Dwight Reynolds

Catheter Ablation of Cardiac Autonomic Nerves for Prevention of Vagal Atrial Fibrillation

BackgroundVagal stimulation shortens the atrial effective refractory period (AERP) and maintains atrial fibrillation (AF). This study investigated whether the parasympathetic pathways that innervate the atria can be identified and ablated by use of transvenous catheter stimulation and radiofrequency current catheter ablation (RFCA) techniques. Methods and ResultsIn 11 dogs, AERPs were determined at 7 atrial sites during bilateral cervical vagal nerve stimulation (VNS) and electrical stimulation of the third fat pad (20 Hz) in the right pulmonary artery (RPA). VNS shortened the AERP at all sites (from 123±4 to 39±4 ms, P <0.001) and increased the covariance of AERP (COV-AERP) (from 9±3% to 27±13%, P <0.001). RPA stimulation shortened the AERP at all sites from 123±4 to 66±13 ms (P <0.001) and increased the COV-AERP from 9±3% to 30±12% (P <0.001). In 7 dogs, transvascular RFCA of the parasympathetic pathways along the RPA was performed, and in 3 dogs, additional RFCA of parasympathetic fibers along the inferior (n=2) or superior (n=1) vena cava was performed. RFCA blunted the AERP shortening at all sites during VNS (114±4 ms after RFCA), abolished the increase of COV-AERP during VNS (12±7% after RFCA), and led to an increase of the baseline AERP (123±4 ms before versus 127±3 ms after RFCA, P =0.002). Before RFCA, AF could be induced and maintained as long as VNS was continued, whereas after RFCA, AF was no longer inducible during VNS. ConclusionsTransvascular atrial parasympathetic nerve system modification by RFCA abolishes vagally mediated AF. This antifibrillatory procedure may provide a foundation for investigating the usefulness of neural ablation in chronic animal models of AF and eventually in patients with AF and high vagal tone.

HRS/EHRA Expert Consensus on the Monitoring of Cardiovascular Implantable Electronic Devices (CIEDs): Description of Techniques, Indications, Personnel, Frequency and Ethical Considerations

Developed in partnership with the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA); and in collaboration with the American College of Cardiology (ACC), the American Heart Association (AHA), the European Society of Cardiology (ESC), the Heart Failure Association of ESC (HFA), and the Heart Failure Society of America (HFSA). Endorsed by the Heart Rhythm Society, the European Heart Rhythm Association (a registered branch of the ESC), the American College of Cardiology, the American Heart Association

Improving Evidence-Based Care for Heart Failure in Outpatient Cardiology Practices Primary Results of the Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF)

Background— A treatment gap exists between heart failure (HF) guidelines and the clinical care of patients. The Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF) prospectively tested a multidimensional practice-specific performance improvement intervention on the use of guideline-recommended therapies for HF in outpatient cardiology practices. Methods and Results— Performance data were collected in a random sample of HF patients from 167 US outpatient cardiology practices at baseline, longitudinally after intervention at 12 and 24 months, and in single-point-in-time patient cohorts at 6 and 18 months. Participants included 34 810 patients with reduced left ventricular ejection fraction (≤35%) and chronic HF or previous myocardial infarction. To quantify guideline adherence, 7 quality measures were assessed. Interventions included clinical decision support tools, structured improvement strategies, and chart audits with feedback. The performance improvement intervention resulted in significant improvements in 5 of 7 quality measures at the 24-month assessment compared with baseline: &bgr;-blocker (92.2% versus 86.0%, +6.2%), aldosterone antagonist (60.3% versus 34.5%, +25.1%), cardiac resynchronization therapy (66.3% versus 37.2%, +29.9%), implantable cardioverter-defibrillator (77.5% versus 50.1%, +27.4%), and HF education (72.1% versus 59.5%, +12.6%) (each P<0.001). There were no statistically significant improvements in angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use or anticoagulation for atrial fibrillation. Sensitivity analyses at the patient level and limited to patients with both baseline and 24-month quality measure data yielded similar results. Improvements in the single-point-in-time cohorts were smaller, and there were no concurrent control practices. Conclusions— The Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting, a defined and scalable practice-specific performance improvement intervention, was associated with substantial improvements in the use of guideline-recommended therapies in eligible patients with HF in outpatient cardiology practices. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00303979.

