Is acquired short QT due to digitalis intoxication responsible for malignant ventricular arrhythmias?
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Aged↗
Biomedical subjects
Fiorenzo Gaita
Publications and source records attributed to Fiorenzo Gaita.
Short QT syndrome: clinical findings and diagnostic-therapeutic implications.
AIMS: Clinical presentation, occurrence of sudden infant death, and results of the available therapies in the largest group of patients with short QT syndrome (SQTS), studied so far, are reported. METHODS AND RESULTS: Clinical history, physical examination, electrocardiogram (ECG), exercise stress testing, electrophysiological study, morphological evaluation, genetic analysis and therapy results in 29 patients with SQTS and personal and/or familial history of cardiac arrest are reported. The median age at diagnosis was 30 years (range 4-80). In all subjects, structural heart disease was excluded. Eighteen patients were symptomatic (62%): 10 had cardiac arrest (34%) and in 8 (28%) this was the first clinical presentation. Cardiac arrest had occurred in the first months of life in two patients. Seven patients had syncope (24%); 9 (31%) had palpitations with atrial fibrillation documented even in young subjects. At ECG, patients exhibited a QT interval < or = 320 ms and QTc < or = 340 ms. Fourteen patients received an implantable cardioverter-defibrillator (ICD) and 10 hydroquinidine prophylaxis. At a median follow-up of 23 months (range 9-49), one patient received an appropriate shock from the ICD; no patient on hydroquinidine had sudden death or syncope. CONCLUSION: SQTS carries a high risk of sudden death and may be a cause of death in early infancy. ICD is the first choice therapy; hydroquinidine may be proposed in children and in the patients who refuse the implant.
Adolescent↗
Acute and long-term outcome of transvenous cryothermal catheter ablation of supraventricular arrhythmias involving the perinodal region.
OBJECTIVE: Cryoenergy is a new valuable treatment option to perform ablation close to the atrioventricular (AV) node in the cure of supraventricular tachycardias because of its favourable properties, such as the possibility of creating reversible lesions. The aim of this study was to report our experience on the effectiveness and safety of catheter cryoablation performed in "critical areas" to treat a large cohort of patients with supraventricular arrhythmias. METHODS: One hundred and thirty-one patients suffering from supraventricular tachycardias underwent catheter cryoablation using a 7F catheter. Eighty-seven patients presented with AV nodal re-entrant tachycardia (AVNRT), 39 had accessory pathways (APs) either manifest or concealed (15 midseptal, 24 parahissian), three had ectopic right atrial tachycardia (AT), and two patients had a permanent junctional reciprocating tachycardia (PJRT). When the optimal parameters were recorded, ice mapping at -30 degrees C was performed for 80 s to validate the ablation site. If the expected result occurred, cryoablation was carried out by lowering the temperature to -75 degrees C for 4 min. RESULTS: In two patients cryoablation was not performed because of technical reasons. Cryoablation was acutely successful in 84 out of 85 patients with AVNRT, in 37 of 39 with APs and in all patients with AT and PJRT. No complications occurred in any patient. Transient AV conduction impairment occurred in seven patients with midseptal APs and in two patients with AVNRT. In particular, in these patients no late permanent AV block was observed at follow-up. At a mean follow-up of 27 +/- 12.9 months, clinical success rate was 87%. CONCLUSIONS: Cryoablation is a safe and effective technique with a high success rate in the long term. It may be particularly useful when performing ablation close to the AV node or His bundle owing to the possibility of validating the ablation site with ice mapping, which creates only a reversible lesion, mainly in the midseptal APs.
Adolescent↗
Short QT syndrome.
The short QT syndrome constitutes a new clinical entity that is associated with a high incidence of sudden cardiac death, syncope, and/or atrial fibrillation even in young patients and newborns. Patients with this congenital electrical abnormality are characterized by rate-corrected QT intervals<320 ms. Missense mutations in KCNH2 (HERG) linked to a gain-of-function of the rapidly activating delayed-rectifier current I(Kr) have been identified in the first two reported families with familial sudden cardiac death. Recently, two further gain-of-function mutations in the KCNQ1 gene encoding the alpha-subunit of the KvLQT1 (I(Ks)) channel and in the KCNJ2 gene encoding the strong inwardly rectifying channel protein Kir2.1 confirmed a genetically heterogeneous disease. The possible substrate for the development of ventricular tachyarrhythmias may be a significant transmural dispersion of the repolarisation due to a heterogeneous abbreviation of the action potential duration. The implantable cardioverter defibrillator is the therapy of choice in patients with syncope and a positive family history of sudden cardiac death. However, ICD therapy in patients with a short QT syndrome has an increased risk for inappropriate shock therapies due to possible T wave oversensing. The impact of sotalol, ibutilide, flecainide, and quinidine on QT prolongation has been evaluated, but only quinidine effectively suppressed gain-of-function in I(Kr) with prolongation of the QT interval. In patients with a mutation in HERG, it rendered ventricular tachycardias/ventricular fibrillation non-inducible and restored the QT interval/heart rate relationship towards a normal range. It may serve as an adjunct to ICD therapy or as a possible alternative treatment, especially for children and newborns.
