Albert C. Lin

Time Dependence of Mortality Risk and Defibrillator Benefit After Myocardial Infarction

Background—Prophylactic implantable defibrillators (ICDs) improve survival in patients with impaired ventricular function after myocardial infarction (MI), but it is uncertain whether mortality risk and survival benefit depend on the elapsed time from MI. Methods and Results—The Multicenter Automatic Defibrillator Implantation Trial II examined the impact of ICDs on survival in post-MI patients with ejection fractions ≤30%. In 1159 patients, mean time from most recent MI to enrollment was 81±78 months. Patients were randomized to an ICD (n=699) or conventional care (n=460) in a 3:2 ratio. Mortality rates (deaths per 100 person-years of follow-up) in both treatment groups were analyzed by time from MI divided into quartiles (<18, 18 to 59, 60 to 119, and ≥120 months). In conventional care patients, these rates increased as time from MI increased (7.8%, 8.4%, 11.6%, 14.0%; P =0.03). Mortality rates in ICD patients were consistently lower in each quartile and showed minimal increase over time (7.2%, 4.9%, 8.2%, 9.0%; P =0.19). Covariate-adjusted hazard ratios for risk of death associated with ICD therapy were 0.97 (95% CI, 0.51 to 1.81; P =0.92) for recent MI (<18 months) and 0.55 (95% CI, 0.39 to 0.78; P =0.001) for remote MI (≥18 months). Conclusions—Mortality risk in patients with ejection fractions ≤30% increases as a function of time from MI. The survival benefit associated with ICDs appears to be greater for remote MI and remains substantial for up to ≥15 years after MI.

Early safety and efficacy of percutaneous left atrial appendage suture ligation: results from the U.S. transcatheter LAA ligation consortium

BACKGROUND Transcatheter left atrial appendage (LAA) ligation may represent an alternative to oral anticoagulation for stroke prevention in atrial fibrillation. OBJECTIVES This study sought to assess the early safety and efficacy of transcatheter ligation of the LAA for stroke prevention in atrial fibrillation. METHODS This was a retrospective, multicenter study of consecutive patients undergoing LAA ligation with the Lariat device at 8 U.S. sites. The primary endpoint was procedural success, defined as device success (suture deployment and <5 mm leak by post-procedure transesophageal echocardiography), and no major complication at discharge (death, myocardial infarction, stroke, Bleeding Academic Research Consortium bleeding type 3 or greater, or cardiac surgery). Post-discharge management was per operator discretion. RESULTS A total of 154 patients were enrolled. Median CHADS2 score (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, prior stroke, transient ischemic attack, or thromboembolism [doubled]) was 3 (interquartile range: 2 to 4). Device success was 94%, and procedural success was 86%. A major complication occurred in 15 patients (9.7%). There were 14 major bleeds (9.1%), driven by the need for transfusion (4.5%). Significant pericardial effusion occurred in 16 patients (10.4%). Follow-up was available in 134 patients at a median of 112 days (interquartile range: 50 to 270 days): Death, myocardial infarction, or stroke occurred in 4 patients (2.9%). Among 63 patients with acute closure and transesophageal echocardiography follow-up, there were 3 thrombi (4.8%) and 13 (20%) with residual leak. CONCLUSIONS In this initial multicenter experience of LAA ligation with the Lariat device, the rate of acute closure was high, but procedural success was limited by bleeding. A prospective randomized trial is required to adequately define clinical efficacy, optimal post-procedure medical therapy, and the effect of operator experience on procedural safety.

