Implantable device therapy

Evaluation of an Integrated Device Diagnostics Algorithm to Risk Stratify Heart Failure Patients - Results From the SCAN-HF Study

BACKGROUND

Integrated device diagnostics, Triage-HF, is useful in risk stratifying patients with heart failure (HF), but its performance for Japanese patients remains unknown. This is a prospective study of Japanese patients treated with a cardiac resynchronization therapy defibrillator (CRT-D), with a Medtronic OptiVol 2.0 feature.

METHODS AND RESULTS

A total of 320 CRT-D patients were enrolled from 2013 to 2017. All received HF treatment in the prior 12 months. Following enrollment, they were followed every 6 months for 48 months (mean, 22 months). Triage-HF-stratified patients at low, medium and high risk statuses at every 30-day period, and HF-related hospitalization occurring for the subsequent 30 days, were evaluated and repeated. The primary endpoint was to assess Triage-HF performance in predicting HF-related hospitalization risk. All device data were available for 279 of 320 patients (NYHA class II or III in 93%; mean left ventricular ejection fraction, 31%). During a total of 5,977 patient-month follow-ups, 89 HF-related hospitalization occurred in 72 patients. The unadjusted event numbers for Low, Medium and High statuses were 19 (0.7%), 42 (1.6%) and 28 (4.1%), respectively. Relative risk of Medium to Low status was 2.18 (95% CI 1.23-3.85) and 5.78 (95% CI 3.34-10.01) for High to Low status. Common contributing factors among the diagnostics included low activity, OptiVol threshold crossing, and elevated night heart rate.

CONCLUSIONS

Triage-HF effectively stratified Japanese patients at risk of HF-related hospitalization.

Stratifying patients at the risk of heart failure hospitalization using existing device diagnostic thresholds

Background

Heart failure hospitalizations (HFHs) cost the US health care system ~$20 billion annually. Identifying patients at risk of HFH to enable timely intervention and prevent expensive hospitalization remains a challenge. Implantable cardioverter defibrillators (ICDs) and cardiac resynchronization devices with defibrillation capability (CRT-Ds) collect a host of diagnostic parameters that change with HF status and collectively have the potential to signal an increasing risk of HFH. These device-collected diagnostic parameters include activity, day and night heart rate, atrial tachycardia/atrial fibrillation (AT/AF) burden, mean rate during AT/AF, percent CRT pacing, number of shocks, and intrathoracic impedance. There are thresholds for these parameters that when crossed trigger a notification, referred to as device observation, which gets noted on the device report. We investigated if these existing device observations can stratify patients at varying risk of HFH.

Methods

We analyzed data from 775 patients (age: 69 ± 11 year, 68% male) with CRT-D devices followed for 13 ± 5 months with adjudicated HFHs. HFH rate was computed for increasing number of device observations. Data were analyzed by both excluding and including intrathoracic impedance. HFH risk was assessed at the time of a device interrogation session, and all the data between previous and current follow-up sessions were used to determine the HFH risk for the next 30 days.

Results

2276 follow-up sessions in 775 patients were evaluated with 42 HFHs in 37 patients. Percentage of evaluations that were followed by an HFH within the next 30 days increased with increasing number of device observations. Patients with 3 or more device observations were at 42× HFH risk compared to patients with no device observation. Even after excluding intrathoracic impedance, the remaining device parameters effectively stratified patients at HFH risk.

Conclusion

Available device observations could provide an effective method to stratify patients at varying risk of heart failure hospitalization.

Predictors of implantable cardioverter-defibrillator use in patients with ischemic cardiomyopathy

OBJECTIVES

The objective of this study was to identify and examine ICD utilization in a large group of eligible coronary artery bypass grafting (CABG) patients with impaired left ventricular function.

METHODS

We conducted a retrospective study of ICD eligible patients who had previously undergone CABG surgery between March 1, 1995 and June 30, 2008 at a single tertiary care institution. All patients with a pre-operative left ventricular ejection fraction (LVEF) ≤ 35% were considered ICD eligible. The events of interest were ICD implantation and mortality, based on administrative data linkage.

RESULTS

A total of 1,169 out of 11,931 CABG patients operated on during the same period had LVEF ≤ 35% and were defined as ICD eligible (mean EF = 27.3% +/- 6.4%). Of these eligible patients, only 101 received an ICD during follow-up (8.6%). The median time to implant was 255 days (14-1078). The single variable that independently predicted eventual ICD implantation was a history of arrhythmia (OR = 7.4; CI, 4.4-12.2). The variables that predicted not having an ICD implanted during follow-up included the need for urgent CABG (OR = 0.5; CI, 0.2-0.9), age > 70 years (OR = 0.5; CI, 0.3-0.8), female gender (OR = 0.2; CI,0.1-0.6), or having chronic obstructive lung disease (OR = 0.5; CI,0.3-0.8). As a data validation step, a series of consecutive patient records were reviewed (n=80) showing that fewer than 23% underwent appropriate follow-up EF assessment post revascularization.

