Cardiac arrhythmias and conduction disorders monitoring after transcatheter aortic valve replacement procedure, using a mobile electrocardiogram 6 lead device

Background

In the early post transcatheter aortic valve replacement (TAVR) discharge era, rate of readmission for permanent pacemaker implantation (PPM-I) due to delayed conduction disturbances (CDs) has significantly increased. This issue has powered post procedural ambulatory electrocardiogram (AECG) monitoring by using implantable cardiac monitors or mobile cardiac telemetry devices, despite several disadvantages as frequent electrode changes and costs.

Purpose

In this scenario we aimed to evaluate the incidence of post-TAVR new onset arrhythmias and delayed CDs, performing an AECG monitoring through a 30s spot digital ECG (AeECG), by using a mobile electrocardiogram 6 lead (ME6L) device in a 30 days period after a TAVR procedure.

Methods

Between March 2021 and February 2022 we consecutively enrolled all patients undergoing a TAVR at the University Hospital of Pisa, excepting who already had a PM. At discharge, all patients received ME6L device and were asked to record a spot eECG for 1 month: 1 eECG per day during the first week and then 1 eECG per week. Clinical and follow-up data were collected and analyzed, and eECG scheduling compliance and quality recordings were explored.

Results

Among 185 consecutive TAVR patients, 12 were excluded due to pre-existing pacing device and 33 due to PPM-I <2 days post TAVR; 3 died before enrollment and 10 refused the enrollment; 18 were excluded because failed the ME6L training phase, 6 for severe postprocedural complications and the last 3 because affected by isolated aortic regurgitation.The remaining ones (100) had 30-day AeECG data. Delayed CDs with a Class I/IIa indications for PPM-Ioccurred in 8 patients with a median of 6 days (range 4–8 days) post-TAVR. New onset documented arrhythmias were AT/AF in 3 patients, isolated PVCs in 10 patients, and competitive transitory junctional rhythm in 2 patients. Delayed PPM-I versus non-delayed PPM-Ipatients were more likely to have a non-self-expandable valve (3 vs 69; p=0.02) and longer PR and QRS intervals at discharge (250.00±53,29 ms vs 179.17±39.17 ms; p=0,003; 125±33.38 ms vs 102.55±30.48 ms; p=0,04). The overall eECG schedule level compliance was 96.5%. Out of a total of 965 sent eECGs, 950 (98,4%) have been correctly recorded and transmitted.

Conclusion

Delayed CDs requiring PPM-I are the most important drawback of TAVR procedure. In our study, AeECG was seen to be safe and helpful in the identification and treatment of delayed CDs requiring PPM-I, with a very high eECG schedule level of compliance and quality. Further prospective studies are needed to better identify patient selection for outpatient monitoring, making safer and safer the early post TAVR discharge approach.

Funding Acknowledgement

Type of funding sources: None.

High density catheter approach with liveview dynamic display improves procedural efficiency of atrial fibrillation ablation

Introduction

PVI isolation confirmation after RF ablation is often time-consuming, especially in case of a single transeptal catheter approach into the left atrium. A novel Live View (LV) dynamic display mapping software, utilized in combination with the High Density (HD) Grid mapping catheter, allows to display beat-to-beat, dynamic regional mapping data.

Purpose

We evaluated the feasibility and the procedural impact of a procedural left atrial workflow with a single transeptal-single HD catheter analysis, incorporating the LV Mapping Software for the assessment of PVI after ablation.

Methods

Paroxysmal and persistent AF patients scheduled for AF ablation were prospectively enrolled. All patients underwent only PVI under LSI guidance (LSI between 5.5 and 6 anteriorly; LSI between 4.5 and 5 posteriorly) with a point by point strategy and an inter-lesion distance <6 mm. According to the HD mapping strategy used to confirm entrance block after first pass PVI, patients were divided in two groups. The HD-LV Group included patients mapped with the HD-LV software and the HD-standard mapping (SM) group included patients which received a conventional PVI validation with a static voltage/activation map. Left PVI was evaluated during distal coronary sinus pacing and right PVI during sinus rhythm. Exit block was also evaluated to confirm bidirectional block. Procedural efficiency parameters were compared between groups.

Results

Forty-six patients with AF (58% paroxysmal) were prospectively enrolled. Twenty-five patients were included in the HD-LV Group and 21 in the HD-SM Group. PVI was successful in all patients. LV dynamic display analysis was feasible in all patients and allowed a simple and fast validation of right and left PVI, without the necessity of introducing a second catheter into the left atrium. The split screen modality, with a dynamic activation map on the left and a dynamic voltage map on the right, allowed to switch from CS pacing to sinus rhythm without the necessity of a remap. The overall mapping time (27±10 vs 37±14 min, p=0.006), total procedure time (138±33 vs 178±50 min, p=0.006) and fluoroscopy time (14±5.3 vs 23±11 min, p=0.006) were significantly lower in the HD-LV Group. No complication was seen in either group.

Conclusions

A simplified clinical utilization of LiveView dynamic display with a single transeptal-single HD catheter approach is feasible and efficient after PVI, potentially simplifying the procedural workflow. A real-time dynamic mapping in daily practice may further enhance the clinical benefits of HD mapping during radiofrequency (RF) catheter ablation procedures.

Funding Acknowledgement

Type of funding sources: None.

Transvenous removal of pacing and ICD leads: single Italian referral center experience

Introduction

Device related complications are rising the need of Transvenous Lead Removal (TLR). Transvenous extraction of Pacing (PL) and Defibrillating Leads (DL) is a highly effective technique. Aim of this report is to analyse the longstanding experience performed in a single Italian Referral Center.

Methods

From January 1997 to December 2021, we managed 2925 consecutive patients (2220 men, mean age 65.3 years) with 5370 leads (mean dwell time 74.0 months, range 1–576). PL were 4209 (1903 ventricular, 1801 atrial, 505 coronary sinus leads), DL were 1161 (1140 ventricular, 6 atrial, 15 superior vena cava leads). Indications to TLR were infection in 78% (systemic 27%, local 51%) of leads. We performed mechanical dilatation using a single polypropylene sheath technique and, if necessary, other intravascular tools; we performed an approach through the Internal Jugular Vein (JA) in case of free-floating leads or failure of the standard approach.

Results

We attempted removal in 5359 leads because the technique was not applicable in 11 PL. Among these, 5223 leads were completely removed (97.4%), 51 (1.0%) were partially removed, 85 (1.6%) were not removed. Among 5271 exposed leads: manual traction removed 879 (16.7%) leads; mechanical dilatation using the venous entry site removed 3860 (73.2%) leads; femoral approach (FA) removed 50 (0.9%) leads; and JA removed 346 (6.6%) leads. All the free-floating leads were completely removed, 26.1% by FA and 73.9% by JA. Major complications occurred in 23 cases (0.78%): cardiac tamponade (21 cases, 5 deaths), hemothorax (2 cases, 1 death).

Conclusions

Our experience shows that in centers with wide experience, TLR using single sheath mechanical dilatation has a high success rate and a very low incidence of serious complications. TLR through the Internal Jugular Vein increases the effectiveness and safety of the procedure also in case of free-floating or challenging leads.

Funding Acknowledgement

Type of funding sources: None.

ELECTRa Registry Outcome Score (EROS): validation in a single center population

Funding Acknowledgements

Type of funding sources: None.

Introduction

The ELECTRa Registry Outcome Score (EROS) was developed to identify patients at increased transvenous lead extraction (TLE) risk

Purpose

Aim of the study is to explore the efficiency of EROS for stratifying patients undergoing TLE.

Methods

We performed a retrospective analysis of 1293 patients who underwent to TLE in our center. We performed extraction procedures with manual traction or mechanical dilatation. We calculated EROS, and we divided patients into 3 groups depending on the EROS class. For this purpose, we made statistical analysis and comparison between EROS 1+2 vs. EROS 3 groups. We used an X2 for among-group comparisons or Fisher’s exact test if the expected cell count was less than five.

Results

Our analysis included 1293 patients. EROS-1 counted 726 patients (56,1%), EROS-2 367 (28,4%) patients and EROS-3 200 (15,5%) patients. There was no statistical difference in peri-procedural death between EROS-1+2 and EROS-3 (0.18% vs 1.50%, p=0.134). Major complications (0.82% vs. 3.00%, p=0.014), minor complications (3.11% vs. 6.50%, p=0.019) and use of internal jugular approach (6.13% vs. 14.50%, p<0.001) was significantly higher in EROS 3 patients.

Conclusion

EROS effectively separates patients at higher risk of complications. Use of internal jugular approach was significantly higher in EROS 3 patients.

The in-ear region as a novel anatomical site for ecg signal detection: validation study on patients affected by atrial tachyarrhythmias

Funding Acknowledgements

Type of funding sources: None.

Purpose

Early detection of cardiac arrhythmias is a major opportunity for mobile health, as portable devices nowadays available can detect multiple-lead electrocardiogram (ECG). The study aims to validate the in-ear region as a new anatomical site for ECG signal detection in patients (pts) affected by atrial tachyarrhythmias.

