Regulatory strategies for early device development and approval.

The development of new technology to treat unmet clinical needs is an important component of modern cardiovascular disease. The need for this has been emphasized in the past several years beginning with the Food and Drug Administration (FDA) guidance document on Early Feasibility Studies in 2012 and then the 21st Century Cures legislation. A number of steps need to be considered in this process by the stakeholders involved including physician innovators and scientists, professional societies such as Society for Cardiovascular Angiography & Interventions, regulatory agencies, and medical device companies. This article focuses on the early iterative steps required to optimize the process and achieve the goal of timely efficient innovation and device development in cardiovascular disease.

Visual estimation versus different quantitative coronary angiography methods to assess lesion severity in bifurcation lesions.

OBJECTIVES: To compare visual estimation with different quantitative coronary angiography (QCA) methods (single-vessel versus bifurcation software) to assess coronary bifurcation lesions. BACKGROUND: QCA has been developed to overcome the limitations of visual estimation. Conventional QCA however, developed in "straight vessels," has proved to be inaccurate in bifurcation lesions. Therefore, bifurcation QCA was developed. However, the impact of these different modalities on bifurcation lesion severity classification is yet unknown METHODS: From a randomized controlled trial investigating a novel bifurcation stent (Clinicaltrials.gov NCT01258972), patients with baseline assessment of lesion severity by means of visual estimation, single-vessel QCA, 2D bifurcation QCA and 3D bifurcation QCA were included. We included 113 bifurcations lesions in which all 5 modalities were assessed. The primary end-point was to evaluate how the different modalities affected the classification of bifurcation lesion severity and extent of disease. RESULTS: On visual estimation, 100% of lesions had side-branch diameter stenosis (%DS) >50%, whereas in 83% with single-vessel QCA, 27% with 2D bifurcation QCA and 26% with 3D bifurcation QCA a side-branch %DS >50% was found (P < 0.0001). With regard to the percentage of "true" bifurcation lesions, there was a significant difference between visual estimate (100%), single-vessel QCA (75%) and bifurcation QCA (17% with 2D bifurcation software and 13% with 3D bifurcation software, P < 0.0001). CONCLUSIONS: Our study showed that bifurcation lesion complexity was significantly affected when more advanced bifurcation QCA software were used. "True" bifurcation lesion rate was 100% on visual estimation, but as low as 13% when analyzed with dedicated bifurcation QCA software.

Dofetilide-Associated QT Prolongation: Total Body Weight Versus Adjusted or Ideal Body Weight for Dosing.

Dofetilide is an antiarrhythmic drug with dosing based on the Cockcroft-Gault formula using total body weight (TBW). We investigated the impact of calculating dofetilide dose using adjusted body weight (ABW) or ideal body weight (IBW) on subsequent dose reduction or discontinuation. We conducted a retrospective review of 265 patients admitted to an academic medical center for initiation of dofetilide using TBW. Dosing was recalculated using ABW or IBW. Patients who would have received a reduced dose using ABW or IBW (reduced dose group) were compared with patients whose dose would not have changed (same dose group). Manual measurement of QT intervals was performed. We found that Forty-one of 265 patients (15%) would have received a lower initial dose of dofetilide based on ABW. Patients in this reduced dose group had 2.95 times greater odds of drug discontinuations or dose reductions due to QTc prolongation (95% confidence interval, 1.47-5.90; P < 0.01) compared with the same dose group. Seventy-seven of 265 patients (29%) would have received a lower initial dose of dofetilide based on IBW. Patients in this reduced dose group had 1.78 times greater odds of drug discontinuations or dose reductions due to QTc prolongation (95% confidence interval, 0.98-3.21; P = 0.056) compared with the same dose group. These data suggest that caution should be used when dosing dofetilide using TBW, as it may lead to a greater frequency of dose reduction or discontinuation compared with dosing using ABW or IBW.