Anti-Arrhythmia Agents↗
Early EPS/ICD strategy in survivors of acute myocardial infarction with severe left ventricular dysfunction on optimal beta-blocker treatment. The BEta-blocker STrategy plus ICD trial.
AIMS: This multicentre prospective randomised trial was undertaken to evaluate the usefulness of an electrophysiological study (EPS)-guided/implantable cardioverter defibrillator (ICD) strategy in patients at high risk of sudden death (SD) early after myocardial infarction (MI). Previous studies have shown the benefits of such a strategy only in high-risk patients late after MI. METHODS AND RESULTS: We enrolled 143 survivors of acute MI (<1 month) with left ventricular ejection fraction < or = 35% and either frequent (> or =10/h) premature ventricular complexes (PVCs), or depressed heart rate variability (SDNN < 70 ms) or abnormal signal-averaged ECG, who were able to tolerate optimised beta-blocker therapy (68 +/- 40 mg/day of metoprolol). Of these, 138 were randomised, in a 2:3 ratio, to two therapeutic strategies: conventional (CONV) strategy (n = 59) or EPS-guided/ICD strategy (n = 79). The latter resulted in ICD implantation in 24 inducible patients and in CONV therapy in the remaining 55. During a mean follow-up of 540 +/- 378 days, 26 patients (19%) died: nine (6.5%) SD, nine (6.5%) non-SD, and four (3%) non-cardiac death; in four patients (3%) the cause of death was unknown. The actuarial overall mortality for the CONV and EPS-guided/ICD arms was 18% vs 14% after 1 year and 29.5% vs 20% after 2 years, respectively (P = 0.3 and 0.2). CONCLUSIONS: Despite optimal therapy, mortality remains significant in high-risk patients following MI. Although there is a trend in favour of EPS-guided/ICD, our data are insufficient to demonstrate a survival benefit of this strategy early after MI.
Adrenergic beta-Antagonists↗
Short QT syndrome: successful prevention of sudden cardiac death in an adolescent by implantable cardioverter-defibrillator treatment for primary prophylaxis.
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Adolescent↗
Short QT syndrome. Genotype-phenotype correlations.
The short QT syndrome is a new congenital entity associated with familial atrial fibrillation and/or sudden death or syncope. Three different gain-of-function mutations in genes encoding for cardiac potassium channels (KCNH2, KCNQ1, and KCNJ2) have been identified up to now to cause short QT syndrome. The syndrome is characterized electrocardiographically by a shortened QTc interval less than 300 to 320 milliseconds and a lack of adaptation during increasing heart rates. During programmed electrical stimulation, atrial and ventricular effective refractory periods are shortened, and in a high percentage, ventricular tachyarrhythmias are inducible. Sudden cardiac death occurs in all age groups and even in newborns. Therapy for choice seems to be the implantable cardioverter-defibrillator because of the high incidence of sudden death. However, ICD therapy may be associated with an increased risk of inappropriate therapies for T wave oversensing, which, however, can be resolved by reprogramming ICD detection algorithms. The impact of sotalol, ibutilide, flecainide, and quinidine on QT prolongation has been evaluated. But only quinidine effectively suppressed gain-of-function in IKr, along with prolongation of the QT interval. Furthermore, in patients with a mutation in HERG (SQT1), quinidine rendered ventricular tachyarrhythmias noninducible and restored the QT interval/heart rate relationship toward a reference range. It may serve as an adjunct to ICD therapy or as possible alternative treatment especially for children and newborns.
Anti-Arrhythmia Agents↗
Further insights into the effect of quinidine in short QT syndrome caused by a mutation in HERG.
