Colchicine for the Prevention of Recurrent Arrhythmia After Catheter Ablation of Atrial Fibrillation: Results of a Single-Center, Retrospective Study.

BACKGROUND: There is evidence to suggest that colchicine reduces the risk of recurrent atrial fibrillation (AF) after catheter ablation; however, the tolerability and safety of colchicine in routine practice is unknown. METHODS: Patients undergoing catheter ablation for AF who received colchicine after ablation were matched 1:1 to patients who did not by age, sex, and renal function. Recurrent AF was compared between groups categorically at 12 months and via propensity weighted Cox proportional hazards models with and without a 3-month blanking period. RESULTS: Overall, 180 patients (n = 90 colchicine and n = 90 matched controls) were followed for a median (Q1, Q3) of 10.3 (7.0, 12.0) months. Mean age was 65.3 ± 9.1 years, 33.9% were women, mean CHA2DS2-VASc score was 2.9 ± 1.5, and 51.1% had persistent AF. Most patients (70%) received colchicine 0.6 mg daily for a median of 30 days. In the colchicine group, 55 patients (61.1%) were receiving at least one known interacting medication with colchicine. After ablation, one patient required colchicine dose reduction and four patients required discontinuation. After adjusting for covariate imbalance using propensity weighting, no significant association between colchicine use and AF recurrence was identified (adjusted hazard ratio 0.94, 95% confidence interval [CI] 0.48-1.85; p = 0.853). No significant association was found between colchicine use and all-cause hospitalizations (adjusted odds ratio 0.74, 95% CI 0.28-1.96; p = 0.548). CONCLUSION: Despite the frequent presence of drug-drug interactions, a 30-day course of colchicine is well-tolerated after AF ablation; however, we did not observe any association between colchicine and lower rates of AF recurrence or hospitalization.

Association of leadless pacing with ventricular and valvular function.

BACKGROUND: Traditional transvenous pacemakers are associated with worsening tricuspid valve function due to lead-related leaflet impingement, as well as ventricular dysfunction related to electromechanical dyssynchrony from chronic right ventricular (RV) pacing. The association of leadless pacing with ventricular and valvular function has not been well established. We aimed to assess the association of leadless pacemaker placement with changes in valvular regurgitation and ventricular function. METHODS AND RESULTS: Echocardiographic features before and after leadless pacemaker implant were analyzed in consecutive patients who received a leadless pacemaker with pre- and postprocedure echocardiography at Duke University Hospital between November 2014 and November 2019. Valvular regurgitation was graded ordinally from 0 (none) to 3 (severe). Among 54 patients, the mean age was mean age was 70.1 ± 14.3 years, 24 (44%) were women, and the most frequent primary pacing indication was complete heart block in 24 (44%). The median RV pacing burden was 45.4 (interquartile range [IQR] 3.5-97.0). On echocardiogram performed 8.9 months (IQR 4.5-14.5) after implant, there was no change in the average severity of tricuspid regurgitation (mean change 0.07 ± 1.15, p = .64) from pre-procedure echocardiogram. We observed a decrease in the average left ventricular ejection fraction (LVEF) (52.3 ± 9.3 to 47.9 ± 12.1, p = .0019) and tricuspid annular plane systolic excursion (TAPSE) (1.8 ± 0.6 to 1.6 ± 0.4, p = .0437). Thirteen patients (24%) had absolute drop in LVEF of ≥10%. CONCLUSION: We did not observe short term worsening valvular function in patients with leadless pacemakers. However, consistent with the pathophysiologic impact of RV pacing, leadless pacing was associated with a reduction in biventricular function.

2023 HRS/EHRA/APHRS/LAHRS Expert Consensus Statement on Practical Management of the Remote Device Clinic.

Remote monitoring is beneficial for the management of patients with cardiovascular implantable electronic devices by impacting morbidity and mortality. With increasing numbers of patients using remote monitoring, keeping up with higher volume of remote monitoring transmissions creates challenges for device clinic staff. This international multidisciplinary document is intended to guide cardiac electrophysiologists, allied professionals, and hospital administrators in managing remote monitoring clinics. This includes guidance for remote monitoring clinic staffing, appropriate clinic workflows, patient education, and alert management. This expert consensus statement also addresses other topics such as communication of transmission results, use of third-party resources, manufacturer responsibilities, and programming concerns. The goal is to provide evidence-based recommendations impacting all aspects of remote monitoring services. Gaps in current knowledge and guidance for future research directions are also identified.

