ObjectivesThis study intends to gain further insights into the natural history, the yield of familial and genetic screening, and the arrhythmogenic mechanisms in the largest cohort of short QT syndrome (SQTS) patients described so far.BackgroundSQTS is a rare genetic disorder associated with life-threatening arrhythmias, and its natural history is incompletely ascertained.MethodsSeventy-three SQTS patients (84% male; age, 26 ± 15 years; corrected QT interval, 329 ± 22 ms) were studied, and 62 were followed for 60 ± 41 months (median, 56 months).ResultsCardiac arrest (CA) was the most frequent presenting symptom (40% of probands; range, <1 month to 41 years). The rate of CA was 4% in the first year of life and 1.3% per year between 20 and 40 years; the probability of a first occurrence of CA by 40 years of age was 41%. Despite the male predominance, female patients had a risk profile superimposable to that of men (p = 0.49). The yield of genetic screening was low (14%), despite familial disease being present in 44% of kindreds. A history of CA was the only predictor of recurrences at follow-up (p < 0.0000001). Two patterns of onset of ventricular fibrillation were observed and were reproducible in patients with multiple occurrences of CA. Arrhythmias occurred mainly at rest.ConclusionsSQTS is highly lethal; CA is often the first manifestation of the disease with a peak incidence in the first year of life. Survivors of CA have a high CA recurrence rate; therefore, implantation of a defibrillator is strongly recommended in this group of patients.

Intramyocardial adiposity, in association with myocardial discontinuity within left ventricular scar borders, is a significant factor associated with altered electrophysiological properties, aberrant connexin43 expression, and increased propensity for VT after MI.

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Background: The optimal timing of exercise stress testing post primary percutaneous coronary intervention is uncertain with anecdotal evidence suggesting an increased risk of acute myocardial infarction and/or death if performed too early. This has translated into a delayed return to normal life activities following an acute myocardial infarction resulting in an increase in socio-economic burden. Aims: We hypothesize that early (within 7 days of primary percutaneous coronary intervention) exercise stress testing is safe. Methods: A prospective study of consecutive patients enrolled into the Cardiac Rehabilitation Program at a tertiary referral centre that underwent primary percutaneous coronary intervention, and who were able to perform a treadmill stress test were recruited. Timing of exercise stress testing was within 7 days post primary percutaneous coronary intervention and outcomes of death, acute myocardial infarction and other major adverse cardiac event were assessed 24 hours post exercise stress testing. Results: Recruited patients (n=230) aged between 29 and 78 (mean age 56 ± 10 years) with 191 being males (83%) and 39 being females (17%). While 28 patients had a positive stress test (12.2%), there were no deaths, acute myocardial infarction or any other major adverse cardiac event within 24 hours of performing the exercise stress testing. Mean METS achieved were 8.1 ± 2.3. Conclusions: Early exercise stress testing after primary percutaneous coronary intervention appears safe.

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We present a patient with symptomatic severe aortic stenosis and atrial fibrillation complicated by tachycardia-bradycardia syndrome, deemed too high-risk for surgical valve replacement and referred for transcatheter aortic valve replacement. We show that concurrent implantation of a leadless pacemaker system can be performed successfully with minimal additional risk to the patient, and also, that it can be used to rapidly pace the ventricles to assist in balloon valvuloplasty and prosthetic aortic valve deployment.

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