Predictive value of device-derived activity level for short-term outcomes in MADIT-CRT

Temporal changes in device-derived daily activity related to ventricular arrhythmias from the CERTITUDE registry

Background

There have been limited data examining the temporal relationship between device-derived daily activity and ventricular arrhythmias (VAs).

Objective

We aimed to assess whether activity predicted VAs or VAs predicted changes in activity.

Methods

The CERTITUDE registry includes over 55,000 implanted devices active on Home Monitoring. Daily data on activity are captured by a 1-axis accelerometer. Temporal changes in activity during treated VAs were analyzed using the first event and 7-day activity windows (baseline, pre-event, and postevent). Baseline period was defined as 31 to 38 days prior to VA. VAs were categorized by heart rate (≤200 beats/min, >200 beats/min) and treatment (shock or antitachycardia pacing). Differences were assessed using the binomial proportion test and case-crossover analysis.

Results

A total of 5631 devices (3688 implantable cardioverter-defibrillators, 1943 cardiac resynchronization therapy defibrillators) were analyzed with a cumulative follow-up duration of 18,354 years (5.6 million days). Patients with VA events >200 beats/min with shock (n = 593) had a significant decline in activity post-VA with a median -8.7% reduction (interquartile range -24.6% to 7.3%, P < 0.001). However, there was no reduction in activity before VA events >200 beats/min (P = .690) or before or after VA events >200 beats/min with antitachycardia pacing. However, VA events ≤200 beats/min with shock had reductions in activity following the event (-5.8%, interquartile range -29.5% to 12.3%, P = .003). Case-crossover analyses confirmed lower activity rates following for VA events >200 beats/min with shock.

Conclusion

In the CERTITUDE registry, we have shown a temporal decline in device-derived activity following VA events >200 beats/min and for VA events <200 beats/min treated with a shock, but we did not find changes in activity preceding a shock event.

Changes in physical activity around the time of major adverse cardiac events in patients with implantable cardioverter-defibrillators

BACKGROUND

With modern implantable cardioverter-defibrillators (ICDs), biometric measures including physical activity have become readily available to physicians. However, despite the increased availability, applications of these data to the clinical setting remain poorly studied. We sought to investigate whether changes in physical activity occur preceding and following cardiac events in patients with ICDs.

METHODS

We reviewed the electronic medical records of patients with ICDs implanted for any indication in 2018 and 2019 in the University of Pennsylvania health system. Patients with ICDs that reported physical activity were included in the study only if they experienced major adverse cardiac event(s) (MACE) that were preceded by at least 6 months without MACE after device implantation.

RESULTS

Seventy-four of the 827 charts reviewed met inclusion criteria. Baseline activity levels from 6 to 2 months prior to MACE were 2.18-2.21 h/day. In the month prior to MACE, average activity decreased significantly to 2.09 h/day, and subsequently decreased again during the calendar month in which MACE occurred to 1.96 h/day. The lowest average monthly activity levels occurred in the month after MACE, with incremental but non-significant recovery occurring over the subsequent 2 months.

CONCLUSIONS

In a cohort of ICD recipients, a significant decrease in physical activity was observed in the month preceding MACE. To our knowledge, this is the first study that observes time-dependent changes in activity in relation to MACE in a generalizable cohort of ICD recipients. ICD activity monitoring in patients at high risk for MACE may enhance patient care.

Physical Activity in Cardiac Implantable Electronic Device Recipients During the COVID-19 Pandemic

OBJECTIVE

To characterize the physical activity (PA) level in patients with a cardiac implantable electronic device (CIED) during the coronavirus disease 2019 (COVID-19) pandemic and compare PA level during the pandemic in 2020 with the year 2019.

METHODS

We performed a retrospective analysis of PA activity in individuals implanted with a CIED enrolled in the BIOTRONIK CERTITUDE Registry. Mean daily and weekly PA from January to August 2020 was compared with 2019.

RESULTS

A total of 21,660 individuals met eligibility criteria, with mean age of 72.6±11.6 years, and 12,411 (57.3)% were males. A significant decline in daily PA was noted following the pandemic declaration in 2020, with a maximum mean reduction of -24.5±36.3 minutes (P<.0001) observed in April 2020 compared with 2019. PA in 2020 increased from April to May (120.6±67.4 to 129.2±70.9 min/d). PA was lower for all months in 2020 compared with 2019. The decrease in PA was observed in all prespecified groups based on age, sex, type of device, and region of the country.

CONCLUSION

After the declaration of the coronavirus disease 2019 pandemic, a significant decline in daily PA was observed in individuals with a CIED. Future investigation to establish the impact of this reduction on short and long-term cardiovascular outcomes is required.