Segmental comparison between a dedicated bifurcation stent and balloon angioplasty using intravascular ultrasound and three-dimensional quantitative coronary angiography: A subgroup analysis of the Tryton IDE randomized trial.

OBJECTIVE: Randomized comparison between the Tryton Side Branch Stent (Tryton Medical, Durham, NC), used in combination with a main branch drug-eluting stent (DES), and side branch balloon angioplasty (SBBA, in combination with a main branch DES) using intravascular ultrasound (IVUS), and three-dimensional quantitative coronary angiography (3D-QCA). BACKGROUND: The Tryton stent has been developed to improve clinical outcomes after percutaneous coronary intervention (PCI) of bifurcation lesions. METHODS: We present the pre-specified IVUS (n = 159) and 3D-QCA (n = 190) sub-group analyses of the Tryton coronary bifurcation trial (randomizing Tryton vs. SBBA). RESULTS: There were no differences in the main branch with regard to minimal lumen area (MLA) (5.33 ± 1.37 in Tryton vs. 5.69 ± 1.72 mm2 in SBBA, P = 0.235) with low neo-intima area in both groups. In the side branch, there were also no statistical significant differences between both groups (3.04 ± 1.02 in Tryton vs. 3.46 ± 1.15 mm2 in SBBA, P = 0.072). On 3D-QCA, no differences in minimal lumen diameter (MLD) and percentage diameter stenosis (%DS) were observed in the proximal and distal main branches. In the side branch, there were also no differences found in %DS and MLD (MLD: 1.34 ± 0.043 mm [Tryton] vs. 1.45 ± 0.31 mm [SBBA], P = 0.090). CONCLUSIONS: There were no differences in 9-month luminal dimensions of the side branch between the Tryton Stent and Side Branch Balloon Angioplasty, as assessed with IVUS (MLA) and 3D QCA (MLD). Angiographic and ultrasound results of the main branch were not negatively influenced by the Tryton stent. © 2016 Wiley Periodicals, Inc.

Outcomes of a dedicated stent in coronary bifurcations with large side branches: A subanalysis of the randomized TRYTON bifurcation study.

OBJECTIVES: To examine the benefit of the Tryton dedicated side branch (SB) stent compared with provisional stenting in the treatment of complex bifurcation lesions involving large SBs. BACKGROUND: The TRYTON Trial was designed to evaluate the utility of a dedicated SB stent to treat true bifurcation lesions involving large (≥2.5 mm by visual estimation) SBs. Patient enrolled in the trial had smaller SB diameters than intended (59% SB ≤2.25 mm by Core Lab QCA). The TRYTON Trial did not meet its primary endpoint due to an increased rate of peri-procedural myocardial infarctions (MIs). METHODS: The TRYTON Trial randomized 704 patients to the Tryton SB stent with main vessel DES versus provisional SB treatment with main vessel DES. The rates of the primary end point of target vessel failure and the secondary powered end point of angiographic percent diameter stenosis in the SB at 9 months were assessed and compared between the two treatment strategies among patients with a SB ≥2.25 mm diameter at baseline determined by Core Lab QCA. RESULTS: Among the 704 patients enrolled in the TRYTON Trial, 289 patients (143 provisional and 146 Tryton stent; 41% of entire cohort) had a SB ≥2.25 mm. The primary end point of TVF was numerically lower in the Tryton group compared with the provisional group (11.3% vs. 15.6%, P = 0.38), and was within the non-inferiority margin. No difference among the rates of clinically driven target vessel revascularization (3.5% vs. 4.3% P = 0.77) or cardiac death (0% both groups) were seen. In-segment percent diameter stenosis of the SB was significantly lower in the Tryton group compared with the provisional group (30.4% vs. 40.6%, P = 0.004). CONCLUSIONS: Analysis of the TRYTON Trial cohort of SB ≥2.25 mm supports the safety and efficacy of the Tryton SB stent compared with a provisional stenting strategy in the treatment of bifurcation lesions involving large SBs. © 2015 Wiley Periodicals, Inc.

