Clinical implication of the patient's disease awareness and adherence to medications in patients undergoing atrial fibrillation ablation

Background

The effects of the patient's disease awareness on the management of postablation of atrial fibrillation (AF) are unknown.

Methods

One hundred thirty-three AF patients undergoing an initial ablation were given a disease awareness questionnaire with a score of 16 points (8 points about AF in general and 8 points about oral anticoagulants) for the Jessa Atrial Fibrillation Knowledge Questionnaire (JAKQ) before and 1-year-after ablation. We divided them into the poor disease awareness group and good disease awareness group according to the median value (75%) of the total JAKQ score about AF in general, and compared the baseline patient characteristics and the 1-year changes in the JAKQ score, medication adherence, blood pressure, laboratory data, echocardiographic parameters, and AF/atrial tachycardia (AT) recurrence rate between the two groups.

Results

Forty-two (31.6%) patients were classified as having poor disease awareness (<75% of the total JAKQ score), which was closely associated with poor medication adherence, hypertension, diabetes, dyslipidemia, and greater left atrial volume (LAV). These trends in the poor disease awareness group remained unchanged 1 year after the ablation. During the 25.3-month follow-up, the AF/AT recurrence rate was significantly higher in the poor disease awareness than the good disease awareness group (23.8% vs. 7.7%; p = .003 by the log-rank test).

Conclusions

Poor disease awareness was linked to poor medication adherence, lifestyle-related diseases, and greater LAV before and even 1 year after the ablation, making it a potential surrogate marker for AF/AT recurrence. These findings highlight the clinical significance of disease awareness in AF management.

Characteristics of tissue temperature during ablation with THERMOCOOL SMARTTOUCH SF versus TactiCath versus QDOT MICRO catheters (Qmode and Qmode+): An in vivo porcine study

INTRODUCTION

High-power short-duration (HPSD) ablation at 50 W, guided by ablation index (AI) or lesion size index (LSI), and a 90 W/4 s very HSPD (vHPSD) setting are available for atrial fibrillation (AF) treatment. Yet, tissue temperatures during ablation with different catheters around venoatrial junction and collateral tissues remain unclear.

METHODS

In this porcine study, we surgically implanted thermocouples on the epicardium near the superior vena cava (SVC), right pulmonary vein, and esophagus close to the inferior vena cava. We then compared tissue temperatures during 50W-HPSD guided by AI 400 or LSI 5.0, and 90 W/4 s-vHPSD ablation using THERMOCOOL SMARTTOUCH SF (STSF), TactiCath ablation catheter, sensor enabled (TacthCath), and QDOT MICRO (Qmode and Qmode+ settings) catheters.

RESULTS

STSF produced the highest maximum tissue temperature (Tmax ), followed by TactiCath, and QDOT MICRO in Qmode and Qmode+ (62.7 ± 12.5°C, 58.0 ± 10.1°C, 50.0 ± 12.1°C, and 49.2 ± 8.4°C, respectively; p = .005), achieving effective transmural lesions. Time to lethal tissue temperature ≥50°C (t-T ≥ 50°C) was fastest in Qmode+, followed by TacthCath, STSF, and Qmode (4.3 ± 2.5, 6.4 ± 1.9, 7.1 ± 2.8, and 7.7 ± 3.1 s, respectively; p < .001). The catheter tip-to-thermocouple distance for lethal temperature (indicating lesion depth) from receiver operating characteristic curve analysis was deepest in STSF at 5.2 mm, followed by Qmode at 4.3 mm, Qmode+ at 3.1 mm, and TactiCath at 2.8 mm. Ablation at the SVC near the phrenic nerve led to sudden injury at t-T ≥ 50°C in all four settings. The esophageal adventitia injury was least deep with Qmode+ ablation (0.4 ± 0.1 vs. 0.8 ± 0.4 mm for Qmode, 0.9 ± 0.3 mm for TactiCath, and 1.1 ± 0.5 mm for STSF, respectively; p = .005), correlating with Tmax .

CONCLUSION

This study revealed distinct tissue temperature patterns during HSPD and vHPSD ablations with the three catheters, affecting lesion effectiveness and collateral damage based on Tmax and/or t-T ≥ 50°C. These findings provide key insights into the safety and efficacy of AF ablation with these four settings.

Trends over the recent 6 years in ablation modalities and strategies, post-ablation medication, and clinical outcomes of atrial fibrillation ablation

Background

Ablation strategies and modalities for atrial fibrillation (AF) have transitioned over the past decade, but their impact on post-ablation medication and clinical outcomes remains to be fully investigated.

Methods

We divided 682 patients who had undergone AF ablation in 2014-2019 (420 paroxysmal AFs [PAF], 262 persistent AFs [PerAF]) into three groups according to the period, that is, the 2014-2015 (n = 139), 2016-2017 (n = 244), and 2018-2019 groups (n = 299), respectively.

Results

Persistent AF became more prevalent and the left atrial (LA) diameter larger over the 6 years. Extra-pulmonary vein (PV)-LA ablation was more frequently performed in the 2014-2015 group than in the 2016-2017 and 2018-2019 groups (41.1% vs. 9.1% and 8.1%; p < .001). The 2-year freedom rate from AF/atrial tachycardias for PAF was similar among the three groups (84.0% vs. 83.1% vs. 86.7%; p = .98) but lowest in the 2014-2015 group for PerAF (63.9% vs. 82.7% and 86.3%; p = .025) despite the highest post-ablation antiarrhythmic drug use. Cardiac tamponade was significantly decreased in the 2018-2019 group (3.6% vs. 2.0% vs. 0.33%; p = 0.021). There was no difference in the 2-year clinically relevant events among the three groups.

Conclusion

Although ablation was performed in a more diseased LA and extra-PV-LA ablation was less frequent in recent years, the complication rate decreased, and AF recurrences for PAF remained unchanged, but that for PerAF decreased. Clinically relevant events remained unchanged over the recent 6 years, suggesting that the impact of the recent ablation modalities and strategies on remote clinically relevant events may be small during this study period.

