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ICD Programming for Shock Reduction Background Shock therapy delivery by implantable cardioverter-defibrillators (ICD) can be painful and may have adverse consequences. Reducing shock burden for patients with ICDs would be beneficial. Methods PROVIDE was a prospective, randomized study of primary prevention ICD patients. Patients in the experimental group received a combination of programmed parameters with higher detection rates, longer detection intervals, empiric antitachycardia pacing (ATP), and optimized supraventricular tachycardia (SVT) discriminators, while those in the control group were programmed with conventional parameters. Shock therapy and arrhythmic syncope were compared. Results Of 1,670 patients enrolled (846 in the experimental group, 824 in the control group) and monitored over a follow-up of 530 ± 241 days, 202 patients received shock therapy for any cause (82 in the experimental group and 120 in the control group). The median time to first shock was significantly prolonged (13.1 vs 7.8 months, hazard ratio [HR]: 0.62, 95% confidence interval [CI]: 0.47 to 0.82, P = 0.0005) and the 2-year shock rate significantly reduced (12.4% vs 19.4%, P < 0.001) in the experimental group compared to the control group. There was no increase in arrhythmic syncope (HR: 1.64, 95% CI: 0.69 to 3.90, P = 0.26), while the overall mortality was reduced (HR: 0.7, 95% CI: 0.50 to 0.98, P = 0.036) in the experimental group compared to the control group. Conclusion A combination of programmed parameters utilizing higher detection rate, longer detection intervals, empiric ATP, and optimized SVT discriminators reduced ICD therapies without increasing arrhythmic syncope and was associated with reduction in all-cause mortality among ICD patients.

This report summarizes the efficacy, safety, and feasibility of intracardiac ultrasound (ICUS) and local electrographic-guided pulmonary vein (PV)-left atrial disconnection, including the isolation of common PV trunks accomplished in 170 consecutive patients with atrial fibrillation (AF). A left common PV was found in 43% of patients with AF. During a follow-up of 549 +/- 330 days after ablation, the AF-free survival rate was 80% and comparable in paroxysmal and persistent AF. PV stenosis was detected in only 1 asymptomatic patient, who required no intervention.

Shock therapy delivery by implantable cardioverter-defibrillators (ICD) can be painful and may have adverse consequences. Reducing shock burden for patients with ICDs would be beneficial.PROVIDE was a prospective, randomized study of primary prevention ICD patients. Patients in the experimental group received a combination of programmed parameters with higher detection rates, longer detection intervals, empiric antitachycardia pacing (ATP), and optimized supraventricular tachycardia (SVT) discriminators, while those in the control group were programmed with conventional parameters. Shock therapy and arrhythmic syncope were compared.Of 1,670 patients enrolled (846 in the experimental group, 824 in the control group) and monitored over a follow-up of 530 ± 241 days, 202 patients received shock therapy for any cause (82 in the experimental group and 120 in the control group). The median time to first shock was significantly prolonged (13.1 vs 7.8 months, hazard ratio [HR]: 0.62, 95% confidence interval [CI]: 0.47 to 0.82, P = 0.0005) and the 2-year shock rate significantly reduced (12.4% vs 19.4%, P 0.001) in the experimental group compared to the control group. There was no increase in arrhythmic syncope (HR: 1.64, 95% CI: 0.69 to 3.90, P = 0.26), while the overall mortality was reduced (HR: 0.7, 95% CI: 0.50 to 0.98, P = 0.036) in the experimental group compared to the control group.A combination of programmed parameters utilizing higher detection rate, longer detection intervals, empiric ATP, and optimized SVT discriminators reduced ICD therapies without increasing arrhythmic syncope and was associated with reduction in all-cause mortality among ICD patients.

Hypertension and Pulmonary Vein Dilation. Introduction: Atrial fibrillation (AF) is associated with increased ostial pulmonary vein (PV) diameter and commonly with hypertension. We sought to investigate ostial PV anatomy in patients with and without AF with the goal of characterizing the relationship to hypertension and cardiovascular disease. Methods and Results: Ostial PV diameter was assessed by preprocedural spiral computed tomography in 100 AF patients undergoing a PV isolation procedure and in 24 age- and sex-matched non-AF control patients. Ostial diameter of 392 PVs in 100 AF patients was increased compared to 106 PVs in 24 non-AF controls (1.50 ′ 0.31 vs 1.20 ′ 0.31 cm, P < 0.001) and diameters of individual PVs were uniformly affected (r = 0.45-0.62, P < 0.001). Left atrial dilation was associated with a larger PV diameter (1.56 ′ 0.32 vs 1.44 ′ 0.29 cm, P < 0.01). PV diameter in AF patients with hypertension (1.55 ′ 0.32 cm), particularly if associated with left ventricular hypertrophy (1.66 ′ 0.37 cm), was larger compared to AF patients without hypertension (1.43 ′ 0.26 cm, P < 0.01). PV diameter in control patients with hypertension (n = 14) was larger than in those without hypertension (n = 10, P < 0.01). Patients with persistent AF had larger PV diameters (1.61 ′ 0.34 cm) than patients with paroxysmal AF (1.47 ′ 0.30 cm, P < 0.01). Male gender (P < 0.01), history of hypertension (P < 0.01), and persistent AF (P < 0.05) were identified as independent cofactors of increased ostial PV diameter. Conclusion: PV dilation affects all PVs uniformly in AF patients. Hypertension and hypertensive heart disease in patients with and without AF are associated with PV dilation, supporting theories that impaired left ventricular diastolic function is associated with a stretch-induced PV arrhythmia mechanism.

T changes are often encountered when normal QRS complexes resume in patients with an abnormal ventricular activation, such as intermittent left bundle branch block, cardiac pacing, wide complex tachycardia, or Wolff-Parkinson-White syndrome. This phenomenon is called “cardiac memory,” and it may be due to changes in the expression of specific potassium channels (e.g., transient outward current [Ito]) in the subepicardial myocardium. Additional channels are also likely to be involved. Directional discordance of the T wave from the R wave may persist for days, weeks, or months after the restoration of a normal QRS pattern. Cardiac memory should be evident during orthodromic atrioventricular tachycardia (AVT), which is associated with the restoration of normal ventricular activation in a previously excited ventricle. Differentiation of AVT from atrioventricular junctional reentrant tachycardia (AVJRT) during narrow complex tachycardia with a short RP interval is often difficult. The objective of this study was to assess whether the presence or absence of directional RT discordance due to cardiac memory might facilitate the surface electrocardiographic differentiation of ongoing AVT from AVJRT.