Contemporary considerations for risk stratification, sudden death and prevention in hypertrophic cardiomyopathy

The role of cardiopulmonary exercise testing in evaluating children with exercise induced dyspnoea

Exercise induced dyspnoea (EID) is a common manifestation in children and adolescents. Although EID is commonly attributed to exercise induced bronchoconstriction, several conditions other than asthma can cause EID in otherwise healthy children and adolescents. Cardiopulmonary exercise testing (CPET) offers a non-invasive comprehensive assessment of the cardiovascular, ventilatory and metabolic responses to exercise and is a powerful diagnostic and prognostic tool. CPET is a reproducible, non-invasive form of testing that allows for comparison against age- and gender-specific norms. CPET can assess the child's exercise capacity, determine the limiting factors associated with this, and be used to prescribe individualised interventions. EID can occur due to asthma, exercise induced laryngeal obstruction, breathing pattern disorders, chest wall restriction and cardiovascular pathology among other causes. Differentiating between these varied causes is important if effective therapy is to be initiated and quality of life improved in subjects with EID.

Echocardiography as a Screening Test for Myocardial Scarring in Children with Hypertrophic Cardiomyopathy

Introduction. Hypertrophic cardiomyopathy (HCM) is burdened with morbidity and mortality including tachyarrhythmias and sudden cardiac death. These complications are attributed in part to the formation of proarrhythmic scars in the myocardium. The presence of extensive LGE is a risk factor for adverse outcomes in HCM. Late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (cMRI) is the standard for the noninvasive evaluation of myocardial scars. However, echocardiography represents an attractive screening tool for myocardial scarring. The aim of this study was to compare the suitability of echocardiography to detect myocardial scars to the standard of cMRI-LGE. Methods. The cMRI studies and echocardiograms from 56 consecutive children with HCM were independently evaluated for the presence of cMRI-LGE and echocardiographic evidence of scarring by expert readers. Results. Echocardiography had a high sensitivity (93%) and negative predictive value (94%) in comparison to LGE. The false positive rate was high, leading to a low specificity (37%) and a low positive predictive value (35%). Conclusions. Given the poor specificity and positive predictive value, echocardiography is not a suitable screening test for the presence of myocardial scarring in children with HCM. However, children without echocardiographic evidence of myocardial scarring may not need to undergo cardiac magnetic resonance imaging to “rule in” LGE.

Role of family history of sudden death in risk stratification and prevention of sudden death with implantable defibrillators in hypertrophic cardiomyopathy

The selection of patients with hypertrophic cardiomyopathy (HC) for the primary prevention of sudden death (SD) with implantable cardioverter-defibrillators (ICDs) has been determined by the assessment of 5 risk factors. We examined one of these markers, the family history of HC-related SD in first-degree relatives, for which few data are available. The rate of appropriate ICD interventions was assessed in 177 consecutive patients with HC (63% men, age 45 ± 14 years) who had undergone prophylactic implantation at 2 tertiary centers, according to the identification of ≥ 1 risk markers. During a follow-up period of 4.6 ± 3 years, 25 patients (14%) had experienced appropriate ICD interventions for ventricular tachycardia/fibrillation. The patients with a risk profile that included a family history of SD experienced interventions at a similar rate (3.7/100 person-years) as the patients without a family history of SD (3.1/100 person-years, p = 0.2). The rate and frequency of appropriate ICD interventions in 42 patients who had undergone implantation solely because of a family history of SD was 2.2/100 person-years (4/42, 10%), similar to that for patients with one risk factor other than SD family history (3.4%/100 person-years; 7/50, 14%; p = 0.2) and patients with multiple risk factors with (4.5/100 person-years; 9/49, 18%) and without (3.5/100 person-years; 5/36, 14%) a family history of SD (p = 0.8). In conclusion, a family history of SD is an important risk marker in patients with HC. Patients receiving ICDs for primary prevention because of a family history of HC-related SD, whether as an isolated risk factor or combined with other markers, experienced rates of appropriate ICD discharge comparable to that of other patient subsets with increased risk.

Assessing myocardial bridging and left ventricular configuration by 64-slice computed tomography in patients with apical hypertrophic cardiomyopathy presenting with chest pain

OBJECTIVE

We aimed to assess the usefulness of multislice computed tomographic (CT) angiography to detect coronary artery disease (CAD), including myocardial bridging (MB) and left ventricular morphology (LVG), in patients with apical hypertrophic cardiomyopathy (AHCM) who presented with angina and apical asynergy.

MATERIALS AND METHODS

Sixty-four-slice CT angiography was performed in 14 patients with echocardiographically diagnosed AHCM who presented with typical or atypical chest pain. Coronary angiography was performed in 7 patients because of either suspected CAD or echocardiographic apical hypokinesia. We assessed the correlations between coronary anatomy, apical thickness, and LV configuration that were determined by echocardiography, LVG, and 64-slice CT angiography.

RESULTS

The multislice CT confirmed the diagnosis of AHCM in 14 patients. The LVGs were all compatible between the 64-slice CT angiography and the LVG in the 7 patients who had "ace-of-spades" configurations, apical sequestrations, and an apical aneurysm. Furthermore, 2 significant CADs and 7 MBs were detected by 64-slice CT angiography.

