Understanding repeat hospitalizations in intermediate-to-high risk aortic stenosis patients following transcatheter aortic valve replacement.

OBJECTIVES: We describe the causes, timing and predictors of readmissions and analyze its impact on clinical outcomes in intermediate-to-high-risk patients with severe symptomatic aortic stenosis (AS) who underwent transcatheter aortic valve replacement (TAVR). BACKGROUND: Intermediate-high risk TAVR patients with severe AS have an increased risk for hospital readmissions due to the high burden of comorbidities. METHODS: Patients who underwent TAVR from 2012 to 2018 at a single tertiary cardiac center were included and followed for 1 year. Readmissions were categorized as noncardiovascular (non-CV) and CV. RESULTS: A total of 611 patients (410 with no readmissions, 201 with ≥1 readmissions) were included. There was a total of 317 readmissions (mean: 1.58 ± 1.09 per readmitted patient) with 65 patients having ≥2 readmissions. 64.0% were non-CV and 36.0% were CV. The top three CV causes were pacemaker/implantable cardioverter-defibrillator placement, bleeding, and stroke. About 23% occurred at 1 m, the majority were CV; 45% occurred between 7 and 12 m, the majority were non-CV. Those with ≥1 readmissions had a higher burden of comorbidities including peripheral arterial disease, diabetes, immunosuppression, prior percutaneous coronary interventions, and dialysis. Readmissions were associated with higher 1-year mortality (adjusted hazard ratio: 2.53, 95% confidence interval: 1.40-4.59; p = 0.002). High-risk patients had higher non-CV readmissions (0.37 ± 0.79 vs. 0.25 ± 0.62; p = 0.044) compared to intermediate-risk patients but similar CV readmissions (p = 0.645). CONCLUSIONS: Understanding readmissions post-TAVR will promote the early identification of at-risk groups and the implementation of preventative measures to improve outcomes and reduce the burden and costs of readmissions.

Multidisciplinary approach to coronary artery revascularization: Optimal strategy for high-risk patients.

High-risk patients that are not candidates for conventional coronary artery bypass grafting surgery can undergo coronary artery revascularization through less invasive procedures. Hybrid approaches have emerged to address coronary artery disease in this subset of patients. This case report highlights the successful application of a multidisciplinary heart team approach for hybrid coronary revascularization in a very high-risk patient with complex coronary anatomy, who would not otherwise be a candidate for conventional modalities of revascularization. The optimal workup, selection criteria based on anatomy, anticoagulation strategies, and timing of intervention of hybrid coronary revascularization are outlined in this case report.

Very late stent thrombosis with second generation drug eluting stents compared to bare metal stents: Network meta-analysis of randomized primary percutaneous coronary intervention trials.

BACKGROUND: The relative safety of drug-eluting stents (DES) and bare-metal stents (BMS) in primary percutaneous coronary intervention (PPCI) in ST elevation myocardial infarction (STEMI) continues to be debated. The long-term clinical outcomes between second generation DES and BMS for primary percutaneous coronary intervention (PCI) using network meta-analysis were compared. METHODS: Randomized controlled trials comparing stent types (first generation DES, second generation DES, or BMS) were considered for inclusion. A search strategy used Medline, Embase, Cochrane databases, and proceedings of international meetings. Information about study design, inclusion criteria, and sample characteristics were extracted. Network meta-analysis was used to pool direct (comparison of second generation DES to BMS) and indirect evidence (first generation DES with BMS and second generation DES) from the randomized trials. RESULTS: Twelve trials comparing all stents types including 9,673 patients randomly assigned to treatment groups were analyzed. Second generation DES was associated with significantly lower incidence of definite or probable ST (OR 0.59, 95% CI 0.39-0.89), MI (OR 0.59, 95% CI 0.39-0.89), and TVR at 3 years (OR 0.50: 95% CI 0.31-0.81) compared with BMS. In addition, there was a significantly lower incidence of MACE with second generation DES versus BMS (OR 0.54, 95% CI 0.34-0.74) at 3 years. These were driven by a higher rate of TVR, MI and stent thrombosis in the BMS group at 3 years. There was a non-significant reduction in the overall and cardiac mortality [OR 0.83, 95% CI (0.60-1.14), OR 0.88, 95% CI (0.6-1.28)] with the use of second generation DES versus BMS at 3 years. CONCLUSIONS: Network meta-analysis of randomized trials of primary PCI demonstrated lower incidence of MACE, MI, TVR, and stent thrombosis with second generation DES compared with BMS. © 2016 Wiley Periodicals, Inc.

