Theofanie Mela

Complication Rates Associated With Pacemaker or Implantable Cardioverter-Defibrillator Generator Replacements and Upgrade Procedures Results From the REPLACE Registry

Background— Prospective studies defining the risk associated with pacemaker or implantable cardioverter-defibrillator replacement surgeries do not exist. These procedures are generally considered low risk despite results from recent retrospective series reporting higher rates. Methods and Results— We prospectively assessed predefined procedure-related complication rates associated with elective pacemaker or implantable cardioverter-defibrillator generator replacements over 6 months of follow-up. Two groups were studied: those without (cohort 1) and those with (cohort 2) a planned transvenous lead addition for replacement or upgrade to a device capable of additional therapies. Complications were adjudicated by an independent events committee. Seventy-two US academic and private practice centers participated. Major complications occurred in 4.0% (95% confidence interval, 2.9 to 5.4) of 1031 cohort 1 patients and 15.3% (95% confidence interval, 12.7 to 18.1) of 713 cohort 2 patients. In both cohorts, major complications were higher with implantable cardioverter-defibrillator compared with pacemaker generator replacements. Complications were highest in patients who had an upgrade to or a revised cardiac resynchronization therapy device (18.7%; 95% confidence interval, 15.1 to 22.6). No periprocedural deaths occurred in either cohort, although 8 later procedure-related deaths occurred in cohort 2. The 6-month infection rates were 1.4% (95% confidence interval, 0.7 to 2.3) and 1.1% (95% confidence interval, 0.5 to 2.2) for cohorts 1 and 2, respectively. Conclusions— Pacemaker and implantable cardioverter-defibrillator generator replacements are associated with a notable complication risk, particularly those with lead additions. These data support careful decision making before device replacement, when managing device advisories, and when considering upgrades to more complex systems. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00395447.

Reduction in Myocardial Collagen Cross-Linking Parallels Left Ventricular Dilatation in Rat Models of Systolic Chamber Dysfunction

Background—The transition from compensated left ventricular hypertrophy (LVH) to heart failure is associated with alterations in the myocardial interstitium. We hypothesized that LV dilatation is associated with modifications in collagen cross-linking. Methods and Results—We studied 2 rat models of LV dilatation: (1) pressure-overload hypertrophy with heart failure (POH-F) induced by suprarenal abdominal aortic banding and (2) LVH induced by 7 months of isoproterenol (ISO, 0.04 mg · kg−1 · d−1) administration. In POH-F rats and in rats receiving ISO, LV dilatation and a reduced systolic chamber performance were noted. Myocardial hydroxyproline concentrations ([HPRO]) were increased in the POH-F rats, whereas in rats receiving ISO, [HPRO] was decreased. In POH-F rats, the ratio of myocardial collagen type I to type III was increased, but in rats receiving ISO, myocardial collagen I/III was unchanged. In contrast to the diverse changes in myocardial collagen concentrations and phenotypes observed in the 2 models of LV dilatation, the ratio of myocardial insoluble to soluble (relationship between cross-linked and non–cross-linked) collagen was decreased in both the POH-F and ISO groups. Moreover, administration of captopril (0.22 mmol · kg−1 · d−1), which inhibited the ISO-induced reduction in myocardial insoluble/soluble collagen but not the reduction in [HPRO], prevented the ISO-induced alterations in LV dimensions and performance. Conclusions—Because decreases in the ratio of myocardial insoluble to soluble collagen parallel LV dilatation in rats, reductions in myocardial collagen cross-linking may be an important mechanism contributing to LV dilatation in heart disease.

Esophageal Injury and Temperature Monitoring During Atrial Fibrillation Ablation

Background— It is common practice to empirically limit the radiofrequency (RF) power when ablating the posterior left atrium during atrial fibrillation ablation to avoid thermal injury to the esophagus. The objective of this study was to determine whether RF energy delivery limited by luminal esophageal temperature (LET) monitoring is associated with a reduction in esophageal injury compared with a strategy of RF power limitation alone. Methods and Results— Eighty-one consecutive patients who underwent atrial fibrillation ablation followed by esophageal endoscopy were included in this observational study. All patients underwent extraostial electric pulmonary vein isolation by using an electroanatomic mapping system and irrigated RF ablation. All RF applications on the posterior left atrium were limited to 35 W. A commercially available, single-thermocouple esophageal probe was used to monitor LET in a subset of patients (n=67). In these cases, applications were promptly interrupted when LET was ≥38.5°C; further applications were performed at reduced power to obtain a LET <38.5°C. Esophageal endoscopy was performed 1 to 3 days after the procedure. Ablation-related esophageal ulcerations were identified in 9 of 81 (11%) patients. All patients were asymptomatic. Of these 81 patients, LET monitoring during ablation occurred in 67 (83%) of patients. Esophageal injury was observed more frequently (36% versus 6%, P<0.006) in the group without LET monitoring. Conclusions— These data suggest that LET monitoring may be associated with a reduction in esophageal injury compared with power limitation alone.

