Outcomes During Intended Fluoroscopy-free Ablation in Adults and Children

Electroanatomic mapping (EAM) systems facilitate the elimination of fluoroscopy during electrophysiologic (EP) studies and ablations. The rate and predictors of fluoroscopy requirements while attempting fluoroscopy-free (FF) ablations are unclear. This study aimed (1) to investigate the rates of fluoroscopic use and acute success in patients initially referred for FF ablation and (2) to identify procedural characteristics associated with fluoroscopic use in patients in whom FF ablation was initially planned (IFF). We performed a retrospective review of all patients who underwent IFF EP study or ablation between 2010 and 2013. Patient and procedural characteristics were compared between those with successful FF procedures and those who subsequently required fluoroscopy during their procedure. An FF EP study with or without ablation was performed in 124 patients during 138 procedures for either supraventricular or idiopathic ventricular arrhythmias. Of the 138 procedures, 105 of them were performed without fluoroscopy. In the remaining 33 cases, fluoroscopy was used for an average of 1.21 minutes ± 1.18 minutes. Acute procedural success was achieved in 97% of both FF and fluoroscopy procedures. The primary reason for fluoroscopy use was as a guide for transseptal puncture. There were no significant differences between FF and fluoroscopy procedures with respect to catheter placement time or complication rate. In conclusion, in this single-center study of IFF procedures, despite careful case selection for IFF ablation, 24% of IFF cases ultimately required minimal fluoroscopy. Fluoroscopy and FF procedures had similar rates of procedural success and complications. Additional large prospective studies are required to further investigate the safety and efficacy of FF ablations.

Impact of a novel protocol for atrial fibrillation management in outpatient gastrointestinal endoscopic procedures: a retrospective cohort study

BACKGROUND

Atrial fibrillation (AF) may result in procedure cancellations and emergency department (ED) referrals for patients presenting for outpatient GI endoscopic procedures. Such cancellations and referrals delay patient care and can lead to inefficient use of resources.

METHODS

All consecutive patients presenting in AF for a colonoscopy or upper endoscopy to the University of Wisconsin Digestive Health Center between October 2013 and September 2014 were defined as the pre-intervention group (Group 1). In 2015, a protocol was initiated for peri-procedural management of patients presenting in AF, new onset or previously known. All consecutive patients after initiation of the protocol from October 2015 to September 2016 were analyzed as the post intervention group (Group 2). Patients with heart failure, hypotension, or chest pain were excluded from the protocol.

RESULTS

One hundred nine and 141 patients were included in Groups 1 and Group 2, respectively. Following protocol initiation, patients were less likely to present to the ED (6.4% Group 1 vs. 1.4% Group 2, RR 0.22, p = 0.04). There was also a trend towards a reduction in procedure cancelations (5.5% Group 1 vs. 1.4% Group 2, RR 0.26, p = 0.08). All attempted procedures were completed and there were no complications in the intervention group.

CONCLUSIONS

Implementation of a standardized protocol for management of atrial fibrillation in patients presenting for outpatient gastrointestinal endoscopic procedures resulted in a significant decrease in emergency department visits with an additional trend toward decreased procedural cancellations without an increased risk of complications.

P-Wave Amplitude and PR Changes in Patients With Inappropriate Sinus Tachycardia: Findings Supportive of a Central Mechanism

BACKGROUND

The mechanism of inappropriate sinus tachycardia (IST) remains incompletely understood.

METHODS AND RESULTS

We prospectively compared 3 patient groups: 11 patients with IST (IST Group), 9 control patients administered isoproterenol (Isuprel Group), and 15 patients with cristae terminalis atrial tachycardia (AT Group). P-wave amplitude in lead II and PR interval were measured at a lower and higher heart rate (HR1 and HR2, respectively). P-wave amplitude increased significantly with the increase in HR in the IST Group (0.16±0.07 mV at HR1=97±12 beats per minute versus 0.21±0.08 mV at HR2=135±21 beats per minute, P=0.001). The average increase in P-wave amplitude in the IST Group was similar to the Isuprel Group (P=0.26). PR interval significantly shortened with the increases in HR in the IST Group (146±15 ms at HR1 versus 128±16 ms at HR2, P<0.001). A similar decrease in the PR interval was noted in the Isuprel Group (P=0.6). In contrast, patients in the atrial tachycardia Group experienced PR lengthening during atrial tachycardia when compared with baseline normal sinus rhythm (153±25 ms at HR1=78±17 beats per minute versus 179±29 ms at HR2=140±28 beats per minute, P<0.01).

