A prediction model for ventricular tachycardia events using 24h ambulatory ECG

Background

Ventricular tachycardia (VT) is a potentially lethal condition that occurs intermittently. The aim of this study was to derive a risk prediction model for VT episodes detected on ≤30 day mobile cardiac telemetry using a 24 hour ambulatory ECG recording.

Methods

We included patients who were monitored for 2–30 full days in the USA using a full-disclosure mobile cardiac telemetry device in 2017. Patients with a VT episode ≥10 beats duration (VT≥10 beats) on the first full recording day were excluded. Arrhythmias were algorithmically detected and manually verified. A LASSO model was derived for the outcome of a VT≥10 beats detected on days 2–30. Potential predictors included age, sex, and ECG data from the first 24h: heart rate (max, min and mean), premature atrial and ventricular complexes occurring as singles, couplets, triplets, and runs ≥4 beats as well as the fastest rate for each event. The population was split into equal random training and testing samples.

Results

In a population of 19,789 patients (mean age 65.3, 43.4% men), and during a median recording time of 18 days there were 1,511 patients with at least one VT≥10 beats. The LASSO model had good discrimination in the testing sample, ROC-statistic 0.7586, 95% CI 0.7398–0.7774 (Figure 1a). A model excluding age and gender had similar discrimination (ROC 0.7528, 95% CI 0.7339–0.7717). In the testing sample the model was well calibrated (Figure 1b). In the top quintile more than one in five patients had a VT≥10 beats, enough to warrant extended monitoring.

Conclusion

A risk score based on variables easily derived from a standard 24h ECG can be used to predict high risk of VT episodes ≥10 beats within 30 days. In the top quintile VT events ≥10 beats were ten times more common than in the bottom quintile.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Hjärt-LungfondenSwedish Society for Medical Research

Activity levels influence frequency of premature atrial contractions

Background

Frequent premature atrial contractions (PACs) are associated with substantially increased risk of atrial fibrillation (AF) and stroke, but PAC count varies substantially day-to-day. With the emergence of potential therapies for primary prevention of AF reliable estimation of PAC frequency is increasingly relevant, as is an understanding of PAC determinants.

Purpose

To determine the effect of daily activity and heart rate on an individuals' daily PAC count.

Methods

We included a random sample of patients 18–85 years without AF who recorded an ambulatory ECG for 7–31 days in the U.S.A during 2019 using a full-disclosure mobile cardiac telemetry device, and who had ≥500PACs on at least one recording day. PACs were algorithmically detected and manually verified. PAC count and activity was sampled for each individual and each recording day during daytime (06–22h). The effect of activity on daily PAC count was assessed in a negative binomial regression model including age, sex and with a random effect for individual, to account for confounding due to inter-individual differences.

Results

The study population consisted of 2,094 patients, of which 48% were men (Fig 1). Mean time spent in activity was 32% (standard deviation (SD 10%) for men and women 31% (SD 10%) for women (Fig 2). The median PAC count was 592 (inter-quartile range 1280). Beyond age, sex and intra-individual differences PAC frequency was determined by activity levels, (intercept 629 PACs; incidence rate ratio per 10 minute increase in activity 1.03, p<0.0001). A 1-hour increase in daily activity was associated with a 20% increase in daily PACs count.

Conclusions

Physical activity is associated with increased PACs counts, implying both that a reliable diagnosis of PAC frequency needs to be conducted during a person's habitual level of activity and that PAC frequency is modifiable. In-hospital assessments of PACs while patients are mainly inactive may underestimate PAC frequency.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): the Swedish Society For Medical Researchthe Swedish Heart and Lung Foundation Age and sex distributionActivity levels by sex

Epidemiology of subclinical atrial fibrillation in patients with cardiac implantable electronic devices: a systematic review and meta-analysis

Background

Sub-clinical atrial fibrillation (SCAF) and atrial high-rate episodes (AHREs), seen as high-frequency atrial tachyarrhythmias in patients with cardiac implantable electronic devices (CIEDs), have gained prominence as determinants of clinical atrial fibrillation (AF) and increased stroke risk. As a result, several studies investigating their role in predicting the onset of AF and AHRE-related outcomes have been conducted but uncertainty exists on the epidemiology of AHRE.

