J. Alison

Long-term performance of submammary defibrillator system

AIMS There are various implantation techniques that have been used to minimize the cosmetic effect of implantable cardioverter defibrillator (ICD) implantation, including submammary implantation. There are limited data on submammary ICD implantation and no data on long-term follow-up. We report the long-term performance of submammary ICD systems implanted in young females. METHODS AND RESULTS We gathered data from August 1994 to September 2009 on all submammary ICD implantations undertaken at two institutes in Melbourne, Australia. Twenty submammary ICDs were implanted. Mean age at implantation was 21 +/- 10 years. Fifteen single chamber (VR) and five dual chamber (DR) systems were implanted. Twenty-five per cent were implanted for primary prophylaxis. Implantable cardioverter defibrillator implantation was predominantly for non-cardiomyopathy indications. Mean follow-up duration was 60 +/- 46 months. There were no deaths during follow-up. There were two early lead dislodgements and three late lead revisions. No extractions were performed. Five patients had appropriate and five patients had inappropriate ICD therapy. Mean duration to first appropriate therapy was 58 +/- 40 months. Stable sensing and high voltage (HV) lead performance were demonstrated (mean lowest effective defibrillation at implant vs. follow-up: 13 +/- 6 vs. 14 +/- 4 J, P = 0.8; R-wave amplitude: 9 +/- 3 vs. 8 +/- 2 mV, P = 0.6; HV lead impedance: 52 +/- 6 vs. 44 +/- 9 ohm, P = 0.1). A clinically insignificant rise in ventricular pacing threshold (0.6 +/- 0.2 V at implant vs. 1.6 +/- 0.6 V at follow-up, P < 0.001) and a decrease in pacing impedance (621 +/- 223 vs. 471 +/- 89 ohm, P = 0.02) were noted. CONCLUSION Submammary ICD implantation in young females is feasible and safe. Long-term follow-up data reveal stable sensing and HV lead performance.

Retrospective Cohort Study Examining Reduced Intensity and Duration of Anticoagulant and Antiplatelet Therapy Following Left Atrial Appendage Occlusion with the WATCHMAN Device.

BACKGROUND Anticoagulant and antiplatelet therapy are recommended following WATCHMAN implantation (45 days and 6 months) to reduce the risk of embolic events. These patients are often also at high risk of recurrent bleeding complications. We aimed to assess the safety of reduced duration of treatment with anticoagulant and antiplatelet therapy in the early post implant period. METHODS This was a retrospective cohort study assessing the duration of antiplatelet and anticoagulant therapy in 47 consecutive patients following WATCHMAN implant. The primary outcome was rate of major bleeding, stroke and systemic embolic complications. The secondary endpoints were rate of device thrombus and peri-device leak >4mm as assessed by transoesophogeal echocardiography. RESULTS Forty-seven patients were followed up for a mean of 2.4+/-1.7 years (111.4 total patient-years). The rate of stroke was 1.8/100 patient-years (two events) and the rate of major bleeding complication was 8.9/100 patient-years. Three patients had peri-device leak >4mm and no patients had device thrombus visualised. 70.2% of patients had discontinued anticoagulation at 45 days, 89.4% had discontinued dual antiplatelet therapy at 90 days. Seven patients were not on any form of anticoagulant or antiplatelet at five months. Comparison of probability of survival free from stroke by time of cessation of anticoagulant and antiplatelet therapy demonstrated no significant differences (p-value for log rank test 0.238 and 0.820). CONCLUSION Following WATCHMAN implant shortened periods of anticoagulants and antiplatelets may be considered, particularly in the context of high bleeding risk.

Role for the left atrial appendage occlusion device in managing thromboembolic risk in atrial fibrillation

Only 50% of patients who would benefit from warfarin therapy for atrial fibrillation (AF) receive treatment because of clinical concerns regarding chronic anti‐coagulation. Percutaneous strategies to treat AF, including pulmonary vein isolation with a curative intent or atrioventricular nodal ablation and implantation of a permanent pacemaker for palliative rate control, have not eliminated the need to manage thromboembolic risk. With the development of a percutaneous left atrial appendage (LAA) occlusion device (the WATCHMAN percutaneous left atrial appendage occluder – Atritech Inc., Plymouth, MN, USA) for thromboembolic protection in non‐valvular AF a significant therapeutic option for select patients may be available. We present the first case performed in Australia (24 November 2009) and explore this new methodology.

A Twist in the Heart

A 69 year-old obese female with poorly controlled ventricular rates in atrial fibrillation (AF) underwent single chamber pacemaker implantation followed by an atrioventricular node ablation one month later. The chest X-ray performed after the ablation showed the header of pulse generator facing medially (arrow) with satisfactory right ventricular, mid-septal lead positioning (Fig. 1A). During a coronary angiogram for angina six months later, the right anterior fluoroscopic view of the pacing lead showed a double twist within the right atrium (arrow) (Fig. 1B). In addition, the pulse generator had flipped horizontally (arrow) (Fig. 1C). The patient denied ‘twiddling’ with the device. Fortunately, pacemaker lead function remained normal. Traditional Twiddler’s syndrome occurs when circular rotation of the device retracts the leads out of the heart with leads

Chronic Threshold Testing of Implantable Cardioverter Defibrillators Does Not Increase Coagulation Activity or Platelet Activation

SMOLICH, J.J., et al.: Chronic Threshold Testing of Implantable Cardioverter Defibrillators Does Not Increase Coagulation Activity or Platelet Activation. It is unknown if the brief periods of circulatory stasis occurring with induction of VF during DFT testing in patients with an ICD activate blood coagulation processes. To address this question, coagulation activity and platelet activation were measured in peripheral venous blood samples obtained from 12 patients undergoing DFT testing under general anesthesia, 3 (n = 11) or 6 months (n = 1) after ICD implantation for recurrent ventricular arrhythmias. Five patients were anticoagulated with warfarin and two to six episodes of VF (median five) were induced per patient. Blood samples were drawn at baseline, after each DFT test and on the following morning. Coagulation activity was assessed by measuring prothrombin fragment 1+2 (F1+2) (a marker of thrombin generation), soluble fibrin (a marker of fibrin production), and D‐dimer (a breakdown product of cross‐linked fibrin). Platelet activation was evaluated by measuring the expression P‐selectin on the platelet surface using flow cytometry. No significant changes in F1+2, soluble fibrin, D‐dimer, or P‐selectin expression occurred during DFT testing, or between baseline and morning after samples. Moreover, results were unaffected by warfarin. These findings suggest that chronic threshold testing of implantable cardioverter defibrillators is not associated with activation of blood coagulation processes.