INTRODUCTION: The principal aim of this study was to assess the efficacy of quinidine in suppressing IKr in vitro and in modulating the rate dependence of the QT interval in the "SQT1" form of the short QT syndrome. METHODS AND RESULTS: Graded-intensity bicycle exercise testing was performed off drug in three patients and during oral quinidine in two patients with short QT syndrome and compared to a control group of healthy normal subjects. The in vitro effects of quinidine on currents in patch clamp technique were investigated. Off drugs QTpV3/heart rate correlation is much weaker in patients with short QT syndrome, and QTpV3 shortens less with heart rate increase compared to normal subjects. In addition to prolonging the QT interval into the normal range, quinidine restored the heart rate dependence of the QT interval toward a range of adaptation reported for normal subjects. Data from heterologous expression of wild-type and mutant HERG genes indicate the mutation causes a 20-fold increase in IC50 of d-sotalol but only a 5.8-fold increase in IC50 of quinidine. CONCLUSION: Oral quinidine is effective in suppressing the gain of function in IKr responsible for some cases of short QT syndrome with a mutation in HERG and thus restoring normal rate dependence of the QT interval and rendering ventricular tachycardia/ventricular fibrillation noninducible.
Adolescent↗
Wave similarity mapping shows the spatiotemporal distribution of fibrillatory wave complexity in the human right atrium during paroxysmal and chronic atrial fibrillation.
INTRODUCTION: The complexity of waveforms during atrial fibrillation may reflect critical activation patterns for the arrhythmia perpetuation. In this study, we introduce a novel concept of map, based on the analysis of the wave morphology, which gives a direct evidence in the human right atrium on the spatiotemporal distribution of fibrillatory wave complexity in paroxysmal (PAF) and chronic (CAF) atrial fibrillation. METHODS AND RESULTS: Electrograms were recorded from a 64-electrode catheter in the right atrium of 15 patients during PAF (n = 8) and CAF (n = 7). Wave similarity maps were constructed by calculating the degree of morphological similarity of activation waves (S) at each atrial site and by following its temporal evolution. During PAF the spatiotemporal distribution of the waveforms was highly consistent across the subjects and was determined by the anatomic location. Wave similarity maps showed the existence of an extended area with low similarity index, which covered the low posteroseptal atrium (S = 0.28 +/- 0.09) and the septal region (S = 0.22 +/- 0.04), and the presence of a large tongue with high similarity index, which penetrated the lateral wall (S = 0.55 +/- 0.08) starting from the high anterolateral atrium (S = 0.54 +/- 0.06). A completely different spatiotemporal pattern was seen during CAF. No distinct regions with different similarity indexes were recognized, but a uniformly distributed low similarity index (S = 0.27 +/- 0.07) was found. The spatial pattern was highly stable in time with fluctuations of S < 0.04. CONCLUSION: Quantification of the spatiotemporal distribution of fibrillatory wave complexity is feasible in humans by wave similarity mapping. Anatomic anchoring of waveforms during PAF and pattern destruction during CAF was determined.
Adult↗
Clinical characteristics and treatment of short QT syndrome.
Short QT syndrome is a new inherited disorder associated with familial atrial fibrillation and/or sudden death or syncope. To date, three different mutations in genes encoding cardiac ion channels (KCNH2, KCNQ1 and KCNJ2) have been identified as causing short QT syndrome. All mutations lead to a gain in function of the affected current (IK(r), IK(s )and IK(1)). The syndrome is characterized in the few patients identified so far by a shortened QT interval of less than 300-325 ms after correction for heart rate at rates below 80 beats per minute. However, no boundary or limit for the QT interval can yet be determined, as more knowledge about this disease is still restricted to a small patient population. Furthermore, the QT interval lacks adaptation to heart rate. The majority of patients exhibit shortened atrial and ventricular effective refractory periods and inducibility of ventricular fibrillation. Death already occurs in newborns, so the short QT syndrome may also account for deaths classified as sudden infant death syndrome. The therapy of choice in families with a history of sudden death or syncope seems to be the implantable cardioverter-defibrillator. Whether patients without a family history of sudden death or symptoms need a defibrillator cannot yet be answered, and requires further investigation. Pharmacologic treatment has only been investigated in patients with a mutation in KCNH2 (HERG), and it could be demonstrated that the mutant currents may be insufficiently suppressed by drugs that are targeted to block the specific current (e.g., sotalol or ibutilide) in patients with a mutation in the IK(r-)coding gene KCNH2 (HERG). Interestingly, in this specific patient population, quinidine proved to be efficient in prolonging the QT interval and normalizing the effective refractory periods. Implantable cardioverter-defibrillator therapy is associated with an increased risk of inappropriate therapies for T-wave oversensing, although this risk can be resolved by reprogramming implantable cardioverter-defibrillator detection algorithms.
