Magnitude of left ventricular hypertrophy and risk of sudden death in hypertrophic cardiomyopathy

Clinical significance of tissue Doppler imaging in patients with hypertrophic cardiomyopathy

BACKGROUND

A transmitral E/septal Ea ratio > or =15 is a predictor of adverse outcome in cardiac disease, so it was hypothesized that a septal E/Ea >/=15 would predict the risk of adverse outcome, including sustained ventricular tachycardia (VT), cardiac arrest, implantable cardioverter defibrillator (ICD) discharge, or sudden death (SD) in patients with hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

The study group comprised 96 consecutive patients with HCM (median age 53 years) who completed all noninvasive tests for risk stratification. The endpoint of the study was defined as death, cardiac arrest, documented sustained VT, or ICD-discharge. The median follow-up was 20.6 months. All patients were alive at the end of follow-up, although 8 patients had reached the endpoint during the study period. The variables that were predictive of adverse clinical outcome were family history of premature SD (p=0.03), syncope (p<0.001), maximum wall thickness > or =3 cm (p=0.02), and septal E/Ea > or =15 (p<0.001). In a stepwise multivariable model the only independent prognostic indicator was a septal E/Ea > or =15 (relative risk 0.26, 95% confidence interval 0.2-0.58, p<0.001). The cumulative event-free survival rate was 78.9% in patients with septal E/Ea > or =15, and 100% in patients with septal E/Ea <15 (p=0.0003).

CONCLUSIONS

Septal E/Ea > or =15 predicts patients with HCM who are at risk of sustained VT, cardiac arrest, ICD-discharge, or SD. (Circ J 2007; 71: 897 - 903).

QT interval prolongation in association with impaired circadian variation of blood pressure and heart rate in adolescents with Type 1 diabetes

AIMS

The aim of our study was to assess diurnal blood pressure (BP) and heart rate variability and their possible relationship to the duration of the QT interval in adolescents with Type 1 diabetes.

METHODS

In 48 normotensive, normoalbuminuric diabetic adolescents, with a mean (+/- sd) age of 17.3 (+/- 4.1) years and a mean (+/- sd) diabetes duration of 8.5 (+/- 3.3) years, 24-h ambulatory BP was recorded. In addition, 24-h heart rate (HR) monitoring was performed and QT and corrected QT (QTc) intervals were estimated as indices of autonomic function. The patients were divided into two groups according to the absence of a decrease (non-dippers) or the presence of a decrease (dippers) in nocturnal diastolic BP (DBP).

RESULTS

In comparison with the dippers, the non-dippers showed reduced mean 24-h HR (79.6 vs. 84.0 beats/min, P = 0.05) and reduced mean daytime HR (81.3 vs. 86.0 beats/min, P = 0.05). The QT interval was prolonged in the non-dippers (366.3 vs. 347.5 ms, P = 0.015), and end systolic (28.7 vs. 25.9 mm, P = 0.004) and end diastolic left ventricular diameters (47.8 vs. 45.5 mm, P = 0.037) were greater. In stepwise multiple regression, HR variables were the most important factors affecting DBP ratio or the duration of the QT interval.

CONCLUSIONS

In conclusion, normotensive diabetic adolescents with impaired nocturnal BP reduction also have impaired autonomic function tests, in association with prolonged QT interval and increased left ventricular diameters. These findings suggest that diabetic adolescents who have the 'non-dipper' phenomenon may need close follow-up for the possible development of vascular complications, such as cardiac arrhythmias and left-ventricular hypertrophy.

Life expectancy gains and cost-effectiveness of implantable cardioverter/defibrillators for the primary prevention of sudden cardiac death in patients with hypertrophic cardiomyopathy

BACKGROUND

Sudden cardiac death (SCD) is a devastating complication of hypertrophic cardiomyopathy (HCM). The optimal strategy for the primary prevention of SCD in HCM remains controversial.

METHODS

Using a Markov model, we compared the health benefits and cost-effectiveness of 3 strategies for the primary prevention of SCD: implantable cardioverter/defibrillator (ICD) insertion, amiodarone therapy, or no therapy. We modeled hypothetical cohorts of 45-year-old patients with HCM with no history of cardiac arrest but at significant risk of SCD (3%/y).

RESULTS

Over a lifetime, compared with no therapy, ICD therapy increased quality-adjusted survival by 4.7 quality-adjusted life years (QALYs) at an additional cost of $142,800 ($30,000 per QALY), whereas amiodarone increased quality-adjusted survival by 2.8 QALYs at an additional cost of $104,900 ($37,300 per QALY). Compared with no therapy, ICD therapy would cost < $50,000 per QALY for patients (i) aged 25, with > or = 1 risk factors for SCD, and (ii) aged 45 or 65, with > or = 2 risk factors for SCD.

CONCLUSIONS

An ICD strategy is projected to yield the greatest increase in quality-adjusted life expectancy of the 3 treatment strategies evaluated. Combined consideration of age and the number of risk factors for SCD may allow more precise tailoring of ICD therapy to its expected benefits.

Genome-wide mapping of modifier chromosomal loci for human hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a disease of mutant sarcomeric proteins (except for phenocopy). Cardiac hypertrophy is the clinical diagnostic hallmark of HCM and a major determinant of morbidity and mortality in various cardiovascular diseases. However, there is remarkable variability in expression of hypertrophy, even among HCM patients with identical causal mutations. We hypothesized modifier genes are partly responsible for the variation in hypertrophic expressivity. To map the modifier loci, we typed 811 short-tandem repeat markers ( approximately 5 cMdense) in 100 members of an HCM family including 36 with the InsG791 mutation in MYBPC3. We performed oligogenic simultaneous segregation and linkage analyses using Markov Chain Monte Carlo methods and detected linkage on 3q26.2 (180 cM), 10p13 (41 cM), 17q24 (108 cM) with log of the posterior placement probability ratio (LOP) of 3.51, 4.86 and 4.17, respectively, and suggestive linkage (LOP of 2.40) on 16q12.2 (73 cM). The effect sizes varied according to the modifier locus, age and sex. It ranged from approximately 8 g shift in left ventricular mass for 10p13 locus heterozygosity for the common allele to approximately 90 g shift for 3q26.2 locus homozygosity for the uncommon allele. Refining the 10p13 locus restricted the candidate modifier genes to ITGA8, C10orf97 (CARP) and PTER. ITGA8 and CARP are biologically plausible candidates as they are implicated in cardiac fibrosis and apoptosis, respectively. Since cardiac hypertrophy is a major determinant of total and cardiovascular mortality and morbidity, regardless of the etiology, identification of the specific modifier genes could have significant prognostic and therapeutic implications for various cardiovascular diseases.

