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Abnormal ventricular repolarization in long QT syndrome carriers is related to short left ventricular filling time and attenuated stroke volume response during exercise
Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Department of Paediatric Cardiology, Evelina London Children’s Hospital, Guy’s and St Thomas’ NHS Foundation Trust, London, UK.ORCID-id: 0000-0001-6566-7867
Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Pediatrik.ORCID-id: 0000-0001-9655-7783
Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Molecular & Clinical Sciences Research Institute, St George University, London, UK.
2018 (Engelska)Ingår i: Echocardiography, ISSN 0742-2822, E-ISSN 1540-8175, Vol. 35, nr 8, s. 1116-1123Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

BACKGROUND: Long QT syndrome (LQTS) carriers are characterized by abnormal ventricular repolarization, prolonged systole, and mechanical dispersion. Prolonged left ventricular (LV) systole has been shown to result in disproportionate shortening of LV filling in other conditions. The aim of this study was to assess LV filling, diastolic function, and stroke volume (SV) response to dynamic exercise, in a group of LQTS carriers.

METHODS: Forty-seven LQTS carriers (45 ± 15 years, 20 symptomatic) and 35 healthy individuals underwent bicycle stress echocardiogram. Electrocardiographic and echocardiographic measurements were obtained at rest, peak exercise, and 4 minutes into recovery.

RESULTS: Long QT syndrome carriers and controls did not differ in age, gender, heart rate, QRS duration, or LV ejection fraction. At rest, LQTS carriers had longer QTc and shorter filling time (FT). At peak exercise, QTc increased and remained longer than controls at recovery. A negative correlation was found between QTc and FT (r = -.398, P = .001) with greater fall in FT in LQTS carriers than in controls at peak exercise (-23% ± 10 vs +2% ± 3, P < .0001). FT correlated with SV (r = +.27, P = .001), which increased more in controls than in LQTS carriers (+32% ± 4 vs +2% ± 1, P < .05). These differences were more pronounced in symptomatic LQTS carriers who had shorter FT and smaller SV at peak exercise and during recovery compared to asymptomatics (P < .05).

CONCLUSIONS: Long QT syndrome carriers have longer QTc, but also shorter FT. These disturbances worsen at peak exercise (particularly in symptomatics) compromising LV filling and SV, hence a potential pathomechanism for adverse events.

Ort, förlag, år, upplaga, sidor
2018. Vol. 35, nr 8, s. 1116-1123
Nyckelord [en]
exercise echocardiography, left ventricular filling, long QT Syndrome
Nationell ämneskategori
Pediatrik
Identifikatorer
URN: urn:nbn:se:umu:diva-148429DOI: 10.1111/echo.13891ISI: 000440648000005PubMedID: 29648704Scopus ID: 2-s2.0-85048160162OAI: oai:DiVA.org:umu-148429DiVA, id: diva2:1213757
Tillgänglig från: 2018-06-05 Skapad: 2018-06-05 Senast uppdaterad: 2023-03-23Bibliografiskt granskad
Ingår i avhandling
1. Myocardial electromechanical function in long QT syndrome
Öppna denna publikation i ny flik eller fönster >>Myocardial electromechanical function in long QT syndrome
2022 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Myokardiell elektromekanisk function i långt QT-syndrom
Abstract [en]

AIM: The aim of this thesis is to assess, in LQTS and according to genotype, the myocardial electromechanical (EM) function response to exercise, its relation to symptoms and its response to b-blocker therapy. To achieve this aim, we conducted 4 studies with the following specific objectives: 

i. To study the ventricular repolarization (QTc interval) behaviour during stress and its potential haemodynamic effects, as reflected in left ventricular filling and stroke volume response to exercise.

ii. To access the exercise response of electromechanical coupling, expressed by the electromechnical window (EMW), and its relation to symptoms.

iii. To access for potential mechanical disturbances during stress by studying the myocardial contraction response to exercise, its effects on myocardial diastolic function and their relation to co-existent ventricular repolarization disturbances.

iv. To investigate the myocardial behaviour during early relaxation an most particularly the longitudinal apico-basal relaxation sequence, its synamic response to exercise and any potentia contribution to the development of symptoms.

v. To investigate the effect of b-blocker therapy on the above electromechanical parameters at rest and during exercise. 

METHODS: Forty seven (age 45±15yrs, 25 female, 20 symptomatic) LQTS mutation carriers and 35 healthy individuals (matched for age and sex) underwent an exercise test (Bruce protocol). ECG and doppler and speckle-tracking echo parameters were recorded at rest, peak exercise and recovery. 

RESULTS: We found that abnormal ventricular repolarization in LQTS carriers was related to marked LV mechanical dispersion and to abnormally reversed LV end-systolic electromechanical relationship and longitudinal early relaxation sequence. These phenomena worsened at peak exercise, especially in LQT1 carriers, and were related to impaired LV daistolic function and attenuated stroke volume response to exercise. Such abnormal electromechanical responses to exercise were more pronounces in LQTS subjects with previous adverse cardiac events and could better identigy these subjects than QTc interval alone. These disturbances were also less pronounced in LQTS carriers treated with b-blockers. 

CONCLUSION: Incorporating stress-echocardiograhic evaluation of electromechanical parameters in the routine assessment of LQTS individuals may help better stratification, symptom interpretation and management. 

Ort, förlag, år, upplaga, sidor
Umeå University, 2022. s. 161
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 2210
Nyckelord
Long QT syndrome, stress-echocardiography, left ventricular filling, mechanical dispersion, diastolic myocardial function, exercise, arrhythmia, electromechanical window, speckle-tracking echocardiography, myocardial relaxation sequence.
Nationell ämneskategori
Kardiologi
Forskningsämne
kardiologi; hjärt- och kärlforskning
Identifikatorer
urn:nbn:se:umu:diva-200917 (URN)9789178559220 (ISBN)9789178559237 (ISBN)
Disputation
2022-12-01, Building 6E, R-1. Auditorium E04, Norrland University Hospital, Umeå, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2022-11-10 Skapad: 2022-11-09 Senast uppdaterad: 2022-11-09Bibliografiskt granskad

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Charisopoulou, DafniKoulaouzidis, GeorgeRydberg, AnnikaHenein, Michael Y.

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Charisopoulou, DafniKoulaouzidis, GeorgeRydberg, AnnikaHenein, Michael Y.
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