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.

We reported the clinical characteristics and biophysical properties of the highly frequent mutation that contributes to genetically identified SQTS probands. These findings extend our understanding of the spectrum of KCNH2 channel defects in SQTS.

No abstract

Typical atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common forms of paroxysmal supraventricular tachycardia (SVT) referred for radiofrequency catheter ablation (RFCA). Dual atrioventricular nodal pathways, which are the substrate for AVNRT, are rarely occurring congenital abnormalities. We report a three-generation family from the southeastern region of Poland (Podkarpackie voivodship) with 6 women having normal hearts and presenting with a history of paroxysmal tachycardia with onset of symptoms in adulthood (Fig. 1). Recordings of clinical SVT, dual AVN electrophysiology, induction of typical AVNRT (Fig. 2), and results of RFCA are available for 5 of the affected women: the proband (57 years old), her 2 sisters (aged 51 and 47 years), proband's daughter (21 years old) and her cousin (26 years old). They underwent RFCA with modification of a slow pathway. The proband's mother (aged 80 years) reported a 30-year history of paroxysmal, regular, and rapid palpitations, usually lasting for several minutes and terminated by vagal manoeuvres. At the time of the evaluation she suffered from advanced lung cancer, and refused regular check-ups and electrophysiological study, so an electrocardiography with documented paroxysmal tachyarrhythmia was not available. Two asymptomatic young women from this family (the second proband's daughter (30 years old) and niece (26 years old) refused an evaluation of dual AVN electrophysiology and inducibility of AVNRT. Interestingly, having never been trained by the doctor, the proband's mother herself found a way to terminate the palpitations and explained to all of her daughters how to perform the Valsalva manoeuvre, so the youngest women in this family were taught by their mothers how to do it, long before the first episode of palpitations occurred. Of note, the symptoms of paroxysmal arrhythmia were not present in males. During 8-year follow-up a second RFCA procedure was required in the proband. The other members of this family have not reported palpitations or arrhythmias requiring invasive evaluation and treatment. There are only limited reports on the familial form of AVNRT (FAVNRT) with up to 4 first-degree relatives within two generations, with no genetic substrate identified so far. To our knowledge, this is the largest family with FAVNRT reported until now, and the first in which inheritance through the maternal line is reported, due to probable autosomal dominant, X-linked dominant, or mitochondrial mode of transmission. Up to now we have observed more than 20 new families with FAVNRT, and further studies are planned to confirm the presumed higher incidence of familial AVNRT in Podkarpackie voivodeship and to evaluate its genetic background. Finally, the history of this family shows the significance of a careful and detailed collection of medical history, and points towards the importance of family screening in AVNRT patients.

ICD is effective in nearly half the patient population; however, the early and late complication rates are high. Although the number of unnecessary ICD shocks and reimplant procedures may be lowered by modern programming and increased longevity of newer ICD generators, other adverse events are less likely to be reduced.