Adverse Events in Total Artificial Heart for End-Stage Heart Failure: Insight From the Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE)

Background and Objectives

Real-world clinical data, outside of clinical trials and expert centers, on adverse events related to the use of SyncCardia total artificial heart (TAH) remain limited. We aim to analyze adverse events related to the use of SynCardia TAH reported to the Food and Drug Administration (FDA)'s Manufacturers and User Defined Experience (MAUDE) database.

Methods

We reviewed the FDA's MAUDE database for any adverse events involving the use of SynCardia TAH from 1/01/2012 to 9/30/2020. All the events were independently reviewed by three physicians.

Results

A total of 1,512 adverse events were identified in 453 "injury and death" reports in the MAUDE database. The most common adverse events reported were infection (20.2%) and device malfunction (20.1%). These were followed by bleeding events (16.5%), respiratory failure (10.1%), cerebrovascular accident (CVA)/other neurological dysfunction (8.7%), renal dysfunction (7.5%), hepatic dysfunction (2.2%), thromboembolic events (1.8%), pericardial effusion (1.8%), and hemolysis (1%). Death was reported in 49.4% of all the reported cases (n=224/453). The most common cause of death was multiorgan failure (n=73, 32.6%), followed by CVA/other non-specific neurological dysfunction (n=44, 19.7%), sepsis (n=24, 10.7%), withdrawal of support (n=20, 8.9%), device malfunction (n=11, 4.9%), bleeding (n=7, 3.1%), respiratory failure (n=7, 3.1%), gastrointestinal disorder (n=6, 2.7%), and cardiomyopathy (n=3, 1.3%).

Conclusions

Infection was the most common adverse event following the implantation of TAH. Most of the deaths reported were due to multiorgan failure. Early recognition and management of any possible adverse events after the TAH implantation are essential to improve the procedural outcome and patient survival.

Comparison of Percutaneous Coronary Intervention Outcomes Among Patients With Obstructive Sleep Apnea, Chronic Obstructive Pulmonary Disease Overlap, and Pickwickian Syndrome (Obesity Hypoventilation Syndrome)

Background

Obstructive sleep apnea (OSA) is often present in coronary artery disease patients and confers a high risk of complications following percutaneous coronary interventions (PCI). The impact of two commonly associated comorbid conditions, chronic obstructive pulmonary disease (COPD) and obesity hypoventilation syndrome (OHS, Pickwickian syndrome) in OSA patients undergoing PCI has never been studied.

Methods

The National Inpatient Sample (NIS; 2007-2014) was queried using the International Classification of Diseases, Clinical Modification 9 (ICD-9-CM) codes to compare baseline characteristics, comorbidities, and outcomes in adults undergoing PCI with OSA, COPD-overlap syndrome, and OSA+OHS.

Results

Of a total of 4,792,177 PCI-related inpatient encounters, OSA, OSA-COPD overlap syndrome, and OSA+OHS were found to be present in 153,706 (median age 62 years, 79.4% male), 65135 (median age 65 years, 66.0% male), and 2291 (median age 63 years, 58.2% males) patients, respectively. The OHS+OSA cohort, when compared to the COPD-OSA and OSA cohorts, was found to have the worst outcomes in terms of all-cause mortality (2.8% vs. 1.5% vs. 1.1%), hospital stay (median 6 vs. 3 vs. 2 days), hospital charges ($147, 209 vs. $101,416 vs. $87,983). Complications, including cardiogenic shock (7.3% vs. 3.4% vs. 2.6%), post-procedural myocardial infarction (11.2% vs. 7.1% vs. 6.0%), iatrogenic cardiac complications (6.1% vs. 3.5% vs. 3.7%), respiratory failure, acute kidney injury, infections, and pulmonary embolism, were also significantly higher in patients with OHS+OSA. Adjusted multivariable analysis revealed equivalent results with OHS+OSA having worse outcomes than OSA-COPD and OSA.

Conclusion

Concomitant OHS and COPD were linked to worse clinical outcomes in patients with OSA undergoing PCI. Future prospective studies are warranted to fully understand related pathophysiology, evaluate and validate long-term outcomes, and formulate effective preventive and management strategies.

Giant high-pressure pulmonary artery aneurysm (PAA) in a patient with COPD and chronic pulmonary embolism (PE)

A woman in her 60s with a history of known severe chronic obstructive pulmonary disease (COPD), former smoker of 50 pack-years and small patent foramen ovale (PFO) without significant shunt was admitted for acute on chronic hypoxic respiratory failure. Diagnostic workup showed severe dilatation of main pulmonary artery (MPA) (75.5 mm axial view and 86.6 mm sagittal view) and left and right PAs measuring 40 mm and 34 mm, respectively, on CT angiography of the chest. Right heart catheterisation showed severe pulmonary hypertension (PH). A diagnosis of giant high-pressure pulmonary arterial aneurysm (PAA) secondary to PH, induced by COPD, and chronic pulmonary embolism was made. Despite aggressive medical management, she passed away on comfort care. Giant high-pressure PAAs are rarely reported. This is a unique case that demonstrates this very rare condition in a living patient. The management of giant PAA is controversial. Experts recommend medical management or aneurysmectomy for sizes of >55-60 mm. Death could have been prevented if our patient was screened earlier and received appropriate medical care.

Alarmingly Increased Public Interest in "Chest Pain" During the COVID-19 Pandemic: Insights From Google Trends Analysis

Background

The coronavirus disease 2019 (COVID-19) pandemic has been linked to a myriad of cardiac symptoms and disorders. Reports also suggest decreased hospital visits by patients with known cardiovascular disorders.

Methodology

To better elucidate the public interest in the information regarding “chest pain” during the COVID-19 pandemic, we conducted a Google Trends analysis from March 2019 to March 2021 to compare the internet searches between pre-COVID era and during the pandemic with country-wise [the United States (US) versus the United Kingdom (UK) versus India] variation.

Results

We observed a significantly rising public interest in “chest pain” internet searches during the peak COVID-19 pandemic. Rising trends were most prominent in the UK, followed by USA and India. Our analysis noted a spike in the trend of “chest pain” search in early March in the UK and USA, whereas in March and June 2020 for India. This shows an important temporal association between the surge of COVID-19 cases and the search for “chest pain” online.

Conclusion

Google Trends analyses indicate rising public interest in chest pain during the pandemic months and the possible association between COVID-19 and chest pain. These findings warrant further research, especially with increasing reports suggesting contradictory reports of decreased hospital visits by patients with known cardiovascular diseases.

