Oliver P Guttmann

How to develop a more accurate risk prediction model when there are few events.

When the number of events is low relative to the number of predictors, standard regression could produce overfitted risk models that make inaccurate predictions. Use of penalised regression may improve the accuracy of risk prediction

Atrial fibrillation and thromboembolism in patients with hypertrophic cardiomyopathy: systematic review

Context HCM is commonly associated with AF. Current guidelines for AF management omit detailed advice for HCM because of a lack of clinical prediction tools that estimate the risk of developing AF and an absence of adequately powered treatment studies. Objective To critically review current literature on atrial fibrillation (AF) and thromboembolism in hypertrophic cardiomyopathy (HCM) and meta-analyse prevalence and incidence. Data Sources PubMed and Web of Science. Study Selection Studies investigating AF and stroke in HCM as primary or secondary endpoint. Data Extraction Two investigators independently reviewed and extracted data from the identified articles. A random effect meta-regression model and I2 statistics were used for analysis. Results A population of 7381 patients (33 studies) revealed overall AF prevalence of 22.45% (95% CI 20.13% to 24.77%), I2=78.9% (p<0.001). Overall prevalence of thromboembolism in HCM patients with AF was 27.09% (95% CI 20.94% to 33.25%), I2=61.4% ( p<0.01). Overall AF incidence was 3.08% per 100 patients per year (95% CI 2.63% to 3.54%, I2=86.5%, p<0.001) and incidence of thromboembolism in HCM patients with AF was 3.75% per 100 patients per year (95% CI 2.88% to 4.61%), I2=37.9% (p=0.1). Left atrial (LA) dimension and age were common predictors for AF and thromboembolism. Meta-analysis revealed an LA diameter of 38.03 mm (95% CI 34.62% to 41.44%) in sinus rhythm and 45.37 mm (95% CI 41.64% to 49.04%) in AF. There were no randomised controlled trials of therapy; anticoagulation was associated with lower stroke incidence but data on other interventions were limited and contradictory. Conclusions AF is common in HCM and associated with high thromboembolic risk. LA dimension and age are independently associated with AF but the literature is insufficient to create robust clinical tools to predict AF or thromboembolism. Most data suggest that AF patients should be anticoagulated.

Novel genotype–phenotype associations demonstrated by high-throughput sequencing in patients with hypertrophic cardiomyopathy

Objective A predictable relation between genotype and disease expression is needed in order to use genetic testing for clinical decision-making in hypertrophic cardiomyopathy (HCM). The primary aims of this study were to examine the phenotypes associated with sarcomere protein (SP) gene mutations and test the hypothesis that variation in non-sarcomere genes modifies the phenotype. Methods Unrelated and consecutive patients were clinically evaluated and prospectively followed in a specialist clinic. High-throughput sequencing was used to analyse 41 genes implicated in inherited cardiac conditions. Variants in SP and non-SP genes were tested for associations with phenotype and survival. Results 874 patients (49.6±15.4 years, 67.8% men) were studied; likely disease-causing SP gene variants were detected in 383 (43.8%). Patients with SP variants were characterised by younger age and higher prevalence of family history of HCM, family history of sudden cardiac death, asymmetric septal hypertrophy, greater maximum LV wall thickness (all p values<0.0005) and an increased incidence of cardiovascular death (p=0.012). Similar associations were observed for individual SP genes. Patients with ANK2 variants had greater maximum wall thickness (p=0.0005). Associations at a lower level of significance were demonstrated with variation in other non-SP genes. Conclusions Patients with HCM caused by rare SP variants differ with respect to age at presentation, family history of the disease, morphology and survival from patients without SP variants. Novel associations for SP genes are reported and, for the first time, we demonstrate possible influence of variation in non-SP genes associated with other forms of cardiomyopathy and arrhythmia syndromes on the clinical phenotype of HCM.

Global longitudinal strain is associated with heart failure outcomes in hypertrophic cardiomyopathy

