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Title: Early repolarisation, sudden arrhythmic death and the role of physical activity
Author: Mellor, Gregory J.
ISNI:       0000 0004 6349 815X
Awarding Body: St George's, University of London
Current Institution: St George's, University of London
Date of Award: 2017
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Background The Sudden Arrhythmic Death Syndrome (SADS) describes sudden unexpected death with a normal post-mortem examination. The Early Repolarisation (ER) ECG pattern is associated with idiopathic ventricular fibrillation, which may be thought of as analogous to SADS. Levels of physical activity have been implicated in both SADS and ER. Methods Analysis of 967 cases of SADS referred to a national cardiac pathology centre was performed. Clinical data was obtained from coronial reports. The ECGs of 401 relatives of SADS victims were analysed for ER and compared to a family- clustered control population. Associations were sought with findings from ajmaline provocation (n=332), exercise ECG (n=304), and signal-averaged ECG when (n=118) performed. The ECGs of 7099 young adults undergoing cardiac screening were analysed for ER. Demographics, medical history and details of physical activity were collected. A subgroup of 513 had an echocardiogram. All­cause mortality was derived from national death certification databases. Results SADS deaths were more common during sleep/restthan during/stress (82% vs. 16%). ER was more common in SADS relatives than in controls (OR 5.14, 3.37- 7.84) independent of a familial cardiac diagnosis. ER was associated with a trend toward late depolarization, in general was suppressed with exercise and was unaffected by ajmaline. ER was present in 21% of young adults. No SCD occurred 4 in the cohort where follow-up was available (7.7±1.2 years; 16,500 person-years). Ascending ER was more common in males and with increasing physical activity (RRR per hour exercise/week 1.03,1.01-1.04). Horizontal ER was less likely with increasing exercise. There were no associations with structural remodeling. Conclusions SADS deaths occur more commonly during sleep or at rest. The ER pattern is over-represented in family members of SADS victims. In healthy adults ER is directly related to the volume of physical activity. ER is not related to cardiac structural changes.
Supervisor: Behr, Elijah R. ; Sharma, Sanjay ; Sheppard, Mary N. Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available