Purpose

To estimate the incidence of SCAF, according to presence of AHREs in patients with CIEDs, through a systematic review and meta-analysis of the available literature.

Methods

PubMed and EMBASE were searched from inception to 27th January 2021 for all studies documenting the incidence of AHREs in patients with CIEDs. We included all studies with ≥100 patients reporting data on AHREs incidence. Pooled prevalence and incidence rates were computed; we also performed meta-regressions for pooled incidence rates, according to relevant study-level characteristics. This study was registered in PROSPERO: CRD42019106994.

Results

Among the 2,515 results retrieved, we included 51 studies in the systematic review and meta-analysis, with a total of 68,414 patients. Meta-analysis of included studies showed a pooled prevalence of 28.2% (95% CI: 24.3–32.5%, I2=99%), with a pooled incidence rate (IR) of 15 new AHRE cases per 100 patient-years (95% CI: 12–19, I2=100%). Given the large heterogeneity showed in the pooled estimates we performed additional analyses. Regarding pooled prevalence, we performed several subgroup analyses, according to various studies baseline characteristics, which did not show any significant difference in any of the subgroups examined. Regarding IR, a multivariable meta-regression analysis showed that decreasing follow-up time and increasing age were the only factors significantly associated with AHRE incidence, explaining a large proportion of heterogeneity (R2=68%, p<0.001; Figure 1, Panel A and B respectively). Accordingly, the AHRE IR was highest at 1 year follow-up and in the oldest subjects. Presence of SCAF was significantly associated with older age, higher CHA2DS2-VASc score, and higher prevalence of hypertension, heart failure and history of cerebrovascular disease.

Conclusions

This systematic review and meta-regression demonstrated that SCAF is very common in patients with CIEDs, with an overall IR for AHREs of up to 15 per 100 patient-years; increasing with age and decreasing with longer follow-up time. Presence of SCAF was associated with an overall higher clinical risk profile compared to those subjects without SCAF.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Meta-regression for AHRE Incidence

74Subclinical atrial fibrillation before and after acute medical illness or noncardiac surgery: insights from ASSERT

OnBehalf

ASSERT Investigators

Background

Atrial fibrillation (AF) is frequently detected perioperatively or during acute medical illness. It is unclear if such AF is reversible and unlikely to recur, or is a manifestation of paroxysmal AF.

Objective

To compare the prevalence of pacemaker-detected, subclinical AF (atrial rate >190 bpm) before and after hospitalization for noncardiac surgery or medical illness in patients without a history of clinical AF.

Methods

ASSERT enrolled patients who were >65 years old and had hypertension but no known AF. Pacemakers and defibrillators recorded episodes of subclinical AF. We identified participants who were hospitalized for noncardiac surgery or medical illness, and created heart rhythm profiles, centred on the day of hospitalization. We compared the prevalence of subclinical AF before and after hospitalization. We blanked the 30 days before hospitalization, because of uncertainty in defining the precise onset of illness.

Results

Among 2580 patients, 436 had a documented surgical or medical hospitalization. In the 30 days following a first hospitalization, 43 patients (9.9%) had >1 episode of >6 minutes of subclinical AF; 20 (4.6%) had >6 hours and 13 (3%) had >24 hours.

A higher proportion of patients had >1 episode of subclinical AF >6 minutes in the 30 days following a first surgical or medical hospitalization, as compared to the period between 30 and 60 days before hospitalization (9.9% versus 4.4%, P < 0.001). There was no significant difference when comparing 0-90 days after hospitalization to 30-120 days before (13.7% versus 10.6%, P = 0.1). Similar results were observed for the same comparisons with episodes >6 hours (4.6% versus 2.3%, P = 0.03 and 5.9% versus 5.6%, P = 0.8, respectively).