Sex disparities in cardiovascular disease outcomes among geriatric patients with prediabetes

AIMS

To analyze the sex-based differences in the prevalence of cardiovascular disease risk factors and outcomes in older patients with prediabetes using demographically matched national cohorts of hospitalized patients aged ≥65 years.

METHODS

We queried the 2007-2014 National Inpatient Database to identify older patients (>65 years) admitted with prediabetes using ICD-9 Clinical Modification codes. The older patients were then subcategorized based on sex. Comparative analyses of their baseline characteristics, the prevalence of cardiovascular(CV) disease comorbidities, hospitalization outcomes, and mortality rates were performed on propensity-matched cohorts for demographics.

RESULTS

A total of 1,197,978 older patients with prediabetes (599,223 males; mean age 75years and 598,755 females; mean age 76years) were identified. Higher admission rates were found commonly among older white males (84.1%) and females (81.7%). Prediabetic older males showed a higher frequency of cardiovascular comorbidities compared to females. Prediabetic older males had higher all-cause in-hospital mortality (4.2% vs. 3.6%, p < 0.001), acute myocardial infarction (7.0% vs. 4.7%, p < 0.001), arrhythmia (36.3% vs. 30.5%, p < 0.001), stroke (4.8% vs. 4.6%, p < 0.001), venous thromboembolism (3.3% vs. 3.0%, p < 0.001) and percutaneous coronary intervention (3.1% vs. 1.5%, p < 0.001) compared to females.

CONCLUSIONS

Our analysis revealed that among older patients hospitalized with prediabetes, males suffered worse in-hospital CV outcomes and survival rates compared to females.

Alarmingly Rising Trends in Venous Thromboembolic Events and Respiratory Failure in Takotsubo Syndrome-Related Hospitalizations in the United States

Background There is very scarce data about the shifting landscape of complications like venous thromboembolic events (VTE) and respiratory failure in Takotsubo syndrome (TTS). We have assessed the rates and trends of these complications in (TTS)-related hospitalizations. Methods The National Inpatient Sample (2007-2014) was queried to identify adult hospitalizations for TTS and subsequent VTE and respiratory failure using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9 CM) codes. Trends were assessed using discharge weights and the linear-by-linear association test for the overall cohort and subgroups based on age, sex, and race. Results Of 156,506 admissions for TTS from 2007-2014, 3.5% (N=5,550) of admissions revealed VTE whereas 17.4% (N=27,252) of admissions revealed respiratory failure. There were significantly rising trends in VTE (from 2.2% to 4.2%) and respiratory failure (10% to 20.7%) with TTS (p<0.05) from 2007-2014. On subgroup analysis, all subgroups showed rising trends in VTE and respiratory failure. However, young (18-44 years), male patients admitted with TTS demonstrated a greater surge in VTE as compared to other groups. In contrast, the frequency of respiratory failure rose more significantly in young, male, non-white TTS patients compared to older, female and white TTS patients. Conclusion There were alarming trends in the VTE and respiratory failure despite the improved understanding of TTS etiopathogenesis and advanced diagnostic modalities among TTS-related admissions, mostly comprising of young, male, and non-white patients. Introduction.

Takotsubo Syndrome in Patients with COVID-19: a Systematic Review of Published Cases

Takotsubo syndrome (TTS) is caused by catecholamine surge, which is also observed in COVID-19 disease due to the cytokine storm. We performed a systematic literature search using PubMed/Medline, SCOPUS, Web of Science, and Google Scholar databases to identify COVID-19-associated TTS case reports and evaluated patient-level demographics, clinical attributes, and outcomes. There are 12 cases reported of TTS associated with COVID-19 infection with mean age of 70.8 ± 15.2 years (range 43–87 years) with elderly (66.6% > 60 years) female (66.6%) majority. The time interval from the first symptom to TTS was 8.3 ± 3.6 days (range 3–14 days). Out of 12 cases, 7 reported apical ballooning, 4 reported basal segment hypo/akinesia, and 1 reported median TTS. Out of 12 cases, during hospitalization, data on left ventricular ejection fraction (LVEF) was reported in only 9 of the cases. The mean LVEF was 40.6 ± 9.9% (male, 46.7 ± 5.7%, and female, 37.7 ± 10.6%). Troponin was measured in all 12 cases and was elevated in 11 (91.6%) without stenosis on coronary angiography except one. Out of 11 cases, 6 developed cardiac complications with 1 case each of cardiac tamponade, heart failure, myocarditis, hypertensive crisis, and cardiogenic shock in 2. Five patients required intubation, 1 patient required continuous positive airway pressure, and 1 patient required venovenous extracorporeal membrane oxygenation. The outcome was reported in terms of recovery in 11 (91.6%) out of 12 cases, and a successful recovery was noted in 10 (90.9%) cases. COVID-19-related TTS has a higher prevalence in older women. Despite a lower prevalence of cardiac comorbidities in COVID-19 patients, direct myocardial injury, inflammation, and stress may contribute to TTS with a high complication rate.

Anemia Among Patients Undergoing Transcatheter Mitral Valve Repair: From the National Inpatient Sample in the United States

Background The prevalence and impact of anemia on the outcomes of transcatheter mitral valve repair (TMVr) have not been well-studied. Anemia is a commonly encountered comorbidity among patients with cardiovascular disorders and is frequently under-recognized. The study aimed to analyze the prevalence of anemia and its impact on post-TMVr in-hospital outcomes. Methods The National Inpatient Sample (NIS) was queried to identify all patients who underwent TMVr from 2011-2015 in the United States by utilizing suitable International Classification of Diseases, Ninth Revision (ICD-9) codes. The baseline characteristics and in-hospital outcomes were compared among patients with and without anemia. Results A total of 4,382 patients were identified. Out of these, 978 (22.3%) patients had baseline anemia. Anemic patients were noted to have a higher burden of co-morbidities, including chronic kidney disease, hypertension, and diabetes mellitus. The in-hospital mortality was higher but not statistically significant between anemic and non-anemic patients (3.6% vs 2.6%; odds ratio (OR): 1.44; confidence interval (CI): 0.85-2.46, p=0.179). The other adverse outcomes, including the length of stay, the requirement for blood transfusions, the incidence of post-implant acute kidney injury, hemodialysis, and the cost of hospitalization, were higher in anemic patients. Conclusion Anemia was present in one out of five patients undergoing TMVr in this nationally representative cohort. Baseline anemia showed numerically higher but not statistically significant in-hospital mortality and was associated with other in-hospital adverse outcomes. Further larger studies are needed to highlight the importance of anemia in the TMVr procedure.