Arrhythmias, Cardiac↗
Linear cryoablation of the left atrium versus pulmonary vein cryoisolation in patients with permanent atrial fibrillation and valvular heart disease: correlation of electroanatomic mapping and long-term clinical results.
BACKGROUND: The aim of this study was to clarify the role of pulmonary vein isolation (PVI) alone versus left atrial linear lesions in the treatment of permanent atrial fibrillation (AF) in patients with left atrial dilatation and valvular disease. The primary end point was to assess the persistence of sinus rhythm (SR) off antiarrhythmic drugs (AADs) at 2-year follow-up and to correlate clinical outcome with surgical results validated with electroanatomic mapping (EAM). METHODS AND RESULTS: A total of 105 patients with permanent AF undergoing valve surgery were assigned to 3 different groups: in groups "U" and "7," left atrial linear cryoablation was performed, whereas in group "PV" patients, anatomic cryoisolation of pulmonary veins only was performed. In groups U and 7, SR was achieved in 57% of patients, whereas it was achieved in 20% of PV patients during 2-year follow-up. In the first 51 patients, the ablation schemes were validated with EAM. The EAM showed that the U lesion was never obtained: in 59% of these patients, a complete 7 lesion was achieved instead; in the 7 group, a complete 7 lesion was present in 65% of patients, whereas a complete PVI was obtained in 71% of patients. Considering patients in whom a complete 7 lesion was demonstrated with the EAM, SR without AADs was achieved in 86% of patients, whereas only 25% of patients with complete PVI were in SR without AADs. CONCLUSIONS: In patients with permanent AF, left atrial dilatation and valvular heart disease linear lesions in the posterior region of the left atrium are more effective than PVI alone. With cryoablation, the surgical intent is fulfilled in only approximately 65% of the cases. Knowing the real anatomic and electrophysiological effects of surgical ablation is necessary to correctly interpret the clinical outcome.
Aged↗
Short QT syndrome: pharmacological treatment.
OBJECTIVES: The purpose of this study was to evaluate the efficacy of various antiarrhythmic drugs at prolonging the QT interval into the normal range and preventing ventricular arrhythmias in patients with short QT syndrome. BACKGROUND: Short QT syndrome is a recently described genetic disease characterized by short QT interval, high risk of sudden death, atrial fibrillation, and short refractory periods. METHODS: Six patients with short QT syndrome, five of whom had received an implantable cardioverter-defibrillator (ICD) and one child, were tested with different antiarrhythmic drugs, including flecainide, sotalol, ibutilide, and hydroquinidine, to determine whether they could prolong the QT interval into the normal range and thus prevent symptoms and arrhythmia recurrences. RESULTS: Class IC and III antiarrhythmic drugs did not produce a significant QT interval prolongation. Only hydroquinidine administration caused a QT prolongation, which increased from 263 +/- 12 ms to 362 +/- 25 ms (calculated QT from 290 +/- 13 ms to 405 +/- 26 ms). Ventricular programmed stimulation showed prolongation of ventricular effective refractory period to > or =200 ms, and ventricular fibrillation was no longer induced. CONCLUSIONS: The ability of quinidine to prolong the QT interval has the potential to be an effective therapy for short QT patients. This is particularly important because these patients are at risk of sudden death from birth, and ICD implant is not feasible in very young children.
Adolescent↗
Typical atrial flutter ablation outcome: correlation with isthmus anatomy using intracardiac echo 3D reconstruction.
AIMS: To verify if sites of conduction gaps on the isthmus correlate with anatomical peculiarities using the intracardiac echo (ICE) and a new 3D device to reconstruct the isthmus in patients undergoing cavotricuspid isthmus ablation. METHODS AND RESULTS: Twenty patients underwent isthmus ablation using an 8 mm tip ablation catheter. Two-dimensional and 3D ICE reconstruction of the isthmus was made before, during and after ablation. At the end of the lesion line isthmus block was validated by electrophysiological criteria. In case of its absence we closed the remaining conduction gaps verifying the position of the sites with ICE. Fourteen patients required a median of 8 RF pulses to obtain complete isthmus block (Group A). In the remaining 6 patients isthmus block was obtained with a median of 25 RF pulses due to conduction gaps 'resistant' to ablation (Group B). Conduction gap positions assessed by ICE were located in the central portion of the isthmus below the coronary sinus os in 71% of cases in Group A and along a prominent Eustachian ridge in Group B patients, respectively. 3D reconstruction showed a smooth isthmus in Group A with a 'peak and valleys' isthmus in Group B. In these latter patients isthmus block was obtained only after the complete ablation of the prominent Eustachian ridge. CONCLUSION: The isthmus presents anatomical variants particularly due to Eustachian ridge peculiarities which may represent a site of conduction gaps "resistant" to ablation.