2023 HRS/EHRA/APHRS/LAHRS Expert Consensus Statement on Practical Management of the Remote Device Clinic.

Remote monitoring is beneficial for the management of patients with cardiovascular implantable electronic devices by impacting morbidity and mortality. With increasing numbers of patients using remote monitoring, keeping up with higher volume of remote monitoring transmissions creates challenges for device clinic staff. This international multidisciplinary document is intended to guide cardiac electrophysiologists, allied professionals, and hospital administrators in managing remote monitoring clinics. This includes guidance for remote monitoring clinic staffing, appropriate clinic workflows, patient education, and alert management. This expert consensus statement also addresses other topics such as communication of transmission results, use of third-party resources, manufacturer responsibilities, and programming concerns. The goal is to provide evidence-based recommendations impacting all aspects of remote monitoring services. Gaps in current knowledge and guidance for future research directions are also identified.

2023 HRS/EHRA/APHRS/LAHRS expert consensus statement on practical management of the remote device clinic.

Remote monitoring is beneficial for the management of patients with cardiovascular implantable electronic devices by impacting morbidity and mortality. With increasing numbers of patients using remote monitoring, keeping up with higher volume of remote monitoring transmissions creates challenges for device clinic staff. This international multidisciplinary document is intended to guide cardiac electrophysiologists, allied professionals, and hospital administrators in managing remote monitoring clinics. This includes guidance for remote monitoring clinic staffing, appropriate clinic workflows, patient education, and alert management. This expert consensus statement also addresses other topics such as communication of transmission results, use of third-party resources, manufacturer responsibilities, and programming concerns. The goal is to provide evidence-based recommendations impacting all aspects of remote monitoring services. Gaps in current knowledge and guidance for future research directions are also identified.

Alert-driven vs scheduled remote monitoring of implantable cardiac defibrillators: A cost-consequence analysis from the TRUST trial.

BACKGROUND: Alert-driven remote patient monitoring (RPM) or fully virtual care without routine evaluations may reduce clinic workload and promote more efficient resource allocation, principally by diminishing nonactionable patient encounters. OBJECTIVE: The purpose of this study was to conduct a cost-consequence analysis to compare 3 postimplant implantable cardioverter-defibrillator (ICD) follow-up strategies: (1) in-person evaluation (IPE) only; (2) RPM-conventional (hybrid of IPE and RPM); and (3) RPM-alert (alert-based ICD follow-up). METHODS: We constructed a decision-analytic Markov model to estimate the costs and benefits of the 3 strategies over a 2-year time horizon from the perspective of the US Medicare payer. Aggregate and patient-level data from the TRUST (Lumos-T Safely RedUceS RouTine Office Device Follow-up) randomized clinical trial informed clinical effectiveness model inputs. TRUST randomized 1339 patients 2:1 to conventional RPM or IPE alone, and found that RPM was safe and reduced the number of nonactionable encounters. Cost data were obtained from the published literature. The primary outcome was incremental cost. RESULTS: Mean cumulative follow-up costs per patient were $12,688 in the IPE group, $12,001 in the RPM-conventional group, and $11,011 in the RPM-alert group. Compared to the IPE group, both the RPM-conventional and RPM-alert groups were associated with lower incremental costs of -$687 (95% confidence interval [CI] -$2138 to +$638) and -$1,677 (95% CI -$3134 to -$304), respectively. Therefore, the RPM-alert strategy was most cost-effective, with an estimated cost-savings in 99% of simulations. CONCLUSIONS: Alert-driven RPM was economically attractive and, if patient outcomes and safety are comparable to those of conventional RPM, may be the preferred strategy for ICD follow-up.

Correlation between AV synchrony and device collected AM-VP sequence counter in atrioventricular synchronous leadless pacemakers: A real-world assessment.