In vivo tissue temperatures during 90 W/4 sec-very high power-short-duration (vHPSD) ablation versus ablation index-guided 50 W-HPSD ablation: A porcine study

INTRODUCTION

Neither the actual in vivo tissue temperatures reached with 90 W/4 s-very high-power short-duration (vHPSD) ablation for atrial fibrillation nor the safety and efficacy profile have been fully elucidated.

METHODS

We conducted a porcine study (n = 15) in which, after right thoracotomy, we implanted 6-8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We compared tissue temperatures close to a QDOT MICRO catheter, between during 90 W/4 s-vHPSD ablation during ablation index (AI: target 400)-guided 50 W-HPSD ablation, both targeting a contact force of 8-15 g.

RESULTS

Maximum tissue temperature reached during 90 W/4 s-vHPSD ablation did not differ significantly from that during 50 W-HPSD ablation (49.2 ± 8.4°C vs. 50.0 ± 12.1°C; p = .69) and correlated inversely with distance between the catheter tip and the thermocouple, regardless of the power settings (r = -0.52 and r = -0.37). Lethal temperature (≥50°C) was best predicted at a catheter tip-to-thermocouple distance cut-point of 3.13 and 4.27 mm, respectively. All lesions produced by 90 W/4 s-vHPSD or 50 W-HPSD ablation were transmural. Although there was no difference in the esophageal injury rate (50% vs. 66%, p = .80), the thermal lesion was significantly shallower with 90 W/4 s-vHPSD ablation than with 50W-HPSD ablation (381.3 ± 127.3 vs. 820.0 ± 426.1 μm from the esophageal adventitia; p = .039).

CONCLUSION

Actual tissue temperatures reached with 90 W/4 s-vHPSD ablation appear similar to those with AI-guided 50 W-HPSD ablation, with the distance between the catheter tip and target tissue being shorter for the former. Although both ablation settings may create transmural lesions in thin atrial tissues, any resulting esophageal thermal lesions appear shallower with 90 W/4 s-vHPSD ablation.

Intravenous Semaphorin 3A Administration Maintains Cardiac Contractility and Improves Electrical Remodeling in a Mouse Model of Isoproterenol-Induced Heart Failure

The effects of recombinant semaphorin 3A (Sema3A) on myocardial contractility and electrical remodeling in mice with isoproterenol (ISP) -induced heart failure were investigated.C57BL/6J mice intraperitoneally received ISP (480 mg/kg/day, ISP group; n = 24) or saline (control group; n = 31) for 14 days. Twenty-one ISP-treated mice received 0.5 mg/kg Sema3A intravenously on days 7 and 11 (ISP+Sema3A group). The sympathetic nervous system was activated upon ISP treatment, but was reduced upon Sema3A administration. Greater myocardial tissue fibrosis was observed in the ISP group than in the control group. However, fibrosis was not significantly different between the ISP+Sema3A and control groups. Fractional shortening of the left ventricle was lower in the ISP group than in the control group and was restored in the ISP+Sema3A group (control, 53 ± 8%; ISP, 37 ± 7%; ISP+Sema3A, 48 ± 3%; P < 0.05). Monophasic action potential duration at 20% repolarization (MAPD₂₀) was prolonged in the ISP group (compared to control group), but this was reversed upon Sema3A administration (control, 29 ± 3 ms; ISP, 35 ± 6 ms; ISP+Sema3A, 29 ± 3 ms; P < 0.05). qPCR revealed Kv4.3, KChIP2, and SERCA2 downregulation in the ISP group and upregulation in the ISP+Sema3A group; however, Western blotting revealed similar changes only for Kv4.3 (P < 0.05).Intravenous Sema3A may maintain myocardial contractility by suppressing the sympathetic innervation of the myocardium and reducing myocardial tissue damage, in addition to restoring MAPD via Kv4.3 upregulation.

In vivo tissue temperature during lesion size index-guided 50W ablation versus 30W ablation: A porcine study

BACKGROUND

Neither the actual in vivo tissue temperatures reached with lesion size index (LSI)-guided high-power short-duration (HPSD) ablation for atrial fibrillation nor the safety profile has been elucidated.

METHODS

We conducted a porcine study (n = 7) in which, after right thoracotomy, we implanted 6-8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We compared tissue temperatures reached during 50 W-HPSD ablation with those reached during standard (30 W) ablation, both targeting an LSI of 5.0 (5-15 g contact force).

RESULTS

T_max  (maximum tissue temperature when the thermocouple was located ≤5 mm from the catheter tip) reached during HPSD ablation was modestly higher than that reached during standard ablation (58.0 ± 10.1°C vs. 53.6 ± 9.2°C; p = .14) and peak tissue temperature correlated inversely with the distance between the catheter tip and the thermocouple, regardless of the power settings (HPSD: r = -0.63; standard: r = -0.66). Lethal temperature (≥50°C) reached 6.3 ± 1.8 s and 16.9 ± 16.1 s after the start of HPSD and standard ablation, respectively (p = .002), and it was best predicted at a catheter tip-to-thermocouple distance cut point of 2.8 and 5.3 mm, respectively. All lesions produced by HPSD ablation and by standard ablation were transmural. There was no difference between HPSD ablation and standard ablation in the esophageal injury rate (70% vs. 75%, p = .81), but the maximum distance from the esophageal adventitia to the injury site tended to be shorter (0.94 ± 0.29 mm vs. 1.40 ± 0.57 mm, respectively; p = .09).

CONCLUSIONS

Actual tissue temperatures reached with LSI-guided HPSD ablation appear to be modestly higher, with a shorter distance between the catheter tip and thermocouple achieving lethal temperature, than those reached with standard ablation. HPSD ablation lasting <6 s may help minimize lethal thermal injury to the esophagus lying at a close distance.