Optical coherence tomography versus intravascular ultrasound in the evaluation of observer variability and reliability in the assessment of stent deployment: the OCTIVUS study.

OBJECTIVES: To compare the variability in the assessment of coronary stents among interventional cardiologists (readers) using optical coherence tomography (OCT) and intravascular ultrasound (IVUS). BACKGROUND: IVUS is established and validated in the evaluation of coronary stent. For cardiologists without core lab expertise, the utility of IVUS is limited by image quality. OCT yields higher image resolution; however, the consistency with which these readers interpret OCT images has not been fully evaluated or compared with IVUS. METHODS: OCT and IVUS image sets (five pairs) obtained after stent placement were reviewed by readers with clinical experience in both modalities. Parameters assessed included stent expansion and symmetry, reference vessel and in-stent cross-sectional area (CSA) and diameter, and stent strut apposition as well as Multicenter Ultrasound Stenting in Coronaries criteria. These interpretations were compared with core lab readings and examined for interobserver variability. RESULTS: The interobserver variability for measurement of in-stent CSA was 1.34 mm(2) using IVUS compared with 0.85 mm(2) using OCT (P = 0.024). Variation in the deviation from core lab measurement of in-stent CSA for IVUS was 1.48 mm(2) compared with 0.87 mm(2) for OCT (P = 0.042). The interobserver agreement for obtaining the Multicenter Ultrasound Stenting in Coronaries criteria using IVUS was 80.4% compared with 81.1% using OCT (P = 0.78). Compared with the corelab measurement, the readers obtained an agreement of 72.7% using IVUS vs. 67.3% using OCT (P = 0.43). CONCLUSION: In the assessment of deployed coronary stents by practicing cardiologists, OCT images are interpreted more consistently compared with IVUS and can be used to assess stent deployment using IVUS-validated metrics.

Serial intravascular ultrasound analysis of complex bifurcation coronary lesions treated with the Tryton Bifurcation Stent in conjunction with an everolimus-eluting stent: IUVANT (Intravascular Ultrasound Evaluation of Tryton Stent) study.

OBJECTIVES: To characterize the treatment of complex bifurcation lesions (BL) with the Tryton Bifurcation Stent (TBS) paired with an everolimus-eluting stent (EES). BACKGROUND: Complex BL are associated with higher procedural complications and poorer long-term outcomes. The TBS is a dedicated side-branch (SB) stent designed to be used in conjunction with a standard drug-eluting stent. METHODS: Prospectively identified, consecutive patients underwent TBS+EES stenting of BL using a protocol which included TBS postdilation and simultaneous final kissing balloon inflations (FKBI). All lesions were systematically evaluated with coronary angiography and IVUS, obtained at procedure completion and at 9 months, and were assessed by independent core laboratories. RESULTS: Thirty-three BL were treated in 32 patients presenting primarily (87.5%) with stable angina and complex BL with angiographic apparent disease in the main vessel (MV) and SB in 87.9% and 75% by site and core evaluation, respectively. Procedural success was 100% and high postprocedure percent stent expansion (MV 96 [93, 109]%, SB 88 [77, 100]%, carina MV 135 [99, 166]%, carina SB 116 [91, 130]%) was demonstrated by IVUS. At 9-month angiographic follow-up (n = 28 patients), one MV in-segment restenosis and one SB in-stent restenosis were observed. SB in-stent late lumen loss was 0.41 ± 0.27 mm. IVUS assessment revealed the absence of stent recoil; percent carinal neointimal hyperplasia (NIH) was 1.8 [0.0,11.2]% in MV and 15.0 [6.7,23.5]% in SB, with NIH volume obstruction of 2.0 [0.7,4.3]% in MV and 14.2 [7.5,29.6]% in SB. CONCLUSIONS: Stenting of complex BL with the TBS+EES provides high acute success with sustained clinical, angiographic, and IVUS results at 9 months. These excellent results are likely due to the extent of stent expansion at the carina.