Comparative Analysis of Physical Activity Detected via an External Accelerometer and Cardiac Implantable Electronic Devices

Background

Physical activity (PA) has become an important health issue for decades. Cardiovascular implantable electronic devices (CIEDs) have built-in PA-recording functions. We aimed to compare PA measurements using an external accelerometer (ActiGraph GT3X+) and internal accelerometers (Abbott, Biotronik, and Medtronic CIEDs).

Methods

This was a prospective, single-center observational study. The device-measured 7-day average PA was collected, and GT3X+ -measured 7-day average PA was used as the gold-standard, including all daily observations of activity. Pearson’s correlation coefficients were used to compare the correlations between GT3X+ -measured and CIED-measured PA. Bland-Altman plots were used to analyze measurement agreement, and intraclass correlation coefficients were used to analyze reliability.

Results

In total, 720 patients treated with CIEDs were surveyed between November 2020 and April 2021, 60 of them were analyzed after patient screening by our protocol. Each manufacturer included 20 patients for the final analysis. The CIED-measured PAs of Abbott, Biotronik, and Medtronic were 3.0 ± 1.5, 2.6 ± 1.8, and 3.8 ± 2.5 h per day, respectively; the GT3X+ -measured PAs were 6.9 ± 2.8, 6.0 ± 2.4, and 6.4 ± 2.5 h per day, respectively. Moderate and significant correlations were found in patients using Abbott, Biotronik, and Medtronic CIEDs (r = 0.534, p = 0.015; r = 0.465, p = 0.039; r = 0.677, p = 0.001, respectively). Bland-Altman plots and intraclass correlation coefficients both showed a significant correlation and reliability between the average PA measured by GT3X+ and CIEDs (hours per day).

Conclusion

Although the PA recording function of CIEDs includes a single-axis accelerometer, it has a moderate correlation compared with the triaxial accelerometer of the GT3X+. However, CIEDs seem to underestimate PA for 3–4 h compared to the GT3X+.

Accelerometer-assessed physical behavior and the association with clinical outcomes in implantable cardioverter-defibrillator recipients: A systematic review

Background

Current implantable cardioverter-defibrillator (ICD) devices are equipped with a device-embedded accelerometer capable of capturing physical activity (PA). In contrast, wearable accelerometer-based methods enable the measurement of physical behavior (PB) that encompasses not only PA but also sleep behavior, sedentary time, and rest-activity patterns.

Objective

This systematic review evaluates accelerometer-based methods used in patients carrying an ICD or at high risk of sudden cardiac death.

Methods

Papers were identified via the OVID MEDLINE and OVID EMBASE databases. PB could be assessed using a wearable accelerometer or an embedded accelerometer in the ICD.

Results

A total of 52 papers were deemed appropriate for this review. Out of these studies, 30 examined device-embedded accelerometry (189,811 patients), 19 examined wearable accelerometry (1601 patients), and 3 validated wearable accelerometry against device-embedded accelerometry (106 patients). The main findings were that a low level of PA after implantation of the ICD and a decline in PA were both associated with an increased risk of mortality, heart failure hospitalization, and appropriate ICD shock. Second, PA was affected by cardiac factors (eg, onset of atrial fibrillation, ICD shocks) and noncardiac factors (eg, seasonal differences, societal factors).

Conclusion

This review demonstrated the potential of accelerometer-measured PA as a marker of clinical deterioration and ventricular arrhythmias. Notwithstanding that the evidence of PB assessed using wearable accelerometry was limited, there seems to be potential for accelerometers to improve early warning systems and facilitate preventative and proactive strategies.

Feasibility and First Results of Heart Failure Monitoring Using the Wearable Cardioverter-Defibrillator in Newly Diagnosed Heart Failure with Reduced Ejection Fraction

The wearable cardioverter-defibrillator (WCD) is used in patients with newly diagnosed heart failure and reduced ejection fraction (HFrEF). In addition to arrhythmic events, the WCD provides near-continuous telemetric heart failure monitoring. The purpose of this study was to evaluate the clinical relevance of additionally recorded parameters, such as heart rate or step count. We included patients with newly diagnosed HFrEF prescribed with a WCD. Via the WCD, step count and heart rate were acquired, and an approximate for heart rate variability (HRV5) was calculated. Multivariate analysis was performed to analyze predictors for an improvement in left ventricular ejection fraction (LVEF). Two hundred and seventy-six patients (31.9% female) were included. Mean LVEF was 25.3 ± 8.5%. Between the first and last seven days of usage, median heart rate fell significantly (p < 0.001), while median step count and HRV5 significantly increased (p < 0.001). In a multivariate analysis, a delta of HRV5 > 23 ms was an independent predictor for LVEF improvement of ≥10% between prescription and 3-month follow-up. Patients with newly diagnosed HFrEF showed significant changes in heart rate, step count, and HRV5 between the beginning and end of WCD prescription time. HRV5 was an independent predictor for LVEF improvement and could serve as an early indicator of treatment response.