The majority of patients with subclinical AF in the 30 days following hospitalization had at least one episode of subclinical AF of the same duration in the 6 months prior (50% for episodes >6 minutes; 69% for >6 hours and 60% for >24 hours). Those who did have subclinical AF in the 30 days following hospitalization were more likely to have had subclinical AF in the past 6 months than those who did not (OR 7.2 95%CI 3.2-15.8 for episodes >6 minutes; OR 32.6, 95%CI 10.3-103.4 for >6 hours and OR 36.3 95%CI 9.0-146.0 for >24 hours).

Conclusions

The prevalence of subclinical AF increased following hospitalization for noncardiac surgery or medical illness.  However, most patients with subclinical AF following hospitalization had previously experienced similar episodes, particularly those with longer episodes of subclinical AF.

P2859Low rates of mechanical failures of silicone-polyurethane copolymer-coated ICD leads: 11 years prospective follow-up

Background

High rates of ICD lead mechanical failures (insulation abrasion and conductor fracture) resulted in FDA recalls and substantial design modifications. Most subsequent reports of lead failures of newer generation leads are based upon modest-sized, retrospective cohorts with relatively brief follow-up and may be unreliable. Following lead modifications (including silicone-polyurethane copolymer insulation coating), in 2007, one manufacturer established 3 prospective registries, and engaged a university-based methods center to independently review the registries, to adjudicate all reports of lead failures and to independently analyze lead survival. Up to 11 years of follow-up is now available.

Purpose

To adjudicate all reports of leads inactivated because of possible mechanical failure and to independently calculate rates of mechanical failure overall and by specific type.

Methods

Manufacturer expert staff confirm each lead inactivation by site interrogation. Following formal algorithms which incorporate lead testing and remote monitoring, they designate all-cause mechanical failure (fracture; insulation abrasion; failure at crimp, bond or weld; or uncertain) based upon the finding of electrical noise, very low or very high or rapidly rising impedance or alternatively they designate non-mechanical dysfunction (e.g. no impedance criteria but elevated thresholds, over or under sensing). The results of returned product analyses are incorporated when available (31%). The methods center receives electronic data transfers twice yearly, reviews all documentation, adjudicates all instances of possible lead failure, assigns probable cause (by 2 electrophysiologists) and conducts independent analyses of lead survival.

Results

10,866 patients (73% male, mean age 65.9 yr., LVEF 29.3%, NYHA class II or III 89%) with 11,132 leads had follow-up of 4.6 yr. (median) and 11 yr. (maximum) (Aug 31, 2018). Lead follow-up was censored at the time of lead inactivation, death/transplant or administrative withdrawal. Of leads enrolled, there were 26.6% still in follow-up and of those not the status was 7.4% inactivated, 29.5% death or transplant, 33.8% administrative withdrawal and 3.7% reason missing. Following adjudication, there were 156 all-cause mechanical failures (1.40% total, 0.29%/yr.). Rates of cause-specific mechanical failures were: fracture 1.02% total, 0.22%/yr.; insulation abrasion 0.28% total, 0.06%/yr.; miscellaneous/uncertain 0.12% total, 0.02%/yr.; and externalized conductors 0%. Life-table rates of freedom from lead failure by 11 years were: all-cause mechanical failure 95.9%, conductor fracture 97.0%, insulation abrasion 99.1%, mechanical failure other/uncertain type 99.9%, and externalized conductors 100%.

Conclusions

Up to 11 yr prospective follow-up of silicone-polyurethane-coated ICD leads with independent adjudication and analyses of events shows low rates of all-cause mechanical failure and no externalized conductors.