Methods

We performed the ECG using KardiaMobile 6L device on 20 patients affected by tachyarrhythmias and admitted to our hospital for electrical cardioversion. All the digital ECGs were detected in a modified modality or using the left in-ear region instead of the right hand. All the recorded ECGs were analyzed by the device and the results checked by two cardiologists.

Results

We successfully collected all 20 modified digital ECGs performed on the group of 20 pts (age 68.4 ± 9.2 years; male 60%; 14pts in atrial fibrillation (AF); 6pts in atrial flutter (AFl); medium HR 94±28.4bpm; 65% affected by hypertension; 5% affected by diabetes mellitus; 95% in NOACs).

In case of AF, the KardiaMobile 6L diagnosis of the ECG detected by this modified modality was correct in 100% of cases. In the 6 pts affected by AFl the KardiaMobile 6L diagnosis was "normal" in 3 cases and "not classified" in the other 3. For that reason, in these 6 pts, we performed a new digital ECG using the KardiaMobile 6L in the standard modality, and the diagnosis for each patients was the same.

Conclusion

The in-ear region could be a reliable novel anatomical site for ECG signal detection in patients affected by atrial fibrillation. Further studies are needed to overcome the misdiagnosis of digital ECG in case of patients affected by atrial flutter. These data support the development of new portable ECG devices using the left in ear region and so leaving at least one hand free.

Never too old for something new: feasibility and long-term outcomes of leadless pacemaker implant in the elderly

Funding Acknowledgements

Type of funding sources: None.

Elderly patients may be at great risk of complications and present a higher incidence of comorbidities which make challenging PM implant procedure. The use of leadless pacing systems has imposed itself to overcome peri- and post-procedural complications related to the presence of transvenous leads and the post-operative recovery, being a favorable option in elderly patients.

The study aimed to investigate feasibility and long-term outcomes of M-TPS implant in a specific patient population, like the elderly, which represent a challenge for conventional cardiac pacing.

Methods

Between May 2014 and November 2021, 155 patients (120 males, mean age 78±9 y) underwent M-TPS implantation in our Center, targeting a non-apical site of delivery when feasible. A subgroup of 69 patients (52 males, 75.36%) were older than 80 years. All patients fulfilled standard criteria for PM implantation with specific indication to receive VVI pacing. Study population was divided into two groups according to age (group 1 < 79 years vs group 2≥80 years). The outcome evaluation included electrical performance (capture threshold, pacing impedance, R wave amplitude) before hospital discharge and then followed at 1, 6, and 12 months and then annually. Major complications were defined as life-threatening events, required surgical intervention or any event causing significant hemodynamic instability or resulting in death.

Results

In 69/155 cases (52 males, 75.36%) M-TPS was implanted in patients older than 80 years. There were no statistically significant differences between groups for demographics characteristics, except for age. The implant procedure was successful in all cases and no device-related events were registered during follow-up. In particular, no device infection and/or malfunction were reported. Patients were followed-up for an average of 24 months (median 18 months). No differences were observed between groups in procedure duration, single device delivery (group 1 vs group 2: 62.79% vs 65.22%, p=0.75), fluoroscopy time (group 1 vs group 2: 11.46 ±6.12 vs 11.37 ± 8.37 minutes, p=0.23), electrical performance at implant (group 1 vs group 2: pacing threshold 0.56 ± 0.37 V/0.24 ms vs 0.58 ± 0.31 V/0.24 ms, p=0.55; impedance 737.86 ± 173.50 Ohm vs 759.56 ± 255.35 Ohm, p=0.87; R wave amplitude 10.5 ± 5.18 mV vs 9.19 ± 4.45 mV, p=0.14) and at 18 [VB2] month F-U (group 1 vs group 2: pacing threshold 0.64 ± 0.55 V/0.24 ms vs 0.51 ± 0.1 V/0.24 ms, p=0.85; impedance 535.34 ± 102.53 Ohm vs 577.34 ± 69 Ohm, p=0.40; R wave amplitude 12.56 ± 4.56 mV vs 12.00 ± 5.8 mV, p=0.77[VB3] ).

Conclusions

The demand for cardiac pacing is strongly related to ageing, driving the clinical practice to look for the best solution for a considered fragile patient population. MTP-S implant is an effective and safe procedure in elderly patients, with similar electrical performance and outcome compared with younger patients at long-term follow.

Local impedance characteristics and advanced mapping capabilities to better understand pulmonary veins reconnections during repeat AF ablation procedures: insight from the CHARISMA registry

Background

Detailed characterization of pulmonary veins (PV) reconnection during repeat AF ablation through high-density mapping (HDM) and local impedance (LI) algorithm is still lacking.

Purpose

We aimed to characterize PV gaps and underlying electrical activity during and after ablation of PVs in AF patients (pts).

Methods

Consecutive patients (pts) undergoing redo AF ablation from the CHARISMA registry with complete characterization of PV gaps (PVG) at 8 Italian centers were included. Rhythmia mapping system was used to map the left atrium and PVs before and after ablation. LI characteristics were collected through a RF ablation catheter equipped with a dedicated LI algorithm (DirectSense). A novel map analysis tool (Lumipoint) that automatically identifies split potentials and continuous activation was used sequentially on each PV component, in order to better assess PVG. Each PVG was characterized in terms of LI and its variations during the procedure. Ablation endpoint was PVI as assessed by entrance and exit block.

Results

Fifty PVGs were automatically identified through the Lumipoint tool in 23 cases, mostly at anterior sites (21, 42%), followed by posterior (15, 30%) and carina (10, 20%) sites. One PVG was identified in 7 (28%) pts, 2 gaps in 10 (43.5%) pts and >2 gaps in 6 (26.1%) pts. The mean LI at PVG sites was 111.3±12Ω prior to ablation: it was significantly higher than LI at scar tissue closer to PVG (99.3±8Ω, p<0.0001) but was significantly lower than LI at healthy tissue (120.8±11Ω, p=0.0015). The mean linear extension of PVGs detected through Lumipoint was significantly lower than the one recognized through voltage map (11.5±8 mm vs 13.3±9 mm, p=0.01) whereas was comparable to the one identified through conventional activation map (11.8±7 mm, p=0.1161 vs Lumipoint). Complete identification of the whole area of PVG was achieved in 31 (62%) and 42 (84%) cases through voltage and activation map, respectively whereas the identification was only partial in 18 (36%) and 7 (14%) cases, respectively. In 1 case both voltage and activation map failed to identify a PVG. No complications during the procedures were reported. All PVs were successfully isolated in all study pts.

Conclusion

Advanced mapping capabilities were useful to pinpoint the search for PVGs, enabling a more targeted ablation approach vs relying on voltage mapping. LI values correlated well with PVGs characteristics and they significantly differ from both scar and healthy tissue.

Funding Acknowledgement

Type of funding sources: None.

Leadless pacemaker implant in the elderly: a safe and feasible solution

 

The use of leadless pacing systems could overcome peri-and post-procedural complications related to the presence of transvenous leads and the post-operative recovery, being a favorable option in elderly patients.

The study aimed to investigate feasibility and outcomes of M-TPS implant in a specific patient population, like the elderly, which represent a challenge for conventional cardiac pacing.

Methods

Between May 2014 and March 2021, 138 patients (106 males, 77%, mean age 78) underwent M-TPS implantation in our Centre, targeting a non-apical site of delivery when feasible. A subgroup of 59 patients (43 males, 73%) were older than 80 years. All patients fulfilled standard criteria for pacemaker implantation with specific indication to receive VVI pacing. Study population was divided into two groups according to age (group 1 <80 years vs group 2 ≥80 years). The outcome evaluation included electrical performance (capture threshold, pacing impedance, R wave amplitude) before hospital discharge and then followed at 1, 6, and 12 months and then annually. Major complications were defined as life-threatening events, requiring surgical intervention or any event causing significant hemodynamic instability or resulting in death. High pacing threshold (HPT) was defined as >1.0 V@ 0.24 ms.

Results

In 59/138 cases (43 males, 73%) M-TPS was implanted in patients older than 80 years. There were no statistically significant differences between groups for demographics characteristics, except for age, and PM implant indications. The implant procedure was successful in all cases and no device-related events were registered during follow-up. In particular, no device infection and/or malfunction were reported. Patients were followed-up for an average of 22,19±20,66 months (median 18 months). No differences were observed between groups in procedure duration (44,97±20,24 min vs 45,80±23,27 min; P=0,83), single device delivery (group 1 vs group 2: 63,16% vs 66,07%; P=0,73), fluoroscopy time (11,64±6,22 min vs 12,13±8,67 min; P=0,72) electrical performance at implant [group 1 vs group 2: pacing threshold 0,56±0,37 vs 0,58±0,32, P=0,78; impedance 727,53±170,36 vs 752,88±256,21, P=0,49; R wave amplitude 10,39±4,86 vs 9,26±4,66, P=0,18] and at median follow-up [group 1 vs group 2: pacing threshold 0,63±0,55 vs 0,51±0,1, P=0,40; impedance 535,34±102,53 vs 577,34±69,02, P=0,20; R wave amplitude 12,56±4,56 vs 12,00±5,80, P=0,77]

Conclusions

The demand for cardiac pacing is strongly related to ageing, driving the clinical practice to look for the best solution for a considered fragile population. MTP-S implant is an effective and safe procedure in elderly patients, with similar electrical performance and outcome compared with younger patients at mid-term follow-up.