Bradyarrhythmia Suspected to be Associated with Sleep Apnea Syndrome

Sleep apnea syndrome (SAS) is a condition in which apnea and hypoventilation at night cause hypoxemia and impaired wakefulness during the day, resulting in a general malaise and dozing. Sleep apnea has been implicated in the development of hypertension, ischemic heart disease, arrhythmia, heart failure, and cerebrovascular disease.¹⁾ Approximately 50% of patients with sleep-disordered breathing have an arrhythmia. In severe cases with an apnea-hypopnea index (AHI) of 30 or more, the frequency of arrhythmias during sleep is two to four times that of individuals without SAS. Bradyarrhythmias such as sinus bradycardia, sinus arrest, and atrioventricular block occurs at night in about 5%-10% of patients with sleep-disordered breathing.²⁾During nocturnal sleep, vagal excitation causes excessive muscle relaxation of the upper airway, leading to periodic airway diameter reduction, which increases snoring and obstructive apnea. As a result, hypoxemia is likely, further increasing vagal tone and leading to bradycardia. An increase in ventilation rate and volume quickly compensates for the decrease in arterial partial pressure of oxygen during apnea, which leads to new bradycardia due to a decrease in the partial pressure of oxygen in arterial blood, which suppresses vagal tone and respiration.³⁾We experienced a case of a 44-year-old patient with bradyarrhythmia that might be associated with SAS. After continuous positive airway pressure treatment, AHI decreased, and very long cardiac arrests resolved.

AV timing in pacemaker patients with first-degree AV block: which is preferable, intrinsic AV conduction or pacing?

Some patients with pacemakers present with first-degree atrioventricular (AV) block. To avoid right ventricular (RV) pacing, preserving intrinsic AV conduction as much as possible is recommended. However, there is no clear cutoff AV interval to determine whether intrinsic AV conduction should be preserved or RV pacing should be delivered. This study aimed to compare a pacing mode-preserving, intrinsic AV conduction with the DDD mode delivering RV pacing in terms of echocardiographic parameters in patients with first-degree AV block and to investigate whether RV pacing induces heart failure (HF). Stroke volume (SV) was measured to determine the optimal AV delay with the intrinsic AV conduction rhythm and the DDD pacing delivering RV pacing. Echocardiographic evaluation was performed for 6-month follow-up period. Seventeen patients were studied. At baseline, mean intrinsic PQ interval was 250 ± 40 ms. SV was greater with RV pacing with optimal AV delay of 160 ms than with intrinsic AV conduction rhythm in all patients. Therefore, pacemakers were set to the DDD to deliver RV pacing. During follow-up, seven patients developed HF. Mean baseline E/E′ ratio in patients who developed HF (HF group) during RV pacing was higher than in patients without HF (non = HF group; 17.9 ± 8 versus 11.5 ± 2, P = 0.018) Even within HF group patients without a high baseline E/E′ ratio, it increased with RV pacing (22.2 ± 6 versus 11.6 ± 2; P < 0.001). In patients with pacemaker and first-degree AV block, RV pacing with the optimal AV delay of 160 ms increased SV. However, the risk of HF may be increased with RV pacing if the E/Eʹ ratio is > 15 during intrinsic AV conduction or RV pacing. RV pacing should be avoided in patients with high E/Eʹ ratio under intrinsic AV conduction or RV pacing.

Prognostic value of the MELD-XI score in patients undergoing cardiac resynchronization therapy

Aims

Multi‐organ dysfunction was recently reported to be a common condition in patients with heart failure (HF). The Model for End‐stage Liver Disease eXcluding International normalized ratio (MELD‐XI) score reflects liver and kidney function. The prognostic relevance of this score has been reported in patients with a variety of cardiovascular diseases who are undergoing interventional therapies. However, the relationship between the severity of hepatorenal dysfunction assessed by the MELD‐XI score and the long‐term clinical outcomes of HF patients receiving cardiac resynchronization therapy (CRT) has not been evaluated.

Methods and results

Clinical records of 283 patients who underwent CRT implantation between March 2003 and October 2020 were retrospectively evaluated (mean age 67 ± 12, 22.6% female). Blood samples were collected before CRT implantation. Patients were divided into three groups based on tertiles of the MELD‐XI score: first tertile (MELD‐XI = 9.44, n = 95), second tertile (9.44 < MELD‐XI < 13.4, n = 94), and third tertile (MELD‐XI ≥ 13.4, n = 94). The primary endpoint was all‐cause mortality. Compared with the other groups, the third tertile group exhibited significantly older age, higher prevalence of diabetes mellitus and hypertension, lower haemoglobin level, and higher N‐terminal pro‐brain natriuretic peptide level (all P < 0.05). The functional CRT response rate was also significantly lower in the third tertile group (P = 0.011). During a median follow‐up of 30 months (inter‐quartile range, 9–67), 105 patients (37.1%) died. Kaplan–Meier analysis revealed that patients with a higher MELD‐XI score had a greater risk of all‐cause mortality (log‐rank test: P < 0.001). Even after adjustment for clinically relevant factors and a conventional risk score, the MELD‐XI score was still associated with mortality (adjusted hazard ratio: 1.04, 95% confidence interval: 1.00–1.07, P = 0.014, and adjusted hazard ratio: 1.04, 95% confidence interval: 1.01–1.09, P = 0.005, respectively). A higher MELD‐XI score was associated with a greater risk of all‐cause mortality than a lower MELD‐XI score regardless of whether a pacemaker or defibrillator was implanted (log‐rank test: P = 0.010 and P < 0.001, respectively).

Conclusions

Impaired hepatorenal function assessed by the MELD‐XI score was associated with older age, higher prevalence of multiple co‐morbidities, severity of HF, lower CRT response rates, and subsequent all‐cause mortality in HF patients undergoing CRT implantation. These results suggest that the MELD‐XI score can provide additional prognostic information and may be useful for improving risk stratification in this population.

Toe white line separation associated with the notch (crena marginalis) on the distal phalanges in Thoroughbred yearling horses

The shape of the white line of the hoof is closely related to the shape of the notch on the dorsal distal bearing border of the distal phalanx (P3). In this study, a radiographic survey of the P3 of both forelimbs of 163 Thoroughbred yearling horses was conducted. The correlation of the depth and width of the notch were analyzed with the toe white line separation grades (0 to 3). As a result, the toe white line separation grade increased, the depth and the width of the notch also increased significantly. Radiographic examination of the P3 of the forelimbs might be useful for deciding whether to implement hoof care to prevent onset of toe white line separation.

