QFR for the Revascularization of Nonculprit Vessels in MI Patients: Insights From the FIRE Trial.

BACKGROUND: The role of quantitative flow ratio (QFR) in the treatment of nonculprit vessels of patients with myocardial infarction (MI) is a topic of ongoing discussion. OBJECTIVES: This study aimed to investigate the predictive capability of QFR for adverse events and its noninferiority compared to wire-based functional assessment in nonculprit vessels of MI patients. METHODS: The FIRE (Functional Assessment in Elderly MI Patients With Multivessel Disease) trial randomized 1,445 older MI patients to culprit-only (n = 725) or physiology-guided complete revascularization (n = 720). In the culprit-only arm, angiographic projections of nonculprit vessels were prospectively collected, centrally reviewed for QFR computation, and associated with endpoints. In the complete revascularization arm, endpoints were compared between nonculprit vessels investigated with QFR or wire-based functional assessment. The primary endpoint was the vessel-oriented composite endpoint (VOCE) at 1 year. RESULTS: QFR was measured on 903 nonculprit vessels from 685 patients in the culprit-only arm. Overall, 366 (40.5%) nonculprit vessels showed a QFR value ≤0.80, with a significantly higher incidence of VOCEs (22.1% vs 7.1%; P < 0.001). QFR ≤0.80 emerged as an independent predictor of VOCEs (HR: 2.79; 95% CI: 1.64-4.75). In the complete arm, QFR was used in 320 (35.2%) nonculprit vessels to guide revascularization. When compared with propensity-matched nonculprit vessels in which treatment was guided by wire-based functional assessment, no significant difference was observed (HR: 0.57; 95% CI: 0.28-1.15) in VOCEs. CONCLUSIONS: This prespecified subanalysis of the FIRE trial provides evidence supporting the safety and efficacy of QFR-guided interventions for the treatment of nonculprit vessels in MI patients. (Functional Assessment in Elderly MI Patients With Multivessel Disease [FIRE]; NCT03772743).

Fractional flow reserve in patients with type 1 or type 2 non-ST elevation acute myocardial infarction.

AIMS: We assessed a combined strategy of fractional flow reserve (FFR) plus angiography in stratifying cardiovascular risk in patients with type 1 myocardial infarction (T1MI) or type 2 (T2MI) non-ST elevation acute myocardial infarction (NSTEMI). METHODS: A cohort of 150 NSTEMI patients were prospectively studied. Clinical and angiographic features guided the identification of T1MI vs T2MI and the treatment of culprit lesions. Subsequently, T1MI patients underwent FFR evaluation of nonculprit stenoses. In T2MI patients all angiographically significant stenoses were evaluated by FFR. FFR < 0.80 was an indication for revascularization. Based on FFR results, two groups were compared: patients with all lesions ≥0.80 ('defer' group, n = 87) and those with at least one lesion <0.80 ('perform' group, n = 63). The primary end point was the composite of all-cause death, nonfatal MI and unplanned coronary revascularization. RESULTS: Median clinical follow-up was of 35 months (interquartile range 14-44). Primary end-point rates in the 'defer' and 'perform' groups were 14.5% and 30.0% at 12 months and 28% and 46% at 36 months, respectively (log-rank test: at 1 year, P = 0.007; at the end of follow-up P = 0.014). On multivariable analysis, chronic kidney disease (HR 3.50, 95% CI: 1.89-6.46, P = 0.0001) and FFR group ('perform' vs 'defer': HR 1.75 95% CI: 1.01-3.04, P = 0.046) were independent predictors of adverse events. CONCLUSIONS: In NSTEMI patients, our results indicated that FFR combined with angiography allowed the treatment of nonfunctional significant lesions to be safely deferred and patient cardiovascular risk to be identified.