Acknowledgement/Funding

Abbott

Design and rationale of the atrial fibrillation occurring transiently with stress (AFOTS) incidence study

BACKGROUND

Atrial fibrillation (AF) is often detected for the first time in patients hospitalized for medical illness or non-cardiovascular surgery. AF occurring transiently with stress (AFOTS) describes this manifestation of AF, which may either be the result of a non-cardiac stressor, or existing paroxysmal AF that was not previously detected. Current estimates of AFOTS incidence are imprecise: ranging from 1 to 44%, owing to the marked heterogeneity in patient populations, identification and methods used to detect AFOTS.

METHODS

The prospective, two-centre epidemiological AFOTS Incidence study will enroll 250 consecutive participants without a history of AF but with at increased risk of AF (Age ≥ 65 or >50 with one risk factor for AF) admitted to intensive care units (ICUs) for medical illness or non-cardiac surgery. Upon admission, participants will wear an ECG patch monitor that will remain in place for 14 days, or until discharge from hospital. Patients' consent to participation is deferred for up to 72 h after admission. The primary endpoint is the incidence of AF lasting ≥30 s. The study is powered to detect an AF incidence of 17% ± 5%.

RESULTS

We conducted a vanguard feasibility study, and 55 participants have completed participation. The median duration of monitoring was seven days. AF was detected by the clinical team in 8 participants (14%; 95% Confidence Interval 7-26%).

CONCLUSIONS

The AFOTS Incidence study will employ a systematic and highly sensitive protocol for detecting AFOTS in medical illness and non-cardiac surgery ICU patients. This study is feasible and will provide a reliable estimate of the true incidence of AFOTS in this population.

Are there increased periprocedural complications with the MRI-conditional Medtronic Revo SureScan Pacing System? : A meta-analysis

BACKGROUND

The use of magnetic resonance imaging (MRI)-conditional permanent pacemakers has increased significantly. In this meta-analysis, we examine the safety of MRI-conditional pacing systems in comparison with conventional systems.

METHODS

An electronic search was performed using major databases, including studies that compared the outcomes of interest between patients receiving MRI-conditional pacemakers (MRI group) versus conventional pacemakers (control group).

RESULTS

Six studies (5 retrospective and 1 prospective non-randomised) involving 2,118 adult patients were identified. The MRI-conditional pacemakers, deployed in 969 patients, were all from a single manufacturer (Medtronic Pacing System with 5086 leads). The rate of pacemaker lead dislodgement (atrial and ventricular) was significantly higher in the MRI group (3% vs. 1%, OR 2.47 (95% CI 1.26; 4.83), p = 0.008). The MRI group had a significantly higher rate of pericardial complications (2% vs. 1%, OR 4.23 (95% CI 1.18; 15.10), p = 0.03) and a numerically higher overall complication rate in comparison with the conventional group (6% vs. 3%, OR 2.02 (95% CI 0.88; 4.66), p = 0.10) but this was not statistically significant.

CONCLUSIONS

In this meta-analysis, the rates of pacemaker lead dislodgement and pericardial complications were significantly higher with the Medtronic MRI-conditional pacing system.

Reduced-dose warfarin or interrupted warfarin with heparin bridging for pacemaker or defibrillator implantation: a randomized trial

BACKGROUND

Perioperative management with reduced-dose warfarin is of potential interest by eliminating the need for bridging while still maintaining a degree of anticoagulation. The outcomes of this regimen have not been well determined.

METHODS

In a randomized controlled trial we compared two regimens for management of anticoagulation with warfarin in patients with implantation of a pacemaker or defibrillator. Half dose of warfarin for 3-6 days, depending on the baseline international normalized ratio (INR), before surgery aiming at an INR of ≤ 1.7 was compared with interrupted warfarin for 5 days with preoperative bridging with low-molecular-weight heparin (LMWH) at therapeutic dose for 2.5 days. Main safety outcome was pocket hematoma. Secondary outcomes were major bleeding, thromboembolism - all within 1 month, days of hospitalization and number of patients requiring correction of INR with vitamin K.