Epidemiology and Outcomes of Takotsubo Syndrome in Hospitalizations With Systemic Sclerosis

Background

Systemic Sclerosis (SSc) is associated with chronic inflammation which leads to macrophage activation and thus vascular insult and fibrosis. Macrophage activation is shown to precede Takotsubo syndrome (TTS) which may be a common pathophysiologic link to SSc. 

Methods

We queried the National Inpatient Sample (2008-2014) for adult SSc-related hospitalizations and TTS using relevant International Classification of Diseases Clinical Modification, 9th Revision codes. We assessed the prevalence and trends in TTS during this time. We further assessed demographics, comorbidities, and outcomes were in SSc with and without TTS. The primary outcomes of the analysis were all-cause mortality and in-hospital complications including cardiac arrest and acute myocardial infarction (AMI), arrhythmias, and venous thromboembolism, and stroke. 

Results

A total of 213,728 SSc-related hospitalizations were found, of which 357 experienced TTS (0.2%) with rising trends in TTS from 2008-2014 (0.06% to 0.3%, relative increase of 24%, p_trend<0.001). The TTS cohort was older (median age 68 vs 62 years), with 92.8% females and 80.1% white adults with TTS (p<0.001). Co-morbidities were higher in the TTS cohort including hypertension (62.2% vs. 51.5%, p<0.001), dyslipidemia (41.5% vs. 22.8, p<0.001), smoking (28.9% vs. 20.1%, p<0.001), peripheral vascular disease (17.8% vs. 9.1%, p<0.001), uncomplicated diabetes (18.1% vs. 11.9%, p<0.001). The all-cause in-hospital mortality (11% vs. 4.6%; adjusted odds ratio=1.82, 95% confidence interval: 1.21-2.72, p<0.005), cardiovascular complications like AMI (29% vs. 2.9%,p<0.001), arrhythmias (38.9% vs. 21.5%, p<0.001), and median length of stay [6 vs. 4 days] were significantly higher in the TTS cohort as compared to the non-TTS cohort.

Conclusion

This analysis revealed a nearly 10 times higher prevalence of TTS in SSc-related hospitalizations compared to the general inpatient population. Concomitant TTS occurrence in SSc-related hospitalizations led to nearly two times higher odds of all-cause mortality. Cardiovascular co-morbidities in SSc may increase the risk of TTS and worsened outcomes.

Nationwide Trends in Prevalent Cardiovascular Risk Factors and Diseases in Young Adults: Differences by Sex and Race and In-Hospital Outcomes

OBJECTIVES

Prevalence and trends in all cardiovascular disease (CVD) risk factors among young adults (18-39 years) have not been evaluated on a large scale stratified by sex and race. The aim of this study was to establish the prevalence and temporal trend of CVD risk factors in US inpatients younger than 40 years of age from 2007 through 2014 with racial and sex-based distinctions. In addition, the impact of these risk factors on inpatient outcomes and healthcare resource utilization was explored.

METHODS

A cross-sectional nationwide analysis of all hospitalizations, comorbidities, and complications among young adults from 2007 to 2014 was performed. The primary outcomes were frequency, trends, and race- and sex-based differences in coexisting CVD risk factors. Coprimary outcomes were trends in all-cause mortality, acute myocardial infarction, arrhythmia, stroke, and venous thromboembolism in young adults with CVD risk factors. Secondary outcomes were demographics and resource utilization in young adults with versus without CVD risk factors.

RESULTS

Of 63 million hospitalizations (mean 30.5 [standard deviation 5.9] years), 27% had at least one coexisting CVD risk factor. From 2007 to 2014, admission frequency with CVD risk factors increased from 42.8% to 55.1% in males and from 16.2% to 24.6% in females. Admissions with CVD risk were higher in male (41.4% vs 15.9%) and white (58.4% vs 53.8%) or African American (22.6% vs 15.9%) patients compared with those without CVD risk. Young adults in the Midwest (23.9% vs 21.1%) and South (40.8% vs 37.9%) documented comparatively higher hospitalizations rates with CVD risk. Young adults with CVD risk had higher all-cause in-hospital mortality (0.4% vs. 0.3%) with a higher average length of stay (4.3 vs 3.2 days) and charges per admission ($30,074 vs $20,124).

CONCLUSIONS

Despite modern advances in screening, management, and interventional measures for CVD, rising trends in CVD risk factors across all sex and race/ethnic groups call for attention by preventive cardiologists.

Nationwide Frequency, Sequential Trends, and Impact of Co-morbid Mental Health Disorders on Hospitalizations, Outcomes, and Healthcare Resource Utilization in Adult Congenital Heart Disease

Despite the growing prevalence of adult congenital heart disease (ACHD), data on trends in prevalence of mental health disorders (MHD) among patients with ACHD remain limited. The National Inpatient Sample (2007 to 2014) was queried to identify the frequency and trends of MHD among ACHD hospitalizations (stratification by age, sex, and race); demographics and co-morbidities for ACHD cohorts, with (MHD+) versus without MHD (MHD-); the rate and trends of all-cause in-hospital mortality, disposition, mean length of stay, and hospitalization charges among both cohorts. A total of 11,709 (13.8%, mean age: 49.1 years, 56.0% females, 78.7% white) out of 85,029 ACHD patient encounters had a coexistent MHD (anxiety, depression, mood disorder, or psychosis). ACHD-MHD+ cohort was more often admitted nonelectively (38.1% vs 32.8%, p <0.001) and had a higher frequency of cardiac/extra-cardiac co-morbidities. The trends in prevalence of coexistent MHD increased from 10.3% to 17.5% (70% relative increase) from 2007 to 2014 with a consistently higher prevalence among females (from 13% to 20.3%) compared to males (from 7.6% to 15.5%) (p_trend <0.001). The hospitalization trends with MHD increased in whites (12.1% to 19.8%) and Hispanics (5.9% to 12.7%). All-cause mortality was lower (0.7% vs 1.1%, p = 0.002) in ACHD-MHD+; however, mean length of stay (∼5.7 vs 4.9 days, p <0.001) was higher without significant difference in charges ($97,710 vs $96,058, p = 0.137). ACHD-MHD+ cohort was less often discharged routinely (declining trend) and more frequently transferred to other facilities and required home healthcare (rising trends). In conclusion, this study reveals increasing trends of MHD, healthcare resource utilization and a higher frequency of co-morbidities in patients with ACHD.

