X-Linked Myotubular Myopathy and Mitochondrial Function in Muscle and Liver Samples

X-linked myotubular myopathy (XLMTM) is a rare congenital myopathy that commonly manifests with liver involvement. In most XLMTM cases, disease-causing variants have been identified in the myotubularin gene (MTM1) on chromosome Xq28, which encodes myotubularin protein (MTM1). The impairment of mitochondrial respiratory chain (MRC) enzyme activity in muscle has been observed in the XLMTM mouse model. Though several reports mentioned possible mechanisms of liver involvement in XLMTM patients and animal models, the precise underlying mechanisms remain unknown, and there is no report focused on mitochondrial functions in hepatocytes in XLMTM. We encountered two patients with XLMTM who had liver involvement. We measured MRC enzyme activities in two muscle biopsy specimens, and one liver specimen from our patients to investigate whether MTM1 variants cause MRC dysfunction and whether mitochondrial disturbance is associated with organ dysfunction. MRC enzyme activities decreased in skeletal muscles but were normal in the liver. In our patients, the impaired MRC enzyme activity found in muscle is consistent with previously reported mechanisms that the loss of MTM1-desmin intermediate filament and MTM1-IMMT (a mitochondrial membrane protein) interaction led to the mitochondrial dysfunction. However, our study showed that liver involvement in XLMTM may not be associated with mitochondrial dysfunction.

Expression of dihomo-γ-linolenic acid and FADS1/2 and ELOVL2/5 in term rabbit placentas

Long-chain polyunsaturated fatty acids (LCPUFAs) are essential for both fetal and placental development. We characterized the FA composition and gene expression levels of FA-metabolizing enzymes in rabbit placentas. Total FA compositions from term rabbit placentas (n = 7), livers, and plasma (both n = 4) were examined: among LCPUFAs with more than three double bonds, dihomo-γ-linolenic acid (DGLA) was the most abundant (11.4 ± 0.69 %, mean ± SE), while arachidonic acid was the second-most rich component (6.90 ± 0.56 %). DGLA was barely detectable (<1 %) in livers and plasma from term rabbits, which was significantly lower than in placentas (both p < 0.0001). Compared with the liver, transcript levels of the LCPUFA-metabolizing enzymes FADS2 and ELOVL5 were 7- and 4.5-fold higher in placentas (both p < 0.05), but levels of FADS1 and ELOVL2 were significantly lower (both p < 0.01). Our results suggest a placenta-specific enzyme expression pattern and LCPUFA profile in term rabbits, which may support a healthy pregnancy.

Sodium-glucose cotransporter 2 inhibitors not only suppress recurrence after atrial fibrillation ablation but also cause atrial reverse remodeling

Background

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown fewer heart failure (HF) hospitalization and cardiovascular death in patients with type-2 diabetes mellitus (DM). Atrial fibrillation (AF) is associated with both HF and DM, and we reported SGLT2 suppressed AF recurrence after catheter ablation (CA) than dipeptidyl peptidase-4 (DPP4) inhibitor.

Purpose

We evaluated whether SGLT2 itself induces atrial reverse remodeling.

Methods

This is a sub-analysis of a prospective randomized controlled open-label clinical study for comparing the suppressive effect of SGLT2 inhibitor with DPP4 inhibitor on AF recurrence after CA. Eighty AF patients with type-2 DM were randomized to Tofogliflozin group or Anagliptin group with a computer-generated random sequence, which was stratified by left atrial diameter and AF type at screening. Primary outcome is AF recurrence at 12 months after CA, and secondary outcomes include the echocardiographic findings.

Results

70 patients (70.3±8.1 years, 58 male, 30 paroxysmal AF, 38 Tofogliflozin) were analyzed. Recurrent AF was detected in 24 patients (34.3%), and the AF recurrence ratio was higher in the Anagliptin group than the Tofogliflozin group. In 46 patients without AF recurrence (17 Anagliptin, 29 Tofogliflozin), LAVI has shrunk in 12 months compared to the baseline (42.8±11.9 to 36.6±11.2ml/m2) and the reduction of LAVI was larger in Tofogliflozin group than Anagliptin group (−8.6±2.0ml/m2 vs. −2.0±2.6ml/m2, P=0.0471).