Objective We hypothesised that abnormal global longitudinal strain (GLS) would predict outcome in hypertrophic cardiomyopathy (HCM) better than current echocardiographic measures. Methods Retrospective analysis of risk markers in relation to outcomes in 472 patients with HCM at a single tertiary institution (2006–2012). Exclusion criteria were left ventricular (LV) hypertrophy of other origin, patients in atrial fibrillation, lost to follow-up and insufficient image quality to perform strain analysis. Standardised echocardiogram recordings were reviewed and standard variables and LV GLS were measured. The primary end-point included all cardiac deaths, appropriate defibrillator shocks and heart failure (HF) admissions. The secondary end-point was death by HF and admissions related to HF. Results Mean age was 50.0±15.0 years; 322 (68%) were men. At a median of 4.3 years (IQR 0.1–7.8) follow-up, 21 (4.4%) patients experienced cardiovascular death: 6 (1.3%) died from HF, 13 (2.7%) had sudden cardiac death and 2 (0.4%) died secondary to stroke. Four (0.8%) patients experienced appropriate defibrillator shock, and 13 (2.7%) were admitted for HF. On multivariate Fine–Gray proportional hazard analyses, GLS was significantly associated with the primary end-point (HR=0.90, 95% CI 0.83 to 0.98, p=0.018) independently of age, maximal provoked LV outflow-tract gradient and LV end-systolic volume. Moreover, GLS was particularly associated with the secondary end-point (HR=0.82, 95% CI 0.75 to 0.90, p<0.0001) independently of age, previous atrial fibrillation, New York Heart Association (NYHA) class III–IV, LV end-systolic volume, E/E′, and outflow-tract gradient. Survival curves confirmed that GLS was associated with HF events (GLS <15.6%, p=0.0035). Conclusions In patients with HCM, reduced GLS is an independent factor associated with poor cardiac outcomes, and particularly HF outcomes.

Prediction of thrombo-embolic risk in patients with hypertrophic cardiomyopathy (HCM Risk-CVA)

Atrial fibrillation (AF) and thrombo‐embolism (TE) are associated with reduced survival in hypertrophic cardiomyopathy (HCM), but the absolute risk of TE in patients with and without AF is unclear. The primary aim of this study was to derive and validate a model for estimating the risk of TE in HCM. Exploratory analyses were performed to determine predictors of TE, the performance of the CHA2DS2‐VASc score, and outcome with vitamin K antagonists (VKAs).

Stress, emotion and the heart: tako-tsubo cardiomyopathy

Tako-tsubo cardiomyopathy is a cardiac syndrome precipitated by profound emotional stress and anxiety, particularly in middle-aged women. It presents as a mimic of acute myocardial infarction, but coronary angiography shows normal coronary arteries and a characteristic left ventriculogram resembling an “octopus pot”. The condition seems to have a favourable prognosis. Initially described in Japan, and with many names in the literature, it is being increasingly recognised in the West owing to early coronary angiography and primary coronary intervention, accounting for up to 1 in 30 primary cases of angioplasty in some institutions. A typical case is described, and the clinical features, pathophysiology and management reviewed.

Predictors of atrial fibrillation in hypertrophic cardiomyopathy.

Objectives Atrial fibrillation (AF) is associated with increased morbidity and mortality in patients with hypertrophic cardiomyopathy (HCM). The primary aim of this study (HCM Risk-AF) was to determine the predictors of AF in a large multicentre cohort of patients with HCM. Exploratory analyses were performed to investigate the association between AF and survival and the efficacy of antiarrhythmic therapy in maintaining sinus rhythm (SR). Methods A retrospective, longitudinal cohort of patients recruited between 1986 and 2008 in seven centres was used to develop multivariable Cox regression models fitted with preselected predictors. HCM was defined as unexplained hypertrophy (maximum left ventricular wall thickness of ≥15 mm or in accordance with published criteria for the diagnosis of familial disease). 28% of patients (n=1171) had coexistent hypertension. The primary end point was paroxysmal, permanent or persistent AF detected on ECG, Holter monitoring or implantable device interrogation. Results Of the 4248 patients with HCM without pre-existing AF, 740 (17.4%) reached the primary end point. Multivariable Cox regression revealed an association between AF and female sex, age, left atrial diameter, New York Heart Association (NYHA) class, hypertension and vascular disease. The proportion of patients with cardiovascular death at 10 years was 4.9% in the SR group and 10.9% in the AF group (difference in proportions=5.9%; 95% CI (4.1% to 7.8%)). The proportion of patients with non-cardiovascular death at 10 years was 3.2% in the SR group and 5.9% in the AF group (difference in proportions=2.8%; 95% CI (0.1% to 4.2%)). An intention-to-treat propensity score analysis demonstrated that β-blockers, calcium channel antagonists and disopyramide initially maintained SR during follow-up, but their protective effect diminished with time. Amiodarone therapy did not prevent AF during follow-up. Conclusion This study shows that patients with HCM who are at risk of AF development can be identified using readily available clinical parameters. The development of AF is associated with a poor prognosis but there was no evidence that antiarrhythmic therapy prevents AF in the long term.