Personalized Telehealth in the Future: A Global Research Agenda.

As telehealth plays an even greater role in global health care delivery, it will be increasingly important to develop a strong evidence base of successful, innovative telehealth solutions that can lead to scalable and sustainable telehealth programs. This paper has two aims: (1) to describe the challenges of promoting telehealth implementation to advance adoption and (2) to present a global research agenda for personalized telehealth within chronic disease management. Using evidence from the United States and the European Union, this paper provides a global overview of the current state of telehealth services and benefits, presents fundamental principles that must be addressed to advance the status quo, and provides a framework for current and future research initiatives within telehealth for personalized care, treatment, and prevention. A broad, multinational research agenda can provide a uniform framework for identifying and rapidly replicating best practices, while concurrently fostering global collaboration in the development and rigorous testing of new and emerging telehealth technologies. In this paper, the members of the Transatlantic Telehealth Research Network offer a 12-point research agenda for future telehealth applications within chronic disease management.

Randomized, controlled trial to improve self-care in patients with heart failure living in rural areas.

BACKGROUND: Patients with heart failure (HF) who live in rural areas have less access to cardiac services than patients in urban areas. We conducted a randomized, clinical trial to determine the impact of an educational intervention on the composite end point of HF rehospitalization and cardiac death in this population. METHODS AND RESULTS: Patients (n=602; age, 66±13 years; 41% female; 51% with systolic HF) were randomized to 1 of 3 groups: control (usual care), Fluid Watchers LITE, or Fluid Watchers PLUS. Both intervention groups included a face-to-face education session delivered by a nurse focusing on self-care. The LITE group received 2 follow-up phone calls, whereas the PLUS group received biweekly calls (mean, 5.3±3.6; range, 1-19) until the nurse judged the patient to be adequately trained. Over 2 years of follow-up, 35% of patients (n=211) experienced cardiac death or hospitalization for HF, with no difference among the 3 groups in the proportion who experienced the combined clinical outcome (P=0.06). Although patients in the LITE group had reduced cardiac mortality compared with patients in the control group over the 2 years of follow-up (7.5% and 17.7%, respectively; P=0.003), there was no significant difference in cardiac mortality between patients in the PLUS group and the control group. CONCLUSIONS: A face-to-face education intervention did not significantly decrease the combined end point of cardiac death or hospitalization for HF. Increasing the number of contacts between the patient and nurse did not significantly improve outcome. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov. Unique identifier: NCT00415545.

Rural patients' knowledge about heart failure.

BACKGROUND: Heart failure (HF) is a potentially disabling condition requiring significant patient knowledge to manage the requirements of self-care. The need for self-care is important for all patients but particularly for those living in rural areas that are geographically remote from healthcare services. OBJECTIVE: The aim of this study was to identify the level of knowledge of rural patients with HF and the clinical and demographic characteristics associated with low levels of HF knowledge. METHODS: Baseline data from 612 patients with HF enrolled in the Rural Education to Improve Outcomes in Heart Failure trial were analyzed using the Heart Failure Knowledge Scale, the Short Test of Functional Health Literacy in Adults, and the anxiety subscale of the Brief Symptom Inventory. Multiple linear regression was used to explore the contribution of sociodemographic and clinical variables to levels of HF knowledge. RESULTS: The mean (SD) age was 66 (13) years; 59% were men, and 50.5% had an ejection fraction of less than 40%. The mean (SD) percent correct on the Heart Failure Knowledge Scale was 69.5% (13%; range, 25%-100%), with the most frequent incorrect items related to symptoms of HF and the need for daily weights. The men and the older patients scored significantly lower in HF knowledge than did the women and the younger patients (P = 0.002 and 0.011, respectively). The patients with preserved systolic function also scored significantly lower than those with systolic HF (P = 0.030). CONCLUSIONS: Patients who are at risk for poor self-care because of low levels of HF knowledge can be identified. Older patients, men, and, patients with HF with preserved systolic function may require special educational strategies to gain the knowledge required for effective self-care.

Dual modality intravascular catheter system combining pulse-sampling fluorescence lifetime imaging and polarization-sensitive optical coherence tomography.