Right ventricular involvement in hypertrophic cardiomyopathy

The aim of this study was to assess, using cardiovascular magnetic resonance (CMR), whether morphologic right ventricular (RV) abnormalities are present in patients with hypertrophic cardiomyopathy (HC). Left ventricular hypertrophy has been considered the predominant phenotypic expression of HC. Whether structural abnormalities of the right ventricle are also present in HC is unknown. CMR provides complete coverage of both ventricles with high spatial resolution. CMR was applied to study RV morphology in HC. CMR was performed on 46 subjects with HC (mean age 39 +/- 16 years; 70% men) free of pulmonary hypertension and 22 healthy subjects (mean age 44 +/- 16 years; 50% men). Mass, wall thickness, chamber volume, the ejection fraction, and fibrosis were assessed for both ventricles. Maximum RV wall thickness was increased in patients with HC compared with referent controls (7 +/- 2 vs 5 +/- 1 mm, p <0.001), including 15 (33%) with maximum wall thicknesses > or =8 mm (> or =2 SDs higher than the mean for controls) and 4 (9%) with extreme hypertrophy (> or =10 mm). RV hypertrophy was predominantly a diffuse process involving the entire or a significant proportion of the RV wall in most patients (n = 8 [53%]). The RV wall mass index was also increased in patients with HC (28 +/- 9 vs 22 +/- 4 g, p <0.001). A significant correlation was found between maximum RV and left ventricular wall thickness (R(2) = 0.4, p <0.001) and between RV and left ventricular mass (R(2) = 0.4, p <0.001). Only 1 (2%) patient with HC had evidence of RV wall fibrosis. In conclusion, morphologic RV abnormalities are present in a substantial proportion of patients with HC.

Phenotypic spectrum and clinical characteristics of apical hypertrophic cardiomyopathy: multicenter echo-Doppler study

OBJECTIVES

The aim of this study was to define the phenotypic spectrum of apical hypertrophic cardiomyopathy (ApHCM) and clinical characteristics pertaining to identified subtypes.

METHODS

In 182 consecutive ApHCM patients (58.9 +/- 11.2 years; 142 men) with left ventricular ejection fraction > or =50%, we measured end-diastolic wall thickness of all 16 left ventricular segments to determine patterns of hypertrophy. Echo-Doppler parameters, electrocardiography patterns, and clinical findings were analyzed.

RESULTS

ApHCM was classified into three types as pure focal (n = 81), pure diffuse (n = 70) and mixed type (n = 31) according to patterns of hypertrophy. Incidence of atrial fibrillation (5% for pure focal vs. 11% for pure diffuse vs. 23% for mixed type, p < 0.05) and left atrial volume index (30.9 +/- 11.8, 35.7 +/- 14.8, and 41.3 +/- 15.9 ml/m(2), respectively, p < 0.001) were significantly different among subtypes. Peak systolic (6.6 +/- 1.0 vs. 6.3 +/- 1.2 vs. 5.9 +/- 1.1 cm/s, respectively, p < 0.05), diastolic (5.1 +/- 1.8 vs. 5.0 +/- 1.2 vs. 4.1 +/- 1.3 cm/s, respectively, p < 0.05) mitral annular velocity, E/E' (13.3 +/- 4.2 vs. 13.7 +/- 5.4 vs. 16.1 +/- 6.1, respectively, p < 0.05) were also significantly different.

CONCLUSIONS

ApHCM contains three morphologically distinct phenotypes and detailed subtyping is important in the prediction of development of atrial fibrillation, left atrial volume index and left ventricular longitudinal function.

RAAS gene polymorphisms influence progression of pediatric hypertrophic cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) is a disease with variable rate of progression. Young age is an independent risk factor for poor outcome in HCM. The influence of renin-angiotensin-aldosterone (RAAS) genotype on the progression of HCM in children is unknown. Children with HCM (n = 65) were enrolled prospectively across two centers (2001-2005). All subjects were genotyped for five RAAS gene polymorphisms previously associated with LV hypertrophy (pro-LVH): AGT M235T, ACE DD, CMA-1903 A/G, AGTR1 1666 A/C and CYP11B2-344 C/T. Linear regression models, based on maximum likelihood estimates, were created to assess the independent effect of RAAS genotype on LV hypertrophy (LVH). Forty-six subjects were homozygous for <2 and 19 were homozygous for > or =2 pro-LVH RAAS polymorphisms. Mean age at presentation was 9.6 +/- 6 years. Forty children had follow-up echocardiograms after a median of 1.5 years. Indexed LV mass (LVMI) and LV mass z-scores were higher at presentation and follow-up in subjects with > or =2 pro-LVH genotypes compared to those with <2 (P < 0.05). Subjects with > or =2 pro-LVH genotypes also demonstrated a greater increase in septal thickness (IVST) and in LV outflow tract (LVOT) obstruction on follow-up (P < 0.05). On multivariate analysis, a higher number of pro-LVH genotypes was associated with a larger effect size (P < 0.05). Pro-LVH RAAS gene polymorphisms are associated with progressive septal hypertrophy and LVOT obstruction in children with HCM. Identification of RAAS modifier genes may help to risk-stratify patients with HCM.

Sudden Cardiac Death: Epidemiology, Mechanisms, and Therapy

Sudden cardiac death is a major public health problem affecting 500,000 patients annually in the United States alone. The major risk factor for sudden cardiac death is the presence of coronary artery disease, usually in the setting of reduced ejection fraction. Globally, the incidence is expected to rise sharply as the prevalence of coronary artery disease and heart failure continue to increase. However, sudden cardiac death is a heterogeneous condition and may be caused by acute ischemia, structural defects, myocardial scar, and/or genetic mutations. Sudden death may occur even in a grossly normal heart. Beta-blockers can reduce the risk of sudden cardiac death, while implantable cardioverter defibrillators are effective at terminating malignant arrhythmias. Ejection fraction remains the major criterion to stratify patients for defibrillator implantation but this strategy alone is insensitive and nonspecific. Novel clinical, electrophysiologic, and genetic markers have been identified that may increase precision in patient selection for primary prevention therapy. This review discusses the epidemiology, mechanisms, etiologies, therapies, treatment guidelines, and future directions in the management of sudden cardiac death.