Prognostic importance of the Controlling Nutritional Status (CONUT) score in patients undergoing cardiac resynchronisation therapy

Aims

Malnutrition is common and associated with worse clinical outcomes in patients with heart failure (HF). The Controlling Nutritional Status (CONUT) score is an integrated index for evaluating diverse aspects of the complex mechanism of malnutrition. However, the relationship between the severity of malnutrition assessed by the CONUT score and clinical outcomes of HF patients receiving cardiac resynchronisation therapy (CRT) has not been fully clarified.

Methods

Clinical records of 263 patients who underwent pacemaker or defibrillator implantation for CRT between March 2003 and October 2020 were retrospectively evaluated. The CONUT score was calculated from laboratory data obtained before CRT device implantation. Patients were divided into three groups: normal nutrition (CONUT scores 0–1, n=58), mild malnutrition (CONUT scores 2–4, n=132) and moderate or severe malnutrition (CONUT scores 5–12, n=73). The primary endpoint was all-cause mortality.

Results

The moderate or severe malnutrition group had a lower body mass index, more advanced New York Heart Association functional class, higher Clinical Frailty Scale score, lower levels of haemoglobin and higher levels of N-terminal probrain natriuretic peptide (all p<0.05). In the moderate or severe malnutrition group, the CRT response rate was significantly lower than for the other two groups (p=0.001). During a median follow-up period of 31 (10–67) months, 103 (39.1%) patients died. Kaplan-Meier analysis revealed that the moderate or severe malnutrition group had a significantly higher mortality rate (log-rank p<0.001). A higher CONUT score and CONUT score ≥5 remained significantly associated with all-cause mortality after adjusting for previously reported clinically relevant factors and the conventional risk score (VALID-CRT risk score) (all p<0.05).

Conclusions

A higher CONUT score before CRT device implantation was strongly associated with HF severity, frailty, lower CRT response rate and subsequent long-term all-cause mortality.

Actual tissue temperature during ablation index-guided high-power short-duration ablation versus standard ablation: Implications in terms of the efficacy and safety of atrial fibrillation ablation

BACKGROUND

Actual in vivo tissue temperatures and the safety profile during high-power short-duration (HPSD) ablation of atrial fibrillation have not been clarified.

METHODS

We conducted an animal study in which, after a right thoracotomy, we implanted 6-8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We recorded tissue temperatures during a 50 W-HPSD ablation and 30 W-standard ablation targeting an ablation index (AI) of 400 (5-15 g contact force).

RESULTS

Maximum tissue temperatures reached with HSPD ablation were significantly higher than that reached with standard ablation (62.7 ± 12.5 vs. 52.7 ± 11.4°C, p = 0.033) and correlated inversely with the distance between the catheter tip and thermocouple, regardless of the power settings (HPSD: r = -0.71; standard: r = -0.64). Achievement of lethal temperatures (≥50°C) was within 7.6 ± 3.6 and 12.1 ± 4.1 s after HPSD and standard ablation, respectively (p = 0.003), and was best predicted at cutoff points of 5.2 and 4.4 mm, respectively. All HPSD ablation lesions were transmural, but 19.2% of the standard ablation lesions were not (p = 0.011). There was no difference between HPSD and standard ablation regarding the esophageal injury rate (30% vs. 33.3%, p > 0.99), with the injury appearing to be related to the short distance from the catheter tip.

CONCLUSIONS

Actual tissue temperatures reached with AI-guided HPSD ablation appeared to be higher with a greater distance between the catheter tip and target tissue than those with standard ablation. HPSD ablation for <7 s may help prevent collateral tissue injury when ablating within a close distance.

Modified ablation index: a novel determinant of a successful first-pass left atrial posterior wall isolation

Although a left atrial posterior wall isolation (LAPWI) in addition to a pulmonary vein isolation is a well-accepted option for persistent atrial fibrillation (AF), a complete isolation can be challenging. This study aimed to evaluate the performance of a modified ablation index (AI) (AI/bipolar voltage along the ablation line) for predicting a durable LAPWI. The study included 55 consecutive patients, aged 65 ± 11 years, who underwent an electroanatomic mapping-guided LAPWI of AF. The association between the gaps (first-pass LAPWI failure and/or acute LAPW reconnections), voltage amplitude along the roof and floor lines, and thickness of the LAPW was investigated. Gaps occurred in 22 patients (40%) and in 26 (8%) of the 330 line segments. Gaps were associated with a relatively high bipolar voltage (3.38 ± 1.83 vs. 1.70 ± 1.12 mV, P < 0.0001) and thick LA wall (2.52 ± 1.15 vs. 1.42 ± 0.44 mm, P < 0.0001). A modified AI ≤ 199 AU/mV, bipolar voltage ≥ 2.64 mV, wall thickness ≥ 2.04 mm, and roof ablation line ≥ 43.4 mm well predicted gaps (AUCs: 0.783, 0.787, 0.858, and 0.752, respectively). A high-voltage zone, thick LAPW, and long roof ablation line appeared to be determinants of gaps, and a modified AI ≥ 199 AU/mV along the ablation lines appeared to predict an acute durable LAPWI.

Different Determinants of the Recurrence of Atrial Fibrillation and Adverse Clinical Events in the Mid-Term Period After Atrial Fibrillation Ablation

BACKGROUND

It is unclear whether there are differences in the clinical factors between atrial fibrillation (AF) recurrence and adverse clinical events (AEs), including stroke/transient ischemic attack (TIA), major bleeding, and death, after AF ablation.Methods and Results:We examined the data from a retrospective multicenter Japanese registry conducted at 24 cardiovascular centers between 2011 and 2017. Of the 3,451 patients (74.1% men; 63.3±10.3 years) who underwent AF ablation, 1,046 (30.3%) had AF recurrence and 224 (6.5%) suffered AEs (51 strokes/TIAs, 71 major bleeding events, and 36 deaths) over a median follow-up of 20.7 months. After multivariate adjustment, female sex, persistent and long-lasting persistent AF (vs. paroxysmal AF), and stepwise increased left atrial diameter (LAd) quartiles were significantly associated with post-ablation recurrences. A multivariate analysis revealed that an age ≥75 years (vs. <65 years), body weight <50 kg, diabetes, vascular disease, left ventricular (LV) ejection fraction <40% (vs. ≥50%), Lad ≥44 mm (vs. <36 mm), and creatinine clearance <50 mL/min were independently associated with AE incidences, but not with recurrences.

