Accurate diagnosis of apical hypertrophic cardiomyopathy using explainable advanced electrocardiogram analysis.

AIMS: Typical electrocardiogram (ECG) features of apical hypertrophic cardiomyopathy (ApHCM) include tall R waves and deep or giant T-wave inversion in the precordial leads, but these features are not always present. The ECG is used as the gatekeeper to cardiac imaging for diagnosis. We tested whether explainable advanced ECG (A-ECG) could accurately diagnose ApHCM. METHODS AND RESULTS: Advanced ECG analysis was performed on standard resting 12-lead ECGs in patients with ApHCM [n = 75 overt, n = 32 relative (<15 mm hypertrophy); a subgroup of which underwent cardiovascular magnetic resonance (n = 92)], and comparator subjects (n = 2449), including healthy volunteers (n = 1672), patients with coronary artery disease (n = 372), left ventricular electrical remodelling (n = 108), ischaemic (n = 114) or non-ischaemic cardiomyopathy (n = 57), and asymmetrical septal hypertrophy HCM (n = 126). Multivariable logistic regression identified four A-ECG measures that together discriminated ApHCM from other diseases with high accuracy [area under the receiver operating characteristic (AUC) curve (bootstrapped 95% confidence interval) 0.982 (0.965-0.993)]. Linear discriminant analysis also diagnosed ApHCM with high accuracy [AUC 0.989 (0.986-0.991)]. CONCLUSION: Explainable A-ECG has excellent diagnostic accuracy for ApHCM, even when the hypertrophy is relative, with A-ECG analysis providing incremental diagnostic value over imaging alone. The electrical (ECG) and anatomical (wall thickness) disease features do not completely align, suggesting that future diagnostic and management strategies may incorporate both features.

The mitral valve in hypertrophic cardiomyopathy.

PURPOSE OF REVIEW: Whilst abnormally increased left ventricular wall thickness is the hallmark feature of hypertrophic cardiomyopathy (HCM), anomalies of the mitral valve and supporting apparatus are well documented. This review addresses the clinical importance of mitral valve abnormalities in HCM, their mechanistic associations with symptoms, and therapeutic strategies targeting mitral valve and apparatus abnormalities. RECENT FINDINGS: The normal mitral valve possesses anatomical features facilitating unrestricted blood flow during LV filling, preventing regurgitation during LV systole, and avoiding obstruction of LV ejection. In HCM, a variety of structural and functional abnormalities can conspire to cause deranged mitral valve function, with implications for management strategy. Identification and characterization of these abnormalities is facilitated by multimodality imaging. Alcohol septal ablation (ASA) cannot address primary mitral valve abnormalities, and so is not preferred to surgical intervention if mitral valve abnormalities are present and are judged to make dominant contributions to LV outflow tract obstruction (LVOTO). Two broadly opposing surgical intervention strategies exist, one advocating isolated septal myectomy and the other including adjuvant mitral apparatus modification. Newer, less invasive surgical and transcatheter techniques will expand interventional options. SUMMARY: Mitral valve abnormalities are a central pathological feature of HCM. Multimodality imaging is crucial for their identification and characterization prior to therapeutic intervention.

Embedding post-doctoral clinical academic careers in practice: The St Bartholomew's Hospital model.

AIMS AND OBJECTIVES: In order to retain and develop pre-doctoral and doctoral staff, we sought to establish and implement a model for supporting postdoctoral clinical academic careers at our hospital. BACKGROUND: Doctorally-prepared nurses can raise clinical practice standards, but there is a deficit of career opportunities and post-doctoral positions. This will inevitably impact delivering the evidence for improving patient outcomes and service delivery. It is therefore imperative that post-doctoral nursing and allied professional post-doctoral clinical academic career opportunities are developed and embedded in practice. DESIGN: We describe the development and implementation of a model to provide and embed post-doctoral clinical academic roles at our hospital. METHODS: A multidisciplinary group devised the model which was approved by the Hospital Executive Board. RESULTS: The model includes having a bespoke plan for each individual, planning the post-doctoral role at time of PhD planning, providing 1 day a week protected research time for a minimum of 12 months after PhD completion, having an appropriate honorary academic contract at a partner University, and providing integrated clinical and academic supervision throughout. Other key components include senior clinical and Executive Board support and an existing vibrant research culture at our organisation. CONCLUSIONS: The St Bartholomew's Hospital model, focusing on individualised posts integrating clinical and academic roles to address service needs, offers a novel approach to supporting post-doctoral clinical academic careers in a clinical setting. RELEVANCE TO CLINICAL PRACTICE: Since doctorally-prepared nurses can raise clinical practice standards we developed a sustainable infrastructure to increase our postdoctoral nursing and allied professional workforce. This model could provide a framework for other hospitals to embed postdoctoral clinical academic careers in practice.

International External Validation Study of the 2014 European Society of Cardiology Guidelines on Sudden Cardiac Death Prevention in Hypertrophic Cardiomyopathy (EVIDENCE-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.