Funding Acknowledgement

Type of funding sources: None.

Early rhythm-control ablation therapy in preventing AF recurrences: insight from the CHARISMA Registry

Funding Acknowledgements

Type of funding sources: None.

Background

An early and comprehensive rhythm-control therapy emerges as a need to treat AF in an effective way and to improve the ablation outcomes, in terms of arrhythmia-free survival.

Purpose

We aimed to investigate the importance of timing of ablation in preventing AF recurrences.

Methods

153 consecutive patients (pts) undergoing AF ablation from the CHARISMA registry at 8 Italian centres were included. Ablations were guided by a novel radiofrequency ablation catheter with local impedance (LI)-sensing capability through a dedicated algorithm (DirectSense, Boston Scientific). Pts were grouped as early treated (ET) if the procedure was performed within 1 year after the first AF episode and as delayed treated (DT) if admitted for ablation after more than 1 year. The ablation endpoint was PVI as assessed by entrance and exit block. Post-ablation follow-up was scheduled at 3, 6 and 12 months. AF and atrial tachycardia (AT) recurrences were considered as long-term endpoint.

Results

Of the 153 pts enrolled (69.9% male, 59 ± 10 years, 61.4% paroxysmal AF, 38.6% persistent AF), 123 (80.4%) met Class I indications, 23 (15%) Class IIa indications and 7 (4.6%) Class IIb indications according to current ESC AF guidelines. The mean time to ablation procedure from the first AF episode was 1034 ± 1483 days. Eighty pts (52.3%) were included in ET group, whereas 73 pts (47.7%) in DT group. No differences were found between AF type in terms of ablation strategy (53.3% of the cases -52 out 94- were classified as ET for paroxysmal AF vs 47.5% of the cases -28 out 59- were ET for persistent AF, p = 0.4346). At the end of the procedures, all PVs had been successfully isolated in all study pts. During a mean follow-up of 366 ± 130 days, 18 pts (11.8%) suffered an AF/AT recurrence after the 90-day blanking period. Recurrences occurred mostly in the DT group compared to the ET one (13 out 73 -17.8%- vs 5 out 80 -6.3%-, p = 0.042) and the time to AT/AF recurrence was longer in the ET group (HR = 0.2876, 95%CI: 0.1029 to 0.8038; p = 0.0181). On multivariate logistic analysis adjusted for baseline confounders, only hypertension (HR = 4.66, 95%CI: 1.5 to 14.48, p = 0.0081) was independently associated with recurrences. An early rhythm-control therapy was associated with a low risk of recurrences beyond the hypertension risk factor, ranging from 2% (no hypertension and an ET ablation therapy) to 30.3% (with hypertension and a DT procedure) (Figure 1).

Conclusion

A LI-guided ablation strategy for PVI proved to be safe and effective and resulted in a very high recurrence-free rate. An early rhythm-control therapy in the absence of common risk factors was associated with the lowest rate of recurrences. Abstract Figure. AT/AF Recurrence

Transvenous removal of pacing and ICD leads: single italian referral center experience

Introduction

Device related complications are rising the need of Transvenous Lead Removal (TLR). Transvenous extraction of Pacing (PL) and Defibrillating Leads (DL) is a highly effective technique. Aim of this report is to analyse the longstanding experience performed in a single Italian Referral Center.

Methods

Since January 1997 to December 2019, we managed 2769 consecutive patients (2100 men, mean age 65.5 years) with 5086 leads (mean pacing period 73.6 months, range 1–576). PL were 3998 (1828 ventricular, 1704 atrial, 466 coronary sinus leads), DL were 1088 (1067 ventricular, 6 atrial, 15 superior vena cava leads). Indications to TLR were infection in 79% (systemic 27%, local 52%) of leads. We performed mechanical dilatation using a single polypropylene sheath technique and if necessary, other intravascular tools; an Approach through the Internal Jugular Vein (JA) was performed in case of free-floating leads or failure of the standard approach.

Results

Removal was attempted in 5076 leads because the technique was not applicable in 10 PL. Among these, 4952 leads were completely removed (97.6%), 49 (1.0%) partially removed, 75 (1.4%) not removed. Among 4989 exposed leads, 818 were removed by manual traction (16.4%), 3664 by mechanical dilatation using the venous entry site (73.4%), 48 by femoral approach (FA) (1.0%) and 335 by JA (6.7%). All the free-floating leads were completely removed, 25.3% by FA and 74.7% by JA. Major complications occurred in 20 cases (0.72%): cardiac tamponade (19 cases, 4 deaths), hemotorax (1 death).

Conclusions

Our experience shows that in centers with wide experience, TLR using single sheath mechanical dilatation has a high success rate and a very low incidence of serious complications. TLR through the Internal Jugular Vein increases the effectiveness and safety of the procedure also in case of free-floating or challenging leads.

Funding Acknowledgement

Type of funding source: None

Off-label combination of leadless pacemakers and subcutaneous defibrillators in bilateral venous occlusion: a new reimplantation strategy after lead extraction

Background

Subcutaneous implantable cardioverter-defibrillator (S-ICD) and leadless pacemakers (LPM) provide an alternative to transvenous implantable devices. Sometimes, after transvenous (TV) lead extraction, patients show a bilateral venous occlusion, resulting not eligible for TV reimplantation.

Purpose

This analysis was designed to provide preliminary data on feasibility and short-term outcome of an hybrid combination (Hyb) of s-ICD plus LPM after TV-ICD explantation, in patients without anatomical transvenous reimplantation options.

Methods

Among 2684 consecutive extracted patients, 31 (1.1%) were reimplanted with a LPM, 66 (2.4%) with a s-ICD and 6 (0.2%) patients with an Hyb combination. Hyb strategy was considered in patients with a pacing plus defibrillating indication, and an anatomical barrier, as bilateral superior venous occlusion or massive bilateral skin erosion.

Results

Hyb patients were old (72±10 years), with a prevalent ischemic disease (4/6) and a reduced ejection fraction (43±16%). Extraction indication was infection in 4 and severe venous occlusion in 2, and included 2 single chamber, 2 dual chamber and 2 biventricular ICD. After extraction, reimplantation timing was 7±6 days, LPM was implanted before and sICD the day after.

LPM reimplantation indication was sinus node dysfunction in 2 and AV block in 4. Implantation duration was 68±23 and fluoroscopy time 9.4±2.3 min. ICD reimplantation indication was primary prevention in 4 and secondary prevention in 2. Implantation duration was 118±10 min. No complications were observed. At 1 year, no complications were observed, including device related cross-talks.

Conclusions

The Hyb strategy is a potential option after TV-ICD explantation in pacemaker dependent patients, when transvenous implantation is not available.

Extraction and Reimplantation Session

Funding Acknowledgement

Type of funding source: None

Transvenous lead extraction: procedural outcomes and in-hospital mortality in octogenarian patients

Background

Managing elderly patients with infection or malfunction deriving from a cardiac implantable electronic device (CIED) may be challenging. The aim of this study was to evaluate safety and efficacy of mechanical transvenous lead extraction (TLE) in elderly patients.

Methods

Patients who had undergone TLE in single tertiary referral center were divided in two groups (Group 1: ≥80 years; group 2:<80 years) and their acute and chronic outcomes were compared. All patients were treated with manual traction or mechanical dilatation.

Results

Our analysis included 1316 patients (group 1: 202, group 2: 1114 patients), with a total of 2513 leads extracted. Group 1 presented more comorbidities and more pacemakers, whereas the dwelling time of the oldest lead was similar, irrespectively of patient's age. In group 1 the radiological success rate for lead was higher (99.0% vs 95.9%; P<0.001) and the fluoroscopy time lower (13.0 vs 15.0 minutes; P=0.04) than in group 2. Clinical success was reached in 1273 patients (96.7%), without significant differences between groups (group 1: 98.0% vs group 2: 96.4%; P=0.36). Major complications occurred in 10 patients (0.7%) without significative differences between patients with more or less than 80 years (group 1: 1.5% vs group 2: 0.6%; P=0.24). In the elderly group no in-hospital mortality occurred (0.0% vs 0.5%; P=0.42).

Conclusions

Mechanical TLE in elderly patients is a safe and effective procedure. In the over-80s, a comparable incidence of major complications with younger patients was observed, with at least a similar efficacy of the procedure and no procedural-related deaths.