CONCLUSIONS

This study disclosed different determinants of post-ablation recurrence and AEs. Female sex, persistent AF, and enlarged LAd were determinants of post-ablation recurrence, whereas an old age, comorbidities, and LV and renal dysfunction rather than post-ablation recurrence were AEs determinants. These findings will help determine ablation indications and post-ablation management.

Formation of low-voltage zones on the anterior left atrial wall due to mechanical compression by the ascending aorta

BACKGROUND

Although low-voltage zones (LVZs) in the left atrium (LA) are considered arrhythmogenic substrates in some patients with atrial fibrillation (AF), the pathophysiologic factors responsible for LVZ formations remain unclear.

OBJECTIVE

To elucidate the anatomical relationship between the LA and ascending aorta responsible for anterior LA wall remodeling.

METHODS

We assessed the relationship between existence of LVZs on the anterior LA wall and the three-dimensional computed tomography image measurements in 102 patients who underwent AF ablation.

RESULTS

Twenty-nine patients (28%) had LVZs grearer than 1.0 cm² on the LA wall in the LA-ascending aorta contact area (LVZ group); no LVZs were seen in the other 73 patients (no-LVZ group). The LVZ group (vs. no-LVZ group) had a smaller aorta-LA angle (21.0 ± 7.7° vs. 24.9 ± 7.1°, p = .015), greater aorta-left-ventricle (LV) angle (131.3 ± 8.8° vs. 126.0 ± 7.9°; p = .005), greater diameter of the noncoronary cusp (NCC; 20.4 ± 2.2 vs. 19.3 ± 2.5 mm; p = .036), thinner LA wall-thickness adjacent to the NCC (2.3 ± 0.7 vs. 2.8 ± 0.8 mm; p = .006), and greater cardiothoracic ratio (percentage of the area in the thoracic area, 40.1 ± 7.1% vs. 35.4 ± 5.7%, p < .001). The aorta-LA angle correlated positively with the patients' body mass index (BMI), and the aorta-LV angle correlated negatively with the body weight and BMI.

CONCLUSION

Deviation of the ascending aorta's course and distention of the NCC appear to be related to the development of LA anterior wall LVZs in the LA-ascending aorta contact area. Mechanical pressure exerted by extracardiac structures on the LA along with the limited thoracic space may contribute to the development of LVZs associated with AF.

Three-dimensional visualization of bidirectional preferential pathway conduction of premature ventricular contractions originating from the outflow tract

INTRODUCTION

Preferential pathway conduction is mostly detected as fractionated presystolic-potentials preceding the QRS during premature ventricular contractions (PVCs) and late-potentials during sinus rhythm (SR), but the electrophysiologic mechanisms and significance of these potentials have not been fully clarified. We describe a PVC case series in which the preferential pathway conduction was three-dimensionally visualized.

METHODS

Five PVCs (two from the left coronary cusp, two from the commissure of the left and right coronary cusps, and one from the pulmonary artery) in four patients for which a fractionated presystolic-potential during the PVCs and late-potential during SR were recorded at the successful ablation site were reviewed, and three-dimensional coherent activation maps with the conduction velocity vector during the PVCs and SR were reconstructed.

RESULTS

At the successful ablation site, an "M"-shaped discrete presystolic-potential and "W"-shaped discrete late-potential were recorded in all patients. The configuration of the inverted electrogram of the presystolic-potential was similar to that of the electrogram exhibiting the late-potential. We created coherent activation maps annotating the onset of the presystolic-potentials during the PVCs and offset of the late-potentials during SR, which suggested bidirectional conduction of the preferential pathway connecting the PVC origin to the myocardium.

CONCLUSION

Detailed activation mapping of these PVCs is consistent with the presence of fibers along the aortic or pulmonic valve ring that have preferential directions for conduction. PVCs produce a presystolic-potential. In SR, the fiber is activated late and from the opposite direction, producing an inverted potential inscribed on the end of the QRS.

Effect of obesity and epicardial fat/fatty infiltration on electrical and structural remodeling associated with atrial fibrillation in a novel canine model of obesity and atrial fibrillation: A comparative study

BACKGROUND

How obesity and epicardial fat influence atrial fibrillation (AF) is unknown.

METHODS

To investigate the effect of obesity/epicardial fat on the AF substrate, we divided 20 beagle dogs of normal weight into four groups (n = 5 each): one of the four groups (Obese-rapid atrial pacing [RAP] group) served as a novel canine model of obesity and AF. The other three groups comprised dogs fed a standard diet without RAP (Control group), dogs fed a high-fat diet without RAP (Obese group), or dogs fed a standard diet with RAP (RAP group). All underwent electrophysiology study, and hearts were excised for histopathologic and fibrosis-related gene expression analyses.

RESULTS

Left atrial (LA) pressure was significantly higher in the Obese group than in the Control, RAP, and Obese-RAP groups (23.4 ± 6.9 vs. 11.4 ± 2.1, 11.9 ± 6.4, and 13.5 ± 2.9 mmHg; p = .005). The effective refractory period of the inferior PV was significantly shorter in the RAP and Obese-RAP groups than in the Control group (p = .043). Short-duration AF was induced at greatest frequency in the Obese-RAP and Obese groups (p < .05). Epicardial fat/Fatty infiltration was greatest in the Obese-RAP group, and greater in the Obese and RAP groups than in the Control group. %interstitial fibrosis/fibrosis-related gene expression was significantly greater in the Obese-RAP and RAP groups (p < .05).

CONCLUSIONS

Vulnerability to AF was associated with increased LA pressure and increased epicardial fat/fatty infiltration in our Obese group, and with increased epicardial fat/fibrofatty infiltration in the RAP and Obese-RAP groups. These may explain the role of obesity/epicardial fat in the pathogenesis of AF.

Impact of the combined use of intracardiac ultrasound and a steerable sheath visualized by a 3D mapping system on pulmonary vein isolation

BACKGROUND

A novel steerable sheath visualized on a three-dimensional mapping system has become available in this era in which a durable pulmonary vein (PV) isolation (PVI) with reduced fluoroscopy is required.