CONCLUSIONS

We have shown that HR increases in patients with IST were associated with an increase in P-wave amplitude in lead II and PR shortening similar to what is seen in healthy controls following isoproterenol infusion. The increase in P-wave amplitude and absence of PR lengthening in IST support an extrinsic mechanism consistent with a state of sympatho-excitation with cephalic shift in sinus node activation and enhanced atrioventricular nodal conduction.

Machine Learning Algorithm Predicts Cardiac Resynchronization Therapy Outcomes: Lessons From the COMPANION Trial

BACKGROUND

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in heart failure patients with reduced left ventricular function and intraventricular conduction delay. However, individual outcomes vary significantly. This study sought to use a machine learning algorithm to develop a model to predict outcomes after CRT.

METHODS AND RESULTS

Models were developed with machine learning algorithms to predict all-cause mortality or heart failure hospitalization at 12 months post-CRT in the COMPANION trial (Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure). The best performing model was developed with the random forest algorithm. The ability of this model to predict all-cause mortality or heart failure hospitalization and all-cause mortality alone was compared with discrimination obtained using a combination of bundle branch block morphology and QRS duration. In the 595 patients with CRT-defibrillator in the COMPANION trial, 105 deaths occurred (median follow-up, 15.7 months). The survival difference across subgroups differentiated by bundle branch block morphology and QRS duration did not reach significance (P=0.08). The random forest model produced quartiles of patients with an 8-fold difference in survival between those with the highest and lowest predicted probability for events (hazard ratio, 7.96; P<0.0001). The model also discriminated the risk of the composite end point of all-cause mortality or heart failure hospitalization better than subgroups based on bundle branch block morphology and QRS duration.

CONCLUSIONS

In the COMPANION trial, a machine learning algorithm produced a model that predicted clinical outcomes after CRT. Applied before device implant, this model may better differentiate outcomes over current clinical discriminators and improve shared decision-making with patients.

Concealed Accessory Pathways with a Single Ventricular and Two Discrete Atrial Insertion Sites

BACKGROUND

Atrioventricular reciprocating tachycardia (AVRT) utilizing a concealed accessory pathway is common. It is well appreciated that some patients may have multiple accessory pathways with separate atrial and ventricular insertion sites.

METHODS

We present three cases of AVRT utilizing concealed pathways with evidence that each utilizing a single ventricular insertion and two discrete atrial insertion sites.

RESULTS

In case one, two discrete atrial insertion sites were mapped in two separate procedures, and only during the second ablation was the Kent potential identified. Ablation of the Kent potential at this site remote from the two atrial insertion sites resulted in the termination of the retrograde conduction in both pathways. Case two presented with supraventricular tachycardia (SVT) with alternating eccentric atrial activation patterns without alteration in the tachycardia cycle length. The two distinct atrial insertion sites during orthodromic AVRT and ventricular pacing were targeted and each of the two atrial insertion sites were successfully mapped and ablated. In case three, retrograde decremental conduction utilizing both atrial insertion sites was identified prior to ablation. After mapping and ablation of the first discrete atrial insertion site, tachycardia persisted utilizing the second atrial insertion site. Only after ablation of the second atrial insertion site was SVT noninducible, and VA conduction was no longer present.

CONCLUSIONS

Concealed retrograde accessory pathways with discrete atrial insertion sites may have a common ventricular insertion site. Identification and ablation of the ventricular insertion site or the separate discrete atrial insertion sites result in successful treatment.

Comparison of Outcomes of Atrial Fibrillation in Patients With Reduced Versus Preserved Left Ventricular Ejection Fraction