Clinical utility of CorVue intrathoracic impedance alert with device-measured physical activity in predicting heart failure events

Cardiac implantable electronic devices (CIEDs) offer heart failure (HF) diagnostic information, including intrathoracic impedance (ITI) or physical activity (PA). However, few studies have evaluated the utility of these parameters measured by CIEDs with CorVue algorithm. The purpose of this study was to investigate the relationship between ITI alerts triggered by the CorVue algorithm and HF development. We also examined the association between device-measured PA and ITI alerts associated with HF development. We retrospectively studied consecutive patients with CIEDs equipped with CorVue algorithm, which were implanted between June 1, 2011 and August 31, 2019. These patients were divided into two groups: patients with decreased ITI followed by the ITI alerts (ITI alert group) and those without the alerts (non-ITI alert group). There were 35 and 14 patients in the ITI and non-ITI alert groups, respectively. A total of 96 ITI alerts were observed. ITI alerts associated with HF development were observed in 21% (20/96); whereas, ITI alerts not associated with HF development were observed in 79% (76/96). Accurate device-measured PA was confirmed in 76 ITI alerts, which consisted of 30 alerts with lower PA and 46 alerts without lower PA. ITI alerts associated with HF development were observed in 30% (9/30) of the alerts with lower PA, whereas observed only in 6.5% (3/46) of the alerts without lower PA. In conclusion, the CorVue ITI alerts indicated a high false-positive rate. However, device-measured PA may be useful to determine whether ITI alerts are associated with HF development or not, which was attributed to the high negative predictive value.

Remotely monitored inactivity due to COVID-19 lockdowns. Potential hazard for heart failure patients

OBJECTIVES

To study the impact of curfews during the COVID-19 pandemic, on the physical activity in patients of heart failure implanted withcardiac implantable electronic devices (CIEDs).

METHODS

This was a retrospective single-center study of heart failure patients inserted with remote monitoring (RM)-capable CIED. We analyzed the transmitted data of physical activity and fluid volume status of all patients, before, and during the lockdown periods between February and April 2020. The clinical status of the patients was also evaluated.  Results: Device data from 429 patients implanted with CIED capable of RM were initially evaluated. Patients with an implantable loop recorder, Brugada or Long QT syndromes, and patients with incomplete transmissions were excluded. Eighty-two patients with heart failure were included. The median age was 65 years (58-72), and 53 (64.6%) subjects were men. There was a 27.1% decline in physical activity, and the median physical activity of patients significantly declined from 2.4 to 1.8 hours/day (p=0.000010).  Conclusion: Data obtained by remotely monitored CIED in heart failure patients suggests a significant decline in physical activity during the country lockdown due to the pandemic. Awareness of the future potential hazards in this group of patients is warranted.

Wearable devices can predict the outcome of standardized 6-minute walk tests in heart disease

Wrist-worn devices with heart rate monitoring have become increasingly popular. Although current guidelines advise to consider clinical symptoms and exercise tolerance during decision-making in heart disease, it remains unknown to which extent wearables can help to determine such functional capacity measures. In clinical settings, the 6-minute walk test has become a standardized diagnostic and prognostic marker. We aimed to explore, whether 6-minute walk distances can be predicted by wrist-worn devices in patients with different stages of mitral and aortic valve disease. A total of n = 107 sensor datasets with 1,019,748 min of recordings were analysed. Based on heart rate recordings and literature information, activity levels were determined and compared to results from a 6-minute walk test. The percentage of time spent in moderate activity was a predictor for the achievement of gender, age and body mass index-specific 6-minute walk distances (p < 0.001; R 2 = 0.48). The uncertainty of these predictions is demonstrated.

Baseline and decline in device-derived activity level predict risk of death and heart failure in patients with an ICD for primary prevention

BACKGROUND

Implanted defibrillators are capable of recording activity data based on company-specific proprietary algorithms. This study aimed to determine the prognostic significance of baseline and decline in device-derived activity level across different device companies in the real world.

METHODS

We performed a retrospective cohort study of patients (n = 280) who underwent a defibrillator implantation (Boston, Medtronic, St. Jude, and Biotronik) for primary prevention at the University of Michigan from 2014 to 2016. Graphical data obtained from device interrogations were retrospectively converted to numerical data. The activity level averaged over a month from a week postimplantation was used as baseline. Subsequent weekly average activity levels (SALs) were standardized to this baseline. SAL below 59.4% was used as a threshold to group patients. All-cause mortality and death/heart failure were the primary end-points of this study.