Cierre de la orejuela izquierda por ictus pese a la anticoagulación oral (ictus resistente): resultados del registro Amplatzer Cardiac Plug / Left atrial appendage occlusion for stroke despite oral anticoagulation (resistant stroke). Results from the Amplatzer Cardiac Plug registry

INTRODUCCIÓN Y OBJETIVOS: A pesar de la eficacia de los anticoagulantes orales (ACO), algunos pacientes mantienen una alto riesgo residual y presentan ictus aun estando en tratamiento con ACO, y falta evidencia sobre el tratamiento de estos pacientes. El objetivo del estudio es analizar la seguridad y la eficacia del cierre percutáneo de la orejuela izquierda (OI) como prevención secundaria para pacientes con fibrilación auricular no valvular que han experimentado un ictus/accidente isquémico transitorio a pesar de los ACO (ictus resistente [IR]). MÉTODOS: Se estudió a 1.047 pacientes consecutivos con fibrilación auricular no valvular sometidos a cierre percutáneo de la OI incluidos en el registro multicéntrico Amplatzer Cardiac Plug. Se seleccionó a los pacientes con IR como indicación para el cierre de la OI, y se los comparó con pacientes con otras indicaciones. RESULTADOS: En un total de 115 pacientes (11%) se produjo un IR. Las escalas CHA2DS2-VASc y HAS-BLED eran significativamente más altas en el grupo de IR (5,5+/-1,5 frente a 4,3+/-1,6; p <0,001 y 3,9+/-1,3 frente a 3,1+/-1,2; p <0,001). No hubo diferencias significativas en los eventos mayores de seguridad periprocedimiento (el 7,8 frente al 4,5%; p = 0,1). Tras 16,2+/-12,2 meses de seguimiento medio, la tasa anual de ictus/accidente isquémico transitorio observada fue del 2,6% (el 65% de reducción del riesgo) y la tasa anual de hemorragia mayor observada fue del 0% (el 100% de reducción del riesgo) en los pacientes con IR. CONCLUSIONES: Los pacientes con IR sometidos a cierre percutáneo de la OI presentaron resultados de seguridad similares que los pacientes sin IR, con una reducción significativa de los eventos de ictus/accidente isquémico transitorio y hemorragia mayor durante el seguimiento

INTRODUCTION AND OBJECTIVES: Despite the efficacy of oral anticoagulant (OAC) therapy, some patients continue to have a high residual risk and develop a stroke on OAC therapy (resistant stroke [RS]), and there is a lack of evidence on the management of these patients. The aim of this study was to analyze the safety and efficacy of left atrial appendage occlusion (LAAO) as secondary prevention in patients with nonvalvular atrial fibrillation who have experienced a stroke/transient ischemic attack despite OAC treatment. METHODS: We analyzed data from the Amplatzer Cardiac Plug multicenter registry on 1047 consecutive patients with nonvalvular atrial fibrillation undergoing LAAO. Patientes with previous stroke on OAC therapy as indication for LAAO were identified and compared with patients with other indications. RESULTS: A total of 115 patients (11%) with RS were identified. The CHA2DS2-VASc and the HAS-BLED score were significantly higher in the RS group (respectively 5.5+/-1.5 vs 4.3+/-1.6; P <.001; 3.9+/-1.3 vs 3.1+/-1.2; P <.001). No significant differences were observed in periprocedural major safety events (7.8 vs 4.5%; P=.1). With a mean clinical follow-up of 16.2+/-12.2 months, the observed annual stroke/transient ischemic attack rate for the RS group was 2.6% (65% risk reduction) and the observed annual major bleeding rate was 0% (100% risk reduction). CONCLUSIONS: Patients with RS undergoing LAAO showed similar safety outcomes to patients without RS, with a significant reduction in stroke/transient ischemic attack and major bleeding events during follow-up. Adequately powered controlled trials are needed to further investigate the use of LAAO in RS patients

Left atrial appendage occlusion for stroke despite oral anticoagulation (resistant stroke). Results from the Amplatzer Cardiac Plug registry.