Burden and impact of takotsubo syndrome in myasthenic crisis: A national inpatient perspective on the under-recognized but potentially fatal association

BACKGROUND

Patients with myasthenia gravis (MG) remain at a higher risk of developing takotsubo syndrome (TS), particularly during a myasthenic crisis (MC) event. The prevalence of MC-associated TS and its impact on subsequent in-hospital outcomes have not been explored previously.

METHODS

We queried the National Inpatient Sample (NIS) databases (2007-2014) using weighted data and ICD-9 CM codes to evaluate the prevalence of MC-associated TS, demographics, comorbidities and inpatient outcomes of TS secondary to MC vs. other triggers.

RESULTS

The nationwide prevalence of MC-associated TS was 0.3% (175/56,472). Of all 156,506 TS encounters, MC was present in 0.11% (n = 175) of cases. The groups were comparable in terms of demographics (median age 68-73 years, Caucasian >70%, females >80%). In comparison to non-MC TS, MC-associated TS demonstrated a higher frequency of coexisting diabetes and a lower frequency of smoking. The MC-TS cohort experienced significantly higher rates of all-cause mortality [8.6% vs. 4.7%, p = 0.014, unadjusted (OR1.91, p = 0.017) and adjusted (OR1.82, p = 0.038)] and complications including respiratory failure, the need of intubation/mechanical ventilation, and arrhythmia. The MC-TS cohort had fewer routine discharges and frequent transfers. The median stay was 6 days longer (10 vs. 4 days) and median hospital charges per admission were nearly $100,000 higher ($133,999 vs. $38,367) with MC-associated TS.

CONCLUSIONS

This population-based analysis revealed a 15 times greater prevalence of secondary TS following MC as compared to the general inpatient population, a nearly 2 times higher odds of all-cause mortality, and significantly higher resource utilization in MC-associated TS as compared to TS triggered by other etiologies.

Modern-Day Nationwide Utilization of Intravascular Ultrasound and Its Impact on the Outcomes of Percutaneous Coronary Intervention With Coronary Atherectomy in the United States

OBJECTIVES

Intravascular ultrasonography (IVUS) and coronary atherectomy (CA) are useful modalities in managing calcified coronary lesions. Considering an inadequacy of data, we aimed to compare the outcomes with versus without IVUS assistance in percutaneous coronary interventions (PCIs) with CA.

METHODS

From the National (Nationwide) Inpatient Sample data set for the years 2012 to 2014, we identified adult patients undergoing PCI and CA with or without IVUS assistance using International Classification of Diseases, Ninth Revision, Clinical Modification codes. We assessed the impact of IVUS on procedural outcomes, length of stay, total hospital charges, and predictors of IVUS utilization by multivariable analyses. Discharge weights were used to calculate national estimates.

RESULTS

A total of 46,095 PCIs with CA procedures were performed from 2012 to 2014, of these, 4800 (10.4%) procedures were IVUS-assisted. IVUS-assisted procedures showed lower odds of in-hospital mortality (odds ratio, 0.57; P = .024) but higher odds of any cardiac complication (odds ratio, 1.25; P = .025). Total hospital charges were higher in IVUS-assisted procedures without any substantial difference in the length of stay between the groups. Cardiac complication rates declined (from 16.2% to 14.8%) from 2012 to 2014, whereas inpatient mortality increased (1.1%-4.4%) in IVUS-assisted procedures during the same period. The odds of IVUS utilization were higher in Asian/Pacific Islander and urban teaching and western region hospitals. Comorbidities, including hypertension, obesity, and chronic pulmonary disease, raised odds of IVUS utilization.

CONCLUSIONS

IVUS-assisted procedures showed lower in-hospital mortality and higher iatrogenic and overall cardiac complications. The mortality rate in patients undergoing IVUS-assisted PCI with CA was on the rise, with declining cardiac complication rates from 2012 to 2014.

Outcomes and Predictors of Mortality in Hospitalized Frail Patients Undergoing Percutaneous Coronary Intervention

Objective To study the impact of frailty on inpatient outcomes among patients undergoing percutaneous coronary intervention (PCI). Methods The National Inpatient Sample data of all PCI-related hospitalizations throughout the United States (US) from 2010 through 2014 was utilized. Patients were divided into two groups: frailty and no-frailty. International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to stratify groups and outcomes. In order to address the substantial difference in the total number of valid observations between the two groups, a propensity-matched analysis was performed at a 1:1 ratio and caliper width of 0.01. Results A total of 2,612,661 PCI-related hospitalizations throughout the US from 2010 through 2014 were identified, out of which 16,517 admissions (0.6%) had coexisting frailty. Only 1:1 propensity-matched data was utilized for the study. Propensity-matched frailty group (n=14,717) as compared to no-frailty (n=14,755) was frequently older, white, and Medicare enrollee (p<0.05). The frailty group had significantly higher rates of comorbidities and complications (p<0.05). All-cause in-hospital mortality was higher in the no-frailty group (p<0.05). Age, white race, non-elective admission, urban hospitals, and comorbidities predicted in-hospital mortality in frailty group (p<0.05). Rheumatoid arthritis, depression, hypertension, obesity, dyslipidemia, and history of previous PCI decreased odds of in-hospital mortality in frailty group (p<0.05). Frailty group had prolonged hospital stay and higher hospital charges (p<0.05). Conclusions Frailty has a significant effect on PCI-related outcomes. We present a previously unknown protective effect of cardiovascular disease risk factors and other health risk factors on frail patients undergoing PCI. Frailty's inclusion in risk stratification will help in predicting the post-procedure complications and improve resource utilization.

Rising Trends in Medication Non-compliance and Associated Worsening Cardiovascular and Cerebrovascular Outcomes Among Hospitalized Adults Across the United States

Introduction

Small-scale studies have described concerning rates of non-compliance/nonadherence towards groups of medications for primary and secondary prevention. Trends in cardiovascular and cerebrovascular events (CCE) among hospitalized patients with a non-compliant behavior towards medication, on the whole, remains unexplored on a large scale.

Methods

Using the National Inpatient Sample databases (2007-2014), we sought to assess the prevalence and trends in all-cause mortality and CCE in adult patients hospitalized with medication non-compliance. We compared baseline characteristics and comorbidities in the non-compliant patients with and without concomitant in-hospital CCE.

