Performance of the PRIMaCY sudden death risk prediction model for childhood hypertrophic cardiomyopathy: implications for implantable cardioverter-defibrillator decision-making

AIMS

The validated HCM Risk-Kids model provides accurate individualized estimates of sudden cardiac death risk in children with hypertrophic cardiomyopathy (HCM). A second validated model, PRIMaCY, also provides individualized estimates of risk, but its performance and clinical impact has not been independently investigated. The aim of this study was to investigate the clinical impact of using the PRIMaCY sudden cardiac death (SCD) risk model in childhood HCM.

METHODS AND RESULTS

The estimated 5-year SCD risk was calculated for children meeting diagnostic criteria for HCM in a large single-centre cohort using PRIMaCY (clinical and genetic) and HCM Risk-Kids model, and model performance was assessed. Three hundred one patients [median age 10 (interquartile range 4-14)] were followed up for an average of 4.9 (±3.8) years, during which 30 (10.0%) reached the SCD or equivalent event endpoint. Harrell's C-statistic for the clinical and genetic models was 0.66 [95% confidence interval (CI) 0.52-0.8] and 0.66 (95% CI 0.54-0.80) with a calibration slope of 0.19 (95% CI 0.04-0.54) and 0.26 (95% CI -0.03-0.62), respectively. The number needed to treat to potentially treat one life-threatening arrhythmia for the PRIMaCY clinical, PRIMaCY genetic, and HCM Risk-Kids models was 13.7, 14.5, and 9.4, respectively.

CONCLUSION

Although PRIMaCY has a similar discriminatory ability to that reported for HCM Risk-Kids, estimated risk estimates did not correlate well with observed risk. A higher proportion of patients met implantable cardioverter-defibrillator thresholds using PRIMaCY model compared with HCM Risk-Kids. This has important clinical implications as these patients will be exposed to a lifetime risk of complications and inappropriate therapies.

Clinical presentation of calmodulin mutations: the International Calmodulinopathy Registry

AIMS

Calmodulinopathy due to mutations in any of the three CALM genes (CALM1-3) causes life-threatening arrhythmia syndromes, especially in young individuals. The International Calmodulinopathy Registry (ICalmR) aims to define and link the increasing complexity of the clinical presentation to the underlying molecular mechanisms.

METHODS AND RESULTS

The ICalmR is an international, collaborative, observational study, assembling and analysing clinical and genetic data on CALM-positive patients. The ICalmR has enrolled 140 subjects (median age 10.8 years [interquartile range 5-19]), 97 index cases and 43 family members. CALM-LQTS and CALM-CPVT are the prevalent phenotypes. Primary neurological manifestations, unrelated to post-anoxic sequelae, manifested in 20 patients. Calmodulinopathy remains associated with a high arrhythmic event rate (symptomatic patients, n = 103, 74%). However, compared with the original 2019 cohort, there was a reduced frequency and severity of all cardiac events (61% vs. 85%; P = .001) and sudden death (9% vs. 27%; P = .008). Data on therapy do not allow definitive recommendations. Cardiac structural abnormalities, either cardiomyopathy or congenital heart defects, are present in 30% of patients, mainly CALM-LQTS, and lethal cases of heart failure have occurred. The number of familial cases and of families with strikingly different phenotypes is increasing.

CONCLUSION

Calmodulinopathy has pleiotropic presentations, from channelopathy to syndromic forms. Clinical severity ranges from the early onset of life-threatening arrhythmias to the absence of symptoms, and the percentage of milder and familial forms is increasing. There are no hard data to guide therapy, and current management includes pharmacological and surgical antiadrenergic interventions with sodium channel blockers often accompanied by an implantable cardioverter-defibrillator.

Funded hospital discharges to care homes: a cohort study

BACKGROUND

Optimising timely discharge from hospitals is an international priority. In 2020, the Coronavirus disease 2019 (COVID-19) pandemic resulted in the United Kingdom Government implementing the Discharge to Assess (D2A) model across England. This funded temporary care home placement to allow further recovery and assessment of care needs outside of the hospital.

OBJECTIVES

Determine if older adults discharged from hospital to care homes after implementation of D2A differ in their characteristics or outcomes.

DESIGN AND METHODS

Two cohorts of older adults discharged from hospital to care homes pre- and post-implementation of the D2A model (n = 244), with 6 months of follow-up. Data were extracted from routinely collected healthcare records.

RESULTS

The mean duration of the hospital admission was reduced (29 vs. 23 days (P = 0.02)) but discharges to care homes did not increase with implementation of D2A (n = 161 in both cohorts prior to exclusions). In July-December 2020 (post-implementation), 28% of people were living in a private residence 6 months post-discharge, compared with 18% in the same period in 2019 (P = 0.09). When those who died were excluded, this changed to 40 vs. 28% (P = 0.19). There was no change in 6-month mortality (26 vs. 35% (P = 0.17)), and no increase in readmission rate (0.48 vs. 0.63 (P = 0.21) readmissions-per-patient over 6 months). No differences in key characteristics were found. However, patients were placed in care homes further from admission addresses (17.3 vs. 9.8 km (P = 0.00001)).

CONCLUSIONS

Implementation of D2A did not result in poorer outcomes but was associated with a reduced length of hospital stay.

External validation of the HCM Risk-Kids model for predicting sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). The newly developed HCM Risk-Kids model provides clinicians with individualized estimates of risk. The aim of this study was to externally validate the model in a large independent, multi-centre patient cohort.

METHODS AND RESULTS

A retrospective, longitudinal cohort of 421 patients diagnosed with HCM aged 1-16 years independent of the HCM Risk-Kids development and internal validation cohort was studied. Data on HCM Risk-Kids predictor variables (unexplained syncope, non-sustained ventricular tachycardia, maximal left ventricular wall thickness, left atrial diameter, and left ventricular outflow tract gradient) were collected from the time of baseline clinical evaluation. The performance of the HCM Risk-Kids model in predicting risk at 5 years was assessed. Twenty-three patients (5.4%) met the SCD end-point within 5 years, with an overall incidence rate of 2.03 per 100 patient-years [95% confidence interval (CI) 1.48-2.78]. Model validation showed a Harrell's C-index of 0.745 (95% CI 0.52-0.97) and Uno's C-index 0.714 (95% 0.58-0.85) with a calibration slope of 1.15 (95% 0.51-1.80). A 5-year predicted risk threshold of ≥6% identified 17 (73.9%) SCD events with a corresponding C-statistic of 0.702 (95% CI 0.60-0.81).

CONCLUSIONS

This study reports the first external validation of the HCM Risk-Kids model in a large and geographically diverse patient population. A 5-year predicted risk of ≥6% identified over 70% of events, confirming that HCM Risk-Kids provides a method for individualized risk predictions and shared decision-making in children with HCM.