METHODS

In 60 patients who underwent a PVI with a visualized sheath (n = 30) and non-visualized conventional sheath (n = 30), the fluoroscopic time and catheter stability during the PVI were analyzed.

RESULTS

The fluoroscopic time during the transseptal access (0 [0, 0.1] vs. 1.4 [0.8, 2.3] minutes, P < .001) and PVI (0 [0, 0.1] vs. 0.4 [0.2, 1.1] minutes, P < .001) were shorter in the visualized sheath group than conventional sheath group. The procedure time during the PVI (32.0 [26.8, 36.3] vs. 41.0 [31.8, 47.3] minutes, P = .01), particularly during the right PVI (15.0 [12.8, 18.0] vs. 23.0 [15.8, 26.3] minutes, P = .009), was shorter in the visualized sheath group than conventional sheath group, however, that during the other steps was equivalent. The standard deviation of the catheter contact force during each radiofrequency application was smaller in the visualized sheath group than conventional sheath group (4.5 ± 2.7 vs. 4.9 ± 3.1 g, P = .001). The impedance drop for each lesion was larger in the visualized sheath group than conventional sheath group (10.7 ± 6.5 vs. 9.8 ± 5.5 ohms, P < .001). The incidence of acute PV reconnections per patient (30% vs. 23%, P = .56) and per PV segment (2.5% vs. 2.3%, P = .83) were similar between the two groups. No major complications occurred in either sheath group.

CONCLUSIONS

The use of visualized sheaths may reduce the fluoroscopic time and improve the catheter stability during the PVI.

Resetting of atrial tachycardia by a scanned extrastimulus at a downstream site on a multielectrode catheter: a simple diagnostic maneuver for locating the macroreentrant atrial tachycardia circuit

PURPOSE

Entrainment is a useful method for locating reentrant atrial tachycardia (AT) circuits, but alterations or termination of the AT can derail this process. We assessed whether resetting an upstream site of a neighboring electrode by a scanned extrastimulus at a downstream site (when the upstream tissue was refractory) could diagnose that site within the AT circuit.

METHODS

The procedure was applied to 48 ATs with a cycle length (CL) of 238 ± 42 ms (26 common flutters, 8 perimitral flutters, 7 left atrial [LA] roof-dependent AT, 3 LA scar-related macroreentrant ATs, 2 pulmonary vein-gap reentry tachycardias, 1 right atrial scar-related macroreentrant AT, and 1 with an unidentified circuit). Entrainment and scanned extrastimulation were attempted at the cavotricuspid isthmus, LA roof, and mitral isthmus and/or critical AT isthmus.

RESULTS

Within the circuit, the post-pacing interval minus the ATCL after entrainment was < 30 ms for all ATs and resetting of the AT cycle by ≥ 5 ms occurred in 94% of the ATs. No ATs were reset by extrastimulation outside the circuit. The positive predictive value of both maneuvers for locating the circuit was 100%, and the negative predictive value of the extrastimulation was similar to that of entrainment (96% vs. 100%, P = 0.25). The incidence of an AT alteration was lower with extrastimulation than with entrainment (1% vs. 9%, P = 0.01). For ATs with a CL < 210 ms, extrastimulation yielded a good diagnostic performance without any AT alterations.

CONCLUSION

AT resetting by a scanned extrastimulus is diagnostic and avoids AT alterations.

A porcine study of the area of heated tissue during hot-balloon ablation: Implications for the clinical efficacy and safety

INTRODUCTION

Hot-balloon ablation depends solely on thermal conduction, and myocardial tissue is ablated by only conductive heating from the balloon surface. Despite growing clinical evidence of the efficacy and safety of hot-balloon ablation for atrial fibrillation (AF), the actual tissue temperature and the mechanism of heating during such ablation has not been clarified. To determine, by means of a porcine study, the temperatures of tissues targeted during hot-balloon ablation of AF performed with hot-balloon set temperatures of 73°C or 70°C, in accordance with the temperatures now used clinically.

METHODS

After a right thoracotomy, thermocouples with markers were implanted epicardially on the superior vena cava (SVC) and pulmonary veins (PVs) in six pigs. The tissue temperatures during hot-balloon ablation (balloon set temperatures of 73°C and 70°C, 180 s/PV) were recorded, and the maximum tissue temperatures and fluoroscopically measured distance from the balloon surface to the target tissues were assessed.

RESULTS

Sixteen SVC- and 18 PV-targeted energy deliveries were performed. Full-thickness circumferential PV lesions were created with all hot-balloon applications. A significant inverse relation was found between the recorded tissue temperatures and distance (r = -.67; p < .001) from the balloon surface. No tissue temperature exceeded either of the balloon set temperatures. The best distance cutoff value for achieving lethal tissue temperatures more than 50°C was 3.6 mm.

CONCLUSION

The hot-balloon set temperature, energy delivery time, and tissue temperature data obtained in this porcine study supported the clinical efficacy and safety of the hot-balloon ablation as currently practiced in patients with AF.

Current Status and Issues Concerning Magnetic Resonance Imaging in Patients with a Magnetic Resonance Conditional Cardiac Implantable Electrical Device: A Single-center Study

Objective Following the introduction of magnetic resonance (MR)-conditional cardiac implantable electrical devices (CIEDs), patients with CIEDs have undergone MRI scanning more frequently. As the required settings of MRI equipment for scanning patients with a CIED vary by device, a number of precautions should be taken to allow safe examinations, including the confirmation of conditions and selection of MRI modes appropriate for pacing status in individual patients. In this study, we examined the current status and issues concerning the performance of MRI examinations in patients with an MRI-conditional CIED. Method and Results We reviewed a total of 262 MRI scans. The most common site of MRI scanning was the head, followed by the spine, abdomen, and heart in order. Regarding the MRI mode, DOO was most often used, followed by OFF, AOO, and finally VOO mode, to maintain atrioventricular synchrony. Although no obvious adverse events were observed related to MRI scanning, there were several cases encountered that might have been predisposed to a significant incident or in which the patient's intrinsic pulse rates or subjective symptoms changed before and during scanning. Conclusion As MRI is a very useful diagnostic tool for cerebrovascular diseases and orthopedic disorders, the demand for MRI scanning is high when treating these areas. Although MRI scanning in patients with MR-conditional devices was performed without any adverse events, there were incidents that could have potentially led to major harm. This highlights the importance of confirming the appropriate MRI mode is being used before scanning and monitoring patients during scanning.