Relation of QRS duration to mortality in a community-based cohort with hypertrophic cardiomyopathy

A prolonged QRS duration on the standard electrocardiogram is associated with an increased risk of cardiovascular death in cardiomyopathies of different origin. However, the relation between QRS duration and prognosis in hypertrophic cardiomyopathy (HC) remains undefined. We assessed the relation between QRS duration and cardiovascular death in 241 consecutive patients with HC. The study cohort was divided into 2 groups according to QRS duration: <120 and > or =120 ms. Of the 241 patients, 191 (79%) had a QRS duration <120 ms and 50 (21%) a QRS duration > or =120 ms. During a mean follow-up of 7.9 +/- 5.1 years, 35 patients died of cardiovascular causes related to HC. Of these 35 patients, 13 (6%) had a QRS duration <120 ms and 22 (43%) had a QRS duration > or =120 ms (p <0.01). Risk of cardiovascular death was significantly higher in patients with a QRS duration > or =120 ms than in those with a QRS duration <120 ms (relative risk 5.2, p <0.0001). At 8-year follow-up, cumulative risks of HC-related death were 7.1% in patients with a QRS duration <120 ms and 55% in those with a QRS duration > or =120 ms. Multivariate analysis confirmed that a QRS duration > or =120 ms was independently associated with an increased risk of cardiovascular death (hazard ratio 3.2, p = 0.007). New York Heart Association functional class III/IV was the only other clinical variable significantly and independently associated with an increased risk of cardiovascular death. In conclusion, in patients with HC, QRS duration on standard electrocardiogram is directly related to cardiovascular mortality, and a QRS duration > or =120 ms is a strong and independent predictor of prognosis.

Cardiovascular magnetic resonance signs of ischemia in hypertrophic cardiomyopathy

BACKGROUND

Recurrent myocardial ischemia has been recognized as playing an important role in the pathophysiology of hypertrophic cardiomyopathy (HCM) and cardiovascular magnetic resonance (CMR), with or without gadolinium, is a promising method of evaluating fibrosis, edema and hypoperfusion. The aim of this study is to evaluate the interrelationship between late enhancement (LE) and other signs of ischemia, such as edema and perfusion defects, and to relate them to clinical data in order to describe the stage of the disease.

METHODS

Forty-four patients were evaluated by CMR cine images, T2-weighted sequences for edema and LE sequences. First-pass perfusion study was obtained in 37 patients. Acute-subacute ischemic events were clinically defined as the presence of chest pain or new onset of ST-segment depression, end-stage phase by left ventricular ejection fraction <50% and maximal left ventricular wall thickness <25 mm.

RESULTS

Intramural patchy LE was found in 35/44 (80%) patients; extensive LE in 4/44 (9%). Edema was present in 24/44 (54%) patients and perfusion defects in 17/37 (46%). Simultaneous presence of patchy LE, edema and hypoperfusion in corresponding segments, was significantly associated to acute-subacute ischemic-phase parameters (p=0.02; RR 1.99, 95% C.I. 0.77-5.02). Extensive LE and perfusion defects in the absence of edema were significantly related to end-stage HCM (p<0.001; RR 13.7, 95% C.I. 1.83-102.05).

CONCLUSIONS

Using CMR in patients with HCM, we found focal tissue abnormalities consistent with regional ischemia at various stages. CMR provides important, clinically relevant information on the acuity, extent and functional relevance of ischemic injuries in HCM.

Quantitative assessment of regional left ventricular wall thickness and thickening using 16 multidetector-row computed tomography: comparison with cine magnetic resonance imaging

PURPOSE

The purpose of this study was to investigate the feasibility of retrospective electrocardiography-gated multidetector-row computed tomography (MDCT) in the assessment left ventricular (LV) wall thickness and thickening and to test its validity compared to cine magnetic resonance imaging (MRI) as a standard of reference.

MATERIALS AND METHODS

We enrolled 19 patients who underwent both cardiac MDCT and cine MRI. End-diastolic wall thickness (EDWT) and end-systolic wall thickness (ESWT) were measured in 16 myocardial segments. Percent systolic wall thickening (%SWT) was generated from the EDWT and ESWT. Nondiagnostic myocardial segments were excluded. Correlation and agreement between MDCT and cine MRI were analyzed.

RESULTS

Segmental assessability values were 86.2% (262/304) and 92.1% (280/304) for MDCT and cine MRI, respectively. In assessable segments by both modalities (80.9%, 246/304), a significant correlation between MDCT and MRI was found (r = 0.89, 0.85, and 0.61, for EDWT, ESWT, and %SWT, respectively; all P < 0.05). Mean EDWT and ESWT values by MDCT were slightly lower than those by cine MRI (9.8 +/- 3.6 vs. 10.0 +/- 3.7 mm and 13.8 +/- 4.4 vs. 14.1 +/- 4.3 mm, respectively; both P < 0.01). Bland-Altman analysis revealed acceptable limits of agreement between MDCT and Cine MRI.

CONCLUSION

MDCT is a feasible method to assess regional LV wall thickness and systolic thickening.

Use of cardiovascular magnetic resonance for diagnosis and management in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disorder characterized by unexplained myocardial hypertrophy. The condition is associated with sudden cardiac death and is therefore often diagnosed postmortem, especially in the young and in competitive athletes. For this reason, intense research focuses on developing strategies to minimize this tragic consequence. Cardiovascular magnetic resonance (CMR) is a novel imaging modality that provides high-resolution images in an infinite number of planes with additional sequences that allows for tissue characterization and quantification of flow. The most exciting development is the application of late gadolinium-enhanced (LGE) imaging, which allows for in vivo detection of myocardial fibrosis. This review summarizes the current applications of CMR in HCM and also speculates on future applications, particularly the potential for risk stratification using LGE-CMR.

Evidence for microvascular dysfunction in hypertrophic cardiomyopathy: new insights from multiparametric magnetic resonance imaging

BACKGROUND

Microvascular dysfunction in hypertrophic cardiomyopathy (HCM) may create an ischemic substrate conducive to sudden death, but it remains unknown whether the extent of hypertrophy is associated with proportionally poorer perfusion reserve. Comparisons between magnitude of hypertrophy, impairment of perfusion reserve, and extent of fibrosis may offer new insights for future clinical risk stratification in HCM but require multiparametric imaging with high spatial and temporal resolution.