Aged↗
Cryoenergy catheter ablation: a new technique for treatment of permanent junctional reciprocating tachycardia in children.
INTRODUCTION: Permanent junctional reciprocating tachycardia (PJRT) is an infrequent form of reciprocating tachycardia, almost incessant from childhood and usually refractory to drug therapy. Radiofrequency catheter ablation currently is the first-line therapy for PJRT, but its application in the septal region may be associated with complications. In contrast, cryoenergy has several advantages, such as the ability to test the effects of ablation while the lesion is still forming, thus reducing the number of ineffective, useless, and potentially harmful lesions. The aim of this study was to investigate the potential clinical utility of percutaneous cryoenergy catheter ablation for treatment of pediatric patients with PJRT. METHODS AND RESULTS: Four patients (age 14 +/- 5 years; mean +/- SD) with a clinical diagnosis of PJRT underwent catheter cryoablation. The ablation was successfully accomplished in 4 (100%) of 4 patients. The mean +/- SD number of cryoapplications was 1.8 +/- 0.8, and from 1 to 6 cryomappings were performed for each permanent cryolesion. The successful site was in the mid-septal region (2 patients), at the coronary sinus orifice (1 patient), and in the middle cardiac vein (1 patient). No complications with cryoablation were reported, nor was there prolongation of the AH interval during cryomapping or cryoablation. No pain was reported by patients during the cryoenergy catheter ablation procedure. PJRT recurrence occurred in 1 patient who underwent a second successful cryoablation procedure. CONCLUSION: The outcomes of cryoenergy catheter ablation in these 4 patients treated for PJRT suggest that cryoablation is a safe, effective, and pain-free technique for treating pediatric patients with PJRT.
Adolescent↗
Atrial fibrillation requiring urgent medical care. Approach and outcome in the various departments of admission. Data from the atrial Fibrillation/flutter Italian REgistry (FIRE).
BACKGROUND: The atrial Fibrillation/flutter Italian REgistry (FIRE) study was designed to obtain updated information regarding the clinical characteristics of and medical approach to patients requiring urgent medical care for atrial fibrillation (AF) or atrial flutter in a nationwide and representative series of hospitals. METHODS: 4570 consecutive patients admitted to the emergency room for AF/atrial flutter were enrolled in 207 hospitals. Of these, 2838 (61.9%) were hospitalized (median 6 days, 43% in cardiology and 57% in internal medicine departments), and constitute the population of this study. RESULTS: AF/atrial flutter represented 1.5% of all emergency room admissions and 3.3% of all hospitalizations. The mean age was 70 +/- 12 years; 89.9% had AF and 10.1% atrial flutter. In 31% of the hospitalized patients no cardiac disease was present, and in 18% no disease (either cardiac or non-cardiac) could be detected. Predictors of no attempt of cardioversion (37.5% of patients) included: onset of AF > 48 hours, heart failure, increasing age, syncope, admission to a non-cardiology department, stroke or transient ischemic attack (TIA). Predictors of in-hospital mortality (2.2%) included: age, heart failure, diabetes, admission to a non-cardiology department, and stroke or TIA. Predictors of the absence of sinus rhythm at discharge (35.6% of patients) included: no attempt of cardioversion, heart failure, chronic anticoagulation, AF duration > 48 hours, increasing age, stroke or TIA, and admission to a non-cardiology department. Transesophageal echocardiography was performed in only 6% of patients. CONCLUSIONS: AF/atrial flutter represent a significant burden on the health care system with a higher than expected hospitalization rate from the emergency room. One out of three discharged patients is not in sinus rhythm. There is still a wide gap between evidence-based medicine and real practice in the treatment of patients with AF.
Admitting Department, Hospital↗
Sudden death associated with short-QT syndrome linked to mutations in HERG.