Results

We identified 7,453,831 adult hospitalizations with medication non-compliance from 2007 to 2014, of which 867,997 (11.6%) patients demonstrated in-hospital CCE. Non-compliant patients with CCE consisted of a higher number of older, white, male patients having greater comorbid risk factors. Non-compliant patients with CCE had higher all-cause in-hospital mortality (3% vs. 0.7%), frequent transfers [4.4% vs. 1.8% transfers to short-term hospitals, and 17.6% vs. 11.6% other transfers (skilled nursing or intermediate care facilities)], lower routine discharges (59.4% vs. 71.1%), and higher mean hospital charges ($52,740 vs. $30,748) compared to non-compliant patients without CCE. Remarkably, this study demonstrates the rising trend in medication non-compliance across all age, sex, and race groups, and related in-hospital mortality, CCE, transfers to other facilities, and the health care cost from 2007 to 2014.

Conclusions

We observed rising trends in the prevalence of medication non-compliance and subsequent in-hospital mortality in hospitalizations among adults from 2007 to 2014. Non-compliant patients with inpatient CCE demonstrated rising trends in all-cause mortality, complications, health care utilization, and cost from 2007 to 2014.

Impact of gout on in-hospital outcomes of acute coronary syndrome-related hospitalizations and revascularizations: Insights from the national inpatient sample

BACKGROUND

Previous studies have established a role of gout in predicting risk and prognosis of cardiovascular diseases. However, large-scale data on the impact of gout on inpatient outcomes of acute coronary syndrome (ACS)-related hospitalizations and post-revascularization is inadequate.

AIM

To evaluate the impact of gout on in-hospital outcomes of ACS hospitalizations, subsequent healthcare burden and predictors of post-revascularization inpatient mortality.

METHODS

We used the national inpatient sample (2010-2014) to identify the ACS and gout-related hospitalizations, relevant comorbidities, revascularization and post-revascularization outcomes using the ICD-9 CM codes. A multivariable analysis was performed to evaluate the predictors of post-revascularization in-hospital mortality.

RESULTS

We identified 3144744 ACS-related hospitalizations, of which 105198 (3.35%) also had gout. The ACS-gout cohort were more often older white males with a higher prevalence of comorbidities. Coronary artery bypass grafting was required more often in the ACS-gout cohort. Post-revascularization complications including cardiac (3.2% vs 2.9%), respiratory (3.5% vs 2.9%), and hemorrhage (3.1% vs 2.7%) were higher whereas all-cause mortality was lower (2.2% vs 3.0%) in the ACS-gout cohort (P < 0.001). An older age (OR 15.63, CI: 5.51-44.39), non-elective admissions (OR 2.00, CI: 1.44-2.79), lower household income (OR 1.44, CI: 1.17-1.78), and comorbid conditions predicted higher mortality in ACS-gout cohort undergoing revascularization (P < 0.001). Odds of post-revascularization in-hospital mortality were lower in Hispanics (OR 0.45, CI: 0.31-0.67) and Asians (OR 0.65, CI: 0.45-0.94) as compared to white (P < 0.001). However, post-operative complications significantly raised mortality odds. Mean length of stay, transfer to other facilities, and hospital charges were higher in the ACS-gout cohort.

CONCLUSION

Although gout was not independently associated with an increased risk of post-revascularization in-hospital mortality in ACS, it did increase post-revascularization complications.

Alarming Increasing Trends in Hospitalizations and Mortality With Heyde's Syndrome: A Nationwide Inpatient Perspective (2007 to 2014)

We studied the trends and outcomes of patients with intestinal angiodysplasia-associated gastrointestinal bleeding (Heyde's syndrome [HS]) with aortic stenosis (AS) who underwent surgical aortic valve replacement (SAVR) versus transcatheter aortic valve implantation (TAVI). The National Inpatient Sample (2007 to 2014) and International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify HS hospitalizations, pertinent co-morbidities, and outcomes of SAVR versus TAVI from 2011 to 2014. The incidence of HS with AS was 3.1%. The trends in hospitalizations and all-cause inpatient mortality showed relative surges of 29.16% (from 48 to 62 per 100,000) and 22.7% (from 3.7 to 4.54 per 100,000) from 2007 to 2014. HS patients were older (mean age ∼80 vs 77 years) females (54.3% vs 52.2%) compared with AS without HS. The all-cause mortality (6.9% vs 4.1%), length of stay (LOS) (∼7.0 vs 5.8 days), and hospitalization charges ($58,519.31 vs $57,598.67) were higher in HS (p<0.001). No differences were reported in all-cause mortality and hospital charges in HS patients who underwent either SAVR or TAVI. However, the TAVI cohort showed lower rates of stroke (1.7% vs 10.0%) and blood transfusion (1.7% vs 11.7%), a shorter LOS (18.3 vs 23.9 days; p<0.001), and more routine discharges (21.7% vs 14.8%, p = 0.01). An older age, male gender, Asian race, congestive heart failure, coagulopathy, fluid and/or electrolytes disorders, chronic pulmonary disease, and renal failure raised the odds of mortality in HS patients. In conclusion, we observed increasing rates of hospitalizations with HS and higher inpatient mortality from 2007 to 2014. The HS patients who underwent TAVI had fewer complications without any difference in the all-cause mortality compared with SAVR.

The safety of morphine use in acute coronary syndrome: a meta-analysis

Background

Morphine is widely used for pain control in patients with acute coronary syndrome (ACS). Several studies have questioned the safety of morphine in this setting with a concern of interaction with and reduced efficacy of antiplatelet agents.

Objective

This study aims to systematically review the safety of morphine use in ACS.

Methods

MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were queried from inception through April 2018. Studies comparing morphine to nonmorphine use in ACS were included. Study endpoints included: in-hospital myocardial infarction (MI), all-cause mortality, stroke, major bleeding, minor bleeding and dyspnoea.

Results

A total of 64 323 patients with ACS were included from eight studies, seven of which were observational studies and one was a randomised controlled trial. The use of morphine was associated with increased risk of in-hospital recurrent MI (OR 1.30, 95% CI 1.18 to 1.43, p < 0.00001). There was, however, no significant difference in terms of all-cause mortality (OR 0.87, 95% CI 0.62 to 1.22, p = 0.44), stroke (OR 0.81, 95% CI 0.39 to 1.66, p = 0.57), major bleeding (OR 0.49, 95% CI 0.24 to 1.00, p = 0.05), minor bleeding (OR 0.98, 95% CI 0.41 to 2.34, p = 0.97), or dyspnoea (OR 0.55, 95% CI 0.16 to 1.83, p = 0.33).