RESULTS

Fifty-six patients died in this study. On average, they experienced a 50% decline in SAL prior to death. Patients (n = 129) who dropped their SAL below threshold were more likely to be older, male, diabetic, and have more symptomatic heart failure. They also had a significantly increased risk of heart failure/death (hazard ratio [HR] 3.6, 95% confidence interval [95% CI] 2.3-5.8, P < .0001) or death (HR 4.2, 95% CI 2.2-7.7, P < .0001) compared to those who had sustained activity levels. Lower baseline activity level was also associated with significantly increased risk of heart failure/death and death.

CONCLUSION

Significant decline in device-derived activity level and low baseline activity level are associated with increased mortality and heart failure in patients with an ICD for primary prevention.

Physical activity is reduced prior to ventricular arrhythmias in patients with a wearable cardioverter defibrillator

INTRODUCTION

The utility of accelerometer-based activity data to identify patients at risk of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) has not previously been investigated. The aim of the current study was to determine whether physical activity is associated with manifesting spontaneous sustained VT/VF requiring emergent defibrillation in patients with an ejection fraction of ≤35%.

METHODS

Patients consecutively prescribed a wearable cardioverter defibrillator (WCD) from April 2015 to May 2018 were included. Shock data and 4 weeks of physical activity data, beginning with the first week of WCD wear, were analyzed.

RESULTS

Based on the ROC curve outcome generated from 4057 patients, average daily step count during the first week accurately predicted those patients with sustained VT/VF compared to those without (shocked (n = 81) vs nonshocked (n = 3976) area under the curve, c-index = 0.71, 95% CI = 0.65-0.77, P < .001). An average cutoff of 3637 daily steps during week 1 separated the groups. Patients who averaged fewer than 3637 steps per day during the first week of WCD use were 4.3 times more likely to experience a shock than those who walked more than 3637 steps per day (OR = 4.29, 95% CI = 2.58-7.15, P < .001).

DISCUSSION

Average daily step counts are lower in WCD patients who manifest spontaneous VT/VF. Whether these findings represent a causal or correlational relationship, future studies to encourage a minimum daily step count in high-risk patients may impact the incidence of sustained VT/VF.

Measuring Physical Activity With Implanted Cardiac Devices: A Systematic Review

Background

Physical activity is predictive of cardiovascular outcomes in patients with cardiovascular implantable electronic devices, yet it is not regularly assessed in routine care. Current‐generation cardiovascular implantable electronic devices, however, continuously monitor patient activity through a built‐in accelerometer, which provides new opportunities to remotely assess patient activity, detect changes in clinical status, and incorporate these data in risk stratification models. This review critically examines the literature on device‐measured physical activity (D‐PA), with a focus on identifying methodological issues that may affect interpretation of study results.

Methods and Results

We conducted a systematic review of D‐PA studies published from January 1 1995 to December 30 2017, identifying 29 studies meeting inclusion criteria, 5 of which were validation reports. Few technical details about D‐PA sensors are reported, and procedures for analyzing and interpreting D‐PA data are heterogeneous. Trends in D‐PA over time and associations with clinical outcomes were reported by 22 studies, and in 7 studies, D‐PA was combined with other device parameters in risk stratification models, demonstrating modest‐to‐good sensitivity in predicting acute heart failure decompensation, hospitalization, and mortality.

Conclusions

Current evidence suggests that D‐PA may be useful for assessing physical activity and predicting clinical outcomes in patients with cardiovascular implantable electronic devices when combined with other device parameters. Future work must address challenges related to D‐PA data measurement, interpretation, and generalizability to support expanded clinical applications of this technology.

[Non-device-based telemonitoring : Toy or tool?]

Non-device-based telemedical management can be useful to prevent decompensation and death in patients suffering from easily disequilibrated conditions like diabetes mellitus, chronic obstructive pulmonary disease and heart failure (HF). This article summarizes current knowledge on non-device-based telemedical care for patients with HF. Several parameters (heart rate, heart rate variability, systolic blood pressure, pulse pressure, body weight, physical activity as derived from accelerometry, and occurrence of atrial and ventricular arrhythmias) have been identified as being associated with imminent clinical deterioration of HF patients. Structured telephone-based support and noninvasive telemonitoring with integrated electronic transfer of physiological data have been applied to care for HF patients and have been evaluated in multiple studies. The impact of telemedical care on clinical outcome appears to depend on the applied telemedical configuration and on the disease severity of targeted populations. The exclusive use of an automated telephone response system has not been successful. In patients with optimal medical therapy and relatively low decompensation risk noninvasive telemonitoring did not significantly reduce mortality. Nevertheless meta-analyses of structured telephone support and of noninvasive telemonitoring combining knowledge from available randomized trials suggest that both of these telemedical approaches may reduce the mortality risk of HF patients by 13-20%. The results of the Telemedical Interventional Management in Heart Failure II (TIM-HF II) trial on noninvasive telemonitoring versus usual care in 1500 high-risk HF patients are awaited in 2018 and will further clarify the usefulness of telemedical care in this field.