Impact of acute coronary syndrome on clinical outcomes after revascularization with the dual-therapy CD34 antibody-covered sirolimus-eluting Combo stent and the sirolimus-eluting Orsiro stent.

OBJECTIVES: To compare the efficacy and safety of the dual-therapy CD34 antibody-covered sirolimus-eluting Combo stent (DTS) and the sirolimus-eluting Orsiro stent (O-SES) in patients with and without acute coronary syndrome (ACS) included in the SORT OUT X study. BACKGROUND: The incidence of target lesion failure (TLF) after treatment with modern drug-eluting stents has been reported to be significantly higher in patients with ACS when compared to patients without ACS. Whether the results from the SORT OUT X study apply to patients with and without ACS remains unknown. METHODS: In total, 3146 patients were randomized to stent implantation with DTS (n = 1578; ACS: n = 856) or O-SES (n = 1568; ACS: n = 854). The primary end point, TLF, was a composite of cardiac death, target-lesion myocardial infarction (MI), or target lesion revascularization (TLR) within 1 year. RESULTS: At 1 year, the rate of TLF was higher in the DTS group compared to the O-SES group, both among patients with ACS (6.7% vs. 4.1%; incidence rate ratio: 1.65 [95% confidence interval, CI: 1.08-2.52]) and without ACS (6.0% vs. 3.2%; incidence rate ratio: 1.88 [95% CI: 1.13-3.14]). The differences were mainly explained by higher rates of TLR, whereas rates of cardiac death and target lesion MI did not differ significantly between the two stent groups in patients with or without ACS CONCLUSION: Compared to the O-SES, the DTS was associated with a higher risk of TLF at 12 months in patients with and without ACS. The differences were mainly explained by higher rates of TLR.

Randomized Clinical Comparison of the Dual-Therapy CD34 Antibody-Covered Sirolimus-Eluting Combo Stent With the Sirolimus-Eluting Orsiro Stent in Patients Treated With Percutaneous Coronary Intervention: The SORT OUT X Trial.

BACKGROUND: Target lesion failure remains an issue with contemporary drug-eluting stents. Thus, the dual-therapy sirolimus-eluting and CD34+ antibody-coated Combo stent (DTS) was designed to further improve early healing. This study aimed to investigate whether the DTS is noninferior to the sirolimus-eluting Orsiro stent (SES) in an all-comers patient population. METHODS: The SORT OUT X (Combo Stent Versus Orsiro Stent) trial, was a large-scale, randomized, multicenter, single-blind, 2-arm, noninferiority trial with registry-based follow-up. The primary end point target lesion failure was a composite of cardiac death, myocardial infarction, or target lesion revascularization within 12 months, analyzed using intention-to-treat. The trial was powered for assessing target lesion failure noninferiority of the DTS compared with the SES with a predetermined noninferiority margin of 0.021. RESULTS: A total of 3146 patients were randomized to treatment with the DTS (1578 patients; 2008 lesions) or SES (1568 patients; 1982 lesions). At 12 months, intention-to-treat analysis showed that 100 patients (6.3%) assigned the DTS and 58 patients (3.7%) assigned the SES met the primary end point (absolute risk difference, 2.6% [upper limit of 1-sided 95% CI, 4.1%]; P (noninferiority)=0.76). The SES was superior to the DTS (incidence rate ratios for target lesion failure, 1.74 [95% CI, 1.26-2.41]; P=0.00086). The difference was explained mainly by a higher incidence of target lesion revascularization in the DTS group compared with the SES group (53 [3.4%] vs. 24 [1.5%]; incidence rate ratio, 2.22 [95% CI, 1.37-3.61]; P=0.0012). CONCLUSIONS: The DTS did not confirm noninferiority to the SES for target lesion failure at 12 months in an all-comer population. The SES was superior to the DTS mainly because the DTS was associated with an increased risk of target lesion revascularization. However, rates of death, cardiac death, and myocardial infarction at 12 months did not differ significantly between the 2 stent groups. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03216733.

Impact of diabetes on clinical outcomes after revascularization with the dual therapy CD34 antibody-covered sirolimus-eluting Combo stent and the sirolimus-eluting Orsiro stent.

