Unexpectedly low left ventricular voltage on ECG in hypertrophic cardiomyopathy

Hypertrophic Cardiomyopathy Diagnosis and Treatment in High- and Low-Income Countries: A Narrative Review

Hypertrophic cardiomyopathy (HCM) is a hereditary cardiac condition characterized by unexplained left ventricular hypertrophy without a hemodynamic cause. This condition is prevalent in the United States, resulting in various clinical manifestations, including diastolic dysfunction, left ventricular outflow obstruction, cardiac ischemia, and atrial fibrillation. HCM is associated with several genetic mutations, with sarcomeric mutations being the most common and contributing to a more complex disease course. Early diagnosis of HCM is essential for effective management, as late diagnosis often requires invasive treatments and creates a substantial financial burden. Disparities in HCM diagnosis and treatment exist between high-income and low-income countries. High-income countries have more resources to investigate and implement advanced diagnostic and treatment modalities. In contrast, low-income countries face challenges in accessing diagnostic equipment, trained personnel, and affordable medications, leading to a lower quality of life and life expectancy for affected individuals. Diagnostic tools for HCM include imaging studies such as 2D echocardiography, cardiovascular magnetic resonance (CMR), and electrocardiograms (ECGs). CMR is considered the gold standard but remains inaccessible to a significant portion of the world's population, especially in low-income countries. Genetics plays a crucial role in HCM, with numerous mutations identified in various genes. Genetic counseling is essential but often limited in low-income countries due to resource constraints. Disparities in healthcare access and adherence to treatment recommendations exist between high-income and low-income countries, leading to differences in patient outcomes. Addressing these disparities is essential to improve the overall management of HCM on a global scale. In conclusion, this review highlights the complex nature of HCM, emphasizing the importance of early diagnosis, genetic counseling, and access to appropriate diagnostic and therapeutic interventions. Addressing healthcare disparities is crucial to ensure that all individuals with HCM receive timely and effective care, regardless of their geographic location or socioeconomic status.

Low QRS voltages and left ventricular hypertrophy: a risky association

AIMS

Low QRS voltages (LQRSV) are an unexpected finding in left ventricular hypertrophy, i.e. hypertrophic cardiomyopathy (HCM) or athlete's heart.

METHODS AND RESULTS

Prevalence and clinical correlates of LQRSV were investigated in 197 consecutive HCM patients, aged 58 ± 13 years and comparatively in 771 Olympic athletes, aged 23 ± 4. Clinical characterization included family/personal history, symptoms, New York Heart Association (NYHA) functional class, electrocardiographic pattern, ventricular arrhythmias, and cardiac magnetic resonance (CMR). Twenty-two (11%) of HCM and 18 (2.3%) of athletes presented LQRSV. At initial evaluation, in HCM, LQRSV showed no differences vs. non-LQRSV for functional class (90% vs. 91%, in Classes I and II; P = 0.983), symptoms (27% vs. 18%; P = 0.478), and ventricular arrhythmias (40% vs. 39%; P = 857) but showed larger extent of late gadolinium enhancement (LGE) at CMR (4.1 ± 1.5 vs. 1.5 ± 0.7 affected segments; P < 0.001). In athletes, LQRSV was associated with larger prevalence of inverted T-waves (22% vs. 9%; P < 0.001) and ventricular arrhythmias (28% vs. 8%; P = 0.005). In one LQRSV athlete, arrhythmogenic cardiomyopathy was identified. Over 4.5 ± 2.6-year follow-up, presence of LQRSV in HCM was associated with larger incidence of functional deterioration (31% vs. 14%; P = 0.038), stroke (22% vs. 6%; P = 0.008), and implantable cardioverter defibrillator (ICD) implant (27% vs. 10%; P = 0.015). No clinical events occurred in LQRSV athletes without initial evidence of cardiac disease.

CONCLUSION

LQRSV are relatively common (11%) in HCM and have clinical relevance, being predictive over a medium term for a worsening functional class, incidence of stroke, and ICD implant. Instead, LQRSV are rare (2.3%) in athletes but may occasionally be a marker that raises suspicion for underlying cardiac disease at risk.

Association of electrocardiographic markers with myocardial fibrosis as assessed by cardiac magnetic resonance in different clinical settings

BACKGROUND

Cardiac magnetic resonance (CMR) is a unique tool for non-invasive tissue characterization, especially for identifying fibrosis.

AIM

To present the existing data regarding the association of electrocardiographic (ECG) markers with myocardial fibrosis identified by CMR - late gadolinium enhancement (LGE).

METHODS

A systematic search was performed for identifying the relevant studies in Medline and Cochrane databases through February 2021. In addition, we conducted a relevant search by Reference Citation Analysis (RCA) (https://www.referencecitationanalysis.com).

RESULTS

A total of 32 studies were included. In hypertrophic cardiomyopathy (HCM), fragmented QRS (fQRS) is related to the presence and extent of myocardial fibrosis. fQRS and abnormal Q waves are associated with LGE in ischemic cardiomyopathy patients, while fQRS has also been related to fibrosis in myocarditis. Selvester score, abnormal Q waves, and notched QRS have also been associated with LGE. Repolarization abnormalities as reflected by increased Tp-Te, negative T-waves, and higher QT dispersion are related to myocardial fibrosis in HCM patients. In patients with Duchenne muscular dystrophy, a significant correlation between fQRS and the amount of myocardial fibrosis as assessed by LGE-CMR was observed. In atrial fibrillation patients, advanced inter-atrial block is defined as P-wave duration ≥ 120 ms, and biphasic morphology in inferior leads is related to left atrial fibrosis.

CONCLUSION

Myocardial fibrosis, a reliable marker of prognosis in a broad spectrum of cardiovascular diseases, can be easily understood with an easily applicable ECG. However, more data is needed on a specific disease basis to study the association of ECG markers and myocardial fibrosis as depicted by CMR.