INTRODUCTION: Micra atrioventricular (AV) provides leadless atrioventricular synchronous pacing by sensing atrial contraction (A4 signal). Real-world operation and reliability of AV synchrony (AVS) assessment using device data have not been described. The purposes of this study were to (1) assess the correlation between AVS and atrial mechanical sensed-ventricular pacing (AM-VP) percentages in patients with permanent high-degree AV block and (2) report on the real-world effectiveness of Micra AV. METHODS: The correlation between ECG-determined AVS in-clinic and device-collected %AM-VP was assessed using data from 40 patients with high-degree AV block enrolled in the Micra Atrial tRacking using a Ventricular AccELerometer (MARVEL) 2 study. A retrospective analysis to assess continuously-sampled %AM-VP since last session, device programming, and electrical parameters was performed using Micra AV transmissions from the Medtronic CareLink database. Patients with transmissions ≥180 days postimplant were included. RESULTS: Among the 40 MARVEL 2 AV block patients with a median %VP of 99.7%, AVS was highly correlated with AM-VP (median AVS 87.1%, median AM-VP 79.1%; R2 = 0.764, p < .001). The CareLink cohort included 4384 patients programmed to VDD mode. The mean A4 amplitude was 2.3 ± 1.8 m/s2 at implant and 2.3 ± 1.6 m/s2 at 28 weeks. In patients with %VP >90% (n = 1662), the median %AM-VP was 74.7%. For the full cohort, median %VP was 65.6% and median projected battery longevity was 10.5 years. CONCLUSION: In patients with a high pacing burden, %AM-VP provides a reasonable estimation of AVS. The first large real-world analysis of Micra AV patients with >90% VP showed stable atrial sensing over time with a median %AM-VP, a correlate of AVS, of 74.7%.

Syncope Recurrence and Downstream Diagnostic Testing after Insertable Cardiac Monitor Placement for Syncope.

Despite advances in syncope evaluation strategies and risk stratification, the high cost of syncope is largely driven by extensive and often repetitive testing. This analysis of a large deidentified US claims database compared the use of diagnostic tests, therapeutic procedures, and the recurrence rate of acute syncope events before and after placement of an insertable cardiac monitor (ICM) in syncope patients. The patients had a minimum of 1 year of continuous enrollment before and 2 years after ICM placement. Among 2140 patients identified, a statistically significant reduction in the use of 14 out of 18 tests was observed during follow-up compared with pre-ICM testing. During the 2-year follow-up, 28.3% of patients underwent cardiac therapeutic interventions after a median of 127 days. Significantly fewer patients experienced acute syncope events during the 1st and 2nd years of ICM follow-up compared with the 1-year pre-ICM period, and the frequency of events per patient also decreased. In conclusion, reductions in diagnostic testing and acute syncope events were observed after ICM placement in a large real-world cohort of unexplained syncope patients. Further studies are needed to prospectively assess the impact of ICM vs. short-term monitoring on patient outcomes and healthcare utilization.

Leadless pacemaker implantation after lead extraction for cardiac implanted electronic device infection.

BACKGROUND: Cardiac implanted electronic device (CIED) pocket and systemic infection remain common complications with traditional CIEDs and are associated with high morbidity and mortality. Leadless pacemakers may be an attractive pacing alternative for many patients following complete hardware removal for a CIED infection by eliminating surgical pocket-related complications as well as lower risk of recurrent complications. OBJECTIVE: To describe use and outcomes associated with leadless pacemaker implantation following extraction of a CIED system due to infection. METHODS: Patient characteristics and postprocedural outcomes were described in patients who underwent leadless pacemaker implantation at Duke University Hospital between November 11, 2014 and November 18, 2019, following CIED infection and device extraction. Outcomes of interest included procedural complications, pacemaker syndrome, need for system revision, and recurrent infection. RESULTS: Among 39 patients, the mean age was 71 ± 17 years, 31% were women, and the most frequent primary pacing indication was complete heart block (64.1%) with 9 (23.1%) patients being pacemaker dependent at the time of Micra implantation. The primary organism implicated in the CIED infection was Staphylococcus aureus (43.6%). Nine of the 39 patients had a leadless pacemaker implanted before or on the same day as their extraction procedure, and the remaining 30 patients had a leadless pacemaker implanted after their extraction procedure. During follow-up (mean 24.8 ± 14.7 months) after leadless pacemaker implantation, there were a total of 3 major complications: 1 groin hematoma, 1 femoral arteriovenous fistula, and 1 case of pacemaker syndrome. No patients had evidence of recurrent CIED infection after leadless pacemaker implantation. CONCLUSIONS: Despite a prior CIED infection and an elevated risk of recurrent infection, there was no evidence of CIED infection with a mean follow up of over 2 years following leadless pacemaker implantation at or after CIED system removal. Larger studies with longer follow-up are required to determine if there is a long-term advantage to implanting a leadless pacemaker versus a traditional pacemaker following temporary pacing when needed during the periextraction period in patients with a prior CIED infection.

