Cardiogenetics, Volume 13, Issue 2 (June 2023) – 4 articles

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiovascular disorder and is characterized by left ventricular hypertrophy (LVH), which is unexplained by abnormal loading conditions. HCM is inherited as an autosomal dominant trait and, in about 40% of patients, the causal mutation is identified in genes encoding sarcomere proteins. According to the results of genetic screening, HCM patients are currently categorized in two main sub-populations: sarcomeric-positive (Sarc+) patients, in whom the causal mutation is identified in a sarcomeric gene; and sarcomeric-negative (Sarc−) patients, in whom a causal mutation has not been identified. In rare cases, Sarc− HCM cases may be caused by pathogenic variants in non-sarcomeric genes. The aim of this review is to describe the differences in the phenotypic expression and clinical outcomes of Sarc+ and Sarc− HCM and to briefly discuss the current knowledge about HCM caused by rare non-sarcomeric mutations. Full article

Left ventricular outflow obstruction (LVOTO) and diastolic dysfunction are the main pathophysiological characteristics of hypertrophic cardiomyopathy (HCM)LVOTO, may be identified in more than half of HCM patients and represents an important determinant of symptoms and a predictor of worse prognosis. This review aims to clarify the LVOTO mechanism in, diagnosis of, and therapeutic strategies for patients with obstructive HCM. Full article

Brugada syndrome (BrS) is an inherited cardiac channelopathy with variable expressivity that can lead to sudden cardiac arrest (SCA). Studies worldwide suggest that BrS and Brugada pattern (BrP) have low prevalences in general. However, studies also note that BrS is most prevalent among certain Asian populations. Among the different global regions, the highest prevalence is believed to be in Southeast Asia, followed by the Middle East, South Asia, East Asia, Europe, and North America. It is not only important to recognize such varying degrees of BrS prevalence within Asia but also to understand that there may be significant differences in terms of presenting symptoms, occult risk factors, and the impact on clinical outcomes. The importance of identifying such differences lies in the necessity to develop improved risk assessment strategies to guide secondary prevention and treatment for these patients. Specifically, the decision to pursue placement of an implantable cardiac defibrillator (ICD) can be lifesaving for high-risk BrS patients. However, there remains a significant lack of consensus on how to best risk stratify BrS patients. While the current guidelines recommend ICD implantation in patients with spontaneous Type 1 ECG pattern BrS who present with syncope, there may still exist additional clinical factors that may serve as better predictors or facilitate more refined risk stratification before malignant arrhythmias occur. This carries huge relevance given that BrS patients often do not have any preceding symptoms prior to SCA. This review seeks to delineate the differences in BrS presentation and prevalence within the Asian continent in the hope of identifying potential risk factors to guide better prognostication and management of BrS patients in the future. Full article

(1) Background. One of the causes of myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) is thrombus formation in situ followed by lysis, resulting in a morphologically normal angiogram but with an underlying prothrombotic state that is potentially predisposed to recurrence. Recent studies have shown that a subset of MINOCA patients may have thrombophilic conditions at screening. Objective: To compare the prothrombotic trend in MINOCA patients with that of subjects with MI and obstructive coronary arteries (MIOCA) by testing for known congenital thrombophilias and markers of coagulation activation. (2) Materials and methods. Screening included congenital thrombophilias (factor V Leiden; assessment of protein C, protein S, and antithrombin III) and eight genes. Of these, four genes represented the folate pathway enzymes: MTHFR 677 C>T (rs1801133), MTHFR 1298 A>C (rs1801131), MTR 2756 A>G (rs1805087), and MTRR 66 A>G (rs1801394). The other four genes represented the blood coagulation system: F13 (163 G>T) rs5985, F1 (−455 G>A) rs1800790, GP IIb–IIIa (1565 T>C) rs5918, and PAI-I (−675 5G>4G) rs1799889. Additionally, we examined the levels of homocysteine and lipoprotein (LP) (a). (3) Results. Our study included 269 patients: 114 MINOCA patients and 155 MIOCA patients with lesions of one coronary artery. The frequencies of polymorphisms in the genes of the blood coagulation system and the folate pathway did not differ between the groups. The following genes were associated with in-hospital mortality in the MINOCA group: MTHFR 1298 A>C rs1801131 (OR 8.5; 95% CI 1.67–43.1) and F1 (−455 G>A) rs1800790 (OR 5.8; 95% CI 1.1–27.8). In the MIOCA group, the following genes were associated with in-hospital mortality: MTHFR 1298 A>C rs1801131 (OR 9.1; 95% CI 2.8–28.9), F1 (−455 G>A) rs1800790 (OR 11.4; 95% CI 3.6–35.9), GP IIb–IIIa (1565 T>C) rs5918 (OR 10.5; 95% CI 3.5–30.8), and PAI-I (−675 5G>4G) rs1799889 (OR 12.9; 95% CI 4.2–39.7). We evaluated long-term outcomes (case fatality rate, recurrent MI, and stroke) over a period of 12 months in both groups. The variables associated with these outcomes were laboratory parameters, such as protein C deficiency, hyperhomocysteinemia, and a content of LP (a) > 30 mg/dL. However, we did not reveal the prognostic value of polymorphisms of the studied genes representing the blood coagulation system and the folate pathway. (4) Conclusion. We established no statistically significant differences between the MINOCA and MIOCA groups in the prevalence of congenital thrombophilias and the prevalence of folate pathway enzyme genes and blood coagulation system genes. The MTHFR 1298 A>C (rs1801131) and F1 (−455 G>A) rs1800790 genes were associated with in-hospital mortality in both groups. More significant prognostic factors in both groups during the one-year period were protein C deficiency, hyperhomocysteinemia, and LP (a) > 30 mg/dL. Full article