Conclusion

Tofogliflozin not only suppressed AF recurrence after CA but also caused atrial reverse remodeling than Anagliptin in type-2 DM patients.

Funding Acknowledgement

Type of funding sources: None.

Advantage of a higher position of the tracheostoma with glottic closure for preventing complications related to tracheostomy tube: a retrospective cohort study

Background

Surgery to prevent aspiration has complications related to tracheostomy tube, such as the trachea-brachiocephalic artery fistula. Glottic closure procedure makes tracheostoma at a position higher than the first ring of the trachea and theoretically has a potential to prevent such complications owing to a longer distance between the tip of tracheostomy tube and the tracheal membrane adjacent to the brachiocephalic artery. Our aim is to evaluate the safety of glottic closure in neurologically impaired patients by comparing outcomes with laryngotracheal separation.

Methods

This study is a single-center retrospective study from 2004 to 2019, using data of 15 and 12 patients who underwent glottic closure (GC) and laryngotracheal separation (LTS). The primary outcome was the incidence of postoperative complications induced by tracheostomy tube placement and adjustment of the tracheostomy tube position to prevent these complications, such as by converting to a length-adjustable tube and/or placing gauze between the skin and tube flange. Additionally, we analyzed the anatomical relationship between the tracheostomy tube tip and brachiocephalic artery and measured the distance between them using postoperative CT images.

Results

No patients in either group had trachea-brachiocephalic artery fistula. Erosion or granuloma formation occurred in 1 patient (7%) and 4 patients (33%) in the GC and LTS groups, respectively. Adjustment of the tracheostomy tube was needed in 2 patients (13%) and 6 patients (50%) in the GC and LTS groups. CT revealed a higher proportion of patients with the tracheostomy tube tip superior to the brachiocephalic artery in GC than LTS group. The mean tracheostoma-brachiocephalic artery distance was 40.8 and 32.4 mm in the GC and LTS groups.

Conclusions

Glottic closure reduces the risk of postoperative complications related to a tracheostomy tube. This may be due to the higher position of the tracheostoma at the level of the cricoid cartilage, increasing the distance between the tracheostoma and brachiocephalic artery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-022-01505-2.

Dexmedetomidine Exerts a Negative Chronotropic Action on Sinoatrial Node Cells Through the Activation of Imidazoline Receptors

ABSTRACT

Dexmedetomidine (DEX), an α2-adrenoreceptor (α2-AR) and imidazoline receptor agonist, is most often used for the sedation of patients in the intensive care unit. Its administration is associated with an increased incidence of bradycardia; however, the precise mechanism of DEX-induced bradycardia has yet to be fully elucidated. This study was undertaken to examine whether DEX modifies pacemaker activity and the underlying ionic channel function through α2-AR and imidazoline receptors. The whole-cell patch-clamp techniques were used to record action potentials and related ionic currents of sinoatrial node cells in guinea pigs. DEX (≥10 nM) reduced sinoatrial node automaticity and the diastolic depolarization rate. DEX reduced the amplitude of hyperpolarization-activated cation current (If or Ih) the pacemaker current, even within the physiological pacemaker potential range. DEX slowed the If current activation kinetics and caused a significant shift in the voltage dependence of channel activation to negative potentials. In addition, efaroxan, an α2-AR and imidazoline I1 receptor antagonist, attenuated the inhibitory effects of DEX on sinoatrial node automaticity and If current activity, whereas yohimbine, an α2-AR-selective antagonist, did not. DEX did not affect the current activities of other channels, including rapidly and slowly activating delayed rectifier K+ currents (IKr and IKs), L-type Ca2+ current (ICa,L), Na+/Ca2+ exchange current (INCX), and muscarinic K+ current (IK,ACh). Our results indicate that DEX, at clinically relevant concentrations, induced a negative chronotropic effect on the sinoatrial node function through the downregulation of If current through an imidazoline I1 receptor other than the α2-AR in the clinical setting.