Funding Acknowledgement

Type of funding source: None

Real-time local impedance monitoring to assess tissue lesion during pulmonary vein isolation: a new tool for AF ablation

Background

Contact force catheter ablation is the gold standard for treatment of atrial fibrillation (AF). Local tissue impedance (LI) evaluation has been recently studied to evaluate lesion formation during radiofrequency ablation.

Purpose

Aim of the study was to assess the outcomes of an irrigated catether with LI alghorithm compared to contact force (CF)-sensing catheters in the treatment of symptomatic AF.

Methods

A prospective, single-center, nonrandomized study was conducted, to compare outcomes between CF-AF ablation (Group 1) and LI-AF ablation (Group 2). For Group 1 ablation was performed using the Carto 3© System with the SmartTouch SF catheter and, as ablation target, an ablation index value of 500 anterior and 400 posterior. For Group 2, ablation was performed using the Rhythmia™ System with novel ablation catheter with a dedicated algorithm (DirectSense) used to measure LI at the distal electrode of this catheter. An absolute impedance drop greater than 20Ω was used at each targeted. According to the Close Protocol, ablation included a point by point pulmonary vein isolation (PVI) with an Inter-lesion space ≤5 mm in both Groups. Procedural endpoint was PVI, with confirmed bidirectional block.

Results

A total of 116 patients were enrolled, 59 patients in Group 1 (CF) and 57 in Group 2 (LI), 65 (63%) with a paroxismal AF and 36 (37%) with a persistent AF. Baseline patients features were not different between groups (P=ns). LI-Group showed a comparable procedural time (180±89 vs 180±56, P=0.59) but with a longer fluoroscopy time (20±12 vs 13±9 min, P=0.002). Wide antral isolation was more often observed in CF-Group (95% vs 80%, P=0.022), while LI-Group 2 required frequently additional right or left carina ablation (28% vs 14%, P=0.013). The mean LI was 106±14Ω prior to ablation and 92.5±11Ω after ablation (mean LI drop of 13.5±8Ω) during a median RF time of 26 [19–34] sec for each ablation spot. No steam pops or complications during the procedures were reported. The acute procedural success was 100%, with all PVs successfully isolated in all study patients. Regarding safety, only minor vascular complications were observed (5%), without differences between groups (p=0.97). During follow up, 9-month freedom from atrial fibrillation/atrial flutter/atrial tachycardia recurrence was 86% in Group 1 and 75% in Group 2 (P=0.2).

Conclusions

An LI-guided PV ablation strategy seems to be safe and effective, with acute and mid-term outcomes comparable to the current contact force strategy. LI monitoring could be a promising complementary parameter to evaluate not only wall contact but also lesion formation during power delivery.

Procedural Outcomes

Funding Acknowledgement

Type of funding source: None

P1470Outcome of leadless pacemaker implantation in a referral centre for lead extraction: a comparison with transvenous pacemaker

Background

Leadless cardiac pacing is a promising technology in terms of efficacy and safety.

Purpose

The aim of the study was to compare the long-term clinical and electrical performance of Micra leadless pacemaker with ventricular single-chamber transvenous pacemaker (VVI TV-PM) in a high-volume centre for transvenous lead extraction (TLE).

Methods

Between May 2014 and April 2019, 100 patients (group 1) underwent Micra implant at our centre. We identified 100 patients (group 2) who underwent VVI TV-PM implant in the same period for a 1:1 comparison matched by age, sex, left ventricular systolic ejection fraction and  previous TLE.

Results

The implant procedure was successful in all patients. In group 1, the procedure duration was lower than in group 2 (43.86 ± 22.38 vs 58.38 ± 17.85 min, p < 0.001), while the fluoroscopy time was longer (12.25 ± 6.84 vs 5.32 ± 4.42 min, p < 0.001). There was no difference about the rate of septal deployment at the right ventricle (group 1 vs group 2: 76% vs 86%, p = 0.10). Patients were followed-up for a median of 12 months. We did not observe any acute and chronic procedure-related complications in group 1, while we reported acute complications in seven patients (0 vs 7%, p = 0.02) and long-term complications in three patients (0 vs 3%, p = 0.24), needing for a system revisions in 6 cases (0 vs 6%, p = 0.038) in group 2. One systemic infection occurred during follow-up in a patient with VVI TV-PM. Electrical measurements were stable during follow-up in both groups, with a longer estimated battery life in group 1 (mean delivered energy at implant group 1 vs group 2: 0.14 ± 0.21 vs 0.26 ± 0.22 μJ, p < 0.001).

Conclusion

Micra pacemaker implant is a safe and effective procedure, with a lower rate of acute complications and system revisions and a longer estimated battery life compared to VVI TV-PM, even in a real life setting including patients who underwent TLE.

P1469Micra pacemaker implant at septal site induces a smaller increase on qrs duration than traditional pacemaker: a single center experience

BACKGROUND

Leadless pacemakers have been introduced into the clinical practice as a breakthrough technology that could tackle most of the major sources of complication of traditional pacemakers (PM). The excellent safety profile and optimal electrical performance of Micra have been already largely described, nevertheless the impact on QRS duration has not been investigated so far. We aimed to compare changes in QRS duration after septal Micra implant in comparison to patients who received transvenous right ventricular leads in the same position.

METHODS

We enrolled all patients who underwent Micra implantation (group 1) at our Center from April 2017 to March 2019. A septal placement was attempted in all cases. Duration of spontaneous and paced QRS and their difference (delta QRS) were measured using a polygraph. To provide a comparison group, we analyzed the QRS duration in a matched group of patients (group 2) who received a traditional single chamber pacing system with a transvenously implanted lead at septal position in the same period. Confounding variables that were used to provide the control group were age, sex, left ventricle ejection fraction, and rhythm at implant. High pacing threshold was defined as ≥1.0 V at pulse duration of 0.24 ms.

RESULTS

Twenty-eight consecutive patients (mean age 78 ± 3 years; 71.43% males) who underwent successful Micra implant were enrolled. A septal position was achieved in all cases with a single device delivery in 17/28 patients (60.7%). Mean pacing threshold at implant was 0.56 ± 0.34V/0.24 ms with only 3/28 patients (10.7%) presenting a high pacing threshold. No significant differences in demographic, clinical characteristics and ventricular pacing site were observed between groups. QRS duration was slightly longer in group 1 compared to group 2 before implant (median 123 ms (IQR 104-146.5 ms) vs median 116 ms (IQR 90-125 ms); p = 0.09). Nevertheless, there was a significantly lower delta QRS after implant in Micra compared to the traditional pacing group (15.82 ± 31.77 ms vs 35.82 ± 22.13 ms, p = 0.008).

CONCLUSION

Right ventricular stimulation induces ventricular dyssynchrony, which is correlated with the amount of QRS enlargement after pacing. Micra implant, in a non-apical position, produces significantly smaller changes on the QRS duration in comparison with transvenous lead implanted at the same site, although larger studies are necessary to confirm these results.

1260Transvenous lead extraction: efficacy and safety of the procedure in octogenarian patients

Introduction

the management of patients with infection or malfunction of a cardiac implantable electronic device (CIED) may be challenging.

Purpose

The aim of the study is to evaluate the safety and efficacy of transvenous lead extraction (TLE) in elderly patients.

Methods

a retrospective analysis of patients who underwent to TLE in our center was performed. Patients were divided in two groups: 1) patients 80 years of age or older, 2) patients younger than 80 years. All patients were treated with manual traction or mechanical dilatation.

Results

our analysis included 1316 patients, with a total of 2513 leads extracted. Group 1 (≥80 years) counted 202 patients and group 2 (<80 years) 1114 patients. The group of elderly patients presented more comorbidities, as hypertension, chronic kidney disease, atrial fibrillation and pulmonary disease. Patients 80 years of age or older had more pacemakers than ICDs, whereas the dwelling time of the oldest lead, the number of leads and the presence of abandoned leads was similar despite patients age. In group 1 the rate of radiological success for lead was higher than in group 2 (99.0% vs 95.9%; P < 0.001). The clinical success was obtained in 1273 patients (96.7%), without significative differences between groups (98.0% vs 96.4%; P = 0.36). Major complications occurred in 10 patients (0.7%), without significative differences (1.5% vs 0.6%; P = 0.24) (figure 1).

Conclusion

TLE in elderly patients is a safe and effective procedure. In patients older than 80 years there are not more major complications than in younger patients, and the efficacy of the procedure seems to be superior.

Abstract Figure 1

P1358Atrial electromechanical interval in patients with arrhythmias: is everyone the same?

Background

Atrial electromechanical delay, assessed calculating the PA-TDI interval using tissue Doppler imaging, is a known and promising determinant for atrial fibrillation recurrence prediction after pulmonary vein isolation and electrical cardioversion.

Purpose

To determine the relationship between atrial electromechanical delay and the presence of atrial fibrillation.

Methods

We prospectively enrolled patients presenting at our Unit in sinus rhythm scheduled for an arrhythmogenic substrate ablation (atrial fibrillation -AF-, supraventricular tachycardia -SVT- and premature ventricular contractions -PVC-). Demographic and echocardiographic characteristics were evaluated upon admission. Atrial electromechanical delay was inferred via the PA-TDI interval, obtained by calculating the time difference between the P wave onset and the A" wave peak on TDI recordings.