The clinical management of coronary artery disease and the prevention of acute coronary syndromes require knowledge of the underlying atherosclerotic plaque pathobiology. Hybrid imaging modalities capable of comprehensive assessment of biochemical and morphological plaques features can address this need. Here we report the first implementation of an intravascular catheter system combining fluorescence lifetime imaging (FLIm) with polarization-sensitive optical coherence tomography (PSOCT). This system provides multi-scale assessment of plaque structure and composition via high spatial resolution morphology from OCT, polarimetry-derived tissue microstructure, and biochemical composition from FLIm, without requiring any molecular contrast agent. This result was achieved with a low profile (2.7 Fr) double-clad fiber (DCF) catheter and high speed (100 fps B-scan rate, 40 mm/s pullback speed) console. Use of a DCF and broadband rotary junction required extensive optimization to mitigate the reduction in OCT performance originating from additional reflections and multipath artifacts. This challenge was addressed by the development of a broad-band (UV-visible-IR), high return loss (47 dB) rotary junction. We demonstrate in phantoms, ex vivo swine coronary specimens and in vivo swine heart (percutaneous coronary access) that the FLIm-PSOCT catheter system can simultaneously acquire co-registered FLIm data over four distinct spectral bands (380/20 nm, 400/20 nm, 452/45 nm, 540/45 nm) and PSOCT backscattered intensity, birefringence, and depolarization. The unique ability to collect complementary information from tissue (e.g., morphology, extracellular matrix composition, inflammation) with a device suitable for percutaneous coronary intervention offers new opportunities for cardiovascular research and clinical diagnosis.

Transradial and transfemoral coronary angiography and interventions: 1-year outcomes after initiating the transradial approach in a cardiology training program.

BACKGROUND: Limited data are available regarding the safety and feasibility of initiating transradial (TR) diagnostic coronary angiography (CA) and percutaneous coronary intervention (PCI) in cardiology fellowship programs. METHODS: From July 2010 to June 2011, University of California, Davis Medical Center, adopted the TR approach with supervised cardiology fellows as the primary operators. Procedural variables and clinical outcomes of TR and transfemoral (TF) procedures were compared. To minimize confounding variables, ST-elevation myocardial infarction, bypass graft interventions, chronic total occlusions, and procedures with concomitant right heart catheterizations were excluded. To reflect the learning curve of the TR approach, this experience was assessed in 2 sequential 6-month periods. RESULTS: A total of 402 diagnostic CAs and 255 PCIs were included. Transradial access was used in 141 (35%) of the CAs and in 72 (28%) of PCIs. Within the TR-CA and TF-CA (n = 261) groups, there was no difference between fluoroscopy (10.4 ± 6.0 vs 11.0 ± 8.9, P = .63) or procedure (31.8 ± 11.5 vs 33.2 ± 13.8, P = .55) time throughout the academic year with a significant trend toward lower contrast use (128 ± 52 vs 110 vs 50, P = .04) by the second half. In addition, during the second half of the academic year, the TR-CA showed significantly higher fluoroscopy (11.0 ± 8.9 vs 6.7 ± 6.8, P = .001) and procedure (33.2 ± 13.8 vs 27.2 ± 11.6, P = .0015) times when compared with TF-CA. Transfemoral PCI (n = 183) and TR-PCI showed no significant difference between all fluoroscopy and procedure time and contrast use when comparing the 2 halves of the academic year. When comparing TF with TR within each academic half year, there was no difference within the PCI group. Vascular complications were less with the TR approach. Overall procedural success rates were high, and there were low rates of crossover and periprocedural complications in both the TR and the TF groups. CONCLUSION: A TR approach is safe for CA and PCI when performed by supervised operators in training. Although the learning curve for trainees appears slower for TR-CA compared with TF-CA, cardiology fellowship training programs should be encouraged to adopt TR procedures as part of their curriculum.

Dynamic tissue analysis using time- and wavelength-resolved fluorescence spectroscopy for atherosclerosis diagnosis.

Simultaneous time- and wavelength-resolved fluorescence spectroscopy (STWRFS) was developed and tested for the dynamic characterization of atherosclerotic tissue ex vivo and arterial vessels in vivo. Autofluorescence, induced by a 337 nm, 700 ps pulsed laser, was split to three wavelength sub-bands using dichroic filters, with each sub-band coupled into a different length of optical fiber for temporal separation. STWRFS allows for fast recording/analysis (few microseconds) of time-resolved fluorescence emission in these sub-bands and rapid scanning. Distinct compositions of excised human atherosclerotic aorta were clearly discriminated over scanning lengths of several centimeters based on fluorescence lifetime and the intensity ratio between 390 and 452 nm. Operation of STWRFS blood flow was further validated in pig femoral arteries in vivo using a single-fiber probe integrated with an ultrasound imaging catheter. Current results demonstrate the potential of STWRFS as a tool for real-time optical characterization of arterial tissue composition and for atherosclerosis research and diagnosis.