Thromboembolic risk of movable type left atrial appendage thrombi in patients with atrial fibrillation under widespread use of anticoagulants

Background

Left atrial appendage thrombi (LAAT), especially movable type LAAT, have been reported to be high-risk for thromboembolic events in patients with atrial fibrillation (AF). However, thromboembolic risk of the movable-type LAAT under widespread use of anticoagulant therapy remains unclear.

Methods

We retrospectively studied 65 LAAT patients taking anticoagulants out of 1381 consecutive patients who underwent transthoracic echocardiography prior to cardioversion or catheter ablation for AF. Patients with significant valvular disease and coagulation disorder were excluded. Clinical data were evaluated at the time of TEE. The LAAT were classified into movable and fixed type LAAT by three independent observers.

Results

Sixteen of 65 LAAT patients showed movable type LAAT. During follow-up (42±34 months), one patient underwent emergency thrombectomy, 5 patients developed thromboembolic event, and 12 patients died. There were no differences in clinical data, parameters, thrombectomy/thromboembolic event, and survival rate between patients with movable and fixed type LAAT.

Conclusion

Thromboembolic risk of the movable-type LAAT is the same as fixed type LAAT, under widespread use of anticoagulant therapy.

Funding Acknowledgement

Type of funding sources: None.

The impact of abnormal conduction zone on outcomes after catheter ablation for atrial fibrillation

Background

The abnormal conduction zone (ACZ) in the left atrium (LA) has attracted attention as an arrhythmia substrate in atrial fibrillation (AF).

Purpose

We investigated whether the ACZ affects outcomes after catheter ablation (CA) for AF.

Methods

We studied 78 patients (42 Non-paroxysmal AF, 49 males, and 68±10 years) who received CA for AF. High-density LA mapping during high right atrial pacing was constructed gaining than 2000 points (average 4377±846 points). Isochronal activation maps created at 5-ms interval setting. ACZ was identified by locating a site with isochronal crowding of ≥3 isochrones, and ≥8 isochrones were defined as the conduction block zone (CBZ) in a 4-mm diameter tag (conduction velocity were calculated as ≤27 cm/s and≤10 cm/s, respectively).

Result

Recurrent AF was detected in 25/78 patients (32%) during the follow-up period (9.2±3.0 month). ACZ and CBZ were distributed linearly, and ACZ was observed in 73 of 78 patients and 8 of these 73 patients had the CBZ. Univariate analysis revealed that elevated body mass index (26.2±3.8 vs. 24.3±3.3 kg/m2, P=0.0303), the higher prevalence of non-paroxysmal AF (72% vs. 45%, P=0.0272), larger LA diameter (47.6±6.6 vs. 42.1±6.9 mm, P=0.0014), and longer length of ACZ (79.7±45.1 vs. 52.9±35.7 mm, P=0.0058) were associated with recurrent AF after CA. On multivariate analysis, longer ACZ was independently associated with recurrent AF. Moreover, patients with longer ACZ (cutoff value: 84 mm) had a higher risk of recurrent AF than shorter ACZ (12/22; 55% vs 13/56; 23%, log-rank P=0.0024).

Conclusion

The length of ACZ was associated with recurrent AF after CA.

Funding Acknowledgement

Type of funding sources: None.

The impact of oral direct thrombin inhibitors on activated clotting time during catheter ablation in patients with atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

Direct thrombin inhibitors (DTIs) unlike factor Xa-inhibitors (Xa-inhibitors) is associated with fewer bleeding complications than warfarin in patients who had catheter ablation (CA) for atrial fibrillation (AF). However, the mechanisms remains unclear, and activated clotting time (ACT) is used to control heparin-dose for thromboembolic prevention during CA. Methods: We retrospectively studied 543 patients taking direct oral anticoagulant (DOAC) who underwent CA for AF (375 males, age 67 ± 10, 251 non-paroxysmal AF, 142 DTIs). Patients with off-label usage of DOAC were excluded. ACT was measured before (Pre-ACT) and after (post-ACT) initial heparin administration (3000U + 100U/kg), and total heparin-dose was evaluated. Results: Pre-ACT and post-ACT were extended in patients with DTIs (150 ± 21 vs 123 ± 15; P &lt; 0.0001 and 322 ± 39 vs 309 ± 42 sec; P = 0.0013). Patients with Xa-inhibitors required higher total heparin-dose (199 ± 43 vs 175 ± 34 U/kg; P &lt; 0.0001). During and after CA, none had thromboembolic events and 14 patients (3 DTIs, 11 Xa-inhibitor) showed bleeding events (Figure). Conclusions: ACT is extended in patients taking DTIs. Xa-inhibitors might have anticoagulant effects which are not reflected in ACT. Abstract Figure.