Optimizing mechanically sensed atrial tracking in patients with atrioventricular-synchronous leadless pacemakers: A single-center experience.

BACKGROUND: Atrioventricular (AV)-synchronous single-chamber leadless pacing using a mechanical atrial sensing algorithm produced high AV synchrony in clinical trials, but clinical practice experience with these devices has not yet been described. OBJECTIVE: To describe pacing outcomes and programming changes with AV-synchronous leadless pacemakers in clinical practice. METHODS: Consecutive patients without persistent atrial fibrillation who received an AV-synchronous leadless pacemaker and completed follow-up between February 2020 and April 2021 were included. We evaluated tracking index (atrial mechanical sense followed by ventricular pace [AM-VP] divided by total VP), total AV synchrony (sum of AM-ventricular sense [AM-VS], AM-VP, and AV conduction mode switch), use of programming optimization, and improvement in AV synchrony after optimization. RESULTS: Fifty patients met the inclusion criteria. Mean age was 69 ± 16.8 years, 24 (48%) were women, 24 (48%) had complete heart block, and 17 (34%) required ≥50% pacing. Mean tracking index was 41% ± 34%. Thirty-five patients (70%) received ≥1 programming change. In 36 patients with 2 follow-up visits, tracking improved by +9% ± 28% (P value for improvement = .09) and +18% ± 19% (P = .02) among 15 patients with complete heart block. Average total AV synchrony increased from 89% [67%, 99%] to 93% [78%, 100%] in all patients (P = .22), from 86% [52%, 98%] to 97% [82%, 99%] in those with complete heart block (P = .04), and from 73% [52%, 80%] to 78% [70%, 85%] in those with ≥50% pacing (P = .09). CONCLUSION: In patients with AV-synchronous leadless pacemakers, programming changes are frequent and are associated with increased atrial tracking and increased AV synchrony in patients with complete heart block.

Evaluation of Women and Underrepresented Racial and Ethnic Group Representation in a General Cardiology Fellowship After a Systematic Recruitment Initiative.

Importance: The proportion of women and underrepresented racial and ethnic groups (UREGs) matriculating into general cardiology fellowships remains low. Objective: To assess a systematic recruitment initiative aimed at ensuring adequate matriculation of women and UREGs in a general cardiology fellowship. Design, Setting, and Participants: This quality improvement study took place at a large, tertiary academic medical center and associated Accreditation Council for Graduate Medical Education Cardiovascular Disease fellowship. Participants included cardiology fellowship and divisional leadership and general cardiology fellow applicants to the Duke Cardiovascular Disease Fellowship Program from 2017 to 2019. Data analysis was performed from December 2019 to May 2020. Exposure: Multipronged initiative that created an environment committed to ensuring equity of opportunity. This included the creation of a fellowship diversity and inclusivity task force that drafted recommendations, which included reorganization of the fellowship recruitment committee, and changes to the applicant screening process, the interview day, applicant ranking process, and postmatch interventions. Main Outcomes and Measures: The percentage of matriculating and overall women and UREGs before and after the interventions were recorded. Results: The fellowship received a mean (SD) of 462 (55) applications annually before the interventions (2006-2016) and 611 (27) applications annually after the interventions (2017-2019). Between the 10-year period before the interventions and the 3-year period during the interventions, there was a significant increase in the annual mean (SD) percentage of women (22.4% [2.9%] vs 26.4% [0.07%]; P < .001) and UREG applicants (10.5% [1.1%] vs 12.5% [1.9%]; P = .01) to the program. Among applicants interviewed, the percentage of women increased from 20.0% to 33.5% (P = .01) and that of and UREGs increased from 14.0% to 20.0% (P = .01). Before the interventions, a mean (SD) of 23.2% (16.2%) women and 9.7% (7.8%) UREGs matriculated as first-year fellows, whereas after the interventions, a mean (SD) of 54.2% (7.2%) women and 33.3% (19.0%) UREGs matriculated as first-year fellows. The proportion of the entire fellowship who were women increased from a 5-year mean (SD) of 27.0% (8.8%) to 54.2% (7.2%) after 3 years of interventions, and that of UREGs increased from 5.6% (4.6%) to 33.3% (19.0%). Overall, the proportion of applicants in the entire population who were either women or from UREGs increased from 27.8% to 66.7%. Conclusions and Relevance: After implementing interventions to promote equity of opportunity in the cardiovascular disease fellowship, the percentage of women and UREGs significantly increased in the fellowship over a 3-year time period. These interventions may be applicable to other cardiovascular disease fellowships seeking to diversify training programs.