Relationship between aetiology and left ventricular systolic dysfunction in hypertrophic cardiomyopathy

Background Severe left ventricular (LV) systolic dysfunction is an uncommon complication of hypertrophic cardiomyopathy (HCM) that is associated with poor prognosis. Small observational series suggest that patients with rare causes of HCM are more likely to develop systolic impairment than those with idiopathic disease or mutations in cardiac sarcomeric protein genes. The aim of this study was to test this hypothesis by comparing the prevalence of systolic dysfunction and its impact on prognosis in patients with different causes of HCM. Methods and results 1697 patients (52 (40–63) years, 1160 (68%) males) with HCM followed at two European referral centres were studied. Diagnosis of specific aetiologies was made on the basis of clinical examination, cardiac imaging and targeted genetic and biochemical testing. The primary survival outcome was all-cause mortality or heart transplantation (HTx) for end-stage heart failure (HF). Secondary outcomes were HF-related death, sudden cardiac death, stroke-related death and non-cardiovascular death. Systolic dysfunction (LV ejection fraction <50% by two-dimensional (2D) echocardiography) at first evaluation was more frequent in rare phenocopies than in idiopathic or sarcomeric HCM (105/409 (26%) vs 40/1288 (3%), respectively (p<0.0001)). All-cause death/HTx and HF-related death were more frequent in rare phenocopies compared with idiopathic or sarcomeric HCM (p<0.0001). All-cause mortality and HF-related death were highest in patients with cardiac amyloidosis (p<0.0001). Conclusions In adults with HCM, LV systolic dysfunction is more frequent in those with rare phenocopies. When combined with age at presentation, it is a marker for specific aetiologies and is associated with poorer long-term survival.

An International External Validation Study of the 2014 European Society of Cardiology Guideline on Sudden Cardiac Death Prevention in Hypertrophic Cardiomyopathy (Evidence from HCM)

Background: Identification of people with hypertrophic cardiomyopathy (HCM) who are at risk of sudden cardiac death (SCD) and require a prophylactic implantable cardioverter defibrillator is challenging. In 2014, the European Society of Cardiology proposed a new risk stratification method based on a risk prediction model (HCM Risk-SCD) that estimates the 5-year risk of SCD. The aim was to externally validate the 2014 European Society of Cardiology recommendations in a geographically diverse cohort of patients recruited from the United States, Europe, the Middle East, and Asia. Methods: This was an observational, retrospective, longitudinal cohort study. Results: The cohort consisted of 3703 patients. Seventy three (2%) patients reached the SCD end point within 5 years of follow-up (5-year incidence, 2.4% [95% confidence interval {CI}, 1.9–3.0]). The validation study revealed a calibration slope of 1.02 (95% CI, 0.93–1.12), C-index of 0.70 (95% CI, 0.68–0.72), and D-statistic of 1.17 (95% CI, 1.05–1.29). In a complete case analysis (n= 2147; 44 SCD end points at 5 years), patients with a predicted 5-year risk of <4% (n=1524; 71%) had an observed 5-year SCD incidence of 1.4% (95% CI, 0.8–2.2); patients with a predicted risk of ≥6% (n=297; 14%) had an observed SCD incidence of 8.9% (95% CI, 5.96–13.1) at 5 years. For every 13 (297/23) implantable cardioverter defibrillator implantations in patients with an estimated 5-year SCD risk ≥6%, 1 patient can potentially be saved from SCD. Conclusions: This study confirms that the HCM Risk-SCD model provides accurate prognostic information that can be used to target implantable cardioverter defibrillator therapy in patients at the highest risk of SCD.

Almanac 2014: cardiomyopathies

Cardiomyopathies are myocardial disorders that are not explained by abnormal loading conditions and coronary artery disease. They are classified into a number of morphological and functional phenotypes that can be caused by genetic and non-genetic mechanisms. The dominant themes in papers published in 2012-2013 are similar to those reported in Almanac 2011, namely, the use (and interpretation) of genetic testing, development and application of novel non-invasive imaging techniques and use of serum biomarkers for diagnosis and prognosis. An important innovation since the last Almanac is the development of more sophisticated models for predicting adverse clinical events.Cardiomyopathies are myocardial disorders that are not explained by abnormal loading conditions and coronary artery disease. They are classified into a number of morphological and functional phenotypes that can be caused by genetic and non-genetic mechanisms. The dominant themes in papers published in 2012–2013 are similar to those reported in Almanac 2011, namely, the use (and interpretation) of genetic testing, development and application of novel non-invasive imaging techniques and use of serum biomarkers for diagnosis and prognosis. An important innovation since the last Almanac is the development of more sophisticated models for predicting adverse clinical events.