METHODS AND RESULTS

Degree of hypertrophy, myocardial blood flow at rest and during hyperemia (hMBF), and myocardial fibrosis were assessed with magnetic resonance imaging in 35 HCM patients (9 [26%] male/26 female) and 14 healthy controls (4 [29%] male/10 female), aged 18 to 78 years (mean+/-SD, 42+/-14 years) with the use of the American Heart Association left ventricular 16-segment model. Resting MBF was similar in HCM patients and controls. hMBF was lower in HCM patients (1.84+/-0.89 mL/min per gram) than in healthy controls (3.42+/-1.76 mL/min per gram, with a difference of -0.95+/-0.30 [SE] mL/min per gram; P<0.001) after adjustment for multiple variables, including end-diastolic segmental wall thickness (P<0.001). In HCM patients, hMBF decreased with increasing end-diastolic wall thickness (P<0.005) and preferentially in the endocardial layer. The frequency of endocardial hMBF falling below epicardial hMBF rose with wall thickness (P=0.045), as did the incidence of fibrosis (P<0.001).

CONCLUSIONS

In HCM the vasodilator response is reduced, particularly in the endocardium, and in proportion to the magnitude of hypertrophy. Microvascular dysfunction and subsequent ischemia may be important components of the risk attributable to HCM.

Cardiac tissue Doppler imaging in sports medicine

The differentiation of training-induced cardiac adaptations from pathological conditions is a key issue in sports cardiology. As morphological features do not allow for a clear delineation of early stages of relevant pathologies, the echocardiographic evaluation of left ventricular function is the technique of first choice in this regard. Tissue Doppler imaging (TDI) is a relatively recent method for the assessment of cardiac function that provides direct, local measurements of myocardial velocities throughout the cardiac cycle. Although it has shown a superior sensitivity in the detection of ventricular dysfunction in clinical and experimental studies, its application in sports medicine is still rare. Besides technical factors, this may be due to a lack in consensus on the characteristics of ventricular function in relevant conditions. For more than two decades there has been an ongoing debate on the existence of a supernormal left ventricular function in athlete's heart. While results from traditional echocardiography are conflicting, TDI studies established an improved diastolic function in endurance-trained athletes with athlete's heart compared with controls.The influence of anabolic steroids on cardiac function also has been investigated by standard echocardiographic techniques with inconsistent results. The only TDI study dealing with this topic demonstrated a significantly impaired diastolic function in bodybuilders with long-term abuse of anabolic steroids compared with strength-trained athletes without abuse of anabolic steroids and controls, respectively.Hypertrophic cardiomyopathy is the most frequent cause of sudden death in young athletes. However, in its early stages, it is difficult to distinguish from athlete's heart. By means of TDI, ventricular dysfunction in hypertrophic cardiomyopathy can be disclosed even before the development of left ventricular hypertrophy. Also, a differentiation of left ventricular hypertrophy due to hypertrophic cardiomyopathy or systemic hypertension is possible by TDI. Besides the evaluation of different forms of left ventricular hypertrophy, the diagnosis of myocarditis is also of particular importance in athletes. Today, it still requires myocardial biopsy. The analysis of focal disturbances in myocardial velocities might be a promising non-invasive method; however, systematic validation studies are lacking. An important future issue for the implementation of TDI into routine examination will be the standardisation of procedures and the establishment of significant reference values for the above-mentioned conditions. Innovative TDI parameters also merit further investigation.

Electrophysiologic manifestations of ventricular tachyarrhythmias provoking appropriate defibrillator interventions in high-risk patients with hypertrophic cardiomyopathy

INTRODUCTION

Our objective was to determine features of ventricular tachyarrhythmias triggering appropriate implantable cardioverter-defibrillator (ICD) interventions in hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

The study cohort was 68 high-risk HCM patients who received ICDs for primary sudden cardiac death prevention from 1995 to 2003. All episodes of sustained ventricular tachyarrhythmias identified by stored intracardiac electrograms were analyzed. Nine patients had 51 episodes of sustained ventricular tachyarrhythmic events that required device therapy (mean follow-up, 3.4 +/- 2.2 years; cumulative event rate, 3.2% per year): five had 47 episodes of monomorphic ventricular tachycardia (VT); four each had one episode of ventricular fibrillation (VF). Sinus tachycardia or atrial fibrillation was the initiating rhythm in five of nine patients and in 43 of 51 episodes of events. Of the 17 episodes of monomorphic VT detected in the VT zone, 16 (94%) were terminated by antitachycardia pacing. Thirty episodes of monomorphic VT were detected in the VF zone and were terminated by defibrillation.

CONCLUSION

Sustained monomorphic VT is common in a high-risk cohort with HCM. Sinus tachycardia is often the initiating rhythm, suggesting that high sympathetic drive may be proarrhythmic when a susceptible substrate is present. Antitachycardia pacing is highly effective in terminating VT in this patient population.

Extent of myocardial infarction and reverse remodeling assessed by cardiac magnetic resonance in patients with and without right bundle branch block following alcohol septal ablation for obstructive hypertrophic cardiomyopathy

Percutaneous alcohol septal ablation (ASA) is an established technique for the relief of refractory symptoms in patients with obstructive hypertrophic cardiomyopathy. Most subjects develop right bundle branch block (RBBB) after ASA, but it is not known whether these patients have similar infarct characteristics, which may influence left ventricular (LV) pressure gradient reduction and reverse remodeling, compared with those without RBBB. Twenty-seven consecutive patients (15 men, 12 women; mean age 62 +/- 16 years) were studied with electrocardiography and cardiac magnetic resonance imaging at baseline and 1 and 6 months (n = 25) after ASA. Infarct size and location were determined at 1 month by delayed contrast-enhanced cardiac magnetic resonance imaging. The 17 subjects who developed RBBB tended to have larger infarcts (creatine kinase-MB 251 +/- 92 vs 148 +/- 97 IU, p = 0.03; cardiac magnetic resonance imaging mass 22.5 +/- 9.3 vs 16.6 +/- 8.3 g, p = 0.1) and were more likely to have sustained anterior and inferior septal transmural infarctions (9 of 17 vs 1 of 10, p = 0.03) than those without RBBB. Those who developed RBBB had greater LV mass reductions at 6 months (46 +/- 26 vs 29 +/- 13 g, p = 0.04) despite similar reductions in LV pressure gradients (64 +/- 31 vs 56 +/- 32 mm Hg). In conclusion, patients who develop RBBB after ASA tend to have more extensive transmural septal infarctions and greater reverse remodeling than those without RBBB.

Hypertrophic cardiomyopathy: electrocardiographic manifestations and other important considerations for the emergency physician

Hypertrophic cardiomyopathy (HCM) is one of the most common inherited primary cardiac disorders and the most common cause of sudden cardiac death in young athletes. With advances in technology, it is now recognized that HCM affects individuals of all ages. Many patients with HCM will have a benign course with few symptoms. Some patients, however, possess risk factors that greatly increase the likelihood of sudden death if their disease remains undiagnosed. Therefore, it is imperative that emergency physicians be familiar with the symptoms and typical electrocardiogram manifestations of HCM. Three illustrative cases are presented with a review of the disease.