Doppler echocardiography underestimates the prevalence and magnitude of mid-cavity obstruction in patients with symptomatic hypertrophic cardiomyopathy.

OBJECTIVES: To evaluate utility of Doppler echocardiography in the assessment of left ventricular (LV) mid-cavity obstructive (LVMCO) hypertrophic cardiomyopathy (HCM). BACKGROUND: LVMCO is a relatively under-diagnosed complication of HCM and may occur alone or in combination with LV outflow tract obstruction (LVOTO). Identifying and quantifying LVMCO and differentiating it from LVOTO has important implications for patient management. We aimed to assess diagnostic performance of Doppler echocardiography in the assessment of suspected LV obstruction. METHODS: Forty symptomatic HCM patients with suspected obstruction underwent cardiac catheterization, and comparison of location and magnitude of Doppler derived gradients with synchronous invasive measurements (reference standard), at rest and isoprenaline stress (IS). RESULTS: Doppler's diagnostic accuracy for any obstruction (≥30 mmHg) in this cohort was 75% with false positive and false negative rates of 2.5 and 22.5%, respectively. During subanalysis, Doppler's diagnostic accuracy for isolated LVOTO in this selected cohort is 83% with false positive and false negative rates of 4 and 12.5%, respectively. For LVMCO, the accuracy is only 50%, with false positive and false negative rates of 10 and 40%, respectively. Doppler gradients for isolated LVOTO were similar to invasive: 85 ± 51 and 87 ± 35 mmHg, respectively (P = 0.77). Doppler gradients in LVMCO were consistently lower than invasive: 45 ± 38 and 81 ± 31 mmHg, respectively (P = 0.0002). Mid-systolic flow cessation and/or contamination of spectral signals were identified as causes of Doppler-derived inaccuracies. CONCLUSIONS: Doppler echocardiography under-diagnoses and underestimates severity of LVMCO in symptomatic HCM patients. Recognition of abrupt mid-systolic flow cessation and invasive measurements may improve detection of LVMCO in HCM.

Characterizing the hypertensive cardiovascular phenotype in the UK Biobank.

AIMS: To describe hypertension-related cardiovascular magnetic resonance (CMR) phenotypes in the UK Biobank considering variations across patient populations. METHODS AND RESULTS: We studied 39 095 (51.5% women, mean age: 63.9 ± 7.7 years, 38.6% hypertensive) participants with CMR data available. Hypertension status was ascertained through health record linkage. Associations between hypertension and CMR metrics were estimated using multivariable linear regression adjusting for major vascular risk factors. Stratified analyses were performed by sex, ethnicity, time since hypertension diagnosis, and blood pressure (BP) control. Results are standardized beta coefficients, 95% confidence intervals, and P-values corrected for multiple testing. Hypertension was associated with concentric left ventricular (LV) hypertrophy (increased LV mass, wall thickness, concentricity index), poorer LV function (lower global function index, worse global longitudinal strain), larger left atrial (LA) volumes, lower LA ejection fraction, and lower aortic distensibility. Hypertension was linked to significantly lower myocardial native T1 and increased LV ejection fraction. Women had greater hypertension-related reduction in aortic compliance than men. The degree of hypertension-related LV hypertrophy was greatest in Black ethnicities. Increasing time since diagnosis of hypertension was linked to adverse remodelling. Hypertension-related remodelling was substantially attenuated in hypertensives with good BP control. CONCLUSION: Hypertension was associated with concentric LV hypertrophy, reduced LV function, dilated poorer functioning LA, and reduced aortic compliance. Whilst the overall pattern of remodelling was consistent across populations, women had greater hypertension-related reduction in aortic compliance and Black ethnicities showed the greatest LV mass increase. Importantly, adverse cardiovascular remodelling was markedly attenuated in hypertensives with good BP control.

Apical Ischemia Is a Universal Feature of Apical Hypertrophic Cardiomyopathy.

BACKGROUND: Apical hypertrophic cardiomyopathy (ApHCM) accounts for ≈10% of hypertrophic cardiomyopathy cases and is characterized by apical hypertrophy, apical cavity obliteration, and tall ECG R waves with ischemic-looking deep T-wave inversion. These may be present even with <15 mm apical hypertrophy (relative ApHCM). Microvascular dysfunction is well described in hypertrophic cardiomyopathy. We hypothesized that apical perfusion defects would be common in ApHCM. METHODS: A 2-center study using cardiovascular magnetic resonance short- and long-axis quantitative adenosine vasodilator stress perfusion mapping. One hundred patients with ApHCM (68 overt hypertrophy [≥15 mm] and 32 relative ApHCM) were compared with 50 patients with asymmetrical septal hypertrophy hypertrophic cardiomyopathy and 40 healthy volunteer controls. Perfusion was assessed visually and quantitatively as myocardial blood flow and myocardial perfusion reserve. RESULTS: Apical perfusion defects were present in all overt ApHCM patients (100%), all relative ApHCM patients (100%), 36% of asymmetrical septal hypertrophy hypertrophic cardiomyopathy, and 0% of healthy volunteers (P<0.001). In 10% of patients with ApHCM, perfusion defects were sufficiently apical that conventional short-axis views missed them. In 29%, stress myocardial blood flow fell below rest values. Stress myocardial blood flow was most impaired subendocardially, with greater hypertrophy or scar, and with apical aneurysms. Impaired apical myocardial blood flow was most strongly predicted by thicker apical segments (ß-coefficient, -0.031 mL/g per min [CI, -0.06 to -0.01]; P=0.013), higher ejection fraction (-0.025 mL/g per min [CI, -0.04 to -0.01]; P<0.005), and ECG maximum R-wave height (-0.023 mL/g per min [CI, -0.04 to -0.01]; P<0.005). CONCLUSIONS: Apical perfusion defects are universally present in ApHCM at all stages. Its ubiquitous presence along with characteristic ECG suggests ischemia may play a disease-defining role in ApHCM.