INTRODUCTION AND OBJECTIVES: Despite the efficacy of oral anticoagulant (OAC) therapy, some patients continue to have a high residual risk and develop a stroke on OAC therapy (resistant stroke [RS]), and there is a lack of evidence on the management of these patients. The aim of this study was to analyze the safety and efficacy of left atrial appendage occlusion (LAAO) as secondary prevention in patients with nonvalvular atrial fibrillation who have experienced a stroke/transient ischemic attack despite OAC treatment. METHODS: We analyzed data from the Amplatzer Cardiac Plug multicenter registry on 1047 consecutive patients with nonvalvular atrial fibrillation undergoing LAAO. Patientes with previous stroke on OAC therapy as indication for LAAO were identified and compared with patients with other indications. RESULTS: A total of 115 patients (11%) with RS were identified. The CHA2DS2-VASc and the HAS-BLED score were significantly higher in the RS group (respectively 5.5±1.5 vs 4.3±1.6; P <.001; 3.9±1.3 vs 3.1±1.2; P <.001). No significant differences were observed in periprocedural major safety events (7.8 vs 4.5%; P=.1). With a mean clinical follow-up of 16.2±12.2 months, the observed annual stroke/transient ischemic attack rate for the RS group was 2.6% (65% risk reduction) and the observed annual major bleeding rate was 0% (100% risk reduction). CONCLUSIONS: Patients with RS undergoing LAAO showed similar safety outcomes to patients without RS, with a significant reduction in stroke/transient ischemic attack and major bleeding events during follow-up. Adequately powered controlled trials are needed to further investigate the use of LAAO in RS patients.

Simultaneous Functional and Morphological Assessment of Left Atrial Appendage by 3D Virtual Models.

Purpose: The left atrial appendage (LAA) is responsible for thrombus formation in patients with atrial fibrillation. The evaluation of both LAA function and morphology is crucial for the patient characterization and the preprocedural planning of LAA closure intervention. Despite the availability of 3D imaging modalities, the current standard image analysis is based on manual delineation of the LAA contours on 2D views. Methods: In this study, a comprehensive approach based on a full 3D analysis of the tomographic dataset by surface extraction and processing (3D-S) is presented. The proposed method allows extracting functional and morphologic information in the entire cardiac cycle by minimalizing manual user interaction. The proposed methodology has been validated on ten computer tomography datasets. Results: The proposed 3D-S method was feasible in all cases. Reproducibility was improved with respect to the reference 2D manual procedure (2D-S) (coefficient of variation 2.9 vs. 4.1% for diastolic ostium area; 3.8 vs. 6.1% for systolic ostium area; 2.4 vs. 5.3% for diastolic LAA volume; 2.7 vs. 5.9% for systolic LAA volume; and 7.7 vs. 17.1% for LAA ejection fraction). No significant differences were found between 2D-S and 3D-S measurements. Conclusions: In this study, we introduced a fully 3D approach for LAA characterization, allowing the simultaneous assessment of LAA function and geometry. The proposed approach could be used to improve the patient selection and the best sizing of the device for LAA closure and to allow a patient-specific 3D printing.

Intracardiac Versus Transesophageal Echocardiographic Guidance for Left Atrial Appendage Occlusion: The LAAO Italian Multicenter Registry.

OBJECTIVES: This study sought to evaluate the feasibility, safety, and efficacy of intracardiac echocardiography (ICE)-guided versus transesophageal echocardiography (TEE)-guided left atrial appendage occlusion (LAAO) by the use of Amplatzer Cardiac Plug or Amulet devices included in a large Italian registry. BACKGROUND: TEE is widely used for LAAO procedure guidance. ICE may be a potential alternative imaging modality in LAAO. METHODS: Data from 604 LAAO procedures performed in 16 Italian centers were reviewed. ICE-guided LAAO was performed in 187 patients, whereas TEE was used in 417 patients. Procedural success was defined as LAAO without occurrence of pericardial tamponade, stroke, systemic embolism with end organ damage, major bleeding, and device embolization. Stroke, transient ischemic attack, major bleeding, overall and cardiovascular death were analyzed. RESULTS: CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke or transient ischemic attack or thromboembolism, vascular disease, age 65 to 74 years, sex category) and HAS-BLED (hypertension, abnormal renal and liver function, stroke, bleeding, labile international normalized ratio, elderly, drugs or alcohol) scores were similar between the ICE and TEE groups. TEE implied lower procedural (delta 12 min) and fluoroscopy time (delta 5 min) when compared with ICE. Procedural success was similarly high (≥94%) between the TEE and ICE groups with a complication rate of 6.5% for TEE versus 4.2% for ICE (odds ratio: 1.468; 95% confidence interval: 0.681 to 3.166; p = 0.327). At median follow-up of 451 days (interquartile range: 162 to 899 days), the rate of cerebral ischemic events was similar between TEE-guided and ICE-guided procedures. CONCLUSIONS: ICE-guided LAAO by means of Amplatzer devices may represent a second alternative imaging modality after an appropriate learning curve and bearing in mind that pre-procedural computed tomography imaging is mandatory. When comparing ICE with TEE, TEE remains the gold standard.

