Genetic investigation and counselling of families with hypertrophic cardiomyopathy

Sudden cardiac death athletes: a systematic review

Previous events evidence that sudden cardiac death (SCD) in athletes is still a reality and it keeps challenging cardiologists. Considering the importance of SCD in athletes and the requisite for an update of this matter, we endeavored to describe SCD in athletes. The Medline (via PubMed) and SciELO databases were searched using the subject keywords "sudden death, athletes and mortality". The incidence of SCD is expected at one case for each 200,000 young athletes per year. Overall it is resulted of complex dealings of factors such as arrhythmogenic substrate, regulator and triggers factors. In great part of deaths caused by heart disease in athletes younger than 35 years old investigations evidence cardiac congenital abnormalities. Athletes above 35 years old possibly die due to impairments of coronary heart disease, frequently caused by atherosclerosis. Myocardial ischemia and myocardial infarction are responsible for the most cases of SCD above this age (80%). Pre-participatory athletes' evaluation helps to recognize situations that may put the athlete's life in risk including cardiovascular diseases. In summary, cardiologic examinations of athletes' pre-competition routine is an important way to minimize the risk of SCD.

Prospective echocardiographic and tissue Doppler imaging screening of a population of Maine Coon cats tested for the A31P mutation in the myosin-binding protein C gene: a specific analysis of the heterozygous status

BACKGROUND

A mutation in the sarcomeric gene coding for the myosin-binding protein C gene has been identified in a colony of Maine Coon cats with hypertrophic cardiomyopathy (MyBPC3-A31P mutation). However, the close correlation between genotype and phenotype (left ventricular hypertrophy [LVH] and dysfunction) has never been assessed in a large population, particularly in heterozygous (Hetero) cats.

OBJECTIVES

To investigate LV morphology and function with echocardiography and tissue Doppler imaging (TDI) in a population of Maine Coon cats tested for the MyBPC3-A31P mutation with focus on Hetero animals.

ANIMALS

Ninety-six Maine Coon cats.

METHODS

Prospective observational study. Cats were screened for the MyBPC3-A31P mutation and examined with both echocardiography and 2-dimensional color TDI.

RESULTS

Fifty-two out of 96 cats did not have the mutation (wild-type genotype, Homo WT), 38/96 and 6/96 were Hetero- and homozygous-mutated (Homo M) cats, respectively. Only 11% of Hetero cats (4/38) had LVH and 29% (10/34) of Hetero cats without LVH were >4 years old (4.1-11.5 years). LVH was also detected in 2 Homo WT cats (4%). A significantly decreased (P < .05) longitudinal E/A (ratio between early and late diastolic myocardial velocities) in the basal segment of the interventricular septum was observed in Hetero cats without LVH (n = 34) compared with Homo WT cats without LVH (n = 50), thus confirming that the Hetero status is associated with regional diastolic dysfunction (P < .05).

CONCLUSIONS

The heterozygous status is not consistently associated with LVH and major myocardial dysfunction. Moreover, Homo WT cats can also develop LVH, suggesting that other genetic causes might be implicated.

Cardiac transplantation for hypertrophic cardiomyopathy: a valid therapeutic option

BACKGROUND

Hypertrophic cardiomyopathy is a rare indication for cardiac transplantation, with only anecdotal reports in the literature. Transplantation has been proposed to patients with hypertrophic cardiomyopathy who remained symptomatic despite optimal medical treatment or who progressed to congestive heart failure, and when conventional surgical correction was not or was no longer possible. In this report, we analyze the clinical results of cardiac transplantation in these patients.

METHODS

We retrospectively reviewed complete clinical data and prospectively gathered complete follow-up data for 14 patients who underwent orthotopic cardiac transplantation for hypertrophic cardiomyopathy at the Montreal Heart Institute and Ste-Justine Hospital between 1984 and 2001.

RESULTS

Ten male (71.4%, 5 adults and 5 children) and 4 female (28.6%, 2 adults and 2 children) patients underwent heart transplantation for hypertrophic cardiomyopathy. The median age of the recipients in the pediatric group was 13 years (range, 6-16) and was 40 years (range, 22-46) in the adult group. Median duration of follow-up was 9.5 years (mean, 8.8 +/- 4.8 years; range, 1-18) and was 100% complete. We found no operative mortality and found 2 late deaths related to coronary graft atherosclerosis. Long-term survival at 5, 10, and 15 years was 100%, 85%, and 64%, respectively. Freedom from acute rejection at 1, 5, and 10 years was 73%, 32%, and 9%, respectively. The remaining 11 survivors exhibit few symptoms and are currently in New York Heart Association Class I or II.

CONCLUSIONS

Cardiac transplantation is a valid therapeutic option for patients with symptomatic hypertrophic cardiomyopathy who do not respond to optimal medical management and who are not candidates for conventional surgical treatment. The long-term outcome is excellent in these patients.