Conclusion

The use of morphine for pain control in ACS was associated with an increased risk of in-hospital recurrent MI. Randomised clinical trials are needed to further investigate the safety of morphine in ACS.

Frequency of Takotsubo Cardiomyopathy in Adult Patients Receiving Chemotherapy (from a 5-Year Nationwide Inpatient Study)

Takotsubo cardiomyopathy (TC) develops in patients who are under significant emotional, psychosocial, or sudden biochemical stress. However, the added burden of TC on the patients receiving chemotherapy has never been studied. We aimed to describe the additional clinical and economic burden, along with the potential predictors of TC and related in-hospital mortality in patients receiving chemotherapy using the largest inpatient cohort. We identified chemotherapy-related adult hospitalizations using the National Inpatient Sample databases (2010 to 2014). Primary end points were the incidence of TC and the odds of in-hospital mortality. Secondary end points were gender-based incidence differences, length of stay (LOS), hospital charges, and discharge disposition. We identified 1,067,977 chemotherapy-related hospitalizations, of which, 562 hospitalizations revealed TC incidence. Other co-morbidities were also significantly higher in the TC cohort. In unmatched analyses, the LOS (median 17 days vs 5 days) and total hospital charges (median $162,825 vs $46,335) were significantly higher in the TC group. A propensity-matched analysis confirmed the increased healthcare burden. Multivariate analysis revealed over 2-times higher odds (odds ratio [OR] 2.17) of in-hospital mortality in the TC group. Female gender (OR 2.48), and nonelective (OR 2.26), and nonfederal government hospital (OR 2.68) admissions had more than twice the odds of developing TC. An advanced age, Asian race, urban-teaching hospital, and complications such as septicemia, fluid-electrolyte disorders, cardiogenic shock, and respiratory failure independently raised mortality odds in the TC group. In conclusion, we observed an overall increasing nationwide trend in TC incidence in patients receiving chemotherapy, which adds to significantly increased in-hospital mortality, LOS, and healthcare charges.

Racial and sex disparities in resource utilization and outcomes of multi-vessel percutaneous coronary interventions (a 5-year nationwide evaluation in the United States)

Background

There is a paucity of data regarding the racial and sex disparities in the outcomes of multi-vessel percutaneous coronary interventions (MVPCI).

Methods

The National Inpatient Sample (NIS) was examined for the years 2010 to 2014 to incorporate adult MVPCI-related hospitalizations using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes. We excluded patients with the missing race or gender data from the final scrutiny. Discharge weights were used to obtain the national estimations. The principal outcomes were MVPCI-related racial and gender disparities in terms of the in-hospital mortality and complications, and diagnostic and therapeutic healthcare resource utilization. Secondary outcomes were the length of hospital stay (LOS) and hospitalization charges. We used the Chi-square test and t-test/ANOVA test to equate dichotomous and continuous variables respectively. A two-tailed P of <0.05 was considered clinically significant.

Results

An estimated 769,502 MVPCI-related hospitalizations were recorded from 2010 to 2014 after excluding patients with the missing data (70,954; 8.4%). Black male and female were the youngest (62±13, 64±14 years). The highest non-elective admissions (M: 72.8%, F: 71.2%) were reported among Hispanics. Non-whites showed a higher proportion of comorbidities with lower resource utilization than whites. Hispanic males (OR 1.23) showed the highest odds of the in-hospital mortality whereas among females, Asians (OR 1.51), blacks (OR 1.35), followed by Hispanics (OR 1.22) revealed higher odds of in-hospital mortality. Odds of cardiac complications were highest amongst Asians (M: OR 1.19, F: OR 1.40). Black (6±8 days) and Hispanic (7±9 days) showed the highest length of stay among males and females respectively. Total hospitalization charges were highest among Asians. There was a greater increase in the all-cause mortality in non-whites from 2010 to 2014.

Conclusions

This study determines the existence of racial disparities in resource utilization and outcomes in MVPCI. There is an instant need for interventions designed to govern these healthcare discrepancies.

Cardiac Sarcoidosis

Clinical and subclinical cardiac sarcoidosis (CS) remains diagnostically challenging as the sensitivity and specificity of the diagnostic modalities are limited. The Japanese Ministry of Health and Welfare criteria and the Heart Rhythm Society expert consensus statement on CS are the most common guidelines used to diagnose CS. However, they are mostly based on expert opinions and lack clinical trial validation. The emergence and increase use of newer imaging modalities such as cardiac magnetic resonance and positron emission tomography may give valuable information for accurate diagnosis and assessment of treatment response in CS patient. Although immunosuppressive therapies, particularly corticosteroids, have been proposed as the mainstay of treatment in CS, there is paucity of data on the optimal initiation, duration, and dosage of immunosuppressive therapies. Recommendations are mostly based on small observational studies. Further studies are warranted to better characterize the use of immunosuppressive therapies in this patient population. Device therapies such as implantable cardioverter-defibrillators are usually recommended for patient with clinical CS. In conclusion, this article synthesizes the current best evidence of utilizing various imaging modalities to diagnose CS and summarizing the main therapeutic approaches to manage and treat CS.

The burden and impact of arrhythmia in chronic obstructive pulmonary disease: Insights from the National Inpatient Sample

BACKGROUND

We aimed to analyze the burden and predictors of arrhythmias and in-hospital mortality in chronic obstructive pulmonary disease (COPD)-related hospitalizations using the nationwide cohort.

METHODS

We queried the National Inpatient Sample (NIS) (2010-2014) databases to identify adult COPD hospitalizations with arrhythmia. Categorical and continuous variables were compared using Chi-square and Student's t-test/ANOVA. Predictors of any arrhythmia including AF and in-hospital mortality were evaluated by multivariable analyses.

RESULTS

Out of 21,596,342 COPD hospitalizations, 6,480,799 (30%) revealed co-existent arrhythmias including 4,767,401 AF-arrhythmias (22.1%) and 1,713,398 non AF-arrhythmias (7.9%). The AF or non-AF arrhythmia cohort consisted mostly of older (mean age~ 75.8 & 69.1 vs. 67.5 years) white male (53.3% & 51.9% vs. 46.9%) patients compared to those without arrhythmias (p < 0.001). The all-cause mortality (5.7% & 5.2 vs. 2.9%), mean length of stay (LOS) (6.4 & 6.5 vs. 5.3 days), and hospital charges ($52,699.49 & $58,102.39 vs. $41,208.02) were higher with AF and non AF-arrhythmia compared to the non-arrhythmia group (p < 0.001). Comorbidities such as cardiomyopathy (OR 2.11), cardiogenic shock (OR 1.88), valvular diseases (OR 1.60), congestive heart failure (OR 1.48) and pulmonary circulation disorders (OR 1.25) predicted in-hospital arrhythmias. Invasive mechanical ventilation (OR 6.41), cardiogenic shock (OR 5.95), cerebrovascular disease (OR 3.95), septicemia (OR 2.30) and acute myocardial infarction (OR 2.24) predicted higher mortality (p < 0.001) in the COPD-arrhythmia cohort.