Interference with Cardiac Pacemakers by Cellular Telephones

BACKGROUND A growing body of evidence suggests that electromagnetic interference may occur between cardiac pacemakers and wireless hand-held (cellular) telephones, posing a potential public health problem. Electromagnetic interference may occur when the pacemaker is exposed to an electromagnetic field generated by the cellular telephone. METHODS In this multicenter, prospective, crossover study, we tested 980 patients with cardiac pacemakers with five types of telephones (one analogue and four digital) to assess the potential for interference. Telephones were tested in a test mode and were programmed to transmit at the maximal power, simulating the worst-case scenario; in addition, one telephone was tested during actual transmission to simulate actual use. Patients were electrocardiographically monitored while the telephones were tested at the ipsilateral ear and in a series of maneuvers directly over the pacemaker. Interference was classified according to the type and clinical significance of the effect. RESULTS The incidence of any type of interference was 20 percent in the 5533 tests, and the incidence of symptoms was 7.2 percent. The incidence of clinically significant interference was 6.6 percent. There was no clinically significant interference when the telephone was placed in the normal position over the ear. Interference that was definitely clinically significant occurred in only 1.7 percent of tests, and only when the telephone was held over the pacemaker. Interference was more frequent with dual-chamber pacemakers (25.3 percent) than with single-chamber pacemakers (6.8 percent, P<0.001) and more frequent with pacemakers without feed-through filters (28.9 to 55.8 percent) than with those with such filters (0.4 to 0.8 percent, P=0.01). CONCLUSIONS Cellular telephones can interfere with the function of implanted cardiac pacemakers. However, when telephones are placed over the ear, the normal position, this interference does not pose a health risk.

A Leadless Intracardiac Transcatheter Pacing System

BACKGROUND A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. METHODS In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies. RESULTS The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval [CI], 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001). CONCLUSIONS In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

Heart Failure Care in the Outpatient Cardiology Practice Setting: Findings from IMPROVE HF

Background—Few data exist regarding contemporary care patterns for heart failure (HF) in the outpatient setting. IMPROVE HF is a prospective cohort study designed to characterize current management of patients with chronic HF and ejection fraction ≤35% in a national registry of 167 US outpatient cardiology practices. Methods and Results—Baseline patient characteristics and data on care of 15 381 patients with diagnosed HF or prior myocardial infarction and left ventricular dysfunction were collected by chart abstraction. To quantify use of therapies, 7 individual metrics (use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, &bgr;-blocker, aldosterone antagonist, anticoagulation, implantable cardioverter defibrillator, cardiac resynchronization therapy, and HF education) and composite metrics were assessed. Care metrics include only patients documented to be eligible and without contraindications or intolerance. Among practices, 69% were nonteaching. Patients were 71% male, with a median age of 70 years, and a median ejection fraction of 25%. Use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (80%) and &bgr;-blocker (86%) was relatively high in eligible patients in the outpatient cardiology setting; other metrics, such as aldosterone antagonist (36%), device therapy (implantable cardioverter defibrillator/cardiac resynchronization therapy with defibrillator, 51%; cardiac resynchronization therapy, 39%), and education (61%), showed lower rates of use. A median 27% of patients received all HF therapies for which they were potentially eligible on the basis of chart documentation. Use of guideline-recommended therapies by practices varied widely. Conclusions—These data are among the first to assess treatment in the outpatient setting since the release of the latest national HF guidelines and to demonstrate substantial variation among cardiology practices in the documented therapies provided to HF patients.

Measurement of pulmonary artery diastolic pressure from the right ventricle

OBJECTIVES This study evaluated the feasibility of estimating pulmonary artery end-diastolic pressure from within the right ventricle. If feasible, this could have important implications for long-term hemodynamic monitoring. BACKGROUND Right ventricular pressure at the time of pulmonary valve opening closely approximates pulmonary artery end-diastolic pressure. Because maximal first derivative of right ventricular pressure (dP/dt) can be easily measured, if it occurs at or very near pulmonary valve opening, right ventricular pressure at maximal right ventricular dP/dt would be an estimation of pulmonary artery end-diastolic pressure. METHODS In 10 patients undergoing routine right and left heart catheterization, simultaneous measurements were made using micromanometers in the right ventricle and pulmonary artery at baseline, during isometric work and Valsalva maneuver. Right ventricular pressure at maximal right ventricular dP/dt was considered the estimated pulmonary artery end-diastolic pressure and was compared with the actual pulmonary artery end-diastolic pressure. RESULTS At baseline, estimated and actual pulmonary artery end-diastolic pressures were (mean +/- SD) 17.7 +/- 6.6 and 16.7 +/- 6.7 mm Hg, respectively (p = NS). During isometric stress, estimated and actual pulmonary artery end-diastolic pressures were 30.4 +/- 12.7 and 28.4 +/- 10.1 mm Hg, respectively (p = NS). During Valsalva maneuvers, estimated and actual pulmonary artery end-diastolic pressures were 36.5 +/- 17.8 and 38.0 +/- 16.1 mm Hg, respectively (p = NS). CONCLUSIONS Although more extensive testing is necessary to evaluate validity in different physiologic and pathologic situations, it appears that right ventricular pressure at maximal right ventricular dP/dt can provide accurate estimation of pulmonary artery end-diastolic pressure.