Left atrial appendage closure using AMPLATZER™ devices: A large, multicenter, Italian registry.

BACKGROUND: Left atrial appendage occlusion (LAAO) has been proven to be effective for stroke prophylaxis in patients with non-valvular atrial fibrillation (NVAF). We aim to assess the safety and efficacy of LAAO by AMPLATZER™ devices in a large, multicenter, single-nation cohort of NVAF patients at high-risk of stroke and bleeding. METHODS: From December 2008 to April 2015 613 NVAF patients (75.1±8.0years, 62.5% male) underwent LAAO in 15 Italian centers by AMPLATZER™ devices. There were no restrictions on any personal/institutional protocols with respect to indications, pre-procedural planning, device implantation, drug therapy and follow-up. All the baseline characteristics, imaging, procedural and follow-up data were collected in a single dataset. RESULTS: AMPLATZER™ devices were successfully implanted in 95.4% of cases. Major complications occurred during 38 procedures (6.2%) and included more frequently major bleeding (3.3%) and pericardial tamponade (2.0%). At a mean follow-up of 20months, the overall annual rates of stroke and thromboembolic events, including those periprocedural, was 1.67% and 2.90%, respectively, consisting in a reduction in the rate of stroke and TIA of 66% compared with the risk-based expectation. Among the 218 patients undergoing transesophageal echocardiography at 6months of follow-up, device thrombosis was present in 1.8% of the patients whilst a significant or mild to moderate peri-device leak was found in 0.5% and 11.9% of cases, respectively. CONCLUSIONS: In this large, multicenter, single-nation study, LAAO with the AMPLATZER™ devices showed high procedural success, early safety and mid-term efficacy for the prevention of NVAF-related thromboembolism.

Characterization of Cerebrovascular Events After Left Atrial Appendage Occlusion.

Cardioembolic strokes are generally more lethal and disabling than other source of strokes. Data from PROTECT AF (Watchman Left Atrial Appendage Closure Technology for Embolic Protection in Patients With Atrial Fibrillation) suggest that strokes after left atrial appendage occlusion (LAAO) with the Watchman device are less disabling than those in the warfarin group. No data assessing the severity of strokes after LAAO with the AMPLATZER Cardiac Plug (ACP) are available. The objective of the study was to evaluate the severity of cerebrovascular events after LAAO with the ACP in a population mostly characterized by an absolute or relative contraindication to oral anticoagulation. Data from the ACP multicenter registry were analyzed. Disabling strokes were defined as those with a modified Rankin score of 3 to 6 at 90 days after the event. A total of 1,047 subjects were included. The mean age and CHADS2 score were 75 ± 8 years and 2.8 ± 1.3, respectively. Procedural success was achieved in 97.3% and 4.9% of the patients presented procedural major adverse events. Clinical follow-up was complete in 98.2% of patients with a median of 13 months. There were 9 strokes (0.9%), 9 transient ischemic attacks (0.9%), and no intracranial hemorrhages (0%) at follow-up. After excluding 2 patients with pre-LAAO disability, functional assessment showed disabling events in 3 (19%) of the remaining 16 patients. The median time of presentation was 420 days (interquartile range 234 to 671) after LAAO, and 17 patients (94%) were on single-antiplatelet therapy when the event occurred. According to our results, cerebrovascular events after LAAO with the ACP system were infrequent and mostly nondisabling.

Left atrial appendage occlusion in high-risk patients with non-valvular atrial fibrillation.