Influence of obesity and epicardial fat on the progression of electrical and structural remodeling in a canine obese rapid atrial pacing model

Background

Metabolic syndrome is a cluster of conditions including obesity, insulin resistance, hypertension, and abnormal cholesterol, which increases the cardiovascular risk. Metabolic syndrome or obesity has been reported to provide systemic inflammation and oxidative stress. Increased epicardial fat volume is a manifestation of obesity or metabolic syndrome. Those systemic and local conditions related to obesity or metabolic syndrome have been linking to the risk of atrial fibrillation (AF). The underlying mechanisms of obesity linking epicardial fat to AF progression have not been fully examined.

Purpose

To investigate the impact of obesity linked to epicardial fat on electrophysiologic and anatomical AF substrates.

Methods

Twenty dogs aged 3 years were divided into four groups (n=5 per each): normal diet for over 20 weeks (control group [median body weight: 12.0 kg]), rapid atrial pacing (RAP) for last 4–15 (median 8) weeks during a normal diet for the same period (RAP group [10.5 kg]), high-fat diet (HFD) maintained for over 20 weeks without RAP (MetS group [16.0 kg]), and RAP for last 4–12 (median 6) weeks during HFD maintained for 24 weeks (MetS-RAP group [17.0 kg]), respectively. Activation/voltage maps of the atria during sinus rhythm were created with Ensite NavX mapping system. The effective refractory period (ERP) at 5 left atrial (LA) and pulmonary vein (PV) sites (LA appendage [LAA], LA body, right and left superior PVs, and inferior PV), and AF inducibility by burst LAA pacing were determined. At study completion, hearts were excised for histopathological and gene expression analyses.

Results

The LA pressure was more significantly increased in MetS than the MetS-RAP, RAP, and control groups (22.5 [17–28.8] mmHg vs. 14.0 [10.5–16.3] mmHg, 10.5 [7.4–17.2] mmHg and 10.7 [9.6–13.5] mmHg, respectively, P&lt;0.05). The LA/PV ERP at a basic cycle length of 400 ms was shorter in the MetS-RAP and RAP than MetS and control groups (118±39 ms and 122±44 ms vs. 136±18 ms and 155±39 ms, respectively, P&lt;0.05). Short duration AF was more induced in the MetS and MetS-RAP than RAP and control groups (3 [0–5.5] sec and 2 [0.5–3.5] sec vs. 0 [0–4.5] sec and 0 [0–0] sec, P&lt;0.05). Histological examinations showed the fatty infiltration extending from epicardial fat increased more in the Mets and Mets-RAP than RAP and control groups (Figure). The Fibronectin 1 and collagen I/III mRNA levels increased more in the MetS-RAP and AF than MetS and control groups.

Conclusions

AF vulnerability was associated with increased LA pressures and fibrofatty infiltration from epicardial fat in the MetS group, and with fibrofatty infiltration from epicardial fat with subtle fibrosis in the MetS-RAP group. This suggested that fibrofatty infiltration and epicardial fat plays an important role in AF pathogenesis in obese patients.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Scientific Research (KAKENHI)

Is Vagal Response During Left Atrial Ganglionated Plexi Stimulation a Normal Phenomenon?

Background:

Ganglionated plexi (GPs) play an important role in both the initiation and maintenance of atrial fibrillation (AF). GPs can be located by using continuous high-frequency stimulation (HFS) to elicit a vagal response, but whether the vagal response phenomenon is common to patients without AF is unknown.

Methods:

HFS of the left atrial GPs was performed in 42 patients (aged 58.0±10.2 years) undergoing ablation for AF and 21 patients (aged 53.2±12.8 years) undergoing ablation for a left-sided accessory pathway. The HFS (20 Hz, 25 mA, 10-ms pulse duration) was applied for 5 seconds at 3 sites within the presumed anatomic area of each of the 5 major left atrial GPs (for a total of 15 sites per patient). We defined vagal response to HFS as prolongation of the R-R interval by >50% in comparison to the mean pre-HFS R-R interval averaged over 10 beats and active-GP areas as areas in which a vagal response was elicited.

Results:

Overall, more active-GP areas were found in the AF group patients than in the non-AF group patients, and at all 5 major GPs, the maximum R-R interval during HFS was significantly prolonged in the AF patients. After multivariate adjustment, association was established between the total number of vagal response sites and the presence of AF.

Conclusions:

The significant increase in vagal responses elicited in patients with AF compared with responses in non-AF patients suggests that vagal responses to HFS reflect abnormally increased GP activity specific to AF substrates.

The modified ablation index: a novel determinant of acute pulmonary vein reconnections after pulmonary vein isolation

BACKGROUND

Although pulmonary vein isolation (PVI) guided by the ablation index (AI) has been well-developed, acute PV reconnections (PVRs) still occur. This study aimed to compare the prognostic performance of the modified AI and its optimal cut-off value for the prediction of acute PVRs to ensure durable PVI.

METHODS

Three-dimensional left atrium (LA) voltage maps created before an extensive encircling PVI in 64 patients with atrial fibrillation (AF) (45 men, 62 ± 10 years) were examined for an association between electrogram voltage amplitude recorded from the PV-LA junction and acute post-PVI PVRs (spontaneous PVRs and/or ATP-provoked dormant PV conduction).

RESULTS

Acute PVRs were observed in 22 patients (34%) and 33 (3%) of the 1012 PV segments. Acute PVRs were significantly associated with segments with higher bipolar voltage zones (3.23 ± 1.17 vs. 1.97 ± 1.20 mV, P < 0.0001), lower mean AI values (449 [428-450] vs. 460 [437-486], P = 0.05), and radiofrequency lesion gaps ≥ 6 mm (48 vs. 32%, P = 0.04), but not with contact force, force-time integral, or power. We created the modified AI calculated as AI/LA bipolar voltage, and found it to be significantly lower in areas with acute PVRs than in those without (152 [109-185] vs. 256 [176-413] AU/mV, P < 0.0001). Univariate analysis showed the prognostic performance of the modified AI, with an area under the curve of 0.801 (0.775-0.825), to be the highest of all the significant parameters.

