methods

We examined 566 asymptomatic/minimally symptomatic HCM patients (54±14 years, 57% men, body mass index 30±6 kg/m2, 84% on beta-blockers) by echo at rest and following maximal exercise. We recorded clinical, echo variables (LV ejection fraction [LVEF], LV thickness, left ventricle mass index [LVMI], left ventricle outflow tract [LVOT] gradient, LV-GLS at rest and at peak stress), and exercise variables (percent of age-gender predicted metabolic equivalents [AGP-METs]).

Results

Echo parameters were as follows: LVEF at rest of 62±6%, wall thickness of 16.9±0.4 mm, LVMI of 117±47 g/m2, LVOT gradient at rest of 27±33 mmHg, LV-GLS at rest of −15.9±3.6%, LV-GLS at peak of stress of −17.4±4.3%, and change in LV strain from rest to stress of −1.9±2.3%. Only 41% of patients achieved >85% of AGP-METs. Logistic regression demonstrating an association between AGP-METs less than 85% and various predictors are shown in Table 1.

Conclusion

Impaired deformation at peak of stress assessed by LV-GLS was associated with reduced exercise capacity measured as AGP-METs less than 85%. These findings suggest that early systolic cardiac deterioration should be considered as a cause of exercise impairment in patients with HCM.

Funding Acknowledgement

Type of funding source: None

Baseline Characteristics of the VANISH Cohort

BACKGROUND

The VANISH trial (Valsartan for Attenuating Disease Evolution in Early Sarcomeric Hypertrophic Cardiomyopathy) targeted young sarcomeric gene mutation carriers with early-stage hypertrophic cardiomyopathy (HCM) to test whether valsartan can modify disease progression. We describe the baseline characteristics of the VANISH cohort and compare to previous trials evaluating angiotensin receptor blockers.

METHODS

Applying a randomized, double-blinded, placebo-controlled design, 178 participants with nonobstructive HCM (age, 23.3±10.1 years; 61% men) were randomized in the primary cohort and 34 (age, 16.5±4.9 years; 50% men) in the exploratory cohort of sarcomeric mutation carriers without left ventricular hypertrophy.

RESULTS

In the primary cohort, maximal left ventricular wall thickness was 17±4 mm for adults and Z score 7.0±4.5 for children. Nineteen percent had late gadolinium enhancement on cardiac magnetic resonance. Mean peak oxygen consumption was 33 mL/kg per minute, and 92% of participants were New York Heart Association functional class I. New York Heart Association class II was associated with older age, MYH7 variants, and more prominent imaging abnormalities. Six previous trials of angiotensin receptor blockers in HCM enrolled a median of 24 patients (range, 19-133) with mean age of 51.2 years; 42% of patients were in New York Heart Association class ≥II, and sarcomeric mutations were not required.

CONCLUSIONS

The VANISH cohort is much larger, younger, less heterogeneous, and has less advanced disease than prior angiotensin receptor blocker trials in HCM. Participants had relatively normal functional capacity and mild HCM features. New York Heart Association functional class II symptoms were associated with older age, more prominent imaging abnormalities, and MYH7 variants, suggesting both phenotype and genotype contribute to disease manifestations.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01912534.

Prevalence and Progression of Late Gadolinium Enhancement in Children and Adolescents With Hypertrophic Cardiomyopathy

BACKGROUND

Late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) is believed to represent dense replacement fibrosis. It is seen in ≈60% of adult patients with hypertrophic cardiomyopathy (HCM). However, the prevalence of LGE in children and adolescents with HCM is not well established. In addition, longitudinal studies describing the development and evolution of LGE in pediatric HCM are lacking. This study assesses the prevalence, progression, and clinical correlations of LGE in children and adolescents with, or genetically predisposed to, HCM.

METHODS

CMR scans from 195 patients ≤21 years of age were analyzed in an observational, retrospective study, including 155 patients with overt HCM and 40 sarcomere mutation carriers without left ventricular (LV) hypertrophy. The extent of LGE was quantified by measuring regions with signal intensity >6 SD above nulled remote myocardium.

RESULTS

Patients were 14.3±4.5 years of age at baseline and 68% were male. LGE was present in 70 (46%) patients with overt HCM (median extent, 3.3%; interquartile range, 0.8-7.1%), but absent in mutation carriers without LV hypertrophy. Thirty-one patients had >1 CMR (median interval between studies, 2.4 years; interquartile range, 1.5-3.2 years). LGE was detected in 13 patients (42%) at baseline and in 16 patients (52%) at follow-up CMR. The median extent of LGE increased by 2.4 g/y (range, 0-13.2 g/y) from 2.9% (interquartile range, 0.8-3.2%) of LV mass to 4.3% (interquartile range, 2.9-6.8%) ( P=0.02). In addition to LGE, LV mass and left atrial volume, indexed to body surface area, and z score for LV mass, as well, increased significantly from first to most recent CMR.

CONCLUSIONS

LGE was present in 46% of children and adolescents with overt HCM, in contrast to ≈60% typically reported in adult HCM. In the subset of patients with serial imaging, statistically significant increases in LGE, LV mass, and left atrial size were detected over 2.5 years, indicating disease progression over time. Further prospective studies are required to confirm these findings and to better understand the clinical implications of LGE in pediatric HCM.

Hypertrophic cardiomyopathy: A complex disease

Hypertrophic cardiomyopathy (HCM) is a complex cardiovascular disease with wide phenotypic variations. Despite significant advances in imaging and genetic testing, more information is needed about the roles and implications of these resources in clinical practice. Patients with suspected or established HCM should be evaluated at an expert referral center to allow for the best multidisciplinary care. Research is needed to better predict the risk of sudden cardiac death in those judged to be at low risk by current risk-stratification methods.

Acute urinary retention associated with flecainide

A case of acute urinary retention, presumably secondary to the use of the antiarrhythmic drug flecainide, is presented. A mechanism for this effect is proposed based on the possibility of a local anesthetic effect on bladder mucosa.