Effect of substance abuse on defibrillation threshold in patients with implantable cardioverter-defibrillator

Stimulant Drugs of Abuse and Cardiac Arrhythmias

Nonmedical use of prescription and nonprescription drugs is a worldwide epidemic, rapidly growing in magnitude with deaths because of overdose and chronic use. A vast majority of these drugs are stimulants that have various effects on the cardiovascular system including the cardiac rhythm. Drugs, like cocaine and methamphetamine, have measured effects on the conduction system and through several direct and indirect pathways, utilizing multiple second messenger systems, change the structural and electrical substrate of the heart, thereby promoting cardiac dysrhythmias. Substituted amphetamines and cocaine affect the expression and activation kinetics of multiple ion channels and calcium signaling proteins resulting in EKG changes, and atrial and ventricular brady and tachyarrhythmias. Preexisting conditions cause substrate changes in the heart, which decrease the threshold for such drug-induced cardiac arrhythmias. The treatment of cardiac arrhythmias in patients who take drugs of abuse may be specialized and will require an understanding of the unique underlying mechanisms and necessitates a multidisciplinary approach. The use of primary or secondary prevention defibrillators in drug abusers with chronic systolic heart failure is both sensitive and controversial. This review provides a broad overview of cardiac arrhythmias associated with stimulant substance abuse and their management.

Amino-terminal Pro-B-Type Natriuretic Peptide Among Patients Living With Both Human Immunodeficiency Virus and Heart Failure

BACKGROUND

Among persons living with human immunodeficiency virus (PHIV), incident heart failure (HF) rates are increased and outcomes are worse; however, the role of amino-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations among PHIV with HF has not been characterized.

METHODS

Patients were derived from a registry of those hospitalized with HF at an academic center in a calender year. We compared the NT-proBNP concentrations and the changes in NT-proBNP levels between PHIV with HF and uninfected controls with HF.

RESULTS

Among 2578 patients with HF, there were 434 PHIV; 90% were prescribed antiretroviral therapy and 62% were virally suppressed. As compared to controls, PHIV had higher admission (3822 [IQR, 2413-7784] pg/ml vs 5546 [IQR, 3257-8792] pg/ml, respectively; P < .001), higher discharge (1922 [IQR, 1045-4652] pg/ml vs 3372 [IQR, 1553-5452] pg/ml, respectively; P < .001), and lower admission-to-discharge changes in NT-proBNP levels (32 vs 48%, respectively; P = .007). Similar findings were noted after stratifying based on left ventricular ejection fraction (LVEF). In a multivariate analysis, cocaine use, a lower LVEF, a higher NYHA class, a higher viral load (VL), and a lower CD4 count were associated with higher NT-proBNP concentrations. In follow-up, among PHIV, a higher admission NT-proBNP concentration was associated with increased cardiovascular mortality (first tertile, 11.5; second tertile, 20; third tertile, 44%; P < .001). Among PHIV, each doubling of NT-proBNP was associated with a 19% increased risk of death. However, among patients living without HIV, each doubling was associated with a 27% increased risk; this difference was attenuated among PHIV with lower VLs and higher CD4 counts.

CONCLUSIONS

PHIV with HF had higher admission and discharge NT-proBNP levels, and less change in NT-proBNP concentrations. Among PHIV, VLs and CD4 counts were associated with NT-proBNP concentrations; in follow-up, higher NT-proBNP levels among PHIV were associated with cardiovascular mortality.

Incidence, Predictors, and Outcomes of Implantable Cardioverter-Defibrillator Discharge Among People Living With HIV

Background

People living with HIV (PHIV) are at an increased risk for sudden cardiac death, and implantable cardioverter‐defibrillators (ICDs) prevent SCD. There are no data on the incidence, predictors, and effects of ICD therapies among PHIV.

Methods and Results

We compared ICD discharge rates between 59 PHIV and 267 uninfected controls. For PHIV, we tested the association of traditional cardiovascular risk factors and HIV‐specific parameters with an ICD discharge and then tested whether an ICD discharge among PHIV was associated with cardiovascular mortality or an admission for heart failure. The indication for ICD insertion was similar among groups. Compared with controls, PHIV with an ICD were more likely to have coronary artery disease and to use cocaine. In follow‐up, PHIV had a higher ICD discharge rate (39% versus 20%; P=0.001; median follow‐up period, 19 months). Among PHIV, cocaine use, coronary artery disease, QRS duration, and higher New York Heart Association class were associated with an ICD discharge. An ICD discharge had a prognostic effect, with a subsequent 1.7‐fold increase in heart failure admission and a 2‐fold increase in cardiovascular mortality, an effect consistent across racial/ethnic and sex categories.

Conclusions

ICD discharge rates are higher among PHIV compared with uninfected controls. Among PHIV, cocaine use and New York Heart Association class are associated with increased ICD discharge, and an ICD discharge is associated with a subsequent increase in admission for heart failure and cardiovascular mortality.