CONCLUSIONS

Low values of the novel modified AI on the PV-encircling ablation line were strongly associated with acute PVRs.

Effect of epicardial fat and metabolic syndrome on reverse atrial remodeling after ablation for atrial fibrillation

BACKGROUND

Metabolic syndrome/epicardial adipose tissue (EAT) plays an important role in atrial fibrillation (AF). Although reverse atrial remodeling (RAR) often occurs after AF ablation, the effects of EAT on RAR remain unknown.

METHODS

Study subjects were 104 patients in whom transthoracic echocardiography (TTE) was performed before AF ablation and 3, 6, and 12 months afterward. EAT was assessed in terms of its thickness adjacent to the right ventricular anterior wall in the TTE parasternal view. RAR was defined as >10% reduction in the left atrial volume (LAV) index by the 3-month follow-up examination.

RESULTS

Postablation RAR occurred in 57/104 (55%) patients. RAR absence was associated with a relatively thick EAT (4.92 ± 1.65 vs. 3.92 ± 1.17 mm, P = 0.0005), small LAV index (24.6 ± 7.5 vs. 28.8 ± 10.6 mL/m2, P = 0.0233), and metabolic syndrome (62% vs. 28%, P = 0.0006). Metabolic syndrome and EAT were shown to be independent predictors of RAR absence. Thick EAT was significantly associated with AF recurrence after ablation (5.05 ± 2.19 mm vs. 4.17 ± 1.16 mm for no AF recurrence group, P = 0.0116), but metabolic syndrome was not (48% vs. 42%, P = 0.6189). Despite no change in body weight, EAT thickness decreased significantly by 12 months in patients without AF recurrence (4.17 ± 1.16 vs. 3.65 ± 1.16 mm, P < 0.0001).

CONCLUSIONS

EAT and metabolic syndrome appear to be strongly associated with RAR absence, but only the thick EAT was significantly associated with the postablation AF recurrence. Our findings, especially the thinning of EAT, suggest that thick EAT lead to AF vulnerability but that EAT reduction favorably affects ablation outcome.

Effect of genetic polymorphisms of azathioprine-metabolizing enzymes on response to rheumatoid arthritis treatment

Azathioprine (AZA) is increasingly being prescribed to rheumatoid arthritis (RA) patients. Following oral administration, AZA is converted into its active form. Inflammatory bowel disease (IBD) and systemic lupus erythematosus (SLE) patients with low thiopurine (S)-methyltransferase (TPMT) activity tend to respond well to AZA therapy. In a previous study of Japanese SLE patients under low-dose AZA therapy, the group with the 94C>A mutation in inosine triphosphatase (ITPA) showed greater improvement in their disease activity index. However, it is not yet clear how genotypes relate to responsiveness to RA treatment. The genotypes ITPA 94C>A, TPMT*3C, NUDT15 595C>T, GST-M1, GST-T1 and MRP4/ABCC4 2269G>A of Japanese patients with RA were determined. The relationship between these genotypes and response to AZA therapy was evaluated using the Disease Activity Score 28 (DAS28) and various medical data. Of the 22 patients 15 had the ITPA 94C/C genotype, 7 had the ITPA 94C/A genotype, none had the TPMT*3C mutation, 4 had the NUDT15 595C>T mutation, 8 had the GST-M1 and T1 null genotypes and 9 had the MRP4/ABCC4 2269G>A mutation. Changes in DAS28 at 6 months after baseline were similar in both ITPA genotype groups. However, the maintenance dose of AZA was significantly lower in the C/A group than in the C/C group (0.85±0.30 mg/kg/day vs. 1.2±0.46 mg/kg/day, respectively; p = 0.043). The ITPA 94C/A group showed the same response to RA treatment as the C/C group, but at a lower dose. This demonstrates that RA patients with the ITPA 94C>A mutation are more responsive to AZA.

Interfacial Structure of PtNi Surface Alloy on Pt(111) Electrode for Oxygen Reduction Reaction

The interfacial structure and activity for the oxygen reduction reaction (ORR) were investigated on a PtNi surface alloy on a Pt(111) electrode (PtNi/Pt(111)). The PtNi surface alloy was prepared by thermal annealing of Ni²⁺ modified on Pt(111) at 573-803 K. After optimizing the alloying temperature and the amount of added Ni, the ORR current density of PtNi/Pt(111) at 0.9 V (reversible hydrogen electrode) is enhanced 9.5 times compared with that of Pt(111), and the activity is decreased by 24% after 1000 potential cycles. The atomic composition and subsurface structure of PtNi/Pt(111) were determined by in situ infrared reflection-absorption spectroscopy and X-ray diffraction. The surface contains a (111)-oriented Pt-skin and the subsurface of the 2nd-5th layers of the PtNi alloy contains less than 11% Ni atoms. The layer spacings of the surface alloy layers are slightly expanded compared with those of bare Pt(111). Homogeneous alloying with a small amount of Ni in the subsurface layers achieves the high ORR activity and durability.

Suppression of infliximab antibody levels by azathioprine in patients with rheumatoid arthritis

In rheumatoid arthritis (RA) treatment, the concomitant use of methotrexate has been shown to reduce the incidence of antibodies to infliximab (ATI), on the other hand, it is unclear whether azathioprine can reduce ATI production. We enrolled a total of 10 Japanese adult patients with RA who were treated with infliximab concomitantly with methotrexate or azathioprine. Serum concentrations of infliximab and ATI of these patients were measured. The mean serum infliximab concentrations was 1.6±1.3 μg/ml in patients with methotrexate and 1.0±0.5 μg/ml in patients with azathioprine. Serum ATI concentrations were below the limit of quantitation in 4 of 5 patients in each group. The results from the present study suggest that azathioprine suppresses ATI production.