Verapamil therapy in infants with hypertrophic cardiomyopathy

We sought to evaluate the safety and efficacy of acute and chronic treatment with verapamil in infants with hypertrophic cardiomyopathy. Prior studies have shown an improvement in adults with hypertrophic cardiomyopathy who were treated with verapamil. Acutely, it reduced the degree of left ventricular outflow tract obstruction. Chronic therapy was associated with an improvement in symptoms and increased long-term survival. To date, no data are available on the efficacy of this drug in infants with hypertrophic cardiomyopathy. We evaluated prospectively the safety and efficacy of verapamil in infants. The acute and chronic effects of verapamil on infants with an echocardiographic diagnosis of hypertrophic cardiomyopathy were evaluated at a single institution between 1980 and 1994, with long-term follow-up available until 1996. Acute effects of an intravenous bolus of 0.1 mg/kg and infusion at 0.007 mg/kg/min were evaluated, where possible, in the cardiac catheterization laboratory. Oral verapamil at 3-5 mg/kg/day was started after catheterization. Follow-up included serial clinical, echocardiographic and Holter monitoring. A total of 22 patients were studied, 17 having a presumed diagnosis of primary hypertrophic cardiomyopathy including three with Noonan's syndrome. Acute infusion of the drug was well tolerated by all, without adverse electrophysiological effects. Haemodynamic effects were consistent with a negative inotropic action with significant falls in cardiac index (4.6+/-1.2 to 4.1+/-0.9 l/min/m2), systolic blood pressure (88+/-16 to 82+/-14 mmHg) and gradient across the left ventricular outflow tract (nine patients 48.2+/-30.4 to 28.4+/-24.1 mmHg). End-diastolic pressure was unchanged (14.0+/-6.8 to 13.9+/-4.7 mmHg). Three patients with primary hypertrophic cardiomyopathy died (two while being treated). In the group with primary hypertrophic cardiomyopathy continuing with long-term treatment, follow-up revealed regression in two, progression in three (two died) and stability in 10. For those treated, there was a trend towards improvement in clinical status. Verapamil is well tolerated acutely in infants with hypertrophic cardiomyopathy. The outcome was considerably better in these patients compared with prior reports, though careful long-term assessment is needed.

Myocardial glucose metabolism is different between hypertrophic cardiomyopathy and hypertensive heart disease associated with asymmetrical septal hypertrophy

Myocardial glucose metabolism has been shown to be heterogeneous in patients with hypertrophic cardiomyopathy (HCM). We tested the hypothesis that myocardial glucose metabolism differs between patients with HCM and those with hypertensive heart disease (HHD) associated with asymmetrical septal hypertrophy. We studied 12 patients with HCM, 7 HHD patients associated with asymmetrical septal hypertrophy using 18F 2-deoxyglucose (FDG) and positron emission tomography. We calculated % FDG fractional uptake in the inter-ventricular septum and posterolateral wall. Heterogeneity of FDG uptake was evaluated by % interregional coefficient of variation of FDG fractional uptake in each wall segment. In both the interventricular septum and posterolateral wall, % FDG fractional uptake was not significantly different between the two groups. The % interregional coefficient of variation for both interventricular septum (10.6 +/- 1.6 vs. 4.1 +/- 0.5, p < 0.01) and posterolateral wall (5.9 +/- 0.7 vs. 3.8 +/- 0.5, p < 0.05) was significantly larger in patients with HCM than in HHD patients associated with asymmetrical septal hypertrophy. Echocardiography demonstrated that the degree of asymmetrical septal hypertrophy was similar between the two groups. These results suggest that myocardial glucose metabolism may be more heterogeneous in patients with HCM compared to HHD patients associated with asymmetrical septal hypertrophy, although the left ventricular shape is similar. The difference in the heterogeneity might have resulted from differences in the pathogeneses of the two diseases.

New diagnostic options in hypertrophic cardiomyopathy

The pathophysiologic features and clinical manifestations of HCM have been elucidated by the introduction of several new diagnostic options. Knowledge of the molecular defects of HCM has advanced rapidly, and genetic screening studies have reemphasized the value of the standard electrocardiogram as an initial screening tool. Analysis of heart rate variability, late potentials, and QT dispersion were not found to be reliable prognostic markers in HCM. However, measurement of dispersion of conduction is probably a sensitive technique in identifying a high risk for sudden cardiac death. Significant developments include transthoracic and transesophageal echocardiography and their role in studying the mitral valve, early detection of left ventricular chamber dilatation, analysis of coronary flow, and intraoperative echocardiography. Finally, advances in the application of magnetic resonance imaging and positron-emission tomography are underway.

Hypertrophic cardiomyopathy--pathology and pathogenesis

Genes on five loci on separate chromosomes are responsible for a familial disease in which all or part of the ventricular muscle undergoes thickening with a histological picture of irregular hypertrophy and disorganized arrangement of myocytes (disarray). The three genes identified so far encode for beta heavy chain myosin (chromosome 14), troponin T (chromosome 1) and alpha tropomyosin (chromosome 15). It is postulated that the phenotype within the heart is produced by abnormal myofibril formation and alignment leading to an abnormal cell shape and, thus, disarray. While all the myocytes carry the gene, the regional selectivity of the hypertrophy is unexplained. The phenotypic expression of the disease within affected members of one family, all of whom are heterozygous for the same gene abnormality, is very varied. Asymptomatic carriers are common, and new mutations do not account for most apparently isolated cases. The phenotypic expression of the disease was studied in 75 hearts. The increase in total heart weight ranged from near normal to over 800 g. Ventricular involvement was diffuse and symmetric in 42%. The commonest asymmetric form involved the anteroseptal region (31%) but sporadic cases involved only the posterior or lateral wall. A minority of cases (9.5%) did not show macroscopic wall thickening. Fibrosis is often associated with dysplastic changes in the media of small intramyocardial arteries and may lead to the ventricular wall simulating a dilated cardiomyopathy. A subaortic patch of endocardial thickening on the ventricular septum due to contact with the anterior cusp of the mitral valve was found in a third of cases.(ABSTRACT TRUNCATED AT 250 WORDS)