Impact of lipoprotein(a) levels on angiographic severity of femoropopliteal lesions

Background

High lipoprotein(a) [Lp(a)] levels are a risk factor for peripheral artery disease (PAD). However, the association between Lp(a) levels and angiographic severity of PAD has not been systematically studied.

Purpose

The aim of this study was to assess the impact of Lp(a) levels on angiographic severity of femoropopliteal lesions in patients with PAD.

Methods

We retrospectively analyzed a single-center database including 108 patients (74±8 years, 69% male) who underwent endovascular therapy for de novo femoropopliteal lesions and measured Lp(a) levels before therapy between June 2016 and September 2019. Patients were divided into low Lp(a) [LP(a) &lt;30 mg/dL; 77 patients] and high Lp(a) [LP(a) ≥30 mg/dL; 31 patients] groups. Trans-Atlantic Inter-Society Consensus (TASC) II classification, calcification [referring to peripheral arterial calcium scoring system (PACSS) classification] and lesion length were compared between the groups.

Results

Median Lp(a) was 16 (7–31) mg/dL.The prevalence of TASC II class D (13% vs 38%, P&lt;0.01) and severe calcification (PACSS 4) (6% vs 23%, P=0.02) was significantly higher and lesion length was longer (123±88 mm vs 175±102 mm, P&lt;0.01) in the high Lp(a) group than in the low Lp(a) group.(Table and Figure) In multivariate analysis, Lp(a)≥30 was an independent predictor for TASC II class D (HR=3.67, P=0.02) and PACSS 4 (HR=4.97, P=0.02) prevalence.

Conclusion

Lp(a) was associated with angiographic severity of femoropopliteal lesions in patients with PAD.

Comparison of angiographic severity

Funding Acknowledgement

Type of funding source: None

Increased left ventricular stiffness assessed by diastolic wall strain causes symptoms in patients with premature ventricular contraction

Background

Premature ventricular contraction (PVC) is one of common arrhythmias and only some patients complain of PVC-related symptoms, however the mechanisms which cause the symptoms remain unclear in patients with PVCs.

Purpose

We investigated whether the left ventricular (LV) stiffness assessed by diastolic wall strain (DWS) relate symptoms or not in patients with PVC.

Methods

We studied 109 patients (48 males, age 60±19) with frequent monomorphic PVCs who underwent 12-leads electrocardiogram (ECG), signal-averaged electrocardiogram (SAECG), 24h-Holter ECG recording, and transthoracic echocardiography (TTE). Patients with structural heart disease or other arrhythmias such as atrial fibrillation were excluded. Clinical factors, blood samples for atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), and filtered QRS duration (f-QRS) and root mean square voltage of the terminal 40ms of the QRS complex (RMS40) obtained by SAECG were evaluated. We assessed PVC-SV (stroke volume during PVC), PVC-CI (CI between the previous sinus beat and VPC), and left ventricular (LV) stiffness assessed by diastolic wall strain (DWS). DWS was calculated from the M-mode echocardiographic measurement of the LV posterior wall thickness at end-systole (PWs) and end-diastole (PWd) during sinus rhythm, and DWS was defined as (PWs − PWd)/PWs.