Applications of the Multisensor HeartLogic Heart Failure Monitoring Algorithm During the COVID-19 Global Pandemic.

In the COVID-19 era, the heart failure community has witnessed an unprecedented reduction in heart failure-related patient visits and hospitalizations. Social distancing measures present a dilemma for patients with heart failure who require frequent surveillance of volume status and vital signs to minimize heart failure-related symptoms and hospitalizations. With the rise of telemedicine comes an increased focus on remote monitoring technologies. This report describes use of a multisensor device algorithm in implantable cardioverter defibrillator devices by Boston Scientific, called HeartLogic. We present 2 cases of patients with advanced heart failure who were actively surveilled by the HeartLogic device algorithm to guide care. (Level of Difficulty: Beginner.).

VVI pacing with normal QRS duration and ventricular function: MOST trial findings relevant to leadless pacemakers.

BACKGROUND: Leadless pacemakers (LPs) provide ventricular pacing without the risks associated with transvenous leads and device pockets. LPs are appealing for patients who need pacing, but do not need defibrillator or cardiac resynchronization therapy. Most implanted LPs provide right ventricular pacing without atrioventricular synchrony (VVIR mode). The Mode Selection Trial in Sinus Node Dysfunction (MOST) showed similar outcomes in patients randomized to dual-chamber (DDDR) versus ventricular pacing (VVIR). We compared outcomes by pacing mode in LP-eligible patients from MOST. METHODS: Patients enrolled in the MOST study with an left ventricular ejection fraction (LVEF) >35%, QRS duration (QRSd) <120 ms and no history of ventricular arrhythmias or prior implantable cardioverter defibrillators were included (LP-eligible population). Cox proportional hazards models were used to test the association between pacing mode and death, stroke or heart failure (HF) hospitalization and atrial fibrillation (AF). RESULTS: Of the 2010 patients enrolled in MOST, 1284 patients (64%) met inclusion criteria. Baseline characteristics were well balanced across included patients randomized to DDDR (N = 630) and VVIR (N = 654). Over 4 years of follow-up, there was no association between pacing mode and death, stroke or HF hospitalization (VVIR HR 1.28 [0.92-1.75]). VVIR pacing was associated with higher risk of AF (HR 1.32 [1.08-1.61], P = .007), particularly in patients with no history of AF (HR 2.38 [1.52-3.85], P < .001). CONCLUSION: In patients without reduced LVEF or prolonged QRSd who would be eligible for LP, DDDR, and VVIR pacing demonstrated similar rates of death, stroke or HF hospitalization; however, VVIR pacing significantly increased the risk of AF development.

Cardiovascular Implantable Electronic Device Surgery Following Left Ventricular Assist Device Implantation.

OBJECTIVES: This study sought to determine the indications, characteristics, and outcomes of cardiovascular implantable electronic device (CIED) surgery in patients with LVAD. BACKGROUND: Many patients with a left ventricular assist device (LVAD) will require implantable cardioverter-defibrillator generator change or device revision or are candidates for de novo implantable cardioverter-defibrillator implantation following LVAD implantation. METHODS: We performed an observational retrospective study of all LVAD recipients who subsequently underwent CIED surgery at Duke University Hospital from 2009 to 2019. RESULTS: A total of 159 patients underwent CIED surgery following LVAD implantation, including generator change (n = 93), device revision (n = 38), and de novo implant (n = 28). The median (interquartile range) time from LVAD implantation to CIED surgery was 18.1 months (5.5 to 35.1 months). Pre-operative risk for infection was elevated in the overall cohort with a median (interquartile range) Prevention of Arrhythmia Device Infection Trial (PADIT) score of 7.0 (5.0 to 9.0). Pocket hematoma occurred in 21 patients (13.2%) following CIED surgery. Antimicrobial envelops were used in 43 patients (27%). Device infection due to CIED surgery occurred in 5 (3.1%) patients and occurred only in patients who developed post-operative pocket hematoma (p < 0.001). Mortality at 1 year following CIED surgery was 20% (n = 32). CONCLUSIONS: CIED surgery following LVAD implantation is associated with an increased risk for pocket hematoma and CIED infection. Further studies are needed to determine the risk-benefit ratio of CIED surgery in patients with LVADs.

