Hypertrophic cardiomyopathy: evaluation and treatment of patients at high risk for sudden death

Late gadolinium enhancement on cardiac magnetic resonance and phenotypic expression in hypertrophic cardiomyopathy

BACKGROUND

Cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE) can identify areas of myocardial fibrosis in vivo in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to examine the association between clinical-morphological variables, risk factor for sudden death, and LGE findings in a consecutive, unselected population of HCM patients.

METHODS

From January 2005 to August 2009, 124 HCM patients (53 ± 17 years, 86 men) were prospectively evaluated with CMR examination, assessing left ventricular (LV) hypertrophy, function, and LGE.

RESULTS

In univariate analysis, patients were divided into tertiles according to the number of segments positive for LGE (first tertile, 0.3 ± 0.4; second tertile, 2.2 ± 0.4; third tertile, 5.2 ± 1.9 segments). Male gender (P = .05), maximum LV wall thickness (P = .002), nonsustained ventricular tachycardia (P = .001), ejection fraction <50% (P = .02), LV mass (P = .02), left atrium dilation (P = .04), perfusion defects (P ≤ .001), and telesystolic volume (P = .04) were all positively related with the number of segments of LGE. In multivariable analysis, male gender (P = .007), maximum LV wall thickness (P = .006), LV mass (P = .031), and perfusion alterations (P = .017) were independent predictors of LGE extent.

CONCLUSIONS

Our study shows an independent association, even at multivariate analysis, between the entity of LGE and maximum LV wall thickness, mass, and perfusion defects in patients with HCM. Whether the presence and the extent of LGE translates into clinical events later on awaits further long-term follow-up studies.

Obstructive Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a primary disease of cardiac muscle characterized by a thickening of the left ventricular wall and often predominantly affecting the interventricular septum. This paper presents a case study of a 53-year-old female with a dynamic and obstructive form of HCM. The study includes a case presentation, clinical findings, investigations, and management. Patient findings were obtained before and after alcohol septal ablation, a novel interventional therapy. The article reviews the various forms of HCM and describes the currently available treatment modalities for obstructive HCM. Further research will be necessary to determine the comparative efficacy between past, present, and future therapies.

Efficacy of implantable cardioverter defibrillator therapy for primary and secondary prevention of sudden cardiac death in hypertrophic cardiomyopathy

Risk stratification and effectiveness of implantable cardioverter-defibrillator (ICD) therapy are unresolved issues in hypertrophic cardiomyopathy (HCM), a cardiac disease that is associated with arrhythmias and sudden death. We assessed ICD therapy in 132 patients with HCM: age at implantation was 34 +/- 17 years, and 44 (33%) patients were aged </= 20 years. Indications were sustained ventricular tachycardia (VT) or cardiac arrest (secondary prevention) in 47 (36%) patients, and clinical features associated with increased risk for sudden death (primary prevention) in 85 (64%) patients. There were 6 deaths and 55 appropriate interventions in 27 (20%) patients during a mean follow-up period of 4.8 +/- 4.2 years: 5-year survival and event-free rates were 96%+/- 2%and 75%+/- 5%, respectively. ICD intervention-free rates were significantly less for secondary than for primary prevention:64%+/- 7%versus 84%+/- 6%at 5 years,P = 0.02. Notably, 59 of 67 events (cardiac arrest and therapeutic ICD interventions), or 88%, occurred during sedentary or noncompetitive activity. Incidence of therapeutic shocks was related to age but not to other reported risk factors, including severity of cardiac hypertrophy, nonsustained VT during Holter monitoring, and abnormal blood pressure response to exercise. ICD related complications occurred in 38 (29%) patients, including 60 inappropriate ICD interventions in 30 (23%) patients. However, 8 (27%) of the patients with inappropriate shocks also had therapeutic interventions. ICD is effective for secondary prevention of sudden death in HCM. However, selection of patients for primary prevention of sudden death, and prevention of device related complications require further refinement.

Sudden cardiac death: a 2400-year-old diagnosis?

Sudden cardiac death is one of the most important causes of mortality in the modern industrialized world. Although it has been described for at least several centuries, we believe in fact that Hippocrates provided a concise, but historically compelling, description of sudden cardiac death in his Aphorisms II, 41: "Those who are subject to frequent and severe fainting attacks without obvious cause die suddenly." This would be the earliest description of sudden cardiac death known. The Aphorism was analyzed in the context of genuine Hippocratic writings as well as ancient Greek culture. The Aphorism describes recurrent syncope in otherwise healthy individuals. Therefore, only certain select cardiac conditions are likely described by this Aphorism. Such conditions-long QT syndrome, hypertrophic cardiomyopathy, congenital coronary artery syndromes, and arrhythmogenic right ventricular dysplasia, chief among them-are linked by a final common pathway of an arrhythmic death. Relying solely on clinical experience based on careful history-taking and keen powers of observation, Hippocrates was the first to describe sudden cardiac death due to a select group of cardiac conditions. This analysis establishes such conditions as being an important cause of sudden death 2400 years ago, much as they are among the most important causes of sudden death today.

Electronic medical devices: a primer for pathologists

CONTEXT

Electronic medical devices (EMDs) with downloadable memories, such as implantable cardiac pacemakers, defibrillators, drug pumps, insulin pumps, and glucose monitors, are now an integral part of routine medical practice in the United States, and functional organ replacements, such as the artificial heart, pancreas, and retina, will most likely become commonplace in the near future. Often, EMDs end up in the hands of the pathologist as a surgical specimen or at autopsy. No established guidelines for systematic examination and reporting or comprehensive reviews of EMDs currently exist for the pathologist.