Results

31patients (28%) had PVC-related symptoms (18 palpitation and 13 pulse deficit). Patients with PVC-related symptoms showed shorter PVC coupling interval index (52±10 vs. 58±11%, p=0.0140), reduced PVC-SV (21±12 vs. 29±17ml, p=0.0103) and decreased DWS (0.38±0.06 vs. 0.42±0.06, p=0.0011). Meanwhile, the level of BNP and ANP, f-QRS, RMS40, QRS morphology of PVC and the total number of PVC per day were not associated with PVC-related symptoms. On multivariate analysis, decreased DWS was only independently associated with PVC-related symptoms (p=0.0357, OR 2.3629 for each 0.1 decrease in DWS 95% CI 1.0583–5.5815).

Conclusion

The reduced diastolic wall strain relates with PVC-related symptoms. The increased left ventricular stiffness might cause symptoms in patients with PVC.

Funding Acknowledgement

Type of funding source: None

Left ventricular stiffness assessed by diastolic wall strain predicts asymptomatic atrial high rate episodes in patients with pacemaker implantation

Background

Asymptomatic atrial fibrillation has been reported to be associated with an increased risk of embolism.

Purpose

We investigated whether the left ventricular (LV) stiffness assessed by diastolic wall strain (DWS) predicts atrial high rate episodes (AHREs) in patients with pacemaker implantation (PMI).

Methods

One hundred forty seven patients (76 males, 75.2±8.9 years, 62 with sick sinus syndrome; SSS and 85 with atrioventricular block) who did not show atrial tachyarrhythmia before PMI were studied. DWS and other measurements were assessed using transthoracic echocardiography before DDD-pacemaker implantation. DWS was calculated from the M-mode echocardiographic measurement of the LV posterior wall thickness at end-systole (PWs) and end-diastole (PWd), and DWS was defined as (PWs-PWd)/PWs.

Results

AHREs (&gt;5 min and &gt;180 beats/min) were detected in 50/147 patients during follow-up periods (38.3±13.8 months). Patients with AHREs showed reduced DWS (0.29±0.07 vs. 0.39±0.06, p&lt;0.0001), larger left atrial volume index, elevated E/e' ratio, thicker LV PWd, higher prevalence of SSS, and left bundle branch block pattern during ventricular pacing. On multivariate analysis, DWS was only independently associated with AHREs (p&lt;0.0001, HR 1.987 for each 0.1 decrease in DWS, 95% CI 1.553–2.650). Patients with reduced DWS (&lt;0.33) had a higher risk of incidences of AHREs (Figure 1).

Conclusions

LV stiffness assessed by DWS predicts AHREs in patients with PMI.

Figure 1

Funding Acknowledgement

Type of funding source: None

Slow conduction zone as an early electrical remodeling change in patients with atrial fibrillation

Background

The slow conduction zone (SCZ) in the left atrium (LA) detected using 3-D mapping and high-resolution imaging system has attracted attention as an arrhythmia substrate of atrial fibrillation (AF). However, the occurrence mechanism of SCZ remains unclear.

Purpose

This aim of this study is to clarify whether SCZ is related to the low voltage zone (LVZ) or the LA anatomical contact areas with other organs such as aorta or thoracic spine in patients with AF.

Methods

We studied 36 patients (21 males, 68±10 years, 14 paroxysmal AF; PAF, 17 persistent AF; PeAF, 5 long-standing persistent AF; LS-PeAF) who received catheter ablation for AF. High-density LA mapping during sinus rhythm or right atrial pacing after pulmonary vein isolation were constructed by acquiring more than 2000 endocardial points in each patient. Isochronal activation maps were created at 5-ms interval setting, and the SCZ was identified on the activation map by finding a site with isochronal crowding of ≥3 isochrones, which are calculated as ≤27 cm/s (figure). The LVZ was defined as the following; mild (&lt;1.5 mV), moderate (&lt;1.0 mV), and severe LA-LVZ (&lt;0.5 mV). The LA contact areas (CoAs; ascending aorta-anterior LA, descending aorta-posterior LA, and vertebrae-posterior LA) were assessed using computed tomography.