OBJECTIVE: Percutaneous left atrial appendage (LAA) occlusion has been developed as a viable option for stroke and thromboembolism prevention in patients with non-valvular atrial fibrillation (NVAF) and at high risk for cerebral cardioembolic events. Data on device implantation and long-term follow-up from large cohorts are limited. METHODS: 110 consecutive patients with NVAF and contraindications to oral anticoagulants (OACs) underwent LAA occlusion procedures and achieved a longer than 1 year follow-up. All patients were enrolled in a prospective registry. Procedures were performed using the Amplatzer Cardiac Plug or Amulet guided by fluoroscopy and intracardiac echocardiography. RESULTS: Mean age of the population was 77±6 years old; 68 were men. Atrial fibrillation was paroxysmal in 20%, persistent in 15.5% and permanent in 64.5% of cases, respectively. Mean CHA2DS2-VASc and HAS-BLED scores were 4.3±1.3 and 3.4±1, respectively. Technical success (successful deployment and implantation of device) was achieved in 100% of procedures. Procedural success (technical success without major procedure-related complications) was achieved in 96.4%, with a 3.6% rate of major procedural complications (three cases of pericardial tamponade requiring drainage and one case of major bleeding). Mean follow-up was 30±12 months (264 patient-years). Annual rates for ischaemic stroke and for other thromboembolic events were respectively 2.2% and 0%, and annual rate for major bleeding was 1.1%. CONCLUSIONS: Our data suggest LAA occlusion in high-risk patients with NVAF not suitable for OACs is feasible and associated with low complication rates as well as low rates of stroke and major bleeding at long-term follow-up.

Comparison of Efficacy and Safety of Left Atrial Appendage Occlusion in Patients Aged <75 to ≥ 75 Years.

Left atrial appendage occlusion (LAAO) is emerging as a promising alternative to oral anticoagulation. Because aged patients present a greater risk of not only cardioembolic events but also major bleeding, LAAO might represent a valid alternative as this would allow oral anticoagulation cessation while keeping cardioembolic protection. The objective of the study was to explore the safety and efficacy of LAAO in elderly patients. Data from the AMPLATZER Cardiac Plug multicenter registry were analyzed. The cohort was categorized in 2 groups (<75 vs ≥ 75 years). A total of 1,053 subjects were included in the registry. Of them, 219 were excluded because of combined procedures. As a result, 828 subjects were included (54.6% ≥ 75 years). Procedural success was high and similar in both groups (97.3%). Acute procedural major adverse events were not statistically different among groups (3.2% in <75 years vs 5.1%; p = 0.17) although stratified analysis showed a higher incidence of cardiac tamponade in elderly patients (0.5% vs 2.2%; p = 0.04). With a median follow-up of 16.8 months, no significant differences in stroke/TIA (1.9% vs 2.3%; p = 0.89) and major bleeding (1.7% vs 2.6%; p = 0.54) were observed. In conclusion, LAAO was associated with similar procedural success in patients aged <75 and ≥ 75 years although older patients had a higher incidence of cardiac tamponade. At follow-up, stroke and major bleeding rates were similar among groups.

Left atrial appendage occlusion for stroke prevention in atrial fibrillation: multicentre experience with the AMPLATZER Cardiac Plug.

AIMS: To investigate the safety, feasibility, and efficacy of left atrial appendage occlusion (LAAO) with the AMPLATZER Cardiac Plug (ACP) for stroke prevention in patients with atrial fibrillation (AF). METHODS AND RESULTS: Data from consecutive patients treated in 22 centres were collected. A total of 1,047 patients were included in the study. Procedural success was 97.3%. There were 52 (4.97%) periprocedural major adverse events. Follow-up was complete in 1,001/1,019 (98.2%) of successfully implanted patients (average 13 months, total 1,349 patient-years). One-year all-cause mortality was 4.2%. No death at follow-up was reported as device-related. There were nine strokes (0.9%) and nine transient ischaemic attacks (0.9%) during follow-up. The annual rate of systemic thromboembolism was 2.3% (31/1,349 patient-years), which is a 59% risk reduction. There were 15 major bleedings (1.5%) during follow-up. The annual rate of major bleeding was 2.1% (28/1,349 patient-years), which is a 61% risk reduction. Patients with single LAAO on aspirin monotherapy or no therapy and longer follow-up had fewer cerebral and fewer bleeding events. CONCLUSIONS: In this multicentre study, LAAO with the ACP showed high procedural success and a favourable outcome for the prevention of AF-related thromboembolism. Modification in antithrombotic therapy after LAAO may result in reduction of bleeding events.

Percutaneous left atrial appendage occlusion in patients with non-valvular atrial fibrillation: implantation and up to four years follow-up of the AMPLATZER Cardiac Plug.