Heart failure in pressure overload hypertrophy ☆: The relative roles of ventricularremodeling and myocardial dysfunction

OBJECTIVES We sought to explore the relative contributions of ventricular remodeling and myocardial dysfunction to heart failure in pressure overload hypertrophy (POH). BACKGROUND The mechanism that underlies heart failure in POH is adverse left ventricular (LV) chamber remodeling or decreased myocardial function, or a combination of these. METHODS Twenty weeks after suprarenal aortic banding in rats, animals with POH were classified as those with heart failure (POH-HF) or those with no heart failure (POH-NHF). The LV chamber and myocardial systolic and diastolic functions were determined from in vivo and ex vivo experiments. RESULTS The LV mass was similar in both POH groups. Chamber remodeling in the POH-HF group was characterized by marked LV enlargement with a normal relative wall thickness (eccentric remodeling), whereas remodeling in the POH-NHF group was characterized by a normal chamber size and increased relative wall thickness (concentric remodeling). The LV systolic function, as determined in vivo from the end-systolic pressure-diameter relationship and ex vivo from the pressure-volume relationship, was lower in the POH-HF group than in the POH-NHF and sham-operated control groups. In contrast, myocardial function was similar in both POH groups, as determined in vivo from the stress-midwall fractional shortening relationship and myocardial systolic stiffness, and ex vivo from the slope of the LV systolic stress-strain relationship. The diastolic chamber stiffness constant was lower in the POH-HF group than in the POH-NHF group, but the myocardial stiffness constant was similar in the two POH groups. CONCLUSIONS The two POH groups differed primarily in their remodeling process, which led to a chronically compensated state in one group and to heart failure in the other. Hence, heart failure in POH is more closely related to deleterious LV remodeling than to depressed myocardial function.

Pulmonary vein isolation with complex fractionated atrial electrogram ablation for paroxysmal and nonparoxysmal atrial fibrillation: A meta-analysis

BACKGROUND Pulmonary vein isolation (PVI) is recognized as a potentially curative treatment for atrial fibrillation (AF). Ablation of complex fractionated atrial electrograms (CFAEs) in addition to PVI has been advocated as a means to improve procedural outcomes, but the benefit remains unclear. OBJECTIVE This study sought t synthesize the available data testing the incremental benefit of adding CFAE ablation to PVI. METHODS We performed a meta-analysis of controlled studies comparing the effect of PVI with CFAE ablation vs. PVI alone in patients with paroxysmal and nonparoxysmal AF. RESULTS Of the 481 reports identified, 8 studies met our inclusion criteria. There was a statistically significant increase in freedom from atrial tachyarrhythmia (AT) with the addition of CFAE ablation (relative risk [RR] 1.15, P = .03). In the 5 reports of nonparoxysmal AF (3 randomized controlled trials, 1 controlled clinical trial, and 1 trial using matched historical controls), addition of CFAE ablation resulted in a statistically significant increase in freedom from AT (n = 112 of 181 [62%] for PVI+CFAE vs. n = 84 of 179 [47%] for PVI alone; RR 1.32, P = .02). In trials of paroxysmal AF (3 randomized controlled trials and 1 trial using matched historical controls), addition of CFAE ablation did not result in a statistically significant increase in freedom from AT (n = 131 of 166 [79%] for PVI+CFAE vs. n = 122 of 164 [74%] for PVI alone; RR 1.04, P = .52). CONCLUSION In these studies of patients with nonparoxysmal AF, addition of CFAE ablation to PVI results in greater improvement in freedom from AF. No additional benefit of this combined approach was observed in patients with paroxysmal AF.

Long-term infection rates associated with the pectoral versus abdominal approach to cardioverter- defibrillator implants

Infection is an uncommon (0% to 6.7%) but serious complication after implantable cardioverter-defibrillator (ICD) implantation. All ICD primary implants, replacements, or revisions performed at the Massachusetts General Hospital between April 1983 and May 1999 were reviewed. A total of 21 ICD-related infections (1.2%) were identified among 1,700 procedures affecting 1.8% of the 1,170 patients who underwent a primary implant, a generator change, or a revision of their systems. The mean follow-up time was 35 +/- 33 months. Of the 959 patients with long-term follow-up, 19 of the 584 patients (3.2%) with abdominal and 2 of the 375 patients (0.5%) with pectoral systems developed ICD-related infections (p = 0.03). There was no significant difference between the infection rate among the 959 primary ICD implants and the 447 replacements or system revisions. Only 5 of the patients (24%) had systemic signs of infection, including fever (T>100.5) and elevated white blood count >12,000. Cultures from the wound revealed staphylococcal species in 16 patients (76%). Nineteen patients were treated with removal of the entire ICD system in addition to intravenous antibiotics for 2 to 4 weeks. A decrease in the incidence of ICD-related infection has occurred since the advent of transvenous pectoral systems. The main organism responsible for ICD infection is Staphylococcus. The mainstay of ICD infection management consists of complete removal of the entire implanted system.