Results

The SCZ was distributed linearly (figure), and observed in 35 of 36 patients (97.2%). The SCZ was often found in the anterior (89%), roof (64%), and septal wall (47%) of LA, and longest in patients with LS-PeAF (PAF: 56±34 mm, PeAF; 79±41 mm, LS-PeAF; 107±34mm, P=0.0351). The prevalence rate of SCZ (97.2%) was higher than LVZ (figure, mild LA-LVZ; 91.7%, moderate LA-LVZ: 66.7%, severe LA-LVZ; 25%). The 55.8% of SCZ overlapped with mild LA-LVZ, 37.6% of SCZ with moderate LA-LVZ, and 19.1% of SCZ with severe LA-LVZ. The LA CoAs were found in all patients. A total of 72 CoAs (average surface area, 7.0±4.0 cm2) were identified. A CoA was found in each of the three representative regions, ascending aorta-anterior LA (4.1±2.0 cm2, 36 of 36 patients, 100%), descending aorta-posterior LA (2.3±1.2 cm2, 12 of 36 patients, 33%), and vertebrae-posterior LA (3.4±2.1 cm2, 24 of 36 patients, 67%). However, only 22% of SCZ matched with the LA anatomical contact areas.

Conclusion

The slow conduction zone reflects LA electrical remodeling and may be a precursor finding of the low voltage zone, not LA contact areas in patients with atrial fibrillation.

Funding Acknowledgement

Type of funding source: None

P3704Silent ischemic brain lesion detected in patients with subclinical paroxysmal atrial fibrillation

Background

Long-lasting atrial fibrillation (AF) has been reported to be associated with an increased risk of dementia, independent of clinical stroke. However, the mechanisms or association in patients with subclinical paroxysmal AF (S-PAF) remain unclear. We evaluated whether S-PAF is associated with silent ischemic brain lesion (S-IBL), one of causes of dementia.

Methods

We studied 46 patients (35 male, 68±15 yrs) without a history of stroke/transient ischemic attack and AF, who implanted insertable cardiac monitoring (ICM) for unexplained syncope (n=33) or embolic stroke of undetermined source (ESUS) (n=13). All patients underwent cerebral magnetic resource imaging (c-MRI), and S-IBL was defined as infarction, lacuna and microbleeds. The lesions in an acute stage were excluded in patients with ESUS.

Results

AF was detected in 15/46 patients (11 with unexplained syncope and 4 with ESUS) during follow-up of 7.0±6.6 months, and S-IBL was observed in 18/46 patients (9 infarction, 8 lacuna, or 8 microbleeds). Univariate analysis revealed that higher prevalence of AF (61% vs. 14%, p=0.0015), elder age (73±10yrs vs. 65±16yrs, p=0.0445), dyslipidemia (67% vs. 25%, p=0.007), structural heart disease (44% vs. 14%, p=0.0383), and larger left atrium diameter (41±6 mm vs. 37±5 mm, p=0.0267) were related to S-IBL. On multivariate analysis, prevalence of AF was independently associated with S-IBL (p=0.0070, OR 13.4, 95% CI 1.945–155.813). When receiver-operating-characteristics (ROC) curve analysis and prevalence of AF were used to detect S-IBL, the area under the ROC curve was 0.7341 (sensitivity: 61.1%, specificity: 85.7%).

Conclusion

Subclinical paroxysmal AF is associated with silent ischemic brain lesion and might cause to dementia.

P5654Brain natriuretic peptide and left atrial volume predict the reduced flow velocity of left atrial appendage during sinus rhythm in patients with atrial fibrillation

Background

It remains controversial whether or not to discontinue anticoagulation therapy after catheter ablation (CA) for atrial fibrillation (AF). The reduced flow velocity of the left atrial appendage (FV-LAA) during AF causes left atrial appendage thrombus and increases the risk of stroke. However, some AF patients show reduced FV-LAA even during sinus rhythm (SR).

Methods

398 patients who showed SR during transesophageal echocardiography (TEE) before CA for AF were studied (259 males, 68±10 years, 77 with non-paroxysmal AF). Clinical factors, transthoracic echocardiography and blood samples were obtained before TEE. Reduced FV-LAA was defined as <35 cm/sec of FV-LAA.

