Muhammad Bilal Munir

Battery longevity in cardiac resynchronization therapy implantable cardioverter defibrillators

AIMS Cardiac resynchronization therapy (CRT) implantable cardioverter defibrillators (ICDs) deliver high burden ventricular pacing to heart failure patients, which has a significant effect on battery longevity. The aim of this study was to investigate whether battery longevity is comparable for CRT-ICDs from different manufacturers in a contemporary cohort of patients. METHODS AND RESULTS All the CRT-ICDs implanted at our institution from 1 January 2008 to 31 December 2010 were included in this analysis. Baseline demographic and clinical data were collected on all patients using the electronic medical record. Detailed device information was collected on all patients from scanned device printouts obtained during routine follow-up. The primary endpoint was device replacement for battery reaching the elective replacement indicator (ERI). A total of 646 patients (age 69 ± 13 years), implanted with CRT-ICDs (Boston Scientific 173, Medtronic 416, and St Jude Medical 57) were included in this analysis. During 2.7 ± 1.5 years follow-up, 113 (17%) devices had reached ERI (Boston scientific 4%, Medtronic 25%, and St Jude Medical 7%, P < 0.001). The 4-year survival rate of device battery was significantly worse for Medtronic devices compared with devices from other manufacturers (94% for Boston scientific, 67% for Medtronic, and 92% for St Jude Medical, P < 0.001). The difference in battery longevity by manufacturer was independent of pacing burden, lead parameters, and burden of ICD therapy. CONCLUSION There are significant discrepancies in CRT-ICD battery longevity by manufacturer. These data have important implications on clinical practice and patient outcomes.

Leadless pacemakers: A new era in cardiac pacing

Cardiac pacemakers are a critical management option for patients with rhythm disorders. Current efforts to develop leadless pacemakers have two primary goals: to reduce lead-associated post-procedural morbidity and to avoid the surgical scar associated with placement. After extensive studies on animal models and technological advancements, these devices are currently under investigation for human use. Herein, we review the evidence from animal studies and the technological advancements that have ushered in the era of use in humans. We also discuss different leadless pacemakers currently under investigation, along with limitations and future developments of this innovative concept.

Trends in hospitalization for congestive heart failure, 1996–2009

Although heart failure (HF) is a common cause of hospital admissions, few data describe temporal trends in HF hospitalization. We present data on number of HF admissions, length of stay (LOS), and inpatient mortality in the United States, 1996–2009.

Clinical Characteristics and Outcomes of Older Cardiac Resynchronization Therapy Recipients Using a Pacemaker versus a Defibrillator

Cardiac resynchronization therapy (CRT) is commonly used to manage heart failure, yet published guidelines do not distinguish between recommendations for pacemakers (CRT‐P) and defibrillators (CRT‐D) despite significant differences in size, longevity, and cost between these devices. The purpose of this study is to compare the clinical characteristics and outcomes between elderly recipients of CRT‐P and CRT‐D.

Effect of body mass index on survival after sudden cardiac arrest

Although elevated body mass index (BMI) is a risk factor for cardiac disease, patients with elevated BMI have better survival in the context of severe illness, a phenomenon termed the “obesity paradox.”

Implantable Defibrillator Therapy in Cardiac Arrest Survivors With a Reversible Cause

Background: Current guidelines recommend implantable cardioverter-defibrillator (ICD) therapy in survivors of sudden cardiac arrest (SCA), except in those with completely reversible causes. We sought to examine the impact of ICD therapy on mortality in survivors of SCA associated with reversible causes. Methods and Results: We evaluated the records of 1433 patients managed at our institution between 2000 and 2012 who were discharged alive after SCA. A reversible and correctable cause was identified in 792 (55%) patients. Reversible SCA cause was defined as significant electrolyte or metabolic abnormality, evidence of acute myocardial infarction or ischemia, recent initiation of antiarrhythmic drug or illicit drug use, or other reversible circumstances. Of the 792 SCA survivors because of a reversible and correctable cause (age 61±15 years, 40% women), 207 (26%) patients received an ICD after their index SCA. During a mean follow-up of 3.8±3.1 years, 319 (40%) patients died. ICD implantation was highly associated with lower all-cause mortality (P<0.001) even after correcting for unbalanced baseline characteristics (P<0.001). In subgroup analyses, only patients whose SCA was not associated with myocardial infarction extracted benefit from ICD (P<0.001). Conclusions: In survivors of SCA because of a reversible and correctable cause, ICD therapy is associated with lower all-cause mortality except if the SCA was because of myocardial infarction. These data deserve further investigation in a prospective multicenter randomized controlled trial, as they may have important and immediate clinical implications.

Complex partial non-convulsive status epilepticus masquerading as hepatic encephalopathy: a case report

IntroductionHepatic encephalopathy is usually suspected in patients who are cirrhotic with neuropsychiatric manifestations. We present a case of suspected hepatic encephalopathy that did not respond to standard empiric therapy and was eventually diagnosed as non-convulsive status epilepticus of complex partial type. Our patient responded dramatically to anti-convulsive therapy.Case presentationWe report the case of a 45-year-old African-American man with hepatitis C virus cirrhosis and human immunodeficiency virus who presented to our facility with a one-day history of confusion and a variable mental status. Our patient’s vital signs were stable and all his electrolytes were within normal range. A clinical diagnosis of hepatic encephalopathy was made and our patient was started on empiric therapy with lactulose and rifaximin. Our patient did not respond to therapy. After five days of treatment, alternative diagnoses were sought and a neurology consult was requested. An electroencephalogram was eventually performed which showed seizure activity in the right parietal lobe. A diagnosis of non-convulsive status epilepticus was made and our patient was started on oral levetiracetam. On day two of therapy, our patient was alert and oriented. He continues to do well on follow-up approximately one year after discharge.ConclusionsNon-convulsive status epilepticus should be considered in the differential diagnosis of patients with suspected hepatic encephalopathy who do not respond to empirical treatment. Further studies are needed to investigate the incidence of this entity in patients with persistent hepatic encephalopathy.