RESULTS

The study was planned for 450 patients but it was discontinued prematurely due to a change in practice. Pocket hematoma occurred in 4 of 85 patients (5%) randomized to the bridged regimen and in 3 of 86 patients (3%) randomized to reduced-dose warfarin. One pocket hematoma in each group was severe. There were no major hemorrhages or thromboembolism within the 1-month window. Duration of hospitalization was similar in the two groups. Correction of INR the day before surgery with vitamin K had to be used for significantly more patients in the reduced-dose warfarin group (41%) than in the bridged regimen group (6%).

CONCLUSION

The reduced-dose warfarin regimen appeared to have similar safety after device implantation as interrupted warfarin with preoperative LMWH bridging. Due to premature discontinuation no firm conclusion can be drawn. The reduced-dose warfarin regimen often failed to achieve the intended preoperative INR. ClinicalTrials.gov Identifier: NCT 02094157.

Anticoagulation management in patients with mechanical heart valves having pacemaker or defibrillator insertion

BACKGROUND

In patients with a high risk for stroke and having invasive procedures with a high risk for bleeding it is unclear how anticoagulant therapy should be managed.

METHODS

We reviewed data from all patients with mechanical heart valves, who had elective insertion or replacement of pacemaker or implantable cardioverter defibrillator (ICD) during the past 8years at our hospital. Data on anticoagulant treatment, pocket hematoma and thromboembolic complications were captured.

RESULTS

Of the 111 patients reviewed, 68 (61%) had a mechanical valve in the mitral position with or without other valves replaced and 43 (39%) had a mechanical valve only in the aortic position. Fifty-nine (53%) were undergoing replacement for their device. Six patients received a tapered warfarin regimen and 102 received preoperative bridging anticoagulation of whom 12 also received postoperative bridging. One stroke occurred 40days after pacemaker replacement in a patient with mitral mechanical valve and without postoperative bridging. Six patients (5.5%) developed pocket hematoma without a significant association to postoperative bridging, type of mechanical valve or to type of device. Predictors for pocket hematoma appeared to be replacement surgery (odds ratio 12.5; 95% confidence interval [CI], 0.69-228) and an international normalized ratio of 1.5 or higher on the day of surgery (odds ratio 8.4; 95% CI, 0.96-68.1).

CONCLUSION

We found a low risk for stroke in the absence of postoperative bridging. For patients with device replacement surgery reversal of the anticoagulant effect at the time of procedure might reduce the risk for pocket hematoma, but this requires prospective evaluation including the risk of thromboembolism.

Stroke prevention in elderly patients with atrial fibrillation: challenges for anticoagulation

Elderly patients with atrial fibrillation (AF), who constitute almost half of all AF patients, are at increased risk of stroke. Anticoagulant therapies, especially vitamin K antagonists (VKA), reduce the risk of stroke in all patients including the elderly but are frequently under-used in older patients. Failure to initiate VKA in elderly AF patients is related to a number of factors, including the limitations of current therapies and the increased risk for major haemorrhage associated with advanced age and anticoagulation therapy. Of particular concern is the risk of intracranial haemorrhages (ICH), which is associated with high rates of mortality and morbidity. Novel oral anticoagulant agents that are easier to use and might offer similar or better levels of stroke prevention with a similar or reduced risk of bleeding should increase the use of antithrombotic therapy in the management of elderly AF patients. Amongst these new agents, the recently approved direct thrombin inhibitor dabigatran provides effective stroke prevention with a significant reduction of ICH, and enables clinicians to tailor the dose according to age and haemorrhagic risk.

Physiologic pacing: where pacing mode selection reflects the indication

Results of recent trials suggest that in patients with left ventricular dysfunction, interventricular synchrony is possibly more important than atrioventricular synchrony. In patients with AV block and conduction system disease, alternatives to right ventricular apical pacing are therefore needed.