Abstract
BackgroundHypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death (SCD) in young adults, mainly ascribed to ventricular tachycardia (VT). Assuming that VT is the major cause of (pre-) syncope in HCM patients, its occurrence is essential for SCD risk stratification and primarily preventive ICD-implantation. However, evidence of VT during syncope is often missing. As the differentiation of potential lethal causes for syncope such as VT from more harmless reasons is crucial, HCM patients were screened for orthostatic dysregulation by using a simple orthostatic blood pressure test.MethodsOver 15 months (IQR [9;20]) 100 HCM patients (55.8±16.2 yrs, 61% male) were evaluated for (pre-)syncope and VT (24h-ECGs, device-memories) within the last five years. Eighty patients underwent an orthostatic blood pressure test. Logistic regression models were used for statistical analysis.ResultsIn older patients (>40 yrs) a positive orthostatic test result increased the chance of (pre-) syncope by a factor of 63 (95%-CI [8.8; 447.9], p<0.001; 93% sensitivity, 95%-CI [76; 99]; 74% specificity, 95%-CI [58; 86]). No correlation with VT was shown. A prolonged QTc interval also increased the chance of (pre-) syncope by a factor of 6.6 (95%-CI [2.0; 21.7]; p=0.002).ConclusionsThe orthostatic blood pressure test is highly valuable for evaluation of syncope and presyncope especially in older HCM patients, suggesting that orthostatic syncope might be more relevant than previously assumed. Considering the high complication rates due to ICD therapies, this test may provide useful information for the evaluation of syncope in individual risk stratification and may help to prevent unnecessary device implantations, especially in older HCM patients.
Highlights
Hypertrophic cardiomyopathy (HCM) is the most common monogenic inherited cardiovascular disease and the most frequent cause of sudden cardiac death (SCD) in young athletes, while being a less common cause in the elderly [1]
The orthostatic blood pressure test is highly valuable for evaluation of syncope and presyncope especially in older HCM patients, suggesting that orthostatic syncope might be more relevant than previously assumed
All patients with additional hypertension were diagnosed of HCM according to at least one of the following criteria: hypertension occurring years after the diagnosis of HCM, detection of HCM-causing gene mutation or family history of HCM, maximum wall thickness exceeding the expected dimension caused by hypertension alone (i.e. 20 mm), presence of marked mitral leaflet elongation [6], dynamic LVOT obstruction ( 30 mmHg) at rest, and distribution of late gadolinium enhancement (LGE) by cardiac magnetic resonance imaging (CMR) consistent with HCM [3,7,8]
Summary
Hypertrophic cardiomyopathy (HCM) is the most common monogenic inherited cardiovascular disease and the most frequent cause of sudden cardiac death (SCD) in young athletes, while being a less common cause in the elderly [1]. As syncope is a common manifestation in all mutation carriers independent of their clinical phenotype, identification of patients at high risk of SCD is essential regarding the clinical decision for prophylactic ICD implantation [2]. Six major clinical parameters for risk stratification are recommended, such as otherwise unexplained syncope, previous cardiac arrest, sustained or non-sustained ventricular tachycardia (VT), extreme left ventricular hypertrophy, abnormal blood pressure response to exercise, or a family history of SCD. Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death (SCD) in young adults, mainly ascribed to ventricular tachycardia (VT). Assuming that VT is the major cause of (pre-) syncope in HCM patients, its occurrence is essential for SCD risk stratification and primarily preventive ICD-implantation. As the differentiation of potential lethal causes for syncope such as VT from more harmless reasons is crucial, HCM patients were screened for orthostatic dysregulation by using a simple orthostatic blood pressure test
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