Label-Free Visualization and Quantification of Biochemical Markers of Atherosclerotic Plaque Progression Using Intravascular Fluorescence Lifetime.

OBJECTIVES: This study aimed to systematically investigate whether plaque autofluorescence properties assessed with intravascular fluorescence lifetime imaging (FLIm) can provide qualitative and quantitative information about intimal composition and improve the characterization of atherosclerosis lesions. BACKGROUND: Despite advances in cardiovascular diagnostics, the analytic tools and imaging technologies currently available have limited capabilities for evaluating in situ biochemical changes associated with luminal surface features. Earlier studies of small number of samples have shown differences among the autofluorescence lifetime signature of well-defined lesions, but a systematic pixel-level evaluation of fluorescence signatures associated with various histological features is lacking and needed to better understand the origins of fluorescence contrast. METHODS: Human coronary artery segments (n = 32) were analyzed with a bimodal catheter system combining multispectral FLIm with intravascular ultrasonography compatible with in vivo coronary imaging. Various histological components present along the luminal surface (200-µm depth) were systematically tabulated (12 sectors) from each serial histological section (n = 204). Morphological information provided by ultrasonography allowed for the accurate registration of imaging data with histology data. The relationships between histological findings and FLIm parameters obtained from 3 spectral channels at each measurement location (n = 33,980) were characterized. RESULTS: Our findings indicate that fluorescence lifetime from different spectral bands can be used to quantitatively predict the superficial presence of macrophage foam cells (mFCs) (area under the receiver-operator characteristic curve: 0.94) and extracellular lipid content in advanced lesions (lifetime increase in 540-nm band), detect superficial calcium (lifetime decrease in 450-nm band area under the receiver-operator characteristic curve: 0.90), and possibly detect lesions consistent with active plaque formation such as pathological intimal thickening and healed thrombus regions (lifetime increase in 390-nm band). CONCLUSIONS: Our findings indicate that autofluorescence lifetime provides valuable information for characterizing atherosclerotic lesions in coronary arteries. Specifically, FLIm can be used to identify key phenomena linked with plaque progression (e.g., peroxidized-lipid-rich mFC accumulation and recent plaque formation).

Technical Considerations for TAVR in the Treatment of Stentless Bioprosthetic Aortic Valve Insufficiency in LVAD Patients.

An 80-year-old man with a history of bicuspid AV complicated by severe AI presented with progressive NYHA class III symptoms and severe bioprosthetic AV insufficiency. Transcatheter aortic valve replacement was planned via transfemoral approach. We encountered several technical challenges and describe them herein.

In search of the false-negative exercise treadmill testing evidence-based use of exercise echocardiography.

BACKGROUND: Controversy exists regarding the role of exercise treadmill testing (ETT) versus exercise stress echocardiography (ESE) as the appropriate initial noninvasive test to risk-stratify patients with chest pain. The majority of studies to date that evaluated these methodologies included patients with poor functional status and baseline electrocardiogram (ECG) abnormalities, potentially limiting the sensitivity of ETT. HYPOTHESIS: We examined the hypothesis that given stringent standards of exercise duration and ECG interpretability, the ETT would have a high diagnostic sensitivity for the presence of significant coronary artery disease (CAD). METHODS: Results of concurrent ETT and ESE in 3,098 patients were examined, and the subset of patients with a negative ETT and positive ESE (-ETT/ + ESE) were reviewed for the presence of CAD as a function of exercise duration (< or > or = 6 min) and baseline ECG normality. RESULTS: In those patients with a - ETT/ + ESE who exercised > or = 6 min, 54 had a normal baseline ECG, 22 underwent angiography and 6 had CAD (all of whom had either small, grafted or collateralized vessels). Patients with a - ETT/ + ESE who were incapable of exercising 6 min were more frequently older and female. Mortality was significantly greater in the < 6 min exercise duration group (31.4 versus 3.1%). CONCLUSIONS: These findings support the use of the ETT without imaging as the initial test in patients with chest pain who have a normal baseline ECG and are able to exercise 6 min. Using these criteria, false negative findings are generally seen in patients without critical large vessel epicardial disease. The ESE should be reserved as the initial test for patients with an abnormal baseline ECG or reduced functional capacity.

