ABSTRACT
INTRODUCTION: Atrial tachycardia/fibrillation (AT/AF) episodes are common in implantable cardioverter-defibrillator (ICD) recipients and can be undetected by standard single-chamber devices. This study aims to explore whether a single-lead ICD with an atrial dipole (ICD DX; BIOTRONIK SE & Co, Berlin, Germany) could improve the AT/AF diagnosis and management as compared to standard ICD (ICD VR). METHODS AND RESULTS: We selected patients without AT/AF history from the THINGS registry which included consecutive patients implanted with ICD for standard indications. The ICD VR and the ICD DX groups included 236 (62.8%) and 140 (37.2%) patients, respectively, and had no significant differences in baseline characteristics. During a median follow-up of 27 months, there were 7 AT/AF diagnoses in the ICD VR and 18 in the ICD DX group. The 2-year incidence of AT/AF diagnosis was 3.6% (95% confidence interval [CI]: 1.6%-9.6%) for the ICD VR and 11.4% (95% CI: 6.8%-18.9%) for the ICD DX group (adjusted hazard ratio [HR]: 3.85 [95% CI: 1.58-9.41]; P = .003). Initiation of oral anticoagulation (OAC) due to AT/AF diagnosis was reported in 15 patients. The 2-year incidence of OAC onset was 3.6% (95% CI: 1.6%-7.8%) for the ICD VR and 6.3% (95% CI: 3.0%-12.7%) for ICD DX group (adjusted HR: 1.99 [95% CI: 0.72-5.56]; P = .184). CONCLUSION: We observed that atrial sensing capability in single-chamber ICD patients without evidence of atrial arrhythmias at implant is associated with a greater likelihood of detecting AT/AF episodes. The management of these diagnosed arrhythmias often led to clinical interventions, mainly represented by initiation of OAC therapy.
Subject(s)
Atrial Fibrillation/diagnosis , Atrial Function , Cardiomyopathies/therapy , Defibrillators, Implantable , Electric Countershock/instrumentation , Electrophysiologic Techniques, Cardiac/instrumentation , Heart Failure/therapy , Tachycardia, Supraventricular/diagnosis , Administration, Oral , Aged , Anti-Arrhythmia Agents/administration & dosage , Anticoagulants/administration & dosage , Atrial Fibrillation/epidemiology , Atrial Fibrillation/physiopathology , Atrial Fibrillation/therapy , Cardiomyopathies/diagnosis , Cardiomyopathies/epidemiology , Cardiomyopathies/physiopathology , Catheter Ablation , Electric Countershock/adverse effects , Female , Heart Failure/diagnosis , Heart Failure/epidemiology , Heart Failure/physiopathology , Humans , Incidence , Male , Middle Aged , Predictive Value of Tests , Prospective Studies , Prosthesis Design , Registries , Tachycardia, Supraventricular/epidemiology , Tachycardia, Supraventricular/physiopathology , Tachycardia, Supraventricular/therapy , Time Factors , Treatment OutcomeABSTRACT
BACKGROUND: The mechanism of inappropriate sinus tachycardia (IST) remains incompletely understood. METHODS AND RESULTS: We prospectively compared 3 patient groups: 11 patients with IST (IST Group), 9 control patients administered isoproterenol (Isuprel Group), and 15 patients with cristae terminalis atrial tachycardia (AT Group). P-wave amplitude in lead II and PR interval were measured at a lower and higher heart rate (HR1 and HR2, respectively). P-wave amplitude increased significantly with the increase in HR in the IST Group (0.16±0.07 mV at HR1=97±12 beats per minute versus 0.21±0.08 mV at HR2=135±21 beats per minute, P=0.001). The average increase in P-wave amplitude in the IST Group was similar to the Isuprel Group (P=0.26). PR interval significantly shortened with the increases in HR in the IST Group (146±15 ms at HR1 versus 128±16 ms at HR2, P<0.001). A similar decrease in the PR interval was noted in the Isuprel Group (P=0.6). In contrast, patients in the atrial tachycardia Group experienced PR lengthening during atrial tachycardia when compared with baseline normal sinus rhythm (153±25 ms at HR1=78±17 beats per minute versus 179±29 ms at HR2=140±28 beats per minute, P<0.01). CONCLUSIONS: We have shown that HR increases in patients with IST were associated with an increase in P-wave amplitude in lead II and PR shortening similar to what is seen in healthy controls following isoproterenol infusion. The increase in P-wave amplitude and absence of PR lengthening in IST support an extrinsic mechanism consistent with a state of sympatho-excitation with cephalic shift in sinus node activation and enhanced atrioventricular nodal conduction.
Subject(s)
Action Potentials , Atrioventricular Node/physiopathology , Heart Rate , Sinoatrial Node/physiopathology , Tachycardia, Sinus/physiopathology , Adult , Aged , Case-Control Studies , Electrocardiography , Electrophysiologic Techniques, Cardiac , Female , Humans , Italy , Male , Middle Aged , Prospective Studies , Tachycardia, Sinus/diagnosis , Time Factors , Wisconsin , Young AdultABSTRACT
Idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) and idiopathic RVOT extrasystoles are generally considered benign arrhythmias. We describe the case of a patient with typical RVOT arrhythmias without any symptoms for many years, who died suddenly the day before a planned electrophysiological study. The only disquieting signs in her clinical history were a relatively short coupling interval of premature ventricular contractions in some ECG recordings and an isolated run of polymorphic nonsustained ventricular tachycardia induced by an RVOT extrasystole during previous ECG monitoring.