CONCLUSIONS

About 30% of COPD hospitalizations revealed co-existent arrhythmias (AF 22.1%). All-cause mortality, LOS and hospital charges were significantly higher with arrhythmias. We observed racial and sex-based disparities for arrhythmias and related mortality.

Accelerated Idioventricular Rhythm at the Termination of an Episode of Vasospastic Angina

A 57-year-old male with gastroesophageal reflux disease and esophageal stricture with dilation presented as a cardiac catheterization lab activation for anterolateral ST-segment elevation myocardial infarction. He had suffered an unwitnessed syncopal episode after severe substernal chest pain. Electrocardiogram (ECG) showed anterolateral ST-segment elevation. Markers of myocardial injury were negative. He subsequently had an unremarkable coronary angiogram, echocardiogram, and cardiac magnetic resonance imaging (MRI). He had another episode of crushing chest pain and palpitations during his hospital stay, which correlated with ST-segment elevation, followed by a slow run of ventricular arrhythmia that terminated after a dose of sublingual nitroglycerin. A diagnosis of accelerated idioventricular rhythm (AIVR) following coronary artery vasospasm (CAV) was made. This clinical vignette presents a unique presentation of AIVR following an episode of Prinzmetal’s angina.

Extra-cardiac comorbidities or complications in adults with congenital heart disease: a nationwide inpatient experience in the United States

With a great interest, we read the article by Neidenbach et al. on non-cardiac comorbidities in German adults with congenital heart disease (ACHD). ACHD always bear an increased risk of developing concomitant non-cardiac comorbidities and complications and impose a great healthcare burden. Limited large-scale data from the United States (US) on this focus incited us to write this brief report. Gilboa et al. estimated nearly 2.4 million people living with CHD (1.4 million adults, 1 million children) in the US in 2010. To have a better nationwide prospect of the current scenario, we looked at the extra-cardiac comorbidities among ACHD patients hospitalized in the US using the National Inpatient Sample database (NIS) for years 2013-2014. The burden of extracardiac comorbidities among the NIS cohort in the US was diverse as compared to the German outpatient ACHD cohort. Our study reports a higher burden of endocrinological, hematological, metabolic, pulmonary, psychiatric, renal and rheumatological comorbidities as compared to the German cohort. However, the burden of gastrointestinal and hepatological comorbidities was higher in the German outpatient cohort. In addition, ACHD patients with non-cardiac comorbidities were older except for those suffering from the psychiatric illnesses as compared to ACHD hospitalizations without comorbidities. It is imperative for the clinicians to understand the non-cardiac complications which a patient might encounter during a lifetime, and which could further complicate the management of ACHD and increases the risk of mortality.

The burden of cardiac arrhythmias in sarcoidosis: a population-based inpatient analysis

Background

Cardiac involvement in the sarcoidosis is known to ensue with diverse clinical forms and its investigation is challenging at times. This article features the under-perceived burden, patterns, and outcomes of different arrhythmias, which may have a prognostic significance in patients with sarcoidosis.

Methods

We queried the National Inpatient Sample (NIS) for 2010-2014 to recognize sarcoidosis, arrhythmia, and comorbidities affecting hospitalizations. The nationwide estimates were attained using discharge records. We assessed incidence and trends in sarcoidosis-related arrhythmia and consequential inpatient mortality, hospital length of stay (LOS), hospitalization charges and predictors of mortality with multivariate analysis.

Results

We identified 369,285 sarcoidosis-related hospitalizations. Of these, nearly one-fifth suffered from arrhythmias (n=73,424). The sarcoidosis patients developing arrhythmias were older (61.9 vs. 56.0 years) compared to those without. Males had the higher incidence of arrhythmias compared to females. Atrial fibrillation (Afib) (10.97%) was the most common subtype, followed by ventricular tachycardia (1.97%). There was a rising trend in arrhythmia-related hospital admissions and mortality among sarcoidosis, with Afib incidence displaying the highest increase. Traditional cardiac comorbidities were higher in the sarcoid-arrhythmia group. The arrhythmia group had significantly higher mortality (3.7% vs. 1.5%), mean hospital LOS (6.4 vs. 5.2 days) and hospital charges ($64,118 vs. $41,565) compared to non-arrhythmia group (P<0.001). Incident arrhythmia significantly increased the mortality odds in sarcoidosis (adjusted odds ratio, 2.06).

Conclusions

The growing trend, deteriorating outcomes and higher mortality associated with sarcoid-related arrhythmias highlight the importance of timely diagnosis and aggressive management in this population.

A QS pattern in leads V1 and V2 is associated with septal scarring independent of scar etiology - A cardiac magnetic resonance imaging study

BACKGROUND

Isolated septal myocardial infarction (MI) is traditionally characterized by the presence of pathological Q waves in leads V₁ and V₂ on the surface electrocardiogram (ECG). The purpose of this study was to determine the relation between this ECG pattern and septal scar on cardiac magnetic resonance (CMR) imaging.

METHODS

We retrospectively reviewed the medical records of 996 consecutive patients who received both ECG and CMR.

RESULTS

Nineteen patients had a Q wave in leads V₁ and V₂. Septal scar was present in all 19 patients. Based on CMR imaging criteria, septal scars were ischemic in 8 patients (42%) and non-ischemic in 11 patients (58%).

CONCLUSION

The results suggest that the presence of a QS pattern in leads V₁ and V₂ on the surface ECG is highly predictive of the presence of a septal myocardial scar, but is not diagnostic for septal MI, even after excluding comorbidities known to produce a pseudo-septal MI pattern.