Influence of patient age and sex on delivery of guideline-recommended heart failure care in the outpatient cardiology practice setting: Findings from IMPROVE HF

BACKGROUND The influence of patient age and sex on delivery of guideline-recommended heart failure (HF) therapies in contemporary outpatient settings has not been well studied. The Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF) is a prospective cohort study designed to characterize current management of outpatients with chronic HF and left ventricular ejection fraction < or =35%. METHODS Baseline data for eligible patients with systolic HF in a national registry of 167 US outpatient cardiology practices were collected by trained chart abstractors. Data were stratified and analyzed as male/female and by age tertiles with generalized estimating equation models constructed for 7 care measures. RESULTS A total of 15,381 patients were enrolled, with 8,770 (71.1%) of these male. Median age of female patients was 72.0 and 70.0 for males. Use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, aldosterone inhibitors, and cardiac resynchronization therapy was not significantly different between male and female patients, but rates for implantable cardioverter defibrillators, anticoagulation therapy for atrial fibrillation, and HF education were significantly lower for females. After adjusting for patient and practice characteristics, 3 of 7 measures significantly differed by patient sex, and 6 of 7 measures by age. Older patients, particularly older women, were significantly less likely to receive guideline-indicated HF therapies. CONCLUSIONS Patient age and sex were independently associated with reduced rates of some, but not all, HF therapies in outpatient cardiology practices. Older women are especially at risk. Further research is needed to understand the causes and consequences of these age- and sex-related differences in care.

Heart Failure Care in the Outpatient Cardiology Practice SettingCLINICAL PERSPECTIVE

Background—Few data exist regarding contemporary care patterns for heart failure (HF) in the outpatient setting. IMPROVE HF is a prospective cohort study designed to characterize current management of patients with chronic HF and ejection fraction ≤35% in a national registry of 167 US outpatient cardiology practices. Methods and Results—Baseline patient characteristics and data on care of 15 381 patients with diagnosed HF or prior myocardial infarction and left ventricular dysfunction were collected by chart abstraction. To quantify use of therapies, 7 individual metrics (use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, &bgr;-blocker, aldosterone antagonist, anticoagulation, implantable cardioverter defibrillator, cardiac resynchronization therapy, and HF education) and composite metrics were assessed. Care metrics include only patients documented to be eligible and without contraindications or intolerance. Among practices, 69% were nonteaching. Patients were 71% male, with a median age of 70 years, and a median ejection fraction of 25%. Use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (80%) and &bgr;-blocker (86%) was relatively high in eligible patients in the outpatient cardiology setting; other metrics, such as aldosterone antagonist (36%), device therapy (implantable cardioverter defibrillator/cardiac resynchronization therapy with defibrillator, 51%; cardiac resynchronization therapy, 39%), and education (61%), showed lower rates of use. A median 27% of patients received all HF therapies for which they were potentially eligible on the basis of chart documentation. Use of guideline-recommended therapies by practices varied widely. Conclusions—These data are among the first to assess treatment in the outpatient setting since the release of the latest national HF guidelines and to demonstrate substantial variation among cardiology practices in the documented therapies provided to HF patients.

Incremental Reduction in Risk of Death Associated With Use of Guideline-Recommended Therapies in Patients With Heart Failure: A Nested Case-Control Analysis of IMPROVE HF

Background Several therapies are guideline-recommended to reduce mortality in patients with heart failure (HF) and reduced left ventricular ejection fraction, but the incremental clinical effectiveness of these therapies has not been well studied. We aimed to evaluate the individual and incremental benefits of guideline-recommended HF therapies associated with 24-month survival. Methods and Results We performed a nested case-control study of HF patients enrolled in IMPROVE HF. Cases were patients who died within 24 months and controls were patients who survived to 24 months, propensity-matched 1:2 for multiple prognostic variables. Logistic regression was performed, and the attributable mortality risk from incomplete application of each evidence-based therapy among eligible patients was calculated. A total of 1376 cases and 2752 matched controls were identified. β-Blocker and cardiac resynchronization therapy were associated with the greatest 24-month survival benefit (adjusted odds ratio for death 0.42, 95% confidence interval (CI), 0.34–0.52; and 0.44, 95% CI, 0.29–0.67, respectively). Angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, implantable cardioverter-defibrillators, anticoagulation for atrial fibrillation, and HF education were also associated with benefit, whereas aldosterone antagonist use was not. Incremental benefits were observed with each successive therapy, plateauing once any 4 to 5 therapies were provided (adjusted odds ratio 0.31, 95% CI, 0.23–0.42 for 5 or more versus 0/1, P<0.0001). Conclusions Individual, with a single exception, and incremental use of guideline-recommended therapies was associated with survival benefit, with a potential plateau at 4 to 5 therapies. These data provide further rationale to implement guideline-recommended HF therapies in the absence of contraindications to patients with HF and reduced left ventricular ejection fraction. (J Am Heart Assoc. 2012;1:16-26.)