CONCLUSION

Our findings suggest that CABG patients with ischemic cardiomyopathy have low rates of ICD utilization. This is particularly evident among females and elderly patients. Furthermore our data suggests that few patients post-revascularization undergo follow-up EF assessment despite current guidelines likely contributing to the low rates of ICD utilization.

A randomized controlled trial of secondary prevention of anxiety and distress in a German sample of patients with an implantable cardioverter defibrillator

OBJECTIVE

To evaluate a minimal, easy, accessible intervention targeting anxiety and reduced quality of life in patients with an implantable cardioverter defibrillator (ICD). An estimated 24% to 87% of patients experience anxiety, and 10% to 15% have reduced quality of life.

METHODS

A total of 119 ICD patients were assigned randomly to usual medical aftercare (n = 63) or additional psychological treatment (n = 56) comprising of written information on medical and psychological consequences of an ICD plus 6 months of individual phone counseling. Treatment efficacy was evaluated by comparing T0 (immediately after implantation) and T1 (6 months later) assessments.

RESULTS

Although 75% of patients considered the program helpful, age moderated treatment efficacy. As indicated by triple interactions, only in the treatment group, anxiety (HADS-Anxiety, p < .01), psychological distress (SCL-K-9, p < .02), and somatic quality of life (SF-36-PCS, p < .01) improved in ICD patients aged <65 years but deteriorated in older patients (age, 65-75 years). Frequency of ICD discharges was associated with a symptom increase from T0 to T1 in all patients (HADS-Depression, CAQ-Avoidance, and ICD-Constraints; all p < .05).

CONCLUSIONS

Our findings confirm that psychological treatments cannot be expected to have uniformly positive effects in ICD patients. Our minimal intervention may have adequately addressed ICD-related concerns in younger patients but may have fostered problems in older patients with fewer concerns. Therefore, our findings warrant custom treatment with particular attention to the elderly as well as patients with frequent ICD discharges.

Clinical characteristics and in-hospital outcome of patients with end-stage renal disease on dialysis referred for implantable cardioverter-defibrillator implantation

BACKGROUND

Little is known about the clinical profile of end-stage renal disease (ESRD) patients who undergo implantable cardioverter-defibrillator (ICD) implantation.

OBJECTIVE

This study sought to analyze the risk profile of ESRD patients admitted for ICD implantation.

METHODS

Patients undergoing first-time device implantation in National Cardiovascular Data Registry/ICD registry from 01/01/06 to 12/31/07 were analyzed (n = 164,069). Patients with ESRD (defined as those requiring dialysis) were compared with patients without ESRD. Primary outcome was in-hospital complications. Because length of hospital stay for ERSD patients was significantly longer (8 vs. 4 days), complications within 2 days of ICD implantation were also examined. The proportion of patients meeting approved indications for ICD implantation was evaluated.

RESULTS

ESRD patients (n = 6,851, 4.4%) had higher rates of comorbid medical conditions, major complications, and total complications, and were less likely to receive an ICD for primary prevention. ESRD patients who received ICD implantation for primary prevention were more likely to meet trial criteria. ESRD patients were less likely to receive beta-blockers and angiotensin inhibitors (P <.0001). Unadjusted in-hospital mortality was almost 5-fold among patients with ESRD (1.9% vs. 0.4%, P <.0001). Multivariable analysis confirmed that ESRD was independently associated with total in-hospital complications (odds ratio [OR] = 1.38, 95% confidence interval: 1.23 to 1.54, P <.0001), and total complications at 2 days (OR = 1.20, 95% confidence interval: 1.05 to 1.36, P = .006).

CONCLUSION

ESRD patients presenting for ICD implantation are sicker, and have higher rates of in-hospital complications even when accounting for overall longer length of hospital stay. Strategies to decrease complications among ESRD patients who undergo ICD implantation need exploration.

Hemodynamic sensing using subcutaneous photoplethysmography

Pacemakers and implantable defibrillators presently operate without access to hemodynamic information. If available, such data would allow tailoring of delivered therapy according to perfusion status, optimization of device function, and enhancement of disease monitoring and management. A candidate method for hemodynamic sensing in these devices is photoplethysmography (PPG), which uses light to noninvasively detect changes in blood volume. The present study tested the hypotheses that PPG can function in a subcutaneous location, that the acute changes in blood volume it detects are directly proportional to changes in arterial pressure, and that optimum pacing intervals identified by it are concordant with those determined by arterial pressure. Aortic pressure and PPG were simultaneously recorded in 10 dogs under general anesthesia during changes in atrioventricular (AV) delay and bursts of rapid pacing to simulate tachyarrhythmias. Direct proportionality between transient changes in pressure and PPG waveforms was tested using regression analysis. Scatter plots had a linear appearance, with correlation coefficients of 0.95 (SD 0.03) and 0.72 (SD 0.24) for rapid-pacing and AV delay protocols, respectively. The data were well described by a directly proportional relationship. Optimum AV delays estimated from the induced changes in aortic pressure and PPG waveforms were concordant. This preliminary canine study demonstrates that PPG can function subcutaneously and that it may serve as a surrogate for acute changes in arterial pressure.