Patients with newly diagnosed atrial fibrillation (AF) and a rapid ventricular response may present with a reduced left ventricular ejection fraction (LVEF). We compared long-term outcomes of these patients with those with preserved LVEF. This retrospective cohort study included 385 consecutive adults with newly diagnosed AF with rapid ventricular response, presenting to a single medical center from January 2006 to August 2014. Patients with a history of coronary artery disease or known cardiomyopathy were excluded. Patients were divided into 2 groups: those with an LVEF ≤55% (n = 147) (REF) and those with an LVEF >55% (n = 238) (PEF). Echocardiographic parameters, all-cause mortality, cardiovascular mortality, and stroke rates were compared between both groups at baseline and a minimum of 1-year follow-up. The mean age of patients was 68 ± 1.1 in REF versus 60 ± 7.4 in PEF (p = 0.39). There were no significant differences in baseline co-morbidities between both groups. The mean LVEF during the index admission was 47.7 ± 0.8% in REF versus 65.5 ± 0.3% in PEF. The average duration of follow-up was 2.8 years. Patients with REF had higher all-cause mortality (32.7% REF vs 20.6% PEF, odds ratio 2.17, p = 0.008). Patients with REF had higher rates of subsequent clinic or ER visits for AF with a rapid ventricular response (32% REF vs 22.7% PEF, p = 0.044). The incidence of stroke was similar between both groups (17% REF vs 18.9% PEF, p = 0.639). Of the patients with REF, 64% had subsequent EF recovery and had similar outcomes compared with patients with PEF. Baseline LV end-diastolic diameter predicted all-cause mortality (odds ratio 1.14, p = 0.003) in the REF group. None of the echocardiographic parameters predicted EF recovery. In conclusion, in patients with new AF with rapid ventricular response, REF was associated with higher long-term all-cause mortality. Those with subsequent LVEF recovery after medical therapy appear to have a similar prognosis compared with those with initial PEF.

Bidirectional ventricular tachycardia in cardiac sarcoidosis

A 73-year-old man with history of pulmonary sarcoidosis was found to have runs of non-sustained bidirectional ventricular tachycardia (BVT) with two different QRS morphologies on a Holter monitor. Cardiac magnetic resonance delayed gadolinium imaging revealed a region of patchy mid-myocardial enhancement within the left ventricular basal inferolateral myocardium. An 18-fluorodeoxyglucose positron emission tomography (FDG-PET) showed increased uptake in the same area, consistent with active sarcoid, with no septal involvement. Follow-up FDG-PET one year later showed disease progression with new septal involvement. Cardiac sarcoidosis, characterized by myocardial inflammation and interstitial fibrosis that can lead to conduction system disturbance and macro re-entrant arrhythmias, should be considered in differential diagnosis of BVT. BVT may indicate septal involvement with sarcoidosis before the lesions are large enough to be detected radiologically.

Restoring Sinus Rhythm Improves Baroreflex Function in Patients With Persistent Atrial Fibrillation

BACKGROUND

Studies have suggested that patients with atrial fibrillation (AF) have impairment in the baroreflex. It is not clear whether these findings are the result of the associated comorbid conditions or the arrhythmia itself. We hypothesized that AF is associated with impairment in baroreflex function and that the arrhythmia itself is a contributing factor.

METHODS AND RESULTS

Twenty-four patients with persistent AF referred for cardioversion were enrolled. A second group of patients with no history of AF matched for age and left ventricular ejection fraction was identified and served as the control group. In the AF group, baroreflex gain (BRG) was measured on the day of cardioversion (Day 1) and again at 30 days post-cardioversion (Day 30) in patients who remained in sinus rhythm (SR). The clinical characteristics of patients with AF were not different than those of the control group. The mean BRG in the AF group on Day 1 was significantly lower than the mean BRG of the control group (5.2±3.6 versus 10.8±5.5 ms/mm Hg, P<0.05). Ten patients experienced AF recurrence before the 30-day follow-up and 14 patients remained in SR. In the group that remained in SR, BRG increased from 4.1±3.7 ms/mm Hg on Day 1 to 7.0±6.0 ms/mm Hg on Day 30 (P<0.01).

CONCLUSION

We have shown that AF is associated with impairment of the baroreflex and that restoration of SR improves BRG. Our data suggest that AF might be a contributing factor to the observed impairment in BRG and that restoring SR might help improve baroreflex function.

Antiarrhythmic drugs in pregnancy

The risk of arrhythmia development or recurrence is increased during pregnancy. For those arrhythmias that are unresponsive to conservative therapy, such as vagal maneuvers or life style interventions, or that present a higher risk to the mother or fetus, medical therapy may be necessary. In each case, the patient and provider must carefully consider the risks and benefits of a particular therapy. This requires an understanding of the data regarding the safety and efficacy of any particular drug, which in some cases may be extensive and in others quite limited. Fortunately, options exist for the treatment of arrhythmias during pregnancy.