AIMS: Percutaneous left atrial appendage occlusion (LAAO) may be considered for stroke prophylaxis in patients with non-valvular atrial fibrillation (NVAF). Data on device implantation safety and feasibility and long-term follow-up are limited. METHODS AND RESULTS: LAAO was performed using the AMPLATZER Cardiac Plug (ACP) device in 134 NVAF patients with long-term OAC contraindication, with median (interquartile range) CHA2DS2-VASc and HAS-BLED scores of four (3-5) and three (2-3.75), respectively. Follow-up data were collected over a mean follow-up period of 680 days (range: 42 days to 4.3 years) comprising a total implant experience of 238 patient-years. Device implantation was successful in 95.5% of the procedures and associated with a rate of major procedural complications of 2.2%. At the most recent follow-up, almost all patients were receiving antiplatelet therapy. Ischaemic stroke was observed at an annual rate of 0.8% and the annual rate of any thromboembolic (TE) event was 2.5%. Major bleeding during follow-up occurred at an annual rate of 1.3%. CONCLUSIONS: LAAO is a safe and effective stroke prevention therapy in a high-risk NVAF cohort, both at implantation and over longer follow-up periods. The long-term assessed ischaemic stroke rate in patients treated with LAAO is markedly reduced compared to the expected rate based on the patients' risk scores.

Multimodality imaging in preoperative assessment of left atrial appendage transcatheter occlusion with the Amplatzer Cardiac Plug.

AIMS: Percutaneous left atrial appendage occlusion (LAAO) with the Amplatzer Cardiac Plug (ACP) emerged as a valid alternative in patients with a formal contraindication to oral anticoagulant therapy. Transoesophageal echocardiography (TEE), cardiac computed tomography angiography (CCTA), intracardiac echocardiography (ICE), and conventional cardiac angiography (CCA) are used to evaluate LAA diameters. The aim of our study was to compare pre- and intraprocedural imaging techniques in determining the correct selection of the device size, with a retrospective evaluation of the results obtained at post-procedural CCTA follow-up. METHODS AND RESULTS: Between September 2009 and July 2013, 66 consecutive patients underwent to LAAO with the ACP at our institution. Preoperative LAA evaluation was realized with TEE, CCTA, ICE, and CCA. Fifty-eight (58) patients underwent to post-procedural CCTA to confirm the LAA complete exclusion, the number and extent of the residual leaks, and the positioning of the device. LAA diameters measured by CCTA correlate with the diameters obtained with CCA and ICE, but they are sized slightly larger than the others. TEE has a lower correlation with every other imaging method and a likely tendency to underestimate. The distribution of the leaks and the positioning of the device in post-procedural CCTA show no substantial differences between the devices used greater or equal to the one selected with CCTA in terms of LAA exclusion. CONCLUSION: The sizing of the device decided using CCTA in the phase of maximum LAA expansion reduces the risk of high-flow leaks and device malposition due to undersizing.

Periprocedural intracardiac echocardiography for left atrial appendage closure: a dual-center experience.

OBJECTIVES: This dual-center study sought to demonstrate the utility and safety of intracardiac echocardiography (ICE) in providing adequate imaging guidance as an alternative to transesophageal echocardiography (TEE) during Amplatzer Cardiac Plug device implantation. BACKGROUND: Over 90% of intracardiac thrombi in atrial fibrillation originate from the left atrial appendage (LAA). Patients with contraindications to anticoagulation are potential candidates for LAA percutaneous occlusion. TEE is typically used to guide implantation. METHODS: ICE-guided percutaneous LAA closure was performed in 121 patients to evaluate the following tasks typically achieved by TEE: assessment of the LAA dimension for device sizing; guidance of transseptal puncture; verification of the delivery sheath position; confirmation of location and stability of the device before and after release and continuous monitoring to detect procedural complications. In 51 consecutive patients, we compared the measurements obtained by ICE and fluoroscopy to choose the size of the device. RESULTS: The device was successfully implanted in 117 patients, yielding a technical success rate of 96.7%. Procedural success was achieved in 113 cases (93.4%). Four major adverse events (3 cardiac tamponades and 1 in-hospital transient ischemic attack) occurred. There was significant correlation in the measurements for device sizing assessed by angiography and ICE (r = 0.94, p < 0.0001). CONCLUSIONS: ICE imaging was able to perform the tasks typically provided by TEE during implantation of the Amplatzer Cardiac Plug device for LAA occlusion. Therefore, we provide evidence that the use of ICE offered accurate measurements of LAA dimension in order to select the correct device sizes.