Funding of Studies Supporting IA Guideline Recommendations in Cardiovascular Medicine-A Systematic Review.

Each guideline recommendation from the American Heart Association and the American College of Cardiology includes an indication of the level of supporting evidence and the associated strength of recommendation with "IA" recommendations representing those with the highest quality supporting evidence and the least amount of uncertainty for benefit. In this analysis, study type and funding sources were systematically tabulated across these IA guideline recommendations over the past 5 years. Nearly half of studies supporting IA guideline recommendations were randomized controlled trials (45%). Overall, about one third of studies supporting IA recommendations were publicly funded (34.9%) with slightly more funded through industry sources (43.5%). Funding sources varied based on the type of intervention being studied with randomized controlled trials of device, diagnostic, and pharmacological interventions reflecting predominantly industry-funded studies. Over time, studies supporting IA cardiology guideline are funded by industry about twice as often as public sources. Thus, data of adequate quality to support cardiovascular guideline recommendations come from a variety of sources.

Preclinical Assessment of a Novel Conformable Foam-Based Left Atrial Appendage Closure Device.

BACKGROUND: Left atrial appendage (LAA) occlusion has been established as an alternative to systemic anticoagulation for stroke prevention in patients with atrial fibrillation; however, limitations of current devices have slowed adoption. We present preclinical evaluations of a novel device, the Conformal Left Atrial Appendage Seal (CLAAS). METHODS: An in vitro assessment of conformability was conducted to evaluate the two CLAAS devices (regular 27 mm and large 35 mm) and a Watchman 2.5 (27 mm). Devices were placed within silicone tubes and compressed in a vise submerged in a water bath at 37°C. Changes in device diameter and visual seal were noted. Acute (n = 1) and chronic 60-day (n = 6) canine studies with gross and histologic assessment were performed. RESULTS: Conformability bench tests demonstrated that the regular CLAAS implant was able to seal oval orifices from 20 × 30 mm to 15 × 33 mm and the large from 30 × 35 mm to 20 × 40 mm. As the CLAAS implant was compressed in the minor diameter, it increased in the major diameter, thereby filling the oval space, whereas the Watchman 2.5 showed gaps and maintained its round configuration when compressed in one direction. Seven devices were successfully implanted in the canine model with complete seal without thrombus. Histologic examination showed complete neointima covering with minimal inflammation at 60 days. CONCLUSIONS: Preclinical testing demonstrated the conformability of the CLAAS implant and its ability to seal the LAA. Clinical studies are ongoing to characterize the utility of the CLAAS implant in the treatment of patients with atrial fibrillation.

Conformal Left Atrial Appendage Seal Device for Left Atrial Appendage Closure: First Clinical Use.

OBJECTIVES: The authors report the first clinical experience with the Conformal Left Atrial Appendage Seal (CLAAS) device. BACKGROUND: The CLAAS device was designed to address the limitations of first-generation left atrial appendage closure (LAAC) devices by providing an implant that is minimally traumatic, can be deployed in a noncoaxial fashion, and does not require postprocedural oral anticoagulation. METHODS: Patients with atrial fibrillation at high stroke risk (CHA2DS2-VASc score ≥2) were recruited using standard selection criteria. The LAAC procedure was guided by transesophageal echocardiography with patients under general anesthesia. The CLAAS device is composed of a foam cup, with a Nitinol endoskeleton with an expanded polytetrafluoroethylene cover, delivered with a standard delivery system using a tether for full recapture. All patients received dual-antiplatelet therapy for 6 months, followed by aspirin alone. Transesophageal echocardiographic follow-up was scheduled for 45 days and 1 year. RESULTS: Twenty-two patients (63.7% with CHA2DS2-VASc scores ≥3, 76.2% with HAS-BLED scores ≥3) were enrolled. The device was successfully implanted in 18 patients and unsuccessfully in 4 patients. There were no serious procedural complications. On transesophageal echocardiography performed at 45 days, 1 significant leak (≥5 mm) was seen, which was due to a large posterior lobe not appreciated at the time of implantation, and 1 device-related thrombus was noted, which resolved on oral anticoagulation. There were no periprocedural strokes, major pericardial effusions, or systemic or device embolization. CONCLUSIONS: This first-in-human study demonstrates the clinical feasibility of the CLAAS device for LAAC.