Interstitial lung abnormality is prevalent and associated with worse outcome in patients undergoing transcatheter aortic valve replacement.

BACKGROUND: Interstitial lung abnormality (ILA) is found in 5-10% of the general population and is associated with increased mortality risk. Risk factors for ILA, including advanced age and smoking history also increase the risk for aortic stenosis (AS). Transcatheter aortic valve replacement (TAVR) has become an increasingly utilized intervention for patients with severe AS, and requires a high-resolution computed tomography (HRCT) of the chest to assess aortic valve dimensions. OBJECTIVES: To determine the prevalence and clinical significance of ILA on HRCT performed in patients referred for TAVR. METHODS: Consecutive pre-TAVR HRCTs performed over a 5-year period were reviewed. ILA was defined as bilateral, nondependent reticular opacities. All-cause mortality among TAVR recipients was compared between ILA cases and non-ILA controls matched 2:1 by age and gender using Cox proportional hazards regression and the Kaplan Meier estimator. RESULTS: Of 623 HRCTs screened, ILA was detected in 92 (14.7%), including 62 patients that underwent TAVR. Among ILA cases, 17 (27.4%) had a typical or probable usual interstitial pneumonia pattern, suggesting a diagnosis of idiopathic pulmonary fibrosis. Survival was worse in ILA cases compared to non-ILA controls (p = 0.008) and ILA was an independent predictor of mortality after multivariable adjustment (HR 3.29, 95% CI 1.34-8.08; p = 0.009). CONCLUSIONS: ILA is a common finding among patients with severe AS and is associated with increased mortality in those undergoing TAVR. Further research is needed to elucidate the biology underpinning this observation and determine whether ILA evaluation and risk stratification modulates this mortality risk.

In vivo label-free structural and biochemical imaging of coronary arteries using an integrated ultrasound and multispectral fluorescence lifetime catheter system.

Existing clinical intravascular imaging modalities are not capable of accurate detection of critical plaque pathophysiology in the coronary arteries. This study reports the first intravascular catheter combining intravascular ultrasound (IVUS) with multispectral fluorescence lifetime imaging (FLIm) that enables label-free simultaneous assessment of morphological and biochemical features of coronary vessels in vivo. A 3.7 Fr catheter with a fiber-optic channel was constructed based on a 40 MHz clinical IVUS catheter. The ability to safely acquire co-registered FLIm-IVUS data in vivo using Dextran40 solution flushing was demonstrated in swine coronary arteries. FLIm parameters from the arterial wall were consistent with the emission of fluorophores present in healthy arterial wall (collagen, elastin). Additionally, structural and biochemical features from atherosclerotic lesions were acquired in ex vivo human coronary samples and corroborated with histological findings. Current results show that FLIm parameters linked to the amount of structural proteins (e.g. collagen, elastin) and lipids (e.g. foam cells, extracellular lipids) in the first 200 µm of the intima provide important biochemical information that can supplement IVUS data for a comprehensive assessment of plaques pathophysiology. The unique FLIm-IVUS system evaluated here has the potential to provide a comprehensive insight into atherosclerotic lesion formation, diagnostics and response to therapy.

Obesity Paradox: Comparison of Heart Failure Patients With and Without Comorbid Diabetes.

BACKGROUND: Diabetes is a common comorbid condition in patients with heart failure and is strongly associated with poor outcomes. Patients with heart failure who have diabetes are more likely to be obese than are those without diabetes. Obesity is positively associated with survival in patients with heart failure, but how comorbid diabetes influences the relationship between obesity and favorable prognosis is unclear. OBJECTIVE: To explore whether the relationship between body mass index and survival differs between patients with heart failure who do or do not have diabetes. METHODS: The sample consisted of 560 ambulatory patients with heart failure (mean age, 66 years; mean body mass index, 32; diabetes, 41%). The association between body mass index and all-cause mortality was examined by using multivariate Cox proportional hazards regression after adjustments for covariates. RESULTS: In patients without diabetes, higher body mass index was associated with a lower risk for all-cause mortality after adjustments for covariates (hazard ratio, 0.952; 95% CI, 0.909-0.998). In patients with diabetes, body mass index was not predictive of all-cause death after adjustments for covariates. CONCLUSION: Obesity was a survival benefit in heart failure patients without comorbid diabetes but not in those with comorbid diabetes. The mechanisms underlying the difference in the relationship between obesity and survival due to the presence of diabetes in patients with heart failure need to be elucidated.

Factors associated with telemonitoring use among patients with chronic heart failure.