Hemodynamic changes and prognosis in patients with hypertrophic cardiomyopathy and abnormal blood pressure responses during exercise

BACKGROUND

An abnormal blood pressure response (BPR) during exercise has been proposed as a risk factor for sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). Some patients with HCM show systolic dysfunction during exercise.

HYPOTHESIS

The aim of this study was to clarify the hemodynamic response during exercise and prognosis in patients with HCM and abnormal BPR.

METHODS

Sixty-five patients with HCM underwent radionuclide monitoring of left ventricular function and measurement of blood pressure during supine ergometer exercise. Thereafter, cardiac events were recorded for an average period of 76 months.

RESULTS

Seven of 65 patients had abnormal BPR, while the others had normal BPR. Changes of heart rate and systemic vascular resistance during exercise did not differ between the two groups. Stroke volume did not increase in the abnormal BPR group but did in the normal BPR group. During a mean follow-up period of 76 months, three of the seven patients (43%) with abnormal but only one patient (2%) with normal BPR suffered a malignant arrhythmia.

CONCLUSIONS

Abnormal BPR occurred in about 11% of patients with nonobstructive HCM and was associated with a high prevalence of cardiac events. The predictor of abnormal BPR during exercise may not be an abnormal response of systemic vascular resistance and heart rate, but the lack of an appropriate increase in stroke volume.

Structural Abnormalities of the Inferoseptal Left Ventricular Wall Detected by Cardiac Magnetic Resonance Imaging in Carriers of Hypertrophic Cardiomyopathy Mutations

OBJECTIVES

The purpose of this study was to evaluate whether structural left ventricular (LV) abnormalities can be observed in hypertrophic cardiomyopathy (HCM) mutation carriers who have not yet developed echocardiographic signs of hypertrophy by using cardiac magnetic resonance imaging (CMR).

BACKGROUND

Hypertrophic cardiomyopathy is caused by mutations of genes encoding for sarcomeric proteins. Myocyte disarray and interstitial fibrosis precede the development of regional hypertrophy in HCM mutation carriers (carriers). No macroscopic LV structural abnormalities have been observed in carriers without LV hypertrophy.

METHODS

A CMR, echocardiogram, and electrocardiogram (ECG) were performed in 16 carriers. Delayed contrast enhancement imaging was used with CMR to detect fibrosis. In 16 age- and gender-matched control subjects, CMR and ECG were performed and an echocardiogram was made when structural abnormalities were detected with CMR. All carriers had an LV wall thickness <13 mm in the year before the study, measured by echocardiography.

RESULTS

In 13 carriers (81%), crypts were discerned with CMR in the basal and mid inferoseptal LV wall, not detected by routine echocardiography and not observed in healthy volunteers. In 4 of the crypt-positive carriers, both the echocardiogram and ECG were normal. Two HCM carriers revealed regional hypertrophy of the inferoseptum not detected by echocardiography, and in both carriers, focal fibrosis was present.

CONCLUSIONS

In carriers who have not yet developed frank hypertrophy, crypts can be detected with CMR in the inferoseptal LV wall, even when echocardiography and ECG are normal. The crypts might represent one of the early pathological alterations of myocardium in carriers that ultimately progress into manifest HCM.

Usefulness of N-terminal pro-B-type natriuretic peptide to predict clinical course in patients with hypertrophic cardiomyopathy

This study was designed to assess the value of plasma N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) levels in predicting clinical courses in 80 patients with hypertrophic cardiomyopathy. Patients were followed for a mean of 571 +/- 294 days for clinical end points, defined as a composite of cardiovascular death and hospitalization for worsening heart failure symptoms. NT-pro-BNP plasma level (hazard ratio 1.6, 95% confidence interval 1.10 to 2.55, p = 0.015) and New York Heart Association (NYHA) functional class (hazard ratio 3.7, 95% confidence interval 1.17 to 12.09, p = 0.025) were the independent variables associated with increased risk for experiencing clinical end points. NT-pro-BNP plasma level > or =1,500 pg/ml detected patients with clinical end points with sensitivity, specificity, and accuracy of 83%, 81%, and 81%, respectively. The hypertrophic cardiomyopathy population was stratified into low-, medium-, and high-risk subgroups using 2 simple variables, NYHA functional class and NT-pro-BNP. Patients in lower NYHA classes and with NT-pro-BNP levels <1,500 pg/ml were significantly free of clinical end points. In conclusion, for patients with hypertrophic cardiomyopathy, plasma levels of NT-pro-BNP seem a reliable parameter to identify those at risk for clinical deterioration at long-term follow-up in conjunction with symptomatic status.

Determinants for clinical diagnosis of hypertrophic cardiomyopathy

Although hypertrophic cardiomyopathy (HC) occurs in 1 of 500 adults, most cardiology practices treat relatively few patients with HC, suggesting that many affected patients evade clinical recognition. Determining the clinical circumstances under which HC is identified will provide clues to its under-recognition. Clinical triggers leading to diagnostic echocardiograms were analyzed in 711 consecutive patients with HC. In most (384 [54%]), HC was initially suspected only after the onset of cardiac symptoms or acute cardiac events. In a substantial minority (327 [46%]), HC was recognized while patients were asymptomatic, including 225 (32%) by routine medical evaluations, in 27 of whom (4%) HC was recognized during preparticipation examinations for competitive sports or other activities. Women, older patients (age > or =50 years), and those with outflow obstruction at rest (gradient > or =30 mm Hg) were more likely suspected to have HC by virtue of cardiac symptoms or events (p <0.0001). Conversely, patients with extreme hypertrophy (wall thickness > or =30 mm) and those at high risk for sudden death were more often asymptomatic and identified by routine or family screenings (p <0.0001 and p = 0.004, respectively). Patients who subsequently died of heart failure or experienced embolic stroke were more often identified by virtue of symptoms or acute events (p = 0.03). In conclusion, although most patients with HC were recognized clinically only after overt disease manifestations, a substantial minority were diagnosed by routine examinations while asymptomatic, including an important subset of patients with HC recognized solely because of findings on sports preparticipation screening. These data underscore the need for heightened awareness and clinical suspicion of HC to increase the number of diagnosed patients, including many who may be at high risk for sudden death.