Postmortem in situ micro-CT evaluation of coronary stent fracture.

UNLABELLED: Coronary stent fracture has been postulated as an important mechanism for in-stent restenosis and late-stent thrombosis. We have developed a nondestructive microcomputed tomography (micro-CT) technique to image en bloc stented arterial segments. CASE REPORT: A 43-year-old man died of sepsis 5 months following placement of a paclitaxel-eluting stent (PES) in the left circumflex coronary artery to treat in-stent restenosis of a sirolimus-eluting stent (SES). Micro-CT three-dimensional images of the overlapping stents were notable for numerous connecting element fractures along the length of the SES. No fractures were observed in the PES. The greatest area of luminal narrowing is related to the region of most extensive stent fracture. Micro-CT of en bloc specimens provides high resolution (16 µm), three-dimensional images allowing for visualization of the stented arterial segment in a nondestructive manner.

The impact of hematocrit drop on long-term survival after cardiac catheterization: insights from the Dartmouth Dynamic Registry.

BACKGROUND: The long-term prognostic implication of post-procedural hematocrit drops in patients undergoing cardiac catheterization outside the clinical trial setting is not well defined. METHODS: Data was prospectively collected from 12,661 patients undergoing diagnostic or interventional cardiac catheterization between July 1998 and July 2006. Patients were divided into three cohorts based upon the degree of hematocrit change: drop greater than 6, drop between 3 and 6, and drop less than 3. In-hospital major adverse events, 30-day mortality, and long-term all-cause mortality were recorded. RESULTS: Patients with larger reductions in hematocrit were more likely to be older, female, and have a higher baseline hematocrit, present with acute myocardial infarction, develop cardiogenic shock, require emergent catheterization, develop retroperitoneal bleeds and large hematomas, receive transfusions, have longer index hospitalizations, develop subacute stent thrombosis, and have higher 30-day and long-term mortality. An increase in long-term mortality was observed with progressive hematocrit drop. This finding is largely driven by early (30 day) mortality, as trends were no longer significant after rezeroing mortality. Hematocrit drop was not an independent risk factor for 30-day mortality. Transfusion and low baseline hematocrit were identified as independent predictors of near and long-term mortality. CONCLUSIONS: Periprocedural bleeding, defined by hematocrit drop, is associated with increased near-term and long-term mortality in patients undergoing diagnostic and therapeutic cardiac catheterization procedures. Long-term mortality is largely driven by up front 30-day mortality. Hematocrit drop was not an independent predictor for near-term mortality. Transfusion and low baseline hematocrit were independent predictors for near and long-term mortality.

Outcomes of diabetics receiving bare-metal stents versus drug-eluting stents.