Results

From October 2018 to August 2019, 200 patients (60% male, mean age 58,21 ± 14,26, mean BSA 1,9 ± 0,21 m2, mean BMI 26,42 ± 6,28 kg/m2, mean EF 60,91% ± 5,43%) were admitted to our unit to undergo AF (group 1: n = 145; 72,50%), SVT or PVC ablation (group 2: n = 55; 27,5%). Compared with the control group (group 2), patients admitted for AF ablation had a larger LA size (group 1 vs group 2: mean LA area 23,21 ± 5,07 vs 16,87 ± 4,01 cm2, p < 0,001; mean indexed LA volume 46,71 ± 20,41 ml vs 32,04 ± 14,7 ml, p < 0,001; mean LAD 41,77 ± 5,66 vs 33,84 ± 6,06, p < 0,001) and a longer PA-TDI interval (lateral 148,55 ± 28,5 vs 128,57 ± 20,9, p < 0,001; medial 125,34 ± 21,02 vs 109,11 ± 21,49, p < 0,001; average 141,43 ± 27,58 vs 119,08 ± 18,63, p < 0,001).

Conclusion

The PA-TDI interval is a non-invasive and easily achievable echocardiographic parameter, which is demonstrated to be prolonged in patients with a history of AF in contrast with patients with other arrhythmias, as expression of atrial conduction heterogeneity.

Abstract Figure. PA-TDI measurement

Activation of I kappa b kinase by herpes simplex virus type 1. A novel target for anti-herpetic therapy

Herpes simplex viruses (HSV) are ubiquitous pathogens causing a variety of diseases ranging from mild illness to severe life-threatening infections. HSV utilize cellular signaling pathways and transcription factors to promote their replication. Here we report that HSV type 1 (HSV-1) induces persistent activation of transcription factor NF-kappa B, a critical regulator of genes involved in inflammation, by activating the I kappa B kinase (IKK) in the early phase of infection. Activated NF-kappa B enhances HSV-1 gene expression. HSV-1-induced NF-kappa B activation is dependent on viral early protein synthesis and is not blocked by the anti-herpetic drug acyclovir. IKK inhibition by the anti-inflammatory cyclopentenone prostaglandin A(1) blocks HSV-1 gene expression and reduces virus yield by more than 3000-fold. The results identify IKK as a potential target for anti-herpetic drugs and suggest that cyclopentenone prostaglandins or their derivatives could be used in the treatment of HSV infection.

Anti-inflammatory cyclopentenone prostaglandins are direct inhibitors of IkappaB kinase

NF-kappaB is a critical activator of genes involved in inflammation and immunity. Pro-inflammatory cytokines activate the IkappaB kinase (IKK) complex that phosphorylates the NF-kappaB inhibitors, triggering their conjugation with ubiquitin and subsequent degradation. Freed NF-kappaB dimers translocate to the nucleus and induce target genes, including the one for cyclo-oxygenase 2 (COX2), which catalyses the synthesis of pro-inflammatory prostaglandins, in particular PGE. At late stages of inflammatory episodes, however, COX2 directs the synthesis of anti-inflammatory cyclopentenone prostaglandins, suggesting a role for these molecules in the resolution of inflammation. Cyclopentenone prostaglandins have been suggested to exert anti-inflammatory activity through the activation of peroxisome proliferator-activated receptor-gamma. Here we demonstrate a novel mechanism of antiinflammatory activity which is based on the direct inhibition and modification of the IKKbeta subunit of IKK. As IKKbeta is responsible for the activation of NF-kappaB by pro-inflammatory stimuli, our findings explain how cyclopentenone prostaglandins function and can be used to improve the utility of COX2 inhibitors.

Heat shock factors and the control of the stress response

Living cells are continually challenged by conditions which cause acute and chronic stress. To adapt to environmental changes and survive different types of injuries, eukaryotic cells have evolved networks of different responses which detect and control diverse forms of stress. One of these responses, known as the heat shock response, has attracted a great deal of attention as a universal fundamental mechanism necessary for cell survival under a variety of unfavorable conditions. In mammalian cells, the induction of the heat shock response requires the activation and translocation to the nucleus of one or more heat shock transcription factors which control the expression of a specific set of genes encoding cytoprotective heat shock proteins. The discovery that the heat shock response is turned on under several pathological conditions and contributes to establish a cytoprotective state in a variety of human diseases, including ischemia, inflammation, and infection, has opened new perspectives in medicine and pharmacology, as molecules activating this defense mechanism appear as possible candidates for novel cytoprotective drugs. This article focuses on the regulation and function of the heat shock response in mammalian cells and discusses the molecular mechanisms involved in its activation by stress and bioactive cyclopentenone prostanoids, as well as its interaction with nuclear factor kappaB, a stress-regulated transcription factor with a pivotal role in inflammation and immunity.

Delta(12)-prostaglandin J(2) is a potent inhibitor of influenza A virus replication

9-Deoxy-Delta(9),Delta(12)-13,14-dihydro-prostaglandin D(2) (Delta(12)-PGJ(2)), a natural cyclopentenone metabolite of prostaglandin D(2), is shown to possess therapeutic efficacy against influenza A virus A/PR8/34 (H1N1) infection in vitro and in vivo. The results indicate that the antiviral activity is associated with induction of cytoprotective heat shock proteins and suggest novel strategies for treatment of influenza virus infection.

Induction of ferritin and heat shock proteins by prostaglandin A1 in human monocytes. Evidence for transcriptional and post-transcriptional regulation

Prostaglandins of the A type (PGA) exert a cytoprotective activity during hyperthermia and virus infection. This effect is associated with induction of heat shock proteins (HSP) in mammalian cells. We now report that, in human monocytes, PGA1 is able to induce the synthesis of the iron-binding, redox-regulated protein ferritin. L-chain ferritin induction is consequent to a substantial increase in the accumulation of L-chain ferritin transcripts in PGA1-treated cells, whereas H-chain ferritin is regulated post-transcriptionally, consequently to reduction of iron-regulatory protein binding to iron-responsive elements in ferritin mRNA. Ferritin induction is specific for cyclopentenone prostaglandins (PGA1, PGA2, PGJ2, Delta12-PGJ2), whereas other arachidonic acid (AA) metabolites have no effect. In human monocytes, PGA1 also induces heat shock gene transcription via heat shock factor activation, as well as the synthesis of the oxidative-stress protein heme oxygenase (HOS). Differently from HSP, the induction of ferritin by PGA1 is specific for monocytes. Monocytes/macrophages play a pivotal role in inflammation, controlling iron metabolism and releasing a variety of mediators, including proinflammatory reactive oxygen species (ROS), cytokines and AA metabolites. As ferritin, together with hsp70 and HO, plays a key role in protection from oxidant damage, these results suggest that PGA1 may have cytoprotective activity also during oxidative injury.

Antiviral effect of hyperthermic treatment in rhinovirus infection

Human rhinoviruses (HRV) are recognized as the major etiologic agents for the common cold. Starting from the observation that local hyperthermic treatment is beneficial in patients with natural and experimental common colds, we have studied the effect of brief hyperthermic treatment (HT) on HRV replication in HeLa cells. We report that a 20-min HT at 45 degrees C is effective in suppressing HRV multiplication by more than 90% when applied at specific stages of the virus replication cycle. Synthesis of virus proteins is not affected by HT, indicating that the target for treatment is a posttranslational event. The antiviral effect is a transient cell-mediated event and is associated with the synthesis of the 70-kDa heat shock protein hsp70. Unlike poliovirus, rhinovirus infection does not inhibit the expression of hsp70 induced by heat. The possibility that hsp70 could play a role in the control of rhinovirus replication is suggested by the fact that a different class of HSP inducers, the cyclopentenone prostaglandins PGA1 and delta 12-PGJ2, were also effective in inhibiting HRV replication in HeLa cells. Inhibition of hsp70 expression by actinomycin D prevented the antiviral activity of prostaglandins in HRV-infected cells. These results indicate that the beneficial effect of respiratory hyperthermia may be mediated by the induction of a cytoprotective heat shock response in rhinovirus-infected cells.

Induction of the heat-shock response by antiviral prostaglandins in human cells infected with human immunodeficiency virus type 1

Cyclopentenone prostaglandins inhibit the replication of several DNA and RNA viruses, including retroviruses. The antiviral activity has been associated with the induction of a 70-kDa heat-shock protein (HSP70), via activation of the heat-shock transcription factor (HSF) in infected cells. In the present study we investigated the effect of prostaglandin A1 (PGA1) on the regulation of HSP70 gene expression as well as on viral RNA and protein synthesis in CEM-SS cells during acute infection with human immunodeficiency virus type 1 (HIV-1). We report that HIV-1 infection does not alter HSF activation by PGA1, whereas it causes an increase in intracellular HSP70 mRNA levels, as a result of enhanced HSP70 mRNA stability. We also show that, as reported in studies of different virus/host cell models, PGA1 inhibits HIV-1 replication by acting at multiple levels during HIV-1 infection. In addition to the previously reported block of HIV-1 mRNA transcription, PGA1 was also found to inhibit viral protein synthesis. These results, together with the fact that prostaglandins are used clinically in the treatment of several diseases, open new perspectives in the search for novel antiretroviral drugs.