Implantable cardioverter-defibrillator lead revision following left ventricular assist device implantation.

INTRODUCTION: Lead dysfunction can lead to serious consequences including failure to treat ventricular tachycardia or fibrillation (VT/VF). The incidence and mechanisms of lead dysfunction following left ventricular assist device (LVAD) implantation are not well-described. We sought to determine the incidence, mechanisms, timing, and complications of right ventricular lead dysfunction requiring revision following LVAD implantation. METHODS: Retrospective observational chart review of all LVAD recipients with pre-existing implantable cardioverter-defibrillator (ICD) from 2009 to 2018 was performed including device interrogation reports, laboratory and imaging data, procedural reports, and clinical outcomes. RESULTS: Among 583 patients with an ICD in situ undergoing LVAD implant, the median (interquartile range) age was 62.5 (15.7) years, 21% were female, and the types of LVADs included HeartWare HVAD (26%), HeartMate II (52%), and HeartMate III (22%). Right ventricular lead revision was performed in 38 patients (6.5%) at a median (25th, 75th) of 16.4 (3.6, 29.2) months following LVAD. Mechanisms of lead dysfunction included macrodislodgement (n = 4), surgical lead injury (n = 4), recall (n = 3), insulation failure (n = 8) or conductor fracture (n = 7), and alterations in the lead-myocardial interface (n = 12). Undersensing requiring revision occurred in 22 (58%) cases. Clinical sequelae of undersensing included failure to detect VT/VF (n = 4) and pacing-induced torsade de pointes (n = 1). Oversensing occurred in 12 (32%) and sequelae included inappropriate antitachycardia pacing ([ATP], n = 8), inappropriate ICD shock (n = 6), and ATP-induced VT (n = 1). CONCLUSION: The incidence of right ventricular lead dysfunction following LVAD implantation is significant and has important clinical sequelae. Physicians should remain vigilant for lead dysfunction after LVAD surgery and test lead function before discharge.

Effectiveness of catheter ablation of atrial fibrillation according to heart failure etiology.

BACKGROUND: Catheter ablation is an important rhythm control therapy in patients with atrial fibrillation (AF) with concomitant heart failure (HF). The objective of this study was to assess the comparative efficacy of AF ablation patients with ischemic vs nonischemic heart failure. METHODS: We conducted a retrospective, observational cohort study of patients with HF who underwent AF ablation. Outcomes were compared based on HF etiology and included in-hospital events, symptoms (Mayo AF Symptom Inventory [MAFSI]), and functional status (New York Heart Association class) and freedom from atrial arrhythmias at 12 months. RESULTS: Among 242 patients (n = 70 [29%] ischemic, n = 172 [71%] nonischemic), patients with nonischemic cardiomyopathy were younger (mean age 64 ± 11.5 vs 69 ± 9.1, P = .002), more often female (36% vs 17%, P = .004), and had higher mean left-ventricular ejection fraction (47% vs 42%, P = .0007). There were no significant differences in periprocedural characteristics, including mean procedure time (243 ± 74.2 vs 259 ± 81.8 minutes, P = .1) and nonleft atrial ablation (17% vs 20%, P = .6). All-cause adverse events were similar in each group (15% vs 17%, P = .7). NYHA and MAFSI scores improved significantly at follow-up and did not differ according to HF etiology (P = .5; P = .10-1.00 after Bonferroni correction). There were no significant differences in freedom from recurrent atrial arrhythmia at 12-months between ischemic (74%) and nonischemic patients (78%): adjusted RR 0.63, 95% confidence interval 0.33-1.19. CONCLUSIONS: Catheter ablation in patients with AF and concomitant heart failure leads to significant improvements in functional and symptom status without significant differences between patients with ischemic vs nonischemic HF etiology.