Myosin essential light chain in health and disease

The essential light chain of myosin (ELC) is known to be important for structural stability of the alpha-helical lever arm domain of the myosin head, but its function in striated muscle contraction is poorly understood. Two ELC isoforms are expressed in fast skeletal muscle, a long isoform and its NH(2)-terminal approximately 40 amino acid shorter counterpart, whereas only the long ELC is observed in the heart. Biochemical and structural studies revealed that the NH(2)-terminus of the long ELC can make direct contacts with actin, but the effects of the ELC on the affinity of myosin for actin, ATPase, force, and the kinetics of force generating myosin cross-bridges are inconclusive. Myosin containing the long ELC has been shown to have slower cross-bridge kinetics than myosin with the short isoform. A difference was also reported among myosins with long isoforms. Increased shortening velocity was observed in atrial compared with ventricular muscle fibers. The common findings suggest that ELC provides the fine tuning of the myosin motor function, which is regulated in an isoform and tissue-dependent manner. The functional importance of the ELC is further implicated by the discovery of ELC mutations associated with Familial Hypertrophic Cardiomyopathy. The pathological phenotypes vary in severity, but more notably, almost all ELC mutations result in sudden cardiac death at a young age. This review summarizes the functional roles of striated muscle ELC in normal healthy muscle and in disease. Transgenic animal models and phenotypic characterization of ELC-mediated remodeling of the heart are also discussed.

Is sudden cardiac death predictable in LEOPARD syndrome?

We report the sudden cardiac death of a young male presenting with classic clinical features of LEOPARD syndrome, shown to be due to a mutation in the PTPN11 gene, and severe non obstructive hypertrophic cardiomyopathy. We also discuss briefly the usefulness of prophylactic risk stratification in patients with syndromic and non syndromic hypertrophic cardiomyopathy.

Noninvasive cardiac imaging in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy and the most common cause of cardiac death in young athletes in the U.S. Noninvasive imaging plays an important role in detecting the disease, understanding its pathophysiology, and selecting as well as guiding appropriate therapy. In this review, we discuss the existing methodology with emphasis on current and emerging clinical applications in patients with HCM.

Hypertrophic cardiomyopathy is predominantly a disease of left ventricular outflow tract obstruction

BACKGROUND

Nonobstructive hypertrophic cardiomyopathy (HCM) has been regarded as the predominant hemodynamic form of the disease on the basis of assessment of outflow gradient under resting conditions. We sought to prospectively define the prevalence, clinical profile, and significance of left ventricular (LV) outflow tract obstruction under resting conditions and with physiological exercise in a large HCM cohort.

METHODS AND RESULTS

We prospectively analyzed 320 consecutive HCM patients (age, 47+/-17 years), measuring LV outflow gradient at rest, with Valsalva maneuver, and with exercise echocardiography. LV outflow obstruction was present at rest and/or with exercise in 225 patients (70%); 119 had rest gradients > or = 50 mm Hg and were not exercised. Of the other 201 patients with gradients < 50 mm Hg at rest (average, 4+/-9 mm Hg), 106 developed mechanical obstruction to LV outflow resulting from mitral valve-septal contact after exercise (80+/-43 mm Hg), including 76 with marked gradients > or = 50 mm Hg and 46 with heart failure symptoms. The remaining 95 patients (30%) had no or small gradients (< 30 mm Hg) both at rest and with exercise. Valsalva maneuver underestimated the presence and magnitude of exercise-induced obstruction.

CONCLUSIONS

Among those patients who come to clinical evaluation, HCM is a predominantly obstructive disease in which LV outflow gradients, frequently associated with heart failure symptoms and often identified only with exercise, are evident in most patients (ie, 70%). Identification of LV outflow obstruction with exercise echocardiography may broaden management options in HCM by identifying symptomatic patients not otherwise regarded as potential candidates for septal reduction therapy. Assessment of subaortic gradients with exercise should be a routine component of the evaluation of HCM patients without outflow obstruction under resting conditions.

Prognosis and prognostic factors in patients with hypertrophic cardiomyopathy in Japan: results from a nationwide study

OBJECTIVE

To investigate prognosis and prognostic factors in patients with hypertrophic cardiomyopathy (HCM) in Japan.

DESIGN

A nationwide epidemiological study.

SETTING

Hospitals selected randomly from among all hospitals in Japan.

PATIENTS

Clinical and epidemiological information for 2155 patients with HCM were collected in 1999.

MAIN OUTCOME MEASURES

Patients were classified on the basis of baseline prognostic factors. Survival rates up to 5 years were calculated by Cox's proportional hazard model for 1605 patients.

RESULTS

During the follow-up period, 241 deaths were recorded. The crude 5-year survival rate for the entire cohort was 86% (95% CI 84 to 88), and annual mortality ranged from 2.2% to 3.0%. A higher cardiothoracic ratio on chest x ray (HR 1.61; 95% CI 1.26 to 2.05, with 1 SD (6.2%) increase), a lower left ventricular ejection fraction (HR 1.42; 95% CI 1.20 to 1.69, with 1 SD (13%) decrease) and the presence of left bundle branch block (HR 3.14; 95% CI 1.28 to 7.71) were independently associated with a poorer prognosis, whereas the presence of apical hypertrophy at baseline (HR 0.58; 95%CI 0.36 to 0.92) predicted a better chance of survival.

CONCLUSIONS

The nationwide survey of patients with hypertrophic cardiomyopathy yielded important information on its prognosis and prognostic factors. These observations afford, for the first time, a measure of risk stratification in patients with HCM in Japan.

Is QT dispersion associated with sudden cardiac death in patients with hypertrophic cardiomyopathy?

QT dispersion is significantly greater in patients with hypertrophic cardiomyopathy (HCM) than that in healthy subjects. Few data exist regarding the prognostic value of QT dispersion in HCM. In this study, we retrospectively investigated the association between QT dispersion and sudden cardiac death in 46 patients with HCM (mean 33.1 +/- 15.5 years, 32 men). The case group consisted of 23 HCM patients who died suddenly, and the control group consisted of 23 HCM patients who survived uneventfully during follow-up. Study patients were pair-matched for age, gender, and maximum left ventricular wall thickness. QT dispersion (maximum minus minimum QT interval) was manually measured on early 12-lead ECGs using a digitizing board. An in-house program was used for calculating QT interval, QT dispersion, JT interval, and JT dispersion (maximum minus minimum J point to T end interval). Patients in the case group tended to have shorter RR intervals than those in the control group (777 +/- 171 vs 856 +/- 192 ms, P = 0.08). Maximum corrected QT and JT intervals did not discriminate the case group from controls (489 +/- 29 vs 479 +/- 27 ms, P = NS; 375 +/- 36 vs 366 +/- 22 ms, P = NS, respectively). Greater QT dispersion and JT dispersion were found in the case group compared with controls (74 +/- 28 vs 59 +/- 21 ms, P = 0.02 and 76 +/- 32 vs 59 +/- 26 ms, P = 0.03, respectively). The measurements of maximum QT, JT, and T peak to T end intervals, precordial QT and JT dispersion, and T peak and T end dispersion were all comparable between the two groups (P = NS for all). No systematic changes in ECG measurements were found from late ECGs of the case group compared to those from early ECGs (P = NS). No correlation between maximum left ventricular wall thickness and QT dispersion, JT dispersion, maximum QTc or JTc intervals was observed (r < 0.29, P > 0.05 for all). Our results show that increased QT dispersion and JT dispersion is weakly associated with sudden cardiac death in the selected patients with HCM.