Atypical Atrial Flutter Originating in the Right Atrial Free Wall

BACKGROUND Data from experimental models of atrial flutter indicate that macro-reentrant circuits may be confined by anatomic and functional barriers remote from the tricuspid annulus-eustachian ridge atrial isthmus. Data characterizing the various forms of atypical atrial flutter in humans are limited. METHODS AND RESULTS In 6 of 160 consecutive patients referred for ablation of counterclockwise and/or clockwise typical atrial flutter, an additional atypical atrial flutter was mapped to the right atrial free wall. Five patients had no prior cardiac surgery. Incisional atrial tachycardia was excluded in the remaining patient. High-density electroanatomic maps of the reentrant circuit were obtained in 3 patients. Radiofrequency energy application from a discrete midlateral right atrial central line of conduction block to the inferior vena cava terminated and prevented the reinduction of atypical atrial flutter in each patient. Atrial flutter has not recurred in any patient (follow-up, 18+/-17 months; range, 3 to 40 months). CONCLUSIONS Atrial flutter can arise in the right atrial free wall. This form of atypical atrial flutter could account for spontaneous or inducible atrial flutter observed in patients referred for ablation and is eliminated with linear ablation directed at the inferolateral right atrium.

Spatial resolution of pacemapping and activation mapping in patients with idiopathic right ventricular outflow tract tachycardia.

Background: The purpose of this study was to compare the spatial resolution of activation mapping and pacemapping in patients undergoing ablation of idiopathic ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT). A direct comparison of the two techniques has not been undertaken.

Use of an electrocardiographic screening tool to determine candidacy for a subcutaneous implantable cardioverter-defibrillator

BACKGROUND An electrocardiographic (ECG) screening test has been developed to identify patients being considered for a totally subcutaneous implantable cardioverter-defibrillator (S-ICD) at risk for T-wave oversensing. OBJECTIVE The purpose of this study was to determine the proportion of potential S-ICD recipients who fail the ECG screening test and to identify predictors of failure. METHODS Patients who already have an ICD but are not receiving antibradycardia pacing are representative of patients who might be considered for an S-ICD. One hundred such outpatients were enrolled in the study. Surface rhythm strips were recorded along the sensing vectors of the S-ICD system and the screening template applied. Clinical and standard ECG characteristics of patients who failed the test were compared to those who passed. RESULTS Patients had the following characteristics: 72% male, age 57 ± 16 years, body mass index 29 ± 6 kg/m(2), left ventricular ejection fraction 43% ± 17%, QRS duration 109 ± 23 ms, QTc interval 447 ± 39 ms, 44% had coronary disease, and 55% had heart failure. Among the 100 patients, 8% failed the screening test. There were no differences in patient clinical characteristics and most standard ECG measurements. However, patients with T-wave inversions in standard ECG leads I, II, and aVF had a 45% chance of failing. CONCLUSION Eight percent of potential S-ICD patients were not eligible for the S-ICD after failing the screening test designed to identify patients susceptible to T-wave oversensing. Patients with T-wave inversions in leads I, II, and aVF on a standard ECG were 23 times more likely to fail. More work is needed in S-ICD sensing algorithms to increase patient eligibility for the S-ICD.

Implications and outcome of permanent coronary sinus lead extraction and reimplantation

Objective: We examined the implications and outcome of coronary sinus (CS) lead removal including the feasibility of laser use within the CS. Background: Cardiac anatomy and lead interactions are more complex with the advent of biventricular pacemakers and atrial cardioverters requiring permanent lead/shocking coil placement in the coronary sinus and its branches. Methods: Fifty‐five permanent cardiac leads were extracted during 2003 in 28 consecutive patients. Our study population included a 10/55 (18%) subset (all males; age 73 ± 6 years; EF = 0.24 ± 0.09) that underwent CS (1/10) or vein branch (9/10) lead extraction. Leads were extracted with an excimer laser sheath (n = 4) or by direct traction (n = 6). Median times between implantation and lead removal were 9.5 months (range 5–59) in the laser group and 3 months (range 3–4) in the direct traction group. Indication for extraction was infection (n = 4), dislodgement (n = 3), diaphragm stimulation (n = 2), and elevated threshold (n = 1). The CS was divided into distal, mid, and proximal segments by venogram. Results: Entry of the laser sheath into the CS was necessary in three of four laser patients. The two distal CS laser cases (left lateral CS coil and anterior‐lateral left ventricular (LV) lead) required both 14‐ and 12‐Fr sheaths, separately. The proximal CS laser case (posterior‐lateral LV lead) required a 12 Fr sheath. The remaining laser patient required a 12‐Fr sheath to pass to the mid SVC. There were no procedural complications as a result of CS lead extraction. Reimplantation of a CS lead was attempted in 7/10 patients at a median of 4 days (range 1–300). CS venograms were available for review in patients before initial implantation (6/10) and after extraction (7/10). The postextraction venograms demonstrated complete occlusion of the vein from which the lead was extracted, and its distal branches, which were unusable in 5/10 (50%). The vein occlusions were present in patients with indwelling leads for greater than 3 months and were independent of extraction method. Conclusions: Laser lead extraction in the coronary sinus appears feasible in carefully selected cases with mandatory indications. However, special intraoperative monitoring and echocardiographic imaging with surgical backup ready is strongly recommended. Target vein selection may be limited for the purpose of reimplantation when leads are indwelling for greater than 3 months.

