Clinical and Molecular Aspects of Cardiomyopathies: Emerging Therapies and Clinical Trials

Hypertrophic cardiomyopathy: prevalence of disease-specific red flags

BACKGROUND AND AIMS

The European Society of Cardiology guidelines recommend a systematic search for diagnostic clues or 'red flags' (RFs) in patients with hypertrophic cardiomyopathy (HCM) to better tailor disease management. To date, the prevalence and clinical significance of RF associated with HCM phenotypes in different clinical settings are unknown.

METHODS

The study cohort comprised 818 patients with a clinical diagnosis of HCM [479 (62%) males, mean age 49 ± 21 years] referred to four European centres. Pre-specified RFs were categorized into one of five domains: (i) family history; (ii) physical examination; (iii) electrocardiography; (iv) echocardiography; and (v) laboratory.

RESULTS

A total of 318 (39%) patients had a pathogenic or likely pathogenic sarcomere gene variant; 240 (29%) a TTR and GLA variant; 154 (19%) a syndromic cause; and 106 (13%) no identifiable cause. In the overall cohort, 2979 RFs were identified. Of these, 1018 (34%) were identifiable from clinical history and examination alone (generalist setting) and 1961 (66%) by 12-lead electrocardiogram and echocardiography (cardiologist's office). Non-sarcomeric patients were diagnosed more often aged <20 and after 60 years (476/500, 95%). Syndromic diseases such as Rasopathies, inherited metabolic disorders, and mitochondrial disorders were diagnosed in neonatal/early childhood (mean age 3 ± 2 years), whereas patients with Danon disease, Friedreich's ataxia, Noonan syndrome, and PRKAG2 cardiomyopathy were identified mostly during adolescence (mean age 16 ± 8 years). Non-cardiac RFs identified by clinical history, physical examination, and routine laboratory testing were most frequent in patients with HCM caused by Rasopathies, inherited metabolic disorders, and mitochondrial disorders (48%, 47%, and 57%, respectively). Physical RFs were almost exclusively observed in patients with a definite non-sarcomeric aetiology [348/350 (99%)]. On the contrary, most RFs associated with geno-positive and geno-negative HCM were derived from electrocardiogram and echocardiography [692/990 (70%) and 332/375 (88%), respectively].

CONCLUSIONS

Red flags are a common finding in patients presenting with HCM, most commonly non-cardiac in non-sarcomeric aetiology and cardiac in sarcomeric HCM. Over 34% of RF, most relevant to rare HCM phenocopies, can be potentially detected in a generalist setting. Investing in high-touch-low tech, widespread awareness for HCM-related RF may provide substantial advantage in terms of diagnostic yield and appropriate use of resources.

Real-World Use and Predictors of Response to Disopyramide in Patients with Obstructive Hypertrophic Cardiomyopathy

Background: Although disopyramide has been widely used to reduce left ventricular outflow obstruction (LVOTO) and to improve symptoms in patients with obstructive hypertrophic cardiomyopathy (oHCM), its use in real world as well as patient characteristics associated with a positive treatment response are still unclear. Methods: From 1980 to 2021, 1527 patients with HCM were evaluated and 372 (23%) had a LVOTO with active follow-up. The efficacy and safety of disopyramide were assessed systematically during 12 months (2-, 6-, and 12-month visits). Responders were patients with a final NYHA = I and a LVOTO < 30 mmHg; incomplete responders were those patients with NYHA > I and a LVOTO < 30 mmHg; and non-responders were symptomatic patients with no change in functional class NYHA and a LVOT gradient > 30 mmHg. Results: Two-hundred-fifty-four (66%) patients were in functional class NYHA I/II and 118 (34%) in NYHA III/IV. A total of 118/372 (32%, 55 ± 16 years) underwent disopyramide therapy. Twenty-eight (24%) patients responded to therapy, 39 (33%) were incomplete responders, and 51 (43%) did not respond. Responder were mainly patients in functional NYHA class I/II (24/28, 86%), whereas incomplete responders and non-responders were more often in functional NYHA class III/IV (50/54 (93%)). An independent predictor of response to disopyramide treatment was the presence of NYHA I/II at the initiation of therapy (HR 1.5 (95% CI 1.1-4.5), p = 0.03). No major life-threatening arrhythmic events or syncope occurred, despite 19 (16%) patients showing reduced QTc from baseline, 19 (16%) having no difference, while 80 (69%) patients had prolonged QTc interval. Thirty-one (26%) patients experienced side effects, in particular, 29 of the anticholinergic type. Conclusions: Disopyramide was underused in oHCM but effective in reducing LVOTO gradients and symptoms in slightly symptomatic patients with less severe disease phenotype with a safe pro-arrhythmic profile.

Hemodynamic Instability in Heart Failure Intensifies Age-Dependent Cognitive Decline

This review attempts to examine two key elements in the evolution of cognitive impairment in the elderly who develop heart failure. First, major left side heart parts can structurally and functionally deteriorate from aging wear and tear to provoke hemodynamic instability where heart failure worsens or is initiated; second, heart failure is a major inducer of cognitive impairment and Alzheimer's disease in the elderly. In heart failure, when the left ventricular myocardium of an elderly person does not properly contract, it cannot pump out adequate blood to the brain, raising the risk of cognitive impairment due to the intensification of chronic brain hypoperfusion. Chronic brain hypoperfusion originates from chronically reduced cardiac output which progresses as heart failure worsens. Other left ventricular heart parts, including atrium, valves, myocardium, and aorta can contribute to the physiological shortfall of cardiac output. It follows that hemodynamic instability and perfusion changes occurring from the aging heart's blood pumping deficiency will, in time, damage vulnerable brain cells linked to specific cognitive regulatory sites, diminishing neuronal energy metabolism to a level where progressive cognitive impairment is the outcome. Could cognitive impairment progress be reversed with a heart transplant? Evidence is presented detailing the errant hemodynamic pathways leading to cognitive impairment during aging as an offshoot of inefficient structural and functional heart parts and their contribution to heart failure.