BACKGROUND: Sudden cardiac death takes the lives of more than 300 000 Americans annually. Malignant ventricular arrhythmias occurring in individuals with structurally normal hearts account for a subgroup of these sudden deaths. The present study describes the genetic basis for a new clinical entity characterized by sudden death and short-QT intervals in the ECG. METHODS AND RESULTS: Three families with hereditary short-QT syndrome and a high incidence of ventricular arrhythmias and sudden cardiac death were studied. In 2 of them, we identified 2 different missense mutations resulting in the same amino acid change (N588K) in the S5-P loop region of the cardiac IKr channel HERG (KCNH2). The mutations dramatically increase IKr, leading to heterogeneous abbreviation of action potential duration and refractoriness, and reduce the affinity of the channels to IKr blockers. CONCLUSIONS: We demonstrate a novel genetic and biophysical mechanism responsible for sudden death in infants, children, and young adults caused by mutations in KCNH2. The occurrence of sudden cardiac death in the first 12 months of life in 2 patients suggests the possibility of a link between KCNH2 gain of function mutations and sudden infant death syndrome. KCNH2 is the binding target for a wide spectrum of cardiac and noncardiac pharmacological compounds. Our findings may provide better understanding of drug interaction with KCNH2 and have implications for diagnosis and therapy of this and other arrhythmogenic diseases.
Adult↗
Implantable cardioverter-defibrillator therapy for prevention of sudden death in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia.
BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a condition associated with the risk of sudden death (SD). METHODS AND RESULTS: We conducted a multicenter study of the impact of the implantable cardioverter-defibrillator (ICD) for prevention of SD in 132 patients (93 males and 39 females, age 40+/-15 years) with ARVC/D. Implant indications were a history of cardiac arrest in 13 patients (10%), sustained ventricular tachycardia in 82 (62%), syncope in 21 (16%), and other in 16 (12%). During a mean follow-up of 39+/-25 months, 64 patients (48%) had appropriate ICD interventions, 21 (16%) had inappropriate interventions, and 19 (14%) had ICD-related complications. Fifty-three (83%) of the 64 patients with appropriate interventions received antiarrhythmic drug therapy at the time of first ICD discharge. Programmed ventricular stimulation was of limited value in identifying patients at risk of tachyarrhythmias during the follow-up (positive predictive value 49%, negative predictive value 54%). Four patients (3%) died, and 32 (24%) experienced ventricular fibrillation/flutter that in all likelihood would have been fatal in the absence of the device. At 36 months, the actual patient survival rate was 96% compared with the ventricular fibrillation/flutter-free survival rate of 72% (P<0.001). Patients who received implants because of ventricular tachycardia without hemodynamic compromise had a significantly lower incidence of ventricular fibrillation/flutter (log rank=0.01). History of cardiac arrest or ventricular tachycardia with hemodynamic compromise, younger age, and left ventricular involvement were independent predictors of ventricular fibrillation/flutter. CONCLUSIONS: In patients with ARVC/D, ICD therapy provided life-saving protection by effectively terminating life-threatening ventricular arrhythmias. Patients who were prone to ventricular fibrillation/flutter could be identified on the basis of clinical presentation, irrespective of programmed ventricular stimulation outcome.
Adolescent↗
Short QT Syndrome: a familial cause of sudden death.
BACKGROUND: A prolonged QT interval is associated with a risk for life-threatening events. However, little is known about prognostic implications of the reverse-a short QT interval. Several members of 2 different families were referred for syncope, palpitations, and resuscitated cardiac arrest in the presence of a positive family history for sudden cardiac death. Autopsy did not reveal any structural heart disease. All patients had a constantly and uniformly short QT interval at ECG. METHODS AND RESULTS: Six patients from both families were submitted to extensive noninvasive and invasive work-up, including serial resting ECGs, echocardiogram, cardiac MRI, exercise testing, Holter ECG, and signal-averaged ECG. Four of 6 patients underwent electrophysiological evaluation including programmed ventricular stimulation. In all subjects, a structural heart disease was excluded. At baseline ECG, all patients exhibited a QT interval <or=280 ms (QTc <or=300 ms). During electrophysiological study, short atrial and ventricular refractory periods were documented in all and increased ventricular vulnerability to fibrillation in 3 of 4 patients. CONCLUSIONS: The short QT syndrome is characterized by familial sudden death, short refractory periods, and inducible ventricular fibrillation. It is important to recognize this ECG pattern because it is related to a high risk of sudden death in young, otherwise healthy subjects.
Adolescent↗