Cardiovascular risk factors in hypertension: rationale and design of studies to investigate the effects of controlled-release carvedilol on regression of left ventricular hypertrophy and lipid profile

Patients at high risk for hypertension may require several therapeutic agents to lower their blood pressure to guideline-recommended targets. Some antihypertensive agents are more effective than others in protecting against cardiovascular morbidity and mortality. Numerous beta-blocking agents have been approved by the US Food and Drug Administration (FDA) for the treatment of hypertension. Previous trials have demonstrated that although all beta-blockers effectively reduce blood pressure, there are differences in how they affect various metabolic factors. In 2 trials, a novel controlled-release (CR) formulation of carvedilol will be tested against other selective beta-blockers to determine whether differences exist in their individual effects on cardiovascular risk factors. These will be the first head-to-head trials using carvedilol CR to determine whether the differing pharmacologic actions among beta-blockers result in varying effects on cardiovascular risk factors.

Prognostic significance of left atrial size in patients with hypertrophic cardiomyopathy (from the Italian Registry for Hypertrophic Cardiomyopathy)

This study assessed left atrial (LA) dimension as a potential predictor of outcome in hypertrophic cardiomyopathy (HC). From the Italian Registry for Hypertrophic Cardiomyopathy, 1,491 patients (mean age 47 +/- 17 years; 61% men; 19% obstructive), followed for 9.4 +/- 7.4 years after the initial echocardiographic evaluation, constituted the study group. The mean LA transverse dimension was 43 +/- 9 mm and was larger in patients with severe symptoms (48 +/- 9 mm for New York Heart Association classes III and IV vs 42 +/- 9 mm for classes I and II, p <0.001), atrial fibrillation (47 +/- 9 vs 42 +/- 8 mm in sinus rhythm, p <0.001), and left ventricular outflow obstruction (46 +/- 9 mm for >or=30 mm Hg at rest vs 42 +/- 9 mm for <30 mm Hg at rest, p <0.001). On univariate analysis, each 5-mm increase in LA size was associated with a hazard ratio (HR) of 1.2 for all-cause mortality (p <0.0001). On multivariate analysis, a LA dimension >48 mm (the 75th percentile) had a HR of 1.9 for all-cause mortality (p = 0.008), 2.0 for cardiovascular death (p = 0.014), and 3.1 for death related to heart failure (p = 0.008) but was unassociated with sudden death (p = 0.81). Similar results were obtained after the exclusion of patients with atrial fibrillation (HR 1.7, p = 0.008) or outflow obstruction (HR 1.8, p = 0.003). The predictive power of LA dimension >48 mm was also validated in an independent HC cohort from the United States, with similar HRs (1.8 for all-cause mortality, p = 0.019). In conclusion, in a large cohort of patients with HC from a nationwide registry, a marked increase in LA dimension were predictive of long-term outcome, independent of co-existent atrial fibrillation or outflow obstruction. LA dimension is a novel and independent marker of prognosis in HC, particularly relevant to the identification of patients at risk for death related to heart failure.

Effect of hypertrophy on left ventricular diastolic function in patients with hypertrophic cardiomyopathy

Background.

Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric LV hypertrophy (LVH) and impairment in diastolic function. We assess the relationship between LVH and invasive indexes of diastolic function.

Methods.

21 HCM patients underwent cardiac catheterization to assess pulmonary capillary wedge pressure, LV end-diastolic pressure (measured by microtip catheters), and LV volumes (calculated by simultaneous radionuclide angiography). We calculated from LV pressure the time constant of isovolumetric relaxation (τ, variable asymptote method, ms), and from LV pressure and volume the constant of chamber stiffness (k, ml⁻¹). LVH was assessed by different indexes: maximal wall thickness, number of hypertrophied LV segments, LVH index, and Wigle’s score. Results. Wigle’s score was directly related to pulmonary capillary Wedge pressure (r=0.436, p=0.048), peak V wave of pulmonary capillary wedge pressure (r=0.503, p=0.024), LV end-diastolic pressure (r=0.643, p=0.002) and k (r=0.564, p=0.015). HCM patients were divided into 2 groups according to Wigle’s score: 10 with mild or moderate LVH (< 8), and 11 with severe LVH (≥ 8). HCM patients with severe LVH showed a higher pulmonary capillary Wedge pressure (15.1±7.2 vs 9.5±2.4, p=0.033), peak V wave of pulmonary capillary wedge pressure (20.7±4.6 vs 14.6±4.9, p=0.011), LV end-diastolic pressure (23.9±10.9 vs 10.6±2.5, p=0.002), k (0.0465±0.032 vs 0.015±0.007, p=0.022) and LV outflow tract gradient (72±36 mmHg vs 29±30 mmHg, p=0.01).τ was similar in the two groups. Other indexes of LVH were not related to diastolic function.

Conclusions.

Wigle’s score is the only index of LVH that relates to invasive indices of diastolic function.

The value of changes in QRS width and in ST-T segment during exercise test in hypertrophic cardiomyopathy for identification of associated coronary artery disease

OBJECTIVES

Non-invasive methods cannot reliably predict the presence of coronary artery disease (CAD) in hypertrophic cardiomyopathy (HCM). This study aims to define the accuracy of QRS width changes versus standard ST-T criteria for recognition of associated ischemic CAD in patients with HCM undergoing exercise testing (ET).

METHODS

A retrospective study including patients with HCM. HCM was defined by left ventricular hypertrophy (LVH) of unknown etiology of at least 15 mm. Coronary angiography was performed as a gold standard for definition of CAD (> or =70% obstruction in at least one major artery). QRS width duration was measured at peak ET by a computerized method employing an optical scanner. No changes in QRS width or shortening during ET were considered normal; QRS width prolongation of more than 3 ms was defined as abnormal.