Therapeutic benefits of distal ventricular pacing in mid-cavity obstructive hypertrophic cardiomyopathy.

INTRODUCTION: Hypertrophic cardiomyopathy (HCM) patients with left ventricular (LV) mid-cavity obstruction (LVMCO) often experience severe drug-refractory symptoms thought to be related to intraventricular obstruction. We tested whether ventricular pacing, guided by invasive haemodynamic assessment, reduced LVMCO and improved refractory symptoms. METHODS: Between December 2008 and December 2017, 16 HCM patients with severe refractory symptoms and LVMCO underwent device implantation with haemodynamic pacing study to assess the effect on invasively defined LVMCO gradients. The effect on the gradient of atrioventricular (AV) synchronous pacing from sites including right ventricular (RV) apex and middle cardiac vein (MCV) was retrospectively assessed. RESULTS: Invasive haemodynamic data were available in 14 of 16 patients. Mean pre-treatment intracavitary gradient was 77 ± 22 mmHg (in sinus rhythm) versus 21 ± 21 mmHg during pacing from optimal ventricular site (95% CI: -70.86 to -40.57, p < 0.0001). Optimal pacing site was distal MCV in 12/16 (86%), RV apex in 1/16 and via epicardial LV lead in 1/16. Pre-pacing Doppler-derived gradients were significantly higher than at follow-up (47 ± 15 versus 24 ± 16 mmHg, 95% CI: -37.19 to -13.73, p < 0.001). Median baseline NYHA class was 3, which had improved by ⩾1 NYHA class in 13 of 16 patients at 1-year post-procedure (p < 0.001). The mean follow-up duration was 4.6 ± 2.7 years with the following outcomes: 8/16 (50%) had continued symptomatic improvement, 4/16 had symptomatic decline and 4/16 died. Contributors to symptomatic decline included chronic atrial fibrillation (AF) (n = 5), phrenic nerve stimulation (n = 3) and ventricular ectopy (n = 1). CONCLUSION: In drug-refractory symptomatic LVMCO, distal ventricular pacing can reduce intracavitary obstruction and may provide long-term symptomatic relief in patients with limited treatment options. A haemodynamic pacing study is an effective strategy for identifying optimal pacing site and configuration.

Pulmonary blood volume index as a quantitative biomarker of haemodynamic congestion in hypertrophic cardiomyopathy.

AIMS: The non-invasive assessment of left ventricular (LV) diastolic function and filling pressure in hypertrophic cardiomyopathy (HCM) is still an open issue. Pulmonary blood volume index (PBVI) by cardiovascular magnetic resonance (CMR) has been proposed as a quantitative biomarker of haemodynamic congestion. We aimed to assess the diagnostic accuracy of PBVI for left atrial pressure (LAP) estimation in patients with HCM. METHODS AND RESULTS: We retrospectively identified 69 consecutive HCM outpatients (age 58 ± 11 years; 83% men) who underwent both transthoracic echocardiography (TTE) and CMR. Guideline-based detection of LV diastolic dysfunction was assessed by TTE, blinded to CMR results. PBVI was calculated as the product of right ventricular stroke volume index and the number of cardiac cycles for a bolus of gadolinium to pass through the pulmonary circulation as assessed by first-pass perfusion imaging. Compared to patients with normal LAP, patients with increased LAP showed significantly larger PBVI (463 ± 127 vs. 310 ± 86 mL/m2, P < 0.001). PBVI increased progressively with worsening New York Heart Association functional class and echocardiographic stages of diastolic dysfunction (P < 0.001 for both). At the best cut-off point of 413 mL/m2, PBVI yielded good diagnostic accuracy for the diagnosis of LV diastolic dysfunction with increased LAP [C-statistic = 0.83; 95% confidence interval (CI): 0.73-0.94]. At multivariable logistic regression analysis, PBVI was an independent predictor of increased LAP (odds ratio per 10% increase: 1.97, 95% CI: 1.06-3.68; P = 0.03). CONCLUSION: PBVI is a promising CMR application for assessment of diastolic function and LAP in patients with HCM and may serve as a quantitative marker for detection, grading, and monitoring of haemodynamic congestion.

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.