Performance of a novel left ventricular lead with short bipolar spacing for cardiac resynchronization therapy: primary results of the Attain Performa quadripolar left ventricular lead study.

BACKGROUND The Medtronic Attain Performa quadripolar leads provide 16 pacing vectors with steroid on every electrode. This includes a short bipolar configuration between the middle 2 electrodes. OBJECTIVE A prospective clinical study was conducted to investigate the safety and effectiveness of these new leads in 27 countries. METHODS Cardiac resynchronization therapy with defibrillator candidates were enrolled (mean age 68 years; 71% men). All implanted subjects were followed at 1, 3, and 6 months postimplant. Pacing capture threshold (PCT) values were measured at each visit. Adverse events were reported upon occurrence. RESULTS Of 1124 subjects in whom a left ventricular (LV) lead was attempted, 1097 (97.6%) were successfully implanted with an Attain Performa lead. Thirty-six LV lead-related complications were reported (the 6-month LV lead-related complication-free survival rate was 96.9%). Phrenic nerve stimulation (PNS) occurred in 81 subjects (7.2%), with only 3 (0.3%) requiring surgical intervention. At 6 months, the mean PCT at the programmed vector was (1.1 ± 0.8) V and 94.4% of subjects had a PCT of ≤2.5 V. All 16 programming polarities were used in at least 1 patient, and short bipolar configurations were used in 17% of subjects. CONCLUSION This large multicenter study demonstrated a high success rate for the implantation of Attain Performa quadripolar LV leads with a low complication rate. The PCT was low and stable over time. A low rate of postimplantation PNS was observed, and cases of PNS were readily resolved with reprogramming. Nonstandard vectors were often used for LV pacing.

Effects of electrocautery on transvenous lead insulation materials

Introduction: Insulation defects are a leading cause of transvenous lead failure. The purpose of this study was to determine the effects of electrocautery on transvenous lead insulation materials.

Left Atrial Thrombus After Appendage Closure Using LARIAT

The left atrial appendage (LAA) is the source of thromboembolism in the vast majority of patients with atrial fibrillation and stroke.1 As a consequence, a newer paradigm of targeting the LAA has evolved, including the use of several percutaneous techniques, including the LARIAT snare device (SentreHEART).2 This minimally invasive strategy involves pericardial suture ligation of the LAA base using a combined percutaneous endocardial and epicardial approach. A 75-year-old male with atrial fibrillation, …

Retrograde fast pathway ablation for atrioventricular nodal reentry associated with markedly prolonged PR intervals

Three patients with typical atrioventricular nodal reentrant tachycardia (AVNRT) and markedly prolonged PR intervals (>300 ms) without dual pathway physiology at baseline or during isoproterenol infusion underwent successful fast pathway ablation and remained asymptomatic without recurrent AVNRT, atrioventricular block, or symptomatic bradycardia for a mean of 19 months. In patients with recurrent AVNRT and markedly prolonged PR intervals, selective ablation of the retrograde fast pathway can eliminate AVNRT without further impairment of anterograde atrioventricular nodal function.