Results

Reduced FV-LAA was observed 70/398 patients (18%). Reduced FV-LAA was significantly associated with elevated brain natriuretic peptide (BNP) (p<0.0001), increased LA volume index (p<0.0001), reduced left ventricular ejection fraction (p=0.0017), high prevalence of non-paroxysmal AF (p=0.0048), prior history of heart failure (p=0.0172), and no administration of angiotensin converting enzyme inhibitor/angiotensin II receptor blocker (ACEI/ARB) (p=0.0403), while CHADS2 factors were not significantly associated.

On multivariate analysis, LA volume index (p<0.0001, OR 1.049 for each 1 increase in LA volume index, 95% CI 1.025–1.073) and no administration of ACEI/ARB (p=0.0015, OR 0.339 for administration, 95% CI 0.173–0.662) and BNP (p=0.0048, OR 1.035 for each 10 pg/ml increase in BNP, 95% CI 1.011–1.061) and were associated with reduced FV-LAA.

Rate of reduced flow velocity

Conclusion

The elevated BNP level and large LA volume index predict reduced FV-LAA during SR. AF patients with increased BNP and larger LA volume index might require long-term anticoagulation taking after CA procedure.

P3790Left ventricular stiffness assessed by diastolic wall strain predicts infrequent atrial fibrillation

Background

Left ventricular (LV) stiffness as the passive LV filling property in the LV diastolic function has been reported to be related with the prevalence of atrial fibrillation (AF). On the other hand, a novel insertable monitoring (ICM) system is a powerful tool to detect AF with rare appearance in patients with embolic stroke of undetermined source (ESUS). We investigated whether the LV stiffness assessed by diastolic wall strain (DWS) predicts infrequent atrial fibrillation.

Methods

Fifty-five patients (41 males, 68±14 years) who underwent ICM implantation for ESUS (n=19) or unexplained syncope (n=36) were studied. DWS, left atrial (LA) stiffness and other measurements were assessed using transthoracic echocardiography before the ICM implantation. DWS was calculated from the M-mode echocardiographic measurement of the LV posterior wall thickness at end-systole (PWs) and end-diastole (PWd) during sinus rhythm, and DWS was defined as PWd/PWs. LA stiffness index was defined as the ratio of E/e' to LA peak strain.

Results

AF was detected in 20 patients (36%) during the follow-up periods (280±243 days). Patients with AF showed reduced DWS (0.30±0.07 vs. 0.41±0.08, p<0.0001), larger LA volume index (39.0±10.9 vs. 32.3±9.0, p=0.0174), and higher age (74.6±10.4 vs. 64.6±14.9, p=0.0105). On the other hand, LA stiffness index, LA function (reservoir, booster, and conduit function estimated by LA volume), and LV relaxation function (E wave, E/A ratio, deceleration time) were not associated with detection of AF. There was no difference on AF detection rate between ESUS and unexplained syncope (26% vs. 42%, p=0.2604). On multivariate analysis, DWS was only independently associated with detection of AF (p<0.0001, OR 5.647 for each 0.1 decrease in DWS, 95% CI 1.084–1.338). Moreover, patients with reduced DWS (<0.38) had a higher risk of incidences of AF than patients with preserved DWS (figure).

Figure 1

Conclusions

LV stiffness assessed by DWS predicts infrequent AF. Reduced LV stiffness rather than LA dysfunction or LV relaxation dysfunction may be the main cause of AF in the early stages.

P5502Comparison of clinical characteristics and prognosis between non-octogenarians and octogenarians with cardiac troponin positive acute myocardial infarction

Background

Cardiac troponin (cTn) is the preferred biomarker for the diagnosis of acute myocardial infarction (AMI). Octogenarians who presented cTn positive AMI are not usually recruited in clinical trials. Therefore, their clinical characteristics and prognosis are rarely investigated.

Objective

To study the characteristics and prognosis in octogenarians who presented cTn positive AMI.