OBJECTIVES: We sought to determine if differences existed in in-hospital outcomes, long-term rates of target vessel revascularization (TVR), and/or long-term mortality trends between patients with diabetes mellitus undergoing percutaneous coronary intervention (PCI) with either a drug-eluting stent(s) (DES) or a bare metal stent(s) (BMS). BACKGROUND: Short- and long-term clinical outcomes of patients with diabetes mellitus undergoing PCI with DES versus BMS remain inconsistent between randomized-controlled trials (RCTs) and observational studies. METHODS: Data were collected prospectively on diabetics undergoing PCI with either DES or BMS from January 2000 to June 2008. Demographic information, medical histories, in-hospital outcomes, and long-term TVR and mortality trends were obtained for all patients. RESULTS: A total of 1,319 patients were included in the study. Diabetics receiving DES had a significant reduction in index admission MACE compared to diabetics receiving BMS. Using multivariable adjustment, after a mean follow-up of 2.5 years (maximum 5 years), diabetics who received DES had a 38% decreased risk of TVR compared to diabetics with BMS [HR 0.62 (95% CI: 0.43-0.90)]; diabetics with DES had an insignificant adjusted improvement in long-term survival compared to diabetics with BMS [HR 0.72 (95% CI: 0.52-1.00)]. These long-term survival and TVR rates were confirmed using propensity scoring. CONCLUSIONS: The use of DES when compared with BMS among diabetics undergoing PCI is associated with significant improvement in long-term TVR, with an insignificant similar trend in all-cause mortality. The long-term results of this observational study are consistent with prior RCTs after adjusting for confounding variables.

Real world, long-term outcomes comparison between paclitaxel-eluting and sirolimus-eluting stent platforms.

We compare real-world, extended target vessel revascularization (TVR)-free survival following percutaneous coronary intervention (PCI) for patients receiving either sirolimus-eluting stents (SES) or paclitaxel-eluting stents (PES) following an index drug-eluting stent (DES) supported procedure. We analyzed 2,363 consecutive patients having first DES-supported PCI at receiving PES (n = 1,012) or SES (n = 1,332) from April 2004 to July 2006. Baseline clinical and procedural characteristics and in-hospital outcomes were recorded during the time of the index procedure and extended clinical outcomes data were obtained thereafter. TVR and all cause mortality were identified during the study period. Adjusted Kaplan-Meier and Cox's proportional hazard survival methods were performed. TVR-free survival at 2.3 years was 91.3% for SES compared with 88.9% for PES (P = 0.06). Kaplan-Meier survival curves did not significantly differ (adjusted hazard ratio -1.39 [95% CI 0.99-1.97]) between the SES and PES patient cohorts. TVR was similar between the stent platforms at one (96.6% for SES [95% CI 95.3-97.6] vs. 95.7% for PES [95% CI 94.1-96.9]) and two (95.0%[95% CI 93.0-96.4] for SES vs. 93.7% for PES [95% CI 91.6-95.3]) years. Overall survival at 2 years was 96.2% for SES (95% CI 94.7-97.3) and 95.3% for PES (95% CI 93.7-96.5). SES and PES drug-eluting stent platforms have good and similar extended outcomes in this real world registry of unselected patients having PCI.

Early Feasibility Studies for Cardiovascular Devices in the United States: JACC State-of-the-Art Review.

The development of technology to treat unmet clinical patient needs in the United States has been an important focus for the U.S. Food and Drug Administration and the 2016 Congressional 21st Century Cures Act. In response, a program of early feasibility studies (EFS) has been developed. One of the important issues has been the outmigration of the development and testing of medical devices from the United States. The EFS committee has developed and implemented processes to address issues to develop strategies for early treatment of these patient groups. Initial implementation of the U.S. Food and Drug Administration EFS program has been successful, but residual significant problems have hindered the opportunity to take full advantage of the program. These include delays in gaining Institutional Review Board approval, timeliness of budget and contractual negotiations, and lack of access to and enrollment of study subjects. This paper reviews improvements that have been made to the U.S. EFS ecosystem and outlines potential approaches to address remaining impediments to program success.

Redefining the Prognostic Value of High-Sensitivity Troponin in COVID-19 Patients: The Importance of Concomitant Coronary Artery Disease.