Stress-inducible responses and heat shock proteins: new pharmacologic targets for cytoprotection

Molecular chaperones protect proteins against environmental and physiologic stress and from the deleterious consequences of an imbalance in protein homeostasis. Many of these stresses, if prolonged, result in defective development and pathologies associated with a diverse array of diseases due to tissue injury and repair including stroke, myocardial reperfusion damage, ischemia, cancer, amyloidosis, and other neurodegenerative diseases. We discuss the molecular nature of the stress signals, the mechanisms that underlie activation of the heat shock response, the role of heat shock proteins as cytoprotective molecules, and strategies for pharmacologically active molecules as regulators of the heat shock response.

Inhibition of rotavirus replication by prostaglandin A: evidence for a block of virus maturation

Rotaviruses are recognized as the leading cause of severe viral gastroenteritis in young children and in immunocompromised patients. Cyclopentenone prostaglandins possess antiviral activity against several single-strand RNA viruses; therefore, the effect of prostaglandin A1 (PGA1) on SA-11 simian rotavirus infection was investigated in cultured cells. PGA1 potently inhibited SA-11 rotavirus replication. Whereas it did not affect virus adsorption or penetration, PGA1 partially inhibited VP4 and VP7 synthesis and selectively reduced glucosamine incorporation into the NSP4 viral enterotoxin. Electron microscopy analysis showed that, despite normal formation of cytoplasmic inclusions and budding of particles into the rough endoplasmic reticulum, virus maturation was impaired in PGA1-treated cells, with most of the virus particles remaining in the membrane-enveloped intermediate form. Because prostaglandins are used clinically as cytoprotective drugs for gastric ulcers, these observations offer new perspectives in the search for therapeutic agents for rotavirus-induced gastroenteritis.

Activation of the heat shock factor 1 by serine protease inhibitors. An effect associated with nuclear factor-kappaB inhibition

Heat shock proteins (HSPs) have a cytoprotective role in several human diseases, including ischemia and viral infection. Nuclear factor-kappaB (NF-kappaB) is a critical regulator of inflammation and virus replication. Here we report that a class of serine protease inhibitors with NF-kappaB-inhibitory activity are potent HSP inducers via activation of heat shock transcription factor 1 (HSF1) in human cells. 3,4-Dichloroisocoumarin, the most effective compound, rapidly induces HSF1 DNA binding activity and phosphorylation, leading to transcription and translation of heat shock genes for a period of several hours. HSF1 activation is independent of de novo protein synthesis and is correlated in a concentration- and time-dependent manner with NF-kappaB inhibition. Cysteine protease inhibitors E64 and calpain inhibitor II, which do not block NF-kappaB activation, do not induce HSF DNA binding activity. HSP induction by 3,4-dichloroisocoumarin is associated with antiviral activity during rhabdovirus infection. These results identify a new class of HSP inducers and indicate a link between the regulatory pathways of HSF and NF-kappaB, suggesting novel strategies to simultaneously switch on cytoprotective genes and down-regulate inflammatory and viral genes.

Antiviral activity of cyclopentenone prostanoids

Cyclopentenone prostanoids inhibit virus replication by turning on an intracellular defence response that involves the induction of cytoprotective heat-shock proteins, the modification of viral glycoprotein maturation and the control of NF-kappa B activation. These molecules represent an interesting model for the development of novel antiviral drugs that can affect different targets during the virus life cycle.

Inhibition of nuclear factor kappa B by prostaglandin A1: an effect associated with heat shock transcription factor activation

Prostaglandins (PGs) function as intracellular signal mediators in the regulation of a variety of physiological and pathological processes, including inflammation and immune responses. Cyclopentenone PGs are characterized by antiviral activity against several viruses, including human immunodeficiency virus type 1 (HIV-1), and by the ability to induce heat shock protein expression through activation of the heat shock transcription factor. Here we report that PGA1 is a potent inhibitor of nuclear factor-kappa B (NF-kappa B) activation in human cells and of NF-kappa B-dependent HIV-1 transcription in long terminal repeat-chloramphenicol acetyl-transferase transient transfection experiments. PGA1 acts by inhibiting phosphorylation and preventing degradation of the NF-kappa B inhibitor I kappa B-alpha. Inhibition does not require protein synthesis, is dependent on the presence of a reactive cyclopentenonic moiety, and is associated with heat shock transcription factor activation. Because NF-kappa B is critically involved in the activation of immunoregulatory and viral genes, inhibition of its activity could be a major component of the immunosuppressive and antiviral activity of PGs.

2-Cyclopenten-1-one, a new inducer of heat shock protein 70 with antiviral activity

The cytoprotective role of heat shock proteins (HSP) described in variety of human diseases, including ischemia, inflammation, and infection, suggests new therapeutic strategies relying upon the development of drugs that selectively turn on heat shock genes. Cyclopentenone prostaglandins, which contain an alpha, beta-unsaturated carbonyl group in the cyclopentane ring and possess antiviral activity against several RNA and DNA viruses, were shown to function as signal for HSP synthesis in a nonstressful situation in a variety of mammalian cells. We now report that 2-cyclopenten-1-one selectively induces the expression of the 70-kDa HSP (HSP70) in human cells, through cycloheximide-sensitive activation of heat shock transcription factor 1 (HSF1). The alpha, beta-unsaturated carbonyl group is the key structure triggering HSF1 activation. Induction is associated with antiviral activity during infection with vesicular stomatitis virus. These results identify the molecular structure of natural prostaglandins responsible for HSF1 activation and open new perspectives in the search for novel antiviral and cytoprotective drugs.

Inhibition of HSP70 expression by calcium ionophore A23187 in human cells. An effect independent of the acquisition of DNA-binding activity by the heat shock transcription factor

Heat shock proteins (HSPs) are induced in mammalian cells in a variety of pathophysiological states and have an important role in cytoprotection in vitro and in vivo. In this study, we report that the calcium ionophore A23187, a glucose-regulated protein (GRP) inducer, dramatically inhibits HSP70 synthesis and HSP70 mRNA transcription after induction by heat shock, sodium arsenite, or prostaglandin A1 treatment in human K562 cells. A23187 does not suppress, and it actually prolongs, the DNA-binding activity of the human heat shock transcription factor (HSF), while it alters HSF1 phosphorylation in heat shock-treated cells. To inhibit HSP70 expression, A23187 needs to be present during heat shock, while treatment before or after heat shock does not affect HSP70 mRNA transcription. The GRP inducer thapsigargin, which specifically inhibits the endoplasmic reticulum Ca2+-ATPase, has no effect on heat-induced HSP70 synthesis, indicating that A23187 inhibitory activity is not due to depletion of intracellular calcium stores and is independent of the concomitant induction of GRP genes. Inhibition of HSP70 expression is correlated with alterations in HSF1 phosphorylation in heat-shocked cells, but not in sodium arsenite-treated cells, indicating that different mechanisms may be involved in mediating A23187 inhibitory activity.

Inhibition of HIV-1 replication by cyclopentenone prostaglandins in acutely infected human cells. Evidence for a transcriptional block

Cyclopentenone prostaglandins (PGs) inhibit virus replication in several DNA and RNA virus models, in vitro and in vivo. In the present report we demonstrate that the cyclopentenone prostaglandins PGA(1) and PGJ(2) at nontoxic concentrations can dramatically suppress HIV-1 replication during acute infection in CEM-SS cells. PGs did not affect HIV-1 adsorption, penetration, reverse transcriptase activity nor viral DNA accumulation in HIV-1 infected cells. A dramatic reduction in HIV-1 mRNA levels was detected up to 48-72 h after infection (p.i.) in PG-treated cells, and HIV-1 protein synthesis was greatly reduced by a single PG-treatment up to 96 h p.i. Repeated PGA(1)-treatments were effective in protecting CEM-SS cells by the cytopathic effect of the virus, and in dramatically reducing HIV-1 RNA levels up to 7 d after infection. The antiviral effect was not mediated by alterations in the expression of alpha-, beta-, or gamma-interferon,TNFalpha, TNFbeta, IL6, and IL10 in HIV-infected CEM-SS cells. The fact that prostaglandins are used clinically in the treatment of several diseases, suggests a potential use of cyclopentenone PGs in the treatment of HIV-infection.