OBJECTIVE

To provide pathologists with a general overview of EMDs, including a brief history; epidemiology; essential technical aspects, indications, contraindications, and complications of selected devices; potential applications in pathology; relevant government regulations; and suggested examination and reporting guidelines.

DATA SOURCES

Articles indexed on PubMed of the National Library of Medicine, various medical and history of medicine textbooks, US Food and Drug Administration publications and product information, and specifications provided by device manufacturers.

STUDY SELECTION

Studies were selected on the basis of relevance to the study objectives.

DATA EXTRACTION

Descriptive data were selected by the author.

DATA SYNTHESIS

Suggested examination and reporting guidelines for EMDs received as surgical specimens and retrieved at autopsy.

CONCLUSIONS

Electronic medical devices received as surgical specimens and retrieved at autopsy are increasing in number and level of sophistication. They should be systematically examined and reported, should have electronic memories downloaded when indicated, will help pathologists answer more questions with greater certainty, and should become an integral part of the formal knowledge base, research focus, training, and practice of pathology.

Application of noninvasive and invasive tests for risk assessment in patients with ventricular arrhythmias

Sudden cardiac death remains a major public health problem in western society. Because most patients who experience cardiac arrest are not successfully resuscitated, primary prevention of sudden death remains an important challenge. A number of noninvasive risk stratification techniques have been suggested as providing useful information in patients with underlying structural heart defects. Unfortunately, the positive predictive value of most of these techniques has been limited. Left ventricular ejection fraction, the presence of nonsustained ventricular tachycardia on Holter monitoring, and inducible sustained ventricular tachycardia at electrophysiologic testing in patients with coronary artery disease remain the best established prognostic test. However, with the exception of two ICD studies using the combination of these markers, prospective studies have not yet completely validated the use of these and other prognostic markers. Further understanding of the pathophysiology of ventricular fibrillation and other risk stratification techniques will be necessary before a clear algorithm can be developed for application to patients at risk for sudden death.

Temporal repolarization lability in hypertrophic cardiomyopathy caused by beta-myosin heavy-chain gene mutations

BACKGROUND

Certain genetic mutations associated with hypertrophic cardiomyopathy (HCM) carry an increased risk of sudden death. QT variability identifies patients at a high risk for sudden death from ventricular arrhythmias. We tested whether patients with HCM caused by beta-myosin heavy-chain (beta-MHC) gene mutations exhibit labile ventricular repolarization using beat-to-beat QT variability analysis.

METHODS AND RESULTS

We measured the QT variability index and heart rate-QT interval coherence from Holter monitor recordings in 36 patients with HCM caused by known beta-MHC gene mutations and in 26 age- and sex-matched controls. There were 7 distinct beta-MHC gene mutations in these 36 patients; 9 patients had HCM caused by the malignant Arg(403)Gln mutation and 8 patients had HCM caused by the more benign Leu(908)Val mutation. The QT variability index was higher in HCM patients than in controls (-1.24+/-0.17 versus -1. 58+/-0.38, P<0.01), and the greatest abnormality was detected in patients with the Arg(403)Gln mutation (-0.99+/-0.49 versus -1. 46+/-0.43 in controls, P<0.05). In keeping with this finding, coherence was lower for the entire HCM group than for controls (P<0. 001). Coherence was also significantly lower in patients with the Arg(403)Gln mutation compared with controls (P<0.05).

CONCLUSIONS

These findings suggest that (1) patients with HCM caused by beta-MHC gene mutations exhibit labile repolarization quantified by QT variability analysis and, hence, may be more at risk for sudden death from ventricular arrhythmias, and (2) indices of QT variability may be particularly abnormal in patients with beta-MHC gene mutations that are associated with a poor prognosis.

Hypertrophic cardiomyopathy: role of the implantable cardioverter-defibrillator

OBJECTIVES

We report the occurrence of cardiac events during long-term follow-up in patients with hypertrophic cardiomyopathy (HCM) after cardioverter-defibrillator implantation.

BACKGROUND

The identification of patients at high risk for sudden death and the prevention of recurrence of sudden death in HCM represents a difficult problem.

METHODS

We retrospectively analyzed the occurrence of cardiac events during follow-up of 13 patients with HCM who received an implantable cardioverter-defibrillator (ICD) because of aborted sudden death (n = 10) or sustained ventricular tachycardia (n = 3) (group I). Findings were compared with those in 215 patients with an ICD and other structural heart disease or idiopathic ventricular fibrillation (group II).

RESULTS

After a mean (+/-SD) follow-up period of 26+/-18 months, 2 of 13 patients in group I received appropriate shocks. The calculated cumulative incidence of shocks was 21% in group I and 66% in group II after 40 months (p < 0.05). We observed a low incidence of recurrence of ventricular tachycardia/fibrillation during follow-up in patients with HCM. No deaths occurred.

CONCLUSIONS

Our data suggest that ventricular tachyarrhythmias may not always be the primary mechanism of syncope and sudden death in patients with HCM. The ICD seems to have a less important impact on prognosis in patients with HCM than in patients with other etiologies of aborted sudden death.