Cough as the sole manifestation of pericardial effusion

A 59-year-old woman with paroxysmal atrial fibrillation (AF) presented with severe non-productive cough, malaise, low-grade fever and AF flare-up 3 weeks following pulmonary vein isolation with radiofrequency catheter ablation. She denied chest pain or dyspnoea. Patient was haemodynamically stable. There was no pulsus paradoxus. Laboratories showed leucocytosis and elevated C-reactive protein. ECG showed sinus tachycardia. CT abdomen and pelvis showed a large pericardial effusion (PE). Shortly after admission, she developed AF with rapid ventricular response, responsive to intravenous amiodarone. Transthoracic echocardiogram revealed 2.4 cm posterior PE without tamponade physiology, non-amenable to pericardiocentesis via sub-xiphoid approach. Patient underwent left thoracoscopic pericardial window with removal of 250 cc bloody fibrinous fluid. Cough improved significantly and she was discharged on oral amiodarone and apixaban. Repeat CT chest after 2 weeks for recurrent cough showed a small PE, treated with oral prednisone for suspected postablation pericarditis, with complete resolution of cough. Amiodarone was stopped without recurrence of AF.

A photic visual cycle of rhodopsin regeneration is dependent on Rgr

During visual excitation, rhodopsin undergoes photoactivation and bleaches to opsin and all-trans-retinal. To regenerate rhodopsin and maintain normal visual sensitivity, the all-trans isomer must be metabolized and reisomerized to produce the chromophore 11-cis-retinal in biochemical steps that constitute the visual cycle and involve the retinal pigment epithelium (RPE; refs. 3-8). A key step in the visual cycle is isomerization of an all-trans retinoid to 11-cis-retinol in the RPE (refs. 9-11). It could be that the retinochrome-like opsins, peropsin, or the retinal G protein-coupled receptor (RGR) opsin12-16 are isomerases in the RPE. In contrast to visual pigments, RGR is bound predominantly to endogenous all-trans-retinal, and irradiation of RGR in vitro results in stereospecific conversion of the bound all-trans isomer to 11-cis-retinal. Here we show that RGR is involved in the formation of 11-cis-retinal in mice and functions in a light-dependent pathway of the rod visual cycle. Mutations in the human gene encoding RGR are associated with retinitis pigmentosa.

Interaction of 11-cis-retinol dehydrogenase with the chromophore of retinal g protein-coupled receptor opsin

Vertebrate opsins in both photoreceptors and the retinal pigment epithelium (RPE) have fundamental roles in the visual process. The visual pigments in photoreceptors are bound to 11-cis-retinal and are responsible for the initiation of visual excitation. Retinochrome-like opsins in the RPE are bound to all-trans-retinal and play an important role in chromophore metabolism. The retinal G protein-coupled receptor (RGR) of the RPE and Müller cells is an abundant opsin that generates 11-cis-retinal by stereospecific photoisomerization of its bound all-trans-retinal chromophore. We have analyzed a 32-kDa protein (p32) that co-purifies with bovine RGR from RPE microsomes. The co-purified p32 was identified by mass spectrometric analysis as 11-cis-retinol dehydrogenase (cRDH), and enzymatic assays have confirmed the isolation of an active cRDH. The co-purified cRDH showed marked substrate preference to 11-cis-retinal and preferred NADH rather than NADPH as the cofactor in reduction reactions. cRDH did not react with endogenous all-trans-retinal bound to RGR but reacted specifically with 11-cis-retinal that was generated by photoisomerization after irradiation of RGR. The reduction of 11-cis-retinal to 11-cis-retinol by cRDH enhanced the net photoisomerization of all-trans-retinal bound to RGR. These results indicate that cRDH is involved in the processing of 11-cis-retinal after irradiation of RGR opsin and suggest that cRDH has a novel role in the visual cycle.

Enamel biomineralization defects result from alterations to amelogenin self-assembly

Enamel formation is a powerful model for the study of biomineralization. A key feature common to all biomineralizing systems is their dependency upon the biosynthesis of an extracellular organic matrix that is competent to direct the formation of the subsequent mineral phase. The major organic component of forming mouse enamel is the 180-amino-acid amelogenin protein (M180), whose ability to undergo self-assembly is believed to contribute to biomineralization of vertebrate enamel. Two recently defined domains (A and B) within amelogenin appear essential for this self-assembly. The significance of these two domains has been demonstrated previously by the yeast two-hybrid system, atomic force microscopy, and dynamic light scattering. Transgenic animals were used to test the hypothesis that the self-assembly domains identified with in vitro model systems also operate in vivo. Transgenic animals bearing either a domain-A-deleted or domain-B-deleted amelogenin transgene expressed the altered amelogenin exclusively in ameloblasts. This altered amelogenin participates in the formation an organic enamel extracellular matrix and, in turn, this matrix is defective in its ability to direct enamel mineralization. At the nanoscale level, the forming matrix adjacent to the secretory face of the ameloblast shows alteration in the size of the amelogenin nanospheres for either transgenic animal line. At the mesoscale level of enamel structural hierarchy, 6-week-old enamel exhibits defects in enamel rod organization due to perturbed organization of the precursor organic matrix. These studies reflect the critical dependency of amelogenin self-assembly in forming a competent enamel organic matrix and that alterations to the matrix are reflected as defects in the structural organization of enamel.

Expression of a recombinant human RGR opsin in Lentivirus-transduced cultured cells

PURPOSE

Our goals were to produce a functional recombinant RPE retinal G protein-coupled receptor (RGR) opsin for biochemical studies and to test the efficiency of a lentiviral vector for transgene expression of human RGR.

METHODS

A human RGR cDNA was cloned into a replication-defective lentiviral vector, and recombinant hRGR-Lentivirus was prepared for transduction of the ARPE-19, a human retinal pigment epithelium (RPE) cell line, and COS-7 cells. Recombinant RGR expression was detected by Western blot analysis, and functionality of the protein was tested by a [3H]all-trans-retinal binding assay.

RESULTS

RGR protein was detected in each cell type after transduction with recombinant virus and was not observed in untreated cells. RGR expression in ARPE-19 cells increased steadily for up to 10 days after transduction and was stable for at least 6 months. The transduced ARPE-19 cells produced approximately 100-fold higher amounts of RGR protein than the transduced COS-7 cells. When cell membranes from the ARPE-19 cells were incubated with [3H]all-trans-retinal, the chromophore bound specifically to the expressed protein. Uptake of [3H]all-trans-retinol into the ARPE-19 cells was followed by specific binding of radiolabeled retinoid to RGR.

CONCLUSIONS

Using a Lentivirus-derived gene delivery system, we were able to express high amounts of human RGR protein in the ARPE-19 human RPE cell line. The transduced ARPE-19 cells remain able to process all-trans-retinol, and the expressed protein is capable of binding to the all-trans-retinal chromophore. The Lentivirus-based expression of functional RGR can be used to study RGR in cultured cells and to test in vivo transduction of quiescent RPE cells.