Remote Magnetic Navigation to Guide Endocardial and Epicardial Catheter Mapping of Scar-Related Ventricular Tachycardia

Background— The present study examines the safety and feasibility of using a remote magnetic navigation system to perform endocardial and epicardial substrate-based mapping and radiofrequency ablation in patients with scar-related ventricular tachycardia (VT). Methods and Results— Using the magnetic navigation system, we performed 27 procedures on 24 consecutive patients with a history of VT related to myocardial infarction, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, or sarcoidosis. Electroanatomic mapping of the left ventricular, right ventricular, and ventricular epicardial surfaces was constructed in 24, 10, and 12 patients, respectively. Complete-chamber VT activation maps were created in 4 patients. A total of 77 VTs were inducible, of which 21 were targeted during VT with the remotely navigated radiofrequency ablation catheter alone. With a combination of entrainment and activation mapping, 17 of 21 VTs (81%) were successfully terminated in a mean of 8.4±8.2 seconds; for the remainder, irrigated radiofrequency ablation was necessary. The mean fluoroscopy times for endocardial and epicardial mapping were 27±23 seconds (range, 0 to 105 seconds) and 18±18 seconds (range, 0 to 49 seconds), respectively. In concert with a manually navigated irrigated ablation catheter, 75 of 77 VTs (97%) were ultimately ablated. Four patients underwent a second procedure for recurrent VT, 3 with the magnetic navigation system. After 1.2 procedures per patient, VT did not recur during a mean follow-up of 7±3 months (range, 2 to 12 months). Conclusions— The present study demonstrates the safety and feasibility of remote catheter navigation to perform substrate mapping of scar-related VT in a wide range of disease states with a minimal amount of fluoroscopy exposure.

Atrial tachycardia after ablation of persistent atrial fibrillation: identification of the critical isthmus with a combination of multielectrode activation mapping and targeted entrainment mapping.

Background—Atrial tachycardia (AT) that develops after ablation of atrial fibrillation often poses a more difficult clinical situation than the index arrhythmia. This study details the use of an impedance-based electroanatomic mapping system (Ensite NavX) in concert with a specialized multielectrode mapping catheter for rapid, high-density atrial mapping. In this study, this activation mapping was combined with entrainment mapping to eliminate ATs developing late after atrial fibrillation ablation. Methods and Results—All study patients developed AT after ablation for atrial fibrillation. The approach to AT ablation consisted of 4 steps: use of a 20-pole penta-array catheter to map the chamber rapidly during the rhythm of interest, analysis of the patterns of atrial activation to identify wave fronts of electric propagation, targeted entrainment at putative channels, and catheter ablation at these “isthmuses.” All ablations were performed with irrigated radiofrequency ablation catheters. Forty-one ATs were identified in 17 patients (2.4±1.6 ATs per patient). Using the multielectrode catheter in conjunction with the Ensite NavX system, we created activation maps of 33 of 41 ATs (81%) (mean cycle length, 284±71 seconds) with a mean of 365±108 points per map and an average mapping time of 8±3 minutes. Of the 33 mapped ATs, 7 terminated either spontaneously or during entrainment maneuvers. Radiofrequency energy was used to attempt ablation of 26 ATs; 25 of 26 of the ATs (96%) were terminated successfully by ablation or catheter pressure. Conclusions—This study demonstrates a strategy for rapidly defining and eliminating the scar-related ATs typically encountered after ablation of atrial fibrillation.

Esophageal Injury and Temperature Monitoring During Atrial Fibrillation AblationCLINICAL PERSPECTIVE

Background— It is common practice to empirically limit the radiofrequency (RF) power when ablating the posterior left atrium during atrial fibrillation ablation to avoid thermal injury to the esophagus. The objective of this study was to determine whether RF energy delivery limited by luminal esophageal temperature (LET) monitoring is associated with a reduction in esophageal injury compared with a strategy of RF power limitation alone. Methods and Results— Eighty-one consecutive patients who underwent atrial fibrillation ablation followed by esophageal endoscopy were included in this observational study. All patients underwent extraostial electric pulmonary vein isolation by using an electroanatomic mapping system and irrigated RF ablation. All RF applications on the posterior left atrium were limited to 35 W. A commercially available, single-thermocouple esophageal probe was used to monitor LET in a subset of patients (n=67). In these cases, applications were promptly interrupted when LET was ≥38.5°C; further applications were performed at reduced power to obtain a LET <38.5°C. Esophageal endoscopy was performed 1 to 3 days after the procedure. Ablation-related esophageal ulcerations were identified in 9 of 81 (11%) patients. All patients were asymptomatic. Of these 81 patients, LET monitoring during ablation occurred in 67 (83%) of patients. Esophageal injury was observed more frequently (36% versus 6%, P <0.006) in the group without LET monitoring. Conclusions— These data suggest that LET monitoring may be associated with a reduction in esophageal injury compared with power limitation alone. Received March 20, 2008; accepted May 30, 2008.

Cardiovascular Implantable Electronic Device Replacement Infections and Prevention: Results from the REPLACE Registry

Background:  Infection following cardiovascular implantable electronic device (CIED) replacement is a serious complication, and rates of infection have increased. Analysis of procedural and clinical data from device replacement procedures collected by the REPLACE Registry may provide insights into infection prevention strategies and outcomes.