BACKGROUND: Although studies assessing cardiovascular comorbidities and myocardial injury in Coronavirus disease 2019 (COVID-19) patients have been published, no reports focused on clinical outcomes of myocardial injury in patients with and without chronic coronary syndromes (CCS) are currently available. METHODS: In this study, consecutive COVID-19 patients admitted to four different institutions were screened for enrolment. Patients were divided into two groups (CCS vs. no-CCS). Association with in-hospital mortality and related predictors represented the main study outcome; myocardial injury and its predictors were deemed secondary outcomes. RESULTS: A total of 674 COVID-19 patients were enrolled, 112 (16.6%) with an established history of CCS. Myocardial injury occurred in 43.8% patients with CCS vs. 14.4% patients without CCS, as confirmed by high-sensitivity cardiac troponin (hs-cTn) elevation on admission or during hospitalization. The mortality rate in the CCS cohort was nearly three-fold higher. After adjusting for disease severity, myocardial injury resulted significantly associated with in-hospital mortality in the no-CCS group but not in CCS patients. CONCLUSIONS: Patients with CCS and COVID-19 showed high mortality rate. Myocardial injury may be a bystander in CCS patients and COVID-19, while in patients without known history of CCS, myocardial injury has a significant role in predicting poor outcomes.

Assessment with optical coherence tomography of a new strategy for bifurcational lesion treatment: the Tryton Side-Branch Stent.

The Tryton-Side Branch Stent (Tryton Medical, Inc., Newton, MA, USA) is a dedicated stent designed to provide complete carinal coverage of bifurcational lesions. After implantation of a 18 mm cobalt chromium Tryton stent from the left circumflex into the obtuse marginal branch, recrossing with an everolimus eluting Promus stent and final kissing balloon dilatation, optical coherence tomography (OCT) (LightLab Imaging Inc., Westford, MA, USA) was performed with a non-occlusive technique with motorized pullback (3 mm/s) during continuous pump injection of iso-osmolar contrast, in both LCx and OM1. OCT imaging showed good strut apposition at the level of the carina, with full coverage and no stent protrusion at the ostium of the side branch. Few malapposed struts were present in the proximal main vessel in the segment of stent superimposition, with a maximal separation from to the vessel wall of 160 microm. The implantation of the Tryton-Side Branch Stent allowed full coverage of the side branch ostium with uniform apposition of the stent struts at the level of the carina assessed by OCT.

Classification and atherosclerosis distribution in patients with left main coronary disease.

OBJECTIVE: The purpose of this investigation was to characterize clinical variables and angiographic distribution of coronary atherosclerosis to classify patients with de novo left main (LM) disease in a real-world population presenting for coronary angiography. BACKGROUND: Limited quantitative and angiographic published data exist that provide detailed quantitative information to classify potential target population for elective LM percutaneous coronary intervention (PCI) and guide development of dedicated LM PCI platforms. METHODS: Medical history and clinical presentation were prospectively collected on 177 consecutive patients with LM stenosis > or =50% by coronary angiography. Blinded quantitative coronary angiography (QCA) was performed on all LM stenoses to classify LM-A (ostial), LM-B (nonostial, non-bifurcation), and LM-C (bifurcation involvement). QCA was performed on the left anterior descending (LAD), left circumflex (LCx), and right coronary arteries (RCA) and branches (> or =2.5 mm) to identify lesions with > or =60% stenosis or occlusion. RESULTS: No differences in baseline clinical history or presentation discriminated the distribution patterns of LM stenosis. QCA revealed 66% of LM stenoses were LM-C. Mean LM reference vessel diameter was 4.65 mm and average lesion length was 11.12 mm. Around 88.7% of patients had at least one lesion > or =60% in a major epicardial artery and 32.2% of patients had RCA chronic total occlusion. Right-to-left coronary collateralization was only identified in patients with obstructive stenosis in the LAD or LCx in addition to the LM stenosis. CONCLUSION: Dedicated LM stent platforms may need to be developed to accommodate larger vessel size and bifurcation distributions. A majority of patients with LM stenosis will require adjunctive epicardial vessel PCI to achieve complete anatomic revascularization.