CONCLUSIONS

Multislice CT can offer high accuracy for the noninvasive detection of apical wall thickness and left ventricular configuration in patients with AHCM. It also provides additional information about significant coronary stenosis and MB in patients with chest pain. This promising technology has a potential to complement invasive cardiac catheterization in clinical practice.

Delayed enhancement on cardiac magnetic resonance and clinical, morphological, and electrocardiographical features in hypertrophic cardiomyopathy

BACKGROUND

The clinical, morphological, and electrocardiographical relevance of delayed enhancement (DE) in cardiac magnetic resonance (CMR) was studied in patients with hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

A total of 56 patients underwent both gadolinium-enhanced CMR and 12-lead electrocardiogram. The CMR demonstrated DE at the left ventricular (LV) wall in 39 patients. The patients with DE included more cases with dilated phase of HCM, higher New York Heart Association (NYHA) classes and incidence of ventricular tachyarrhythmias (VT), lower LV ejection fraction (LVEF) and mean LV wall thickness (WT), and a larger ratio of maximum to minimum LVWT. The QRS duration was prolonged and the QRS axis deviated toward left with increases in the DE volume (r = 0.58 and r = 0.41, P < .01). Abnormal Q waves were present in 5 patients and the location coincided with the DE segments in 4 patients, but the concordance was not significant. The amplitude of T waves correlated with the ratio of the apex to basal LVWT (r = 0.38, P < .01) and was more negative in cases with DE at the apex.

CONCLUSIONS

In HCM, the DE was associated with higher NYHA classes and prevalence of VT, impaired global LV function and asymmetrical hypertrophy, and conduction disturbance, abnormal Q waves, and giant negative T waves.

Occurrence and frequency of arrhythmias in hypertrophic cardiomyopathy in relation to delayed enhancement on cardiovascular magnetic resonance

OBJECTIVES

Our aim was to determine whether myocardial fibrosis, detected by cardiovascular magnetic resonance (CMR), represents an arrhythmogenic substrate in hypertrophic cardiomyopathy (HCM).

BACKGROUND

Myocardial fibrosis is identified frequently in HCM; however, the clinical significance of this finding is uncertain.

METHODS

We studied prevalence and frequency of tachyarrhythmias on 24-h ambulatory Holter electrocardiogram (ECG) with regard to delayed enhancement (DE) on contrast-enhanced CMR in 177 HCM patients (age 41 +/- 16 yrs; 95% asymptomatic or mildly symptomatic).

RESULTS

Premature ventricular contractions (PVCs), couplets, and nonsustained ventricular tachycardia (NSVT) were more common in patients with DE than those without DE (PVCs: 89% vs. 72%; couplets: 40% vs. 17%; NSVT: 28% vs. 4%; p < 0.0001 to 0.007). Patients with DE also had greater numbers of PVCs (202 +/- 655 vs. 116 +/- 435), couplets (1.9 +/- 5 vs. 1.2 +/- 10), and NSVT runs (0.4 +/- 0.8 vs. 0.06 +/- 0.4) than non-DE patients (all p < 0.0001); DE was an independent predictor of NSVT (relative risk 7.3, 95% confidence interval 2.6 to 20.4; p < 0.0001). However, extent (%) of DE was similar in patients with and without PVCs (8.2% vs. 9.1%; p = 0.93), couplets (8.5% vs. 8.4%; p = 0.99), or NSVT (8.3% vs. 8.5%; p = 0.35).

CONCLUSIONS

In this large HCM cohort with no or only mild symptoms, myocardial fibrosis detected by CMR was associated with greater likelihood and increased frequency of ventricular tachyarrhythmias (including NSVT) on ambulatory Holter ECG. Therefore, contrast-enhanced CMR identifies HCM patients with increased susceptibility to ventricular tachyarrhythmias.

ESCAPE-HCM study: Evaluation of SCreening of Asymptomatic PatiEnts with Hypertrophic CardioMyopathy

The ESCAPE-HCM study is a prospective followup study of asymptomatic mutation-carrying relatives of HCM patients aiming at optimising anamnestic and cardiological evaluation and surveillance for this group. All relatives undergo regular cardiological evaluation and risk status is prospectively estimated, according to known HCM-related risk factors for sudden cardiac death. (Neth Heart J 2007;15:216-20.).

Sudden cardiac death in Athletes

The impact of sudden cardiac death (SCD) in athletes has been highlighted by increasing media coverage, as well as medical and lay awareness of the entities associated with SCD. Common etiologies include cardiac abnormalities such as hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD), and coronary artery anomalies, each with varying geographic incidence. New recommendations regarding noninvasive preparticipation screening have emerged in Europe, where the Italian experience of mandatory annual screening of athletes has been the forerunner in efforts to identify individuals at risk. Ongoing clinical efforts are underway to help define the role of implantable cardioverter defibrillators as a preventive measure in appropriate candidates with HCM or ARVD, as well as methods to limit the potential for SCD as a result of chest blows sustained in sports and other recreational activities by means of chest protectors and special sporting equipment for young athletes.