Hypertrophic cardiomyopathy: electrical abnormalities detected by the extended-length ECG and their relation to syncope
Introduction
Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease and it is an important cause of disability and death in patients of all ages, although sudden and unexpected death in young people is perhaps the most devastating component of its natural history [1].
The clinical course for individual HCM patients is most appropriately viewed in terms of specific subgroups rather than only from perceptions of the overall spectrum of the disease. In fact, while most affected individuals remain asymptomatic or experience only paroxysmal manifestations [2], others die suddenly due to ventricular tachycardia or fibrillation. Abnormalities of ventricular repolarization can represent one of the triggers able to induce lethal arrhythmias [3].
Recently, together with well-known parameters such as QT interval and QT dispersion, newly developed indices have been introduced to explore ventricular repolarization, such as T-wave complexity and the activation–recovery index dispersion, whose clinical significance, however, is far from being completely understood.
We recently validated [4] the new noninvasive “extended-length electrocardiogram” (XL-ECG, Mortara Instruments, WI, USA) which allows, in a single recording, to simultaneously evaluate the parameters (QRS duration, QT dispersion, QT interval, T-wave complexity, activation recovery index dispersion) able to explore ventricular repolarization.
The aim of the present investigation was to assess whether patients with HCM, when compared to healthy subjects, exhibit changes in repolarization detectable non-invasively by this new computerized analysis of 12-lead ECG, and if this approach has a clinical application in discriminating between patients who experienced syncope and those who did not.
Section snippets
Methods
We enrolled 28 patients with HCM (14 males, mean age 44±15 years). All of them had an echocardiographic diagnosis of asymmetric hypertrophy on a septal thickness greater than 15 mm [5]. Four of them exhibited mild dynamic left ventricular outflow obstruction (peak outflow gradient under basal condition of 40, 34, 30, 30 mm Hg, respectively). As a control group, we used 102 healthy subjects (51 males, mean age 41±14) without remarkable past medical history and with normal physical examination,
Results
Echocardiographic data of HCM patients are reported in Table 1. The ECG patterns comprised increased QRS voltage in 16 patients, pathologic Q waves in 9, left and right bundle branch block in 2 and one, respectively. Six patients were on verapamil, six on beta-blockers and one on amiodarone. The presence of therapy was significantly correlated to the maximal interventricular septum thickness (r=0.59).
Eight patients reported a history of unexplained recurrent syncopal episodes (more than two in
Discussion
Longer QRS duration and prolonged QT interval are common findings in hypertrophic cardiomyopathy and data pertaining an increased risk of cardiac events related to these parameters [17], [18] should be considered cautiously. Likely, the increased left ventricular mass, in the QRS duration range of our population [19], determines longer QRS and QT intervals as suggested by the strict relationship between QRS duration and the maximal myocardial thickness. QT dispersion was also increased in our,
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Cited by (14)
Syncope in hypertrophic cardiomyopathy (part I): An updated systematic review and meta-analysis
2022, International Journal of CardiologyCitation Excerpt :From the initial 232 results, we excluded editorial letters, comments, reviews, systematic reviews, case reports, practical guidelines and replicated populations from the same authors. We found 51 articles that assessed syncope at initial evaluation in HCM population [3–53] and we included 9 additional articles from personal files [2,54–61]. The PRISMA flow diagram depicts the flow of information through the different phases of the systematic review (Supplementary Fig. 1).
Diagnostic accuracy of extended-length electrocardiogram in differentiating between athlete's heart and hypertrophic cardiomyopathy
2009, Journal of ElectrocardiologyCitation Excerpt :In athletes with PLVH, in fact, a variety of electrocardiographic abnormalities can be found, which not uncommonly mimic those seen in patients with HCM.2 Recently, extended-length electrocardiogram (XL-ECG), which provides, simultaneously, several arrhythmic risk parameters by using a 5-minute surface ECG recording, has proved useful in distinguishing between control subjects and patients with HCM.3 To date however, a direct comparison of PLVH and HCM has not been performed with this methodology.
XL-ECG in athlete's physiological heart hypertrophy: A time saving procedure
2008, International Journal of CardiologyCitation Excerpt :It should be underlined that both in presence and in absence of athletic hypertrophy, values of XL-ECG parameters were always within the range of those previously recorded in normal subjects. This is remarkable considering that previous studies using the same device evidenced abnormal values of the same parameters in patients with hypertrophic or hypertensive cardiomyopathy [11]. The presence of normal value in our athletes should be underlined considering that during the follow-up they have maintained the same training level, and no event was observed, thus suggesting low arrhythmologic risk in presence of physiologic hypertrophy.
Can QT/RR Relationship Differentiate between Low- and High-Risk Patients with Hypertrophic Cardiomyopathy?
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