Methods and results

The Japanese registry of acute Myocardial INfarction diagnosed by Universal dEfiniTion (J-MINUET) is a prospective and multicenter registry. A total of 3,283 consecutive AMI patients who were diagnosed by cTn-based criteria were included. The patients were divided into non-octogenarians (n=2,593) and octogenarians (n=690). Compared with non- octogenarians, octogenarians showed significantly lower incidence of diabetes mellitus (37.6% and 31.9%, p=0.006) and dyslipidemia (53.6% and 45.6%, p<0.001), and significantly higher incidence of hypertension (64.1% and 75.3%, p<0.001) and chronic kidney disease (38.7% and 68.7%, p<0.001). Octogenarians showed significantly longer onset to door time (p<0.001) and longer door to device time (p<0.001). Though, compared with non-octogenarians, octogenarians showed lower peak CK (2,506 and 1,926, p<0.001), LVEF was significantly lower in octogenarians (54.6% and 52.6%, p=0.005). The presentation of AMI was different between the two group. The incidence of ST-segment elevation MI (STEMI) was 70.7% in non-octogenarians and 62.0% in octogenarians. Non-STEMI with CK elevation and without CK elevation were 16.2% and 13.1% in non- octogenarians, and 20.9% and 17.1% in octogenarians. In-hospital mortality was higher in octogenarians (4.7% and 13.2%, P<0.001). Especially, octogenarians with STEMI and non-STEMI with CK elevation showed the highest in-hospital mortality. And octogenarians without CK elevation showed similar in hospital mortality with non-octogenarians with STEMI (Figure).

Conclusions

J-MINUET showed the poor prognosis of octogenarians who were diagnosed as AMI based on cTn.

Acknowledgement/Funding

None

P3392Potential of imaging-guided PCI for event suppression in Japanese acute myocardial infarction patients: J-MINUET substudy

Background

Intravascular ultrasound (IVUS) and Optical Coherence Tomography (OCT) has been widely used in clinical settings. Although favorable results of imaging-guided percutaneous coronary intervention (PCI) compared with angio-guided PCI were observed in several studies, impacts of institutional-based usage frequency, about imaging-guided PCI, have not been well elucidated.

Methods

To elucidate the impact of imaging-guided PCI and the effects of frequency of its usage, we analyzed data of the Japanese registry of acute Myocardial INfarction diagnosed by Universal dEfiniTion (J-MINUET). This was a prospective and multicenter registry consisting of 3,283 AMI patients, who were hospitalized within 48 hours of onset from July 2012 to March 2014. Clinical follow-up data was obtained for 3 years. In this sub-study, a total of 2,788 patients who underwent urgent PCI having detailed procedural information were enrolled. We analyzed the differences of utilization rates of imaging-guided PCI among the participating institutions and the impacts for the clinical events. The participating institutions were divided into 3 groups by the frequency of IVUS usage: low frequency institutions: under 50%; moderate frequency institutions: 50% to 90%; and, high frequency institutions: over 90%.

Results

In this cohort registry, patients were enrolled from 28 institutions. The utilization rate of coronary imaging varied widely depending on each institution from 15.4% to 100% (mean 85.7%±24.3, median 97.4%). When the institutions were divided into 3 groups by the frequency of intravascular imaging usage, four low frequency institutions enrolled 295 patients, five moderate frequency institutions enrolled 624 patients, and 19 high frequency institutions enrolled 1,491 patients. Although the incidence of MACE (death, MI, stroke, cardiac failure, or revascularization for unstable angina) decreased stepwise (33.2%, 23.7%, and 19.7%) (gray bar in the Figure), the event rates of the imaging-guided PCI cases among the 3 groups were comparable (21.6%, 21.9%, and 19.6%) (white bar in the Figure). On the other hand, a gradual event reduction between the 3 groups was observed in the angio-guided PCI cases (black bar in the Figure). In comparison of MACE rate between imaging-guided and angio-guided PCI, there were statistically significant differences in the low frequency and moderate frequency institutions (p=0.001 and p=0.012, respectively). In contrast, comparable event rates were observed in the high frequency institutions (p=0.441).

MACE rate by imaging usage frequency

Conclusions

In Japanese ACS patients treated with imaging-guided PCI, better suppression of clinical events during 3-year was found in the institutions with the more frequent use of intravascular imaging, mainly due to stepwise event suppression in the cases of angio-guided PCI. On the other hand, the clinical benefit of coronary imaging was obtained independently of the frequency of use and its experience.