Echocardiographic diagnosis of the different phenotypes of hypertrophic cardiomyopathy

Abstract

Hypertrophic Cardiomyopathy (HCM) is an inherited cardiovascular disorder of great genetic heterogeneity and has a prevalence of 0.1 – 0.2 % in the general population. Several hundred mutations in more than 27 genes, most of which encode sarcomeric structures, are associated with the HCM phenotype. Then, HCM is an extremely heterogeneous disease and several phenotypes have been described over the years. Originally only two phenotypes were considered, a more common, obstructive type (HOCM, 70 %) and a less common, non-obstructive type (HNCM, 30 %) (Maron BJ, et al. Am J Cardiol 48:418 –28, 1981). Wigle et al. (Circ 92:1680–92, 1995) considered three types of functional phenotypes: subaortic obstruction, midventricular obstruction and cavity obliteration. A leader american working group suggested that HCM should be defined genetically and not morphologically (Maron BJ, et al. Circ 113:1807–16, 2006). The European Society of Cardiology Working Group on Myocardial and Pericardial Diseases recommended otherwise a morphological classification (Elliott P, et al. Eur Heart J 29:270–6, 2008). Echocardiography is still the principal tool for the diagnosis, prognosis and clinical management of HCM. It is well known that the echocardiographic picture may have a clinical and prognostic impact. For this reason, in this article, we summarize the state of the art regarding the echocardiographic pattern of the HCM phenotypes and its impact on clinical course and prognosis.

Left atrial function and phenotypes in asymmetric hypertrophic cardiomyopathy

“…Impaired LA function has demonstrated to be associated with the occurrence of myocardial fibrosis, 30 which is considered as a key feature in the pathogenesis and perpetuation of atrial fibrillation. Also, consistent with the review by Parato et al, 28 LVOT obstruction and severity of LV hypertrophy (assessed by septal LS in our study) were independent associates of LA volume. In fact, it has prognostic importance to evaluate the LA size and mechanical function in patients with HCM.…”

“…Sanada et al 27 reported that increased LA stiffness, which has shown to be increased in patients with HCM, affects reservoir function and may in turn affect cardiac output. As Parato et al 28 summarized in their review, LA enlargement in patients with HCM has multifactorial origins. In addition to diastolic dysfunction, LA enlargement refers to a time-dependent adaptive regulation of cardiac myocytes to maintain homeostasis against external stressors such as valvular disease, 29 as well as LA myocardial disarray.…”

Acute Limb Ischemia in a Previously Undiagnosed Case of Mid-Ventricular Non-Obstructive Hypertrophic Cardiomyopathy

“…Symptoms are also more common in HCM patients with moderate degrees of hypertrophy (wall thickness of 16 -24 mm) as opposed to those with severe hypertrophy (> 30 mm) or mild hypertrophy (< 15 mm) [9] as was seen in our patient. Patients could experience syncope, palpitations, chest pain or dyspnea while others may present with resuscitated cardiac arrest even in the absence of a family history of sudden cardiac death.…”

“…The mechanisms of apical aneurysm formation are incompletely understood but include increased intraventricular pressure, microvascular ischemia, left anterior descending artery bridging and genetic predisposition [1,4,7,8]. Patients may be asymptomatic [7], but the presence of aneurysm is associated with increased risk of complications [1,4,7] particularly when they are medium or large-sized [9]. The dyskinetic or akinetic apical aneurysm provides a structural basis for intracavitary thrombus formation [5].…”

“…The dyskinetic or akinetic apical aneurysm provides a structural basis for intracavitary thrombus formation [5]. The diagnostic accuracy for LV apical aneurysm is 57% for echocardiogram, 80% for contrast echocardiography and 100% for cardiac MRI [9]. In older patients, the likelihood of HCM is increased by the presence of marked LV thickness > 25 mm, LV outflow tract (LVOT) obstruction, systolic anterior motion of the mitral valve and/or the presence of mitral valve to septal wall contact [6].…”