Background In adults with chronic heart failure (HF; defined as people with previously diagnosed left ventricular dysfunction) telemonitoring randomized controlled trials (RCTs) failed to consistently demonstrate improved clinical outcomes. We aimed to examine if patient and HF characteristics are associated with device preferences and use. Methods Using a cross-sectional, multicenter, international design, ambulatory and hospitalized adults with HF in Ohio, California, and Denmark viewed a six-minute video of telemonitoring configurations (tablet, smart phone, and key fob) and completed questionnaires. Comparative analyses were performed and when significant, pairwise comparisons were performed using Bonferroni-adjusted significance levels. Results Of 206 participants, 48.2% preferred smart phones for telemonitoring, especially when traveling (54.8%), with new/worsening symptoms (50%), for everyday use (50%), and connecting with doctors (48.5%). Participants preferred two-way communication and a screen with words over voice or number pads. Of device purposes, allowing for nurse communication ranked highest, followed by maintaining overall health. Very few patient and HF factors were associated with device preferences. Patients with higher health literacy ( p = 0.007), previous/current device use history ( p = 0.008), higher education level ( p = 0.035), and married/cohabitating status ( p = 0.023) had higher perceptions of ease of using devices. Those who were asymptomatic or had mild HF had higher self-confidence for health devices ( p = 0.024) and non-white patients perceived devices as more useful ( p = 0.033). Conclusion Telemonitoring use may be enhanced by simple plug-and-play type devices, two-way communication, and features that meet patients' personal learning and use needs.

Clinical Significance of Persistent Global and Focal Computed Tomography Nephrograms After Cardiac Catheterization and Their Relationships to Urinary Biomarkers of Kidney Damage and Procedural Factors: Pilot Study.

OBJECTIVES: We evaluate the relationships between persistent computed tomography (CT) nephrograms and acute kidney injury after cardiac catheterization (CC). We compare changes in urinary biomarkers kidney injury molecule 1 (KIM-1), cystatin C, and serum creatinine to procedural factors. MATERIALS AND METHODS: From 159 eligible patients without renal insufficiency (estimated glomerular filtration rate >60 mL/min), 40 random patients (age range, 42-81 years; mean age, 64 years; 25 men, 15 women) gave written informed consent to undergo unenhanced CT limited to their kidneys 24 hours after CC. Semiquantitative assessment for global nephrograms and quantitative assessment of focal nephrograms in each kidney was performed. Computed tomography attenuation (Hounsfield units) of the renal cortex was measured. Serum creatinine, KIM-1, and cystatin C were measured before and 24 hours after CC. RESULTS: Robust linear regression showed that both relative changes in KIM-1 and cystatin C had positive relationships with kidney CT attenuation (P = 0.012 and 0.002, respectively). Spearman rank correlation coefficient showed that both absolute changes and relative changes in KIM-1 and cystatin C had positive correlations with global nephrogram grades (P = 0.025 and 0.040, respectively, for KIM-1; P = 0.013 and 0.019, respectively, for cystatin C). CONCLUSIONS: Global nephrograms on unenhanced CT in patients who have undergone CC are significantly correlated with changes in urinary biomarkers for kidney damage.

Fluorescence Lifetime Imaging Combined with Conventional Intravascular Ultrasound for Enhanced Assessment of Atherosclerotic Plaques: an Ex Vivo Study in Human Coronary Arteries.

This study evaluates the ability of label-free fluorescence lifetime imaging (FLIm) to complement intravascular ultrasound (IVUS) for concurrent visualization of human coronary vessel composition, structure, and pathology. Co-registered FLIm and IVUS data from 16 coronary segments were correlated to eight distinct pathological features including thin-cap fibroatheroma (TCFA). The sensitivity, specificity, and positive predictive value for combined FLIm-IVUS (89, 99, 89 %) were better than FLIm (70, 98, 88 %) and IVUS (45, 94, 62 %) alone in distinguishing between pathologies. FLIm can assess compositional changes in luminal surface through variations in fluorescence lifetime values (<3.5 ns for lipid-rich areas; >4 ns for collagen-rich areas) enabling detection of macrophages in fibrous caps (sensitivity, 86 %) and distinguishing between relatively stable thick-cap fibroatheromas and rupture-prone TCFA (sensitivity, 80 %) amongst other features. Current results demonstrate the potential of FLIm-IVUS as a new intravascular method for improved evaluation of plaques that may subsequently aid in guiding coronary intervention.