Effect of combined alpha IFN and prostaglandin A1 treatment on vesicular stomatitis virus replication and heat shock protein synthesis in epithelial cells

The antiviral activity of prostaglandin A (PGA) and interferons (IFNs) has been widely described. In the present report, we investigated the effect of combined alpha IFN and PGA1 treatment on vesicular stomatitis virus (VSV) replication and on heat shock protein (HSP) induction in monkey epithelia cells. In uninfected cells, PGA1 caused a dose-dependent induction of HSP70, HSP90 and HSP110, while alpha IFN did not affect HSP synthesis. Alpha-IFN suppressed VSV replication dose-dependently, even when cells were treated after virus infection. VSV protein synthesis was not affected by alpha IFN, indicating a block at the level of virus assembly or maturation. PGA1 caused a dose-dependent inhibition of VSV replication, and suppressed VSV protein synthesis at concentrations which induced the synthesis of high levels of HSP70. The combined treatment with low doses of alpha IFN or PGA1, which only moderately inhibited VSV replication when administered separately, was found to suppress VSV production by more than 95%, and resulted in a 3-fold increase of HSP70 synthesis as compared to PGA1 alone. These results demonstrate a co-operative effect of PGA1 and alpha IFN against VSV infection and suggest that alpha IFN can potentiate the cellular response to HSP induction in virus-infected cells.

Inhibition of poliovirus replication by prostaglandins A and J in human cells

Cyclopentenone prostaglandins (PGs) inhibit the replication of a wide variety of enveloped DNA and RNA viruses. The antiviral activity is associated with alterations in the synthesis, maturation, and intracellular translocation of viral proteins. In the present report, we describe the effects of cyclopentenone PGs PGA1 and delta 12-PGJ2 on poliovirus (PV) replication in HeLa cells. Both PGs were found to inhibit PV replication dose dependently. Virus yield was significantly reduced at nontoxic concentrations, which did not suppress RNA or protein synthesis in uninfected or PV-infected cells. Both the pattern of PV proteins synthesized and the kinetics of viral protein synthesis and degradation appeared to be similar in PGA1-treated cells and control cells. Antiviral PGs have been shown to selectively inhibit virus protein synthesis during the replication of several viruses, including vesicular stomatitis virus (VSV), and this effect has been recently associated with the induction of a 70-kDa heat shock protein (HSP70). PGA1 and delta 12-PGJ2 were found to induce HSP70 synthesis in uninfected or VSV-infected HeLa cells. PV infection was found to inhibit PG-induced HSP70 synthesis in these cells, suggesting that the lack of ability of cyclopentenone PGs to block PV protein synthesis could be related to an impaired heat shock response in PV-infected cells. The finding that PV protein synthesis was not inhibited by PGs suggests that cyclopentenone PGs could interfere with a late event in the virus replication cycle, such as protein assembly and maturation of PV virions.

Modulation of prostaglandin A1-induced thermotolerance by quercetin in human leukemic cells: role of heat shock protein 70

Prostaglandins of the A type (PGAs) function as signals for heat shock protein (hsp) synthesis in mammalian cells. In human K562 erythroleukemic cells, PGA1 induces the synthesis of a M(r) 70,000 hsp (hsp70) by cycloheximide-sensitive activation of heat shock transcription factor (HSF). Induction of hsp70 has been associated recently with the ability of PGA to protect K562 cells from thermal injury, establishing a thermotolerant state; however, the role of hsp70 in thermotolerance is still controversial. Because quercetin was shown to modulate hsp70 expression after heat shock in K562 cells, we have investigated the effect of this flavonoid on HSF activation, hsp70 synthesis, and thermotolerance in human K562 cells after induction with PGA1. Quercetin was found to inhibit hsp70 synthesis for a period of 3-6 h after PGA1 treatment. This transient block was exerted at the transcriptional level and was not due to the loss of HSF DNA-binding activity. After the initial delay, hsp70 synthesis reached the same rate as the PGA1-treated control, and it was actually prolonged in the presence of quercetin. In PGA1-treated cells, quercetin suppressed PGA1-induced thermotolerance completely if the heat shock was applied at a time (6 h) when hsp70 synthesis was inhibited, whereas it could not prevent the establishment of a thermotolerant state if the heat challenge was applied 24 h after treatment, when hsp70 synthesis was not affected. These results support strongly the hypothesis that hsp70 is involved in the establishment of thermotolerance in human cells.

Viral infection

The relationship between viruses and the cellular stress response is a multifaceted and complex phenomenon which depends on the structural and genetic characteristics of the virus, on the type of infection, as well as on the environmental conditions. It is now well documented that infection of mammalian cells by several types of RNA and DNA viruses often results in alterations of the cellular stress response. Interactions between stress proteins and viral components have been described in a large variety of experimental models at different stages of the viral life cycle, depending on the type of virus and host cell. The presence of heat shock proteins in intact virions has also been described. On the other hand, induction of HSP expression by hyperthermia or other agents results in alterations of the virus replication cycle during acute or persistent infections of mammalian cells, and a possible role of heat shock proteins in the beneficial effect of fever and local hyperthermia during acute infection has been hypothesized. This chapter describes the different aspects of the interaction between viruses and the stress response, and discusses the possible role of stress proteins in the control of virus replication and morphogenesis.

Aspirin enhances thermotolerance in human erythroleukemic cells: an effect associated with the modulation of the heat shock response

Heat shock protein (HSP) synthesis is induced by hyperthermia and other types of stress in mammalian cells in vitro and in vivo. In the present report we describe that in human erythroleukemic cells, aspirin (400 microM), when administered during or immediately after a hyperthermic treatment, causes an increase in the amount of HSP70 synthesized and prolongs HSP70 synthesis for a period of several hours. This effect is not due to increased HSP70 mRNA stability. In the presence of aspirin, the heat shock transcription factor is maintained in the activated DNA-binding state for a period twice as long as control, an effect which results in enhanced and prolonged HSP70 mRNA transcription. A different cyclooxygenase inhibitor, indomethacin (10(-7) M), also provokes similar effects. The modulation of the heat shock response by aspirin and indomethacin is associated with the ability of these drugs to potentiate the effect of hyperthermia and prolong thermotolerance for a period of 48 h. These results indicate that the use of aspirin and indomethacin should be carefully monitored in cancer patients undergoing hyperthermic treatment. On the other hand, the ability of aspirin to enhance HSP70 synthesis suggests that nonsteroidal anti-inflammatory drugs could potentiate the cytoprotective role of HSPs in pathological states, including fever, inflammation, and ischemia.

Induction by prostaglandin A1 of haem oxygenase in myoblastic cells: an effect independent of expression of the 70 kDa heat shock protein

Prostaglandins of the A type (PGA) induce the synthesis of 70 kDa heat shock proteins (hsp70) in a large variety of mammalian cells. Induction of hsp70 has been associated with a cytoprotective effect of PGA1 after virus infection or thermal injury. In the present report we provide evidence that, in murine myoblasts, PGA1 is not able to induce hsp70 expression, whereas it increases the synthesis of the constitutive protein, hsc70, and dramatically induces the synthesis of a 32 kDa protein (p32). The p32 protein has been identified as haem oxygenase. PGA1 acts at the transcriptional level by inducing haem oxygenase mRNA synthesis, and the signal for induction appears to be associated with decreased intracellular GSH levels. Haem oxygenase, a low-molecular-mass stress protein induced in mammalian cells by oxidant stress, is known to be part of a general inducible antioxidant defence pathway. The fact that prostaglandin synthesis is stimulated in muscle during contraction and in the heart in response to ischaemia raises the possibility that induction of haem oxygenase by PGA in myoblasts could be part of a protective mechanisms in operation during stress and hypoxia.

Heat shock proteins and virus replication: hsp70s as mediators of the antiviral effects of prostaglandins

Acute infection of mammalian cells with several types of RNA and DNA viruses often results in induction of heat-shock gene expression. The presence of hsp70 in intact virions, as well as the transient association of HSP with viral proteins and assembly intermediates during virus replication, has also been reported in several experimental models. Moreover, a possible role of heat shock proteins in the beneficial effect of fever and local hyperthermia during acute virus infection has been hypothesized. However, the role of HSP in virus replication remains to be defined. At the beginning of the 1980s, the use of virus models to investigate the molecular events that follow the exposure of mammalian cells to prostaglandins led to the serendipitous discovery that specific arachidonic acid derivatives are potent inhibitors of virus replication. This finding was rapidly followed by the observation that treatment of virus-infected cells with the antiviral prostaglandin A1 (PGA1) resulted in the accumulation of a 70 KDa cellular protein, which was identified as hsp70. It is now well established that cyclopentenone prostaglandins, which exert potent antiviral activity in several DNA and RNA virus models, induce hsp70 synthesis through cycloheximide-sensitive activation of heat shock transcription factor. This chapter discusses the role of heat shock proteins in the control of virus replication and summarizes the results of our recent work, which indicate that hsp70 is actively involved in the antiviral activity of prostaglandins.