RESULTS

68 patients (56/12 M/F) aged 60+/-12 y were studied. During ET, abnormal QRS response was found in 40 (58.8%) and Ischemic ST-T changes in 52 (76.5%) patients. CAD in at least one artery was diagnosed in 31 patients (45.5%). The sensitivity of QRS width versus ST-T changes during ET for associated CAD was 82% and 28%, respectively. Specificity was 75% and 48%, respectively. Positive and negative predictive values were 88%; 68% for QRS width and 67%; 59% for ST-T changes respectively.

CONCLUSIONS

In patients with HCM undergoing ET, the association with CAD was more accurately predicted by an increase in QRS complex width than by standard criteria of ST-T segment changes. Thus, its use should be encouraged, especially in patients with HCM.

Pathophysiology and Treatment of Hypertrophic Cardiomyopathy

All patients with hypertrophic cardiomyopathy (HCM) should have five aspects of care addressed. An attempt should be made to detect the presence or absence of risk factors for sudden arrhythmic death. If the patient appears to be at high risk, discussion of the benefits and risks of ICD are indicated, and many such patients will be implanted. Symptoms are appraised and treated. Bacterial endocarditis prophylaxis is recommended. Patients are advised to avoid athletic competition and extremes of physical exertion. First degree family members should be screened with echocardiography and ECG.

Magnetic resonance imaging of delayed enhancement in hypertrophic cardiomyopathy: relationship with left ventricular perfusion and contractile function

PURPOSE

The aim of the study was to analyze the relationship between myocardial delayed enhancement, first-pass perfusion, and contractile function in hypertrophic cardiomyopathy (HCM) patients, using MR.

METHODS

Fifty-three patients diagnosed with HCM were prospectively examined using a 1.5-T MR unit. Multiphase gradient-echo sequences were performed to study global left ventricular function, wall thickness, and left ventricular mass. Myocardial tissue tagging was conducted to evaluate contractile function. T1-weighted inversion-recovery sequences were obtained at rest to study myocardial contrast enhancement at first pass and delayed enhancement 10 minutes later.

RESULTS

Delayed enhancement found in 30 patients (56.6%) was most commonly seen in hypertrophic segments. Nine patients exhibited delayed enhancement in segments with normal wall thickness (<15 mm). Sixteen patients (30.1%) showed first-pass perfusion defects at rest, which were associated with significantly lower stroke volume (P<0.05) and lower cardiac output (P<0.01). The hypokinetic segments found in 16 patients (30.1%) were significantly thicker at end diastole (P<0.01). Delayed enhancement correlated positively with perfusion defects (r=0.5, P<0.01) and hypokinetic segments (r=0.3, P<0.05).

CONCLUSION

Delayed myocardial enhancement is most commonly found in hypertrophic segments but also can be seen in segments with normal wall thickness. Perfusion defects at rest and impaired contractile function are related abnormalities with delayed myocardial enhancement. Further studies are necessary to assess the role of myocardial tagging, first-pass perfusion, and delayed enhancement in risk stratification for patients with HCM.

Left ventricular outflow tract obstruction and sudden death risk in patients with hypertrophic cardiomyopathy

AIMS

Left ventricular outflow tract obstruction (LVOTO) is associated with reduced survival in patients with hypertrophic cardiomyopathy (HCM). The influence of LVOTO on survival from SD in relation to other recognized clinical risk markers is unknown.

METHODS AND RESULTS

A total of 917 patients with HCM (554 males, 43+/-15 years) were studied; 288 (31.4%) had LVOTO at rest (> or =30 mmHg). During follow-up [median 61 (30;99) months], 54 (5.9%) patients died suddenly (SD), survived ventricular fibrillation, or had an appropriate ICD discharge; 25 (2.7%) died from heart failure or were transplanted; 17 (1.8%) died from other cardiovascular causes. Five-year survival from all-cause death or cardiac transplantation was lower in patients with LVOTO [86.5% (95% CI: 81.7-91.2) vs. 90.1% (95% CI: 87.3-92.8), P=0.006], with a trend towards higher all-cause death and transplantation with increasing LVOTO [(RR per 20 mmHg=1.24 (95% CI: 1.08-1.42), P=0.003)]. In patients with obstruction, there was a significant relation between 5-year survival from all-cause death and functional limitation (NYHA class I: 91.0%; NYHA class II: 83.3%; NYHA class III/IV: 82.6%, P=0.002). LVOTO was associated with reduced survival from SD and ICD discharge (SD/ICD) [91.4% (95% CI: 87.4-95.3) vs. 95.7% (95% CI: 93.8-97.6), P=0.0004]. Magnitude of LVOTO was related to a higher occurrence of SD/ICD [RR per 20 mmHg=1.36 (95% CI: 1.12-1.65), P=0.001]. There was no relation between survival from SD/ICD, LVOTO, and NYHA class. The annual rate of SD/ICD in patients with LVOTO and no risk factors was 0.37% (95%CI: 0.05-1.35). There was a trend towards lower survival from SD/ICD, with increasing numbers of risk factors in patients with and without LVOTO (P=0.002 and P=0.002, respectively). Multivariable analysis demonstrated that LVOTO was an independent predictor of SD/ICD, with a 2.4-fold (P=0.003) increase in the risk of SD/ICD.

CONCLUSION

LVOTO is associated with an increased risk of SD/ICD that is related to the severity of obstruction and the presence of other recognized risk factors for SD. The low sudden death mortality in asymptomatic patients with LVOTO and no other SD risk markers suggests that aggressive interventions to reduce LVOTO are unwarranted in this group. Further studies are required to determine the most appropriate treatment strategies (ICD or gradient reduction) in patients with additional risk factors.

Use of Echocardiography in Patients with Hypertrophic Cardiomyopathy: Clinical Implications of Massive Hypertrophy

We examined the 10-year outcome of 107 patients with hypertrophic cardiomyopathy and massive myocardial hypertrophy as assessed by echocardiography. These patients demonstrated excess mortality in comparison with their expected survival with respect to a general population of individuals (10-year survival 77% vs 95%, P < .001). Adverse events occurred primarily in the youngest and oldest patients. Sudden cardiac death was the most frequent cause of death among the young (overall survival 80%), whereas other causes predominated in older patients (overall survival 31%). For patients aged 30 to 59 years, survival was 97%, no different from their expected survival. Patients with hypertrophic cardiomyopathy and massive hypertrophy identified by echocardiography are at increased risk of death, but this risk is related to age at presentation. Sudden cardiac death is the primary cause in those who are young, whereas other causes predominate in older patients. Middle-aged patients with massive hypertrophy do not experience an excess mortality.