A Novel Subcutaneous Counterpulsation Device: Acute Hemodynamic Efficacy During Pharmacologically Induced Hypertension, Hypotension, and Heart Failure: LETTERS TO THE EDITOR

To the Editor, The debut of a new counterpulsation device (CPD) through experimental testing by Bartoli et al. (1) has struck us as very promising. It is our view that the authors have developed a reliable apparatus for providing acute hemodynamic support in various pathophysiologic states. The potential for chronic or acute circulatory support in heart failure conditions with the advantage of diminished invasiveness during implantation may prove very important to improved future treatment. This is especially true for patients on the margin, not yet indicated for a full sternotomy and ventricular assist device insertion but in need of hemodynamic stability. This study builds on this need through an innovative design and device, but questions still remain. The pathophysiological model for hypertension the authors utilize relies on phenylephrine, which is an alpha-1 receptor agonist and acts to constrict the peripheral vasculature and increase total peripheral resistance. Studies on human hypertension have, however, shown that early blood pressure elevation tends to be due to increased heart rate and cardiac output (2). Considering the ultimate applicability of this device to humans, it would be better to induce the same physiological state in the animal models of hypertension. The animal model nature of this study may also make its applicability to human subjects tenuous. Studies have shown a marked difference in compliance and vascular resistance between bovine and human models (3).The authors note that this is likely to raise the CPD’s efficacy at improving hemodynamic states in a system with lower compliance and greater impedance.This may, however, come at the cost of the CPD’s ability to reduce cardiac afterload as it must fill through a greater pressure barrier. Conversely, the stiffer, less compliant vessels in the human may retain architecture better in the face of the CPD’s negative pressure and allow for increased device filling. Regardless, the CPD’s performance and results are likely to be attenuated in a tenser system (4). Vasculature differences between model and human systems are also likely to result in different pressure dynamics (3). Intra-aortic balloon pump and CPD involvement is usually indicated for diastolic dysfunction that results in insufficient coronary perfusion. This compromise in coronary blood flow is often caused and exacerbated, in part, by the lowered compliance and increased impedance of peripheral arterial vasculature. This phenomenon may be explained by the mismatch in timing of the reflection wave which takes place prematurely thereby reaching the heart while it is still in systole and before the aortic valve has closed, thus diminishing coronary perfusion (5,6). Clinical application of a CPD will often be in patients with stiffened arteries, significantly more than calf models, and pressure dynamics of earlier and more proximately originating reflection waves. In calf models where compliance is high, the reflection waves are likely to be well timed and have a small effect in hemodynamic dysfunction while they will play a larger role in human hemodynamics The larger role waveform dynamics play in clinical cases and lessened exposure of the CPD to whole blood flow may show a different picture when applied to humans. Cerebral autoregulation is another area that deserves close attention. Cerebral blood vessels have the unique ability to provide uniform blood flow to the brain within a specific arterial pressure range (60– 160 mm Hg) (7).This regulatory mechanism prevents edema and ischemia in brain tissue during times of hemodynamic instability.The lack of normal pressure rhythms leads to disrupted autoregulatory functions, which, when in the cerebrum, can cause disastrous effects. Proof of concept that a CPD when anastomosed to the axillary artery can achieve hemodynamic efficiency and stability in volatile conditions as shown by our respectable colleagues is indeed very valuable. However, stronger model mimicry can lead to increased certainty. Also, whereas this interesting device definitely appears to help the heart, it does not significantly improve the cardiac output. If the intent is to help patients with chronic heart failure, it would be critical to take into account measures that would enable such a device to help increase the cardiac output in order to ensure that more flow to end organs is provided. We hope that some of the concerns noted in this commentary will be doi:10.1111/j.1525-1594.2010.01176.x Artificial Organs 35(1):92–98, Wiley Periodicals, Inc.

Causes and predictors of 30-day readmission after cardiovascular implantable electronic devices implantation: Insights from Nationwide Readmissions Database.

Readmissions are a burden on health care resources and have negative impact on patients. Cardiovascular implantable electronic devices (CIEDs) are frequently used in the management of rhythm disorders and advanced heart failure. We assessed 30‐day readmissions in patients admitted for CIED implantation in a sample of United States patients.

CLINICAL CHARACTERISTICS AND OUTCOMES OF CRT-P VERSUS CRT-D RECIPIENTS IN PATIENTS 80 YEARS AND OLDER

Results: CRT-P patients were older (82.9 years vs. 80.9 years, p<0.001) and had more comorbid conditions (Charlson index=4.9 ± 2.3 vs. 4.4 ± 1.9 for CRT-D, p=0.001). During 45.7 months, there were 280 deaths. CRT-P patients had significantly increased unadjusted mortality compared to CRT-D patients (HR=1.54, 95% CI 1.15-2.08, p value = 0.004). However, there was no significant mortality difference after adjusting for baseline differences (HR=1.34, 95% CI 0.93-1.94, p value = 0.121 Figure).