Selective inhibition of virus protein synthesis by prostaglandin A1: a translational block associated with HSP70 synthesis

Cyclopentenone prostaglandins are potent inhibitors of virus replication. The antiviral activity has been associated with the induction of 70-kDa heat shock protein (HSP70) synthesis. In this report, we describe that in African green monkey kidney cells infected with Sendai virus (SV) and treated with prostaglandin A1 (PGA1), SV protein synthesis was selectively blocked as long as HSP70 was being synthesized by the host cell. The block appeared to be at the translational level, as indicated by the following (i) PGA1 had no effect on SV primary transcription, and a dramatic decrease in the abundance of SV mRNA occurred only at later stages of infection; and (ii) treatment with PGA1 started at 6 h postinfection, at which time SV mRNA had already accumulated in infected cells, did not suppress the levels of NP mRNA, but it reduced the amount of ribosome-bound NP mRNA and caused a dramatic decrease in the level of genomic RNA. The PGA1-induced block of SV protein synthesis appeared to be cell mediated, since it was prevented by actinomycin D, while PGA1 had no effect on SV mRNA translation in vitro. The possibility that HSP70 could be a mediator of the antiviral effect is suggested by the fact that treatment with other classical inducers of HSP70, including sodium arsenite, cadmium, and heat shock at 42 degrees C for 5 h, also selectively prevented SV protein synthesis as long as heat shock protein synthesis occurred. Moreover, SV protein synthesis was not inhibited by PGA1 in murine Friend erythroleukemic cells, which lack the ability to induce HSP70 expression in response to PGA1.

Regulation of heat shock protein synthesis by quercetin in human erythroleukaemia cells

Synthesis of heat-shock proteins (HSPs) is universally induced in eukaryotic and prokaryotic cells by exposure to elevated temperatures or to other types of environmental stress. In mammalian cells, HSPs belonging to the 70 kDa family (HSP70) have a regulatory role in several cellular processes, and have been shown to be involved in the control of cell proliferation and differentiation. Although many types of HSP70 inducers have been identified, only a few compounds, all belonging to the flavonoid group, have been shown to inhibit HSP70 induction. Because inhibitors of HSP70 synthesis could be an important tool with which to study the function of this protein, we have investigated the effect of quercetin, a flavonoid with antiproliferative activity which is widely distributed in nature, on HSP70 synthesis in human K562 erythroleukaemia cells after treatment with severe or mild heat shock and with other inducers. Quercetin was found to affect HSP70 synthesis at more than one level, depending on the conditions used. Indeed, after severe heat shock (45 degrees C for 20 min) treatment with quercetin, at non-toxic concentrations, was found to inhibit HSP70 synthesis for a period of 3-4 h. This block appeared to be exerted at the post-transcriptional level and to be cell-mediated, as the addition of quercetin during translation of HSP70 mRNA in vitro had no effect. After prolonged (90 min) exposure at 43 degrees C, however, quercetin was found to inhibit also HSP70 mRNA transcription. Pretreatment of K562 cells with quercetin had no effect on HSP70 expression, and quercetin needed to be present during induction to be effective. Under all conditions tested, the quercetin-induced block of HSP70 synthesis was found to be transient and, after an initial delay, synthesis of HSP70 reached the control rate and continued at the same level for several hours after the time at which HSP70 synthesis had been turned off in control cells. Finally, inhibition of HSP70 synthesis by quercetin appeared to be dependent on the temperature used and on the type of stressor.

Induction of thermotolerance by prostaglandin A in human cells

Cyclopentenone prostaglandins (PGs) induce the synthesis of heat shock proteins (HSPs) in mammalian cells. Since arachidonic acid metabolites are implicated in the control of fever, we investigated the effect of PG treatment on thermal injury in human K562 erythro-leukemia cells. Prostaglandin A1 (PGA1) was found to protect cells after severe heat shock and to induce a thermotolerant state, which persisted for 24-48 h. Prostaglandins of the B, E, and F type were not effective. Kinetics of thermotolerance induction was comparable to heat-induced heat resistance. Establishment of a thermotolerant state was not a direct effect of PGA1, since it was dependent on de novo protein synthesis and was associated with HSP70 induction. This activity of PGA1 could be part of a protective control mechanism during fever.

Antiviral effect of short hyperthermic treatment at specific stages of vesicular stomatitis virus replication cycle

Starting from the observation that the antiviral activity of cyclopentenone prostaglandins is associated with the synthesis of a 70K heat shock protein (HSP70), we have analysed the effect of short hyperthermic treatment (HT) on HSP70 induction and virus production in monkey epithelial cells during the replication of vesicular stomatitis virus (VSV). The heat shock response, as determined by HSP70 synthesis, appeared to be unaltered in VSV-infected cells in the first 4 h following virus infection, after which time it started to decline. No induction of HSP70 synthesis was observed when HT was applied 8 h after VSV infection. A 20 min HT at 45 degrees C was effective in suppressing VSV multiplication by more than 90% when applied at specific stages of the virus replication cycle. Synthesis of virus proteins was not affected by HT, indicating that the target for the treatment is a post-translational event. The HT-induced block of virus replication appeared to be associated with inhibition of VSV G protein maturation and HSP70 induction.

Inhibition of Sindbis virus replication by cyclopentenone prostaglandins: a cell-mediated event associated with heat-shock protein synthesis

Cyclopentenone prostaglandins (PGs) have been shown to inhibit the replication of several DNA and RNA viruses. Here we report on the effect of prostaglandin A1 (PGA1) on the multiplication of a positive strand RNA virus, Sindbis virus, in Vero cells under one-step multiplication conditions. PGA1 was found to inhibit Sindbis virus production dose-dependently, and virus yield was reduced by more than 90% at the concentration of 8 micrograms/ml, which was non-toxic to the cells and did not inhibit DNA, RNA or protein synthesis in Vero cells. The cyclopentenone prostaglandin delta 12-PGJ2 was also shown to be a potent inhibitor of Sindbis virus replication. Virus-induced reduction of [3H]uridine uptake by cells was partially prevented by PGA1 treatment, which also caused a 1 h delay in the peak of virus RNA synthesis. SDS-PAGE analysis of [35S]methionine-labeled proteins showed that PGA1 moderately inhibited the synthesis of the viral structural proteins E1, E2 and C, and induced the synthesis of a 72 kDa M(r) protein, identified as a heat-shock protein related to the HSP70 group, in both virus-infected and uninfected cells. Actinomycin D treatment completely prevented PGA1-antiviral activity, indicating that a cellular product is responsible for this action. PGA1-induced HSP70 is a good candidate for this role.

Inhibition of vesicular stomatitis virus replication by delta 12-prostaglandin J2 is regulated at two separate levels and is associated with induction of stress protein synthesis

delta 12-Prostaglandin J2 (delta 12-PGJ2), a naturally occurring dehydration product of prostaglandin D2, is shown to suppress the replication of vesicular stomatitis virus (VSV) in two different epithelial monkey cell lines. A significant delay in the virus-induced cytopathic effect and a dramatic inhibition of virus production can be obtained at doses which do not inhibit protein synthesis in uninfected cells, and induce the synthesis of heat shock proteins (HSPs) in both uninfected and VSV-infected cells. delta 12-PGJ2 is shown to block VSV replication at two separate levels in the early and late phase of the virus replication cycle. Treatment started soon after VSV infection greatly suppresses viral (but not cellular) protein synthesis and prevents the virus-induced shut-off of host cell protein synthesis. This effect is accompanied by the induction of HSP synthesis. delta 12-PGJ2-treatment in a late phase of the virus replication cycle, when all virus proteins have been synthesized, still causes a dramatic block of infectious virus production. This block is accompanied by a decrease in [3H]glucosamine incorporation into the virus glycoprotein G, at concentrations which do not alter glucosamine uptake by the cells, suggesting that a defect in virus protein glycosylation could be responsible for the antiviral activity. Finally, delta 12-PGJ2 causes a decrease of glucosamine incorporation into at least two host cell polypeptides, while the majority of cellular proteins are unaffected and glycosylation of a 47 kDa cellular protein is strongly induced. These selective alterations of protein glycosylation suggest that delta 12-PGJ2 affects a specific group of glycosylated proteins. The finding that cyclopentenone prostaglandins act on different events during the virus cycle explains the effectiveness of these compounds in controlling the replication of different types of viruses and presents an attractive new approach to antiviral chemotherapy.

Inhibition of Sendai virus replication by delta 12-prostaglandin J2: induction of heat shock protein synthesis and alteration of protein glycosylation

delta 12-Prostaglandin J2 (delta 12-PGJ2), a natural dehydration product of prostaglandin D2 present in human body fluids, was shown to suppress Sendai virus replication in monkey kidney cells, at doses non-toxic to uninfected cells. Dramatic inhibition of virus production could be obtained at doses of delta 12-PGJ2 which did not inhibit cellular or viral protein synthesis, suggesting an effect on virus assembly and/or maturation. At the active concentration, delta 12-PGJ2 caused a decrease in glucosamine incorporation into the virus glycoproteins HN and F, and in at least one host cell polypeptide, while it did not affect most cellular glycoproteins and it induced the glycosylation of a 47-kDa cellular polypeptide. These effects were accompanied by the induction of heat shock protein synthesis, which was found to differ in its specificity and kinetics from induction by prostaglandin A1.