OBJECTIVES: To compare the efficacy and safety of the dual therapy CD34 antibody-covered sirolimus-eluting Combo stent (DTS) and the sirolimus-eluting Orsiro stent (SES) in patients with and without diabetes mellitus (DM) included in the Scandinavian Organization for Randomized Trials with Clinical Outcome (SORT OUT) X study. BACKGROUND: The incidence of target lesion failure (TLF) after treatment with modern drug-eluting stents has been reported to be significantly higher in patients with DM when compared to patients without DM. Thus, whether the results from the SORT OUT X study apply to patients with and without DM remains unknown. METHODS: In total 3146 patients were randomized to stent implantation with DTS (n = 1578; DM: n = 279) or SES (n = 1568; DM: n = 271). The primary end point, TLF, was a composite of cardiac death, target-lesion myocardial infarction (MI), or target lesion revascularization (TLR) within 1 year. RESULTS: At 1 year, the rate of TLF was increased in the DTS group compared to the SES group, both among patients with DM (9.3% vs. 4.8%; risk difference: 4.5%; incidence rate ratio: 1.99, 95% confidence interval [CI]: 1.02-3.90) and without DM (5.7% vs. 3.5%; incidence rate ratio: 1.67, 95% CI: 1.15-2.42). The differences were mainly explained by higher rates of TLR. CONCLUSION: Compared to the SES, the DTS was associated with an increased risk of TLF at 12 months in patients with and without DM. The differences were mainly explained by higher rates of TLR, whereas rates of cardiac death and target lesion MI did not differ significantly between the two stent groups in patients with or without DM.

Translation of experimental cardioprotective capability of P2Y12 inhibitors into clinical outcome in patients with ST-elevation myocardial infarction.

We studied the translational cardioprotective potential of P2Y12 inhibitors against acute myocardial ischemia/reperfusion injury (IRI) in an animal model of acute myocardial infarction and in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). P2Y12 inhibitors may have pleiotropic effects to induce cardioprotection against acute myocardial IRI beyond their inhibitory effects on platelet aggregation. We compared the cardioprotective effects of clopidogrel, prasugrel, and ticagrelor on infarct size in an in vivo rat model of acute myocardial IRI, and investigated the effects of the P2Y12 inhibitors on enzymatic infarct size (48-h area-under-the-curve (AUC) troponin T release) and clinical outcomes in a retrospective study of STEMI patients from the CONDI-2/ERIC-PPCI trial using propensity score analyses. Loading with ticagrelor in rats reduced infarct size after acute myocardial IRI compared to controls (37 ± 11% vs 52 ± 8%, p < 0.01), whereas clopidogrel and prasugrel did not (50 ± 11%, p > 0.99 and 49 ± 9%, p > 0.99, respectively). Correspondingly, troponin release was reduced in STEMI patients treated with ticagrelor compared to clopidogrel (adjusted 48-h AUC ratio: 0.67, 95% CI 0.47-0.94). Compared to clopidogrel, the composite endpoint of cardiac death or hospitalization for heart failure within 12 months was reduced in STEMI patients loaded with ticagrelor (HR 0.63; 95% CI 0.42-0.94) but not prasugrel (HR 0.84, 95% CI 0.43-1.63), prior to PPCI. Major adverse cardiovascular events did not differ between clopidogrel, ticagrelor, or prasugrel. The cardioprotective effects of ticagrelor in reducing infarct size may contribute to the clinical benefit observed in STEMI patients undergoing PPCI.

Impact of hyperglycemia on myocardial ischemia-reperfusion susceptibility and ischemic preconditioning in hearts from rats with type 2 diabetes.

BACKGROUND: The mechanisms underlying increased mortality in patients with diabetes and admission hyperglycemia after an acute coronary syndrome may involve reduced capacity for cardioprotection. We investigated the impact of hyperglycemia on exogenously activated cardioprotection by ischemic preconditioning (IPC) in hearts from rats with type 2 diabetes mellitus (T2DM) that were endogenously cardioprotected by an inherent mechanism, and the involvement of myocardial glucose uptake (MGU) and myocardial O-linked ß-N-acetylglucosamine (O-GlcNAc). METHODS AND RESULTS: In isolated, perfused rat hearts subjected to ischemia-reperfusion, infarct size (IS) was overall larger during hyper- ([Glucose] = 22 mmol/L]) than normoglycemia ([Glucose] = 11 mmol/L]) (p < 0.001). IS was smaller in 12-week old Zucker diabetic fatty rats with recent onset T2DM (fa/fa) than in rats without T2DM (fa/+) (n = 8 in each group) both during hyperglycemia (p < 0.05) and normoglycemia (p < 0.05). IPC (2 × 5 min cycles) reduced IS during normo- (p < 0.01 for both groups) but not during hyperglycemia independently of the presence of T2DM. During hyperglycemia, an intensified IPC stimulus (4 × 5 min cycles) reduced IS only in hearts from animals with T2DM (p < 0.05). IPC increased MGU and O-GlcNAc levels during reperfusion in animals with and without T2DM at normoglycemia (MGU: p < 0.05, O-GlcNAc: p < 0.01 for both groups) but not during hyperglycemia. Intensified IPC at hyperglycemia increased MGU (p < 0.05) and O-GlcNAc levels (p < 0.05) only in hearts from animals with T2DM. CONCLUSION: While the effect of IPC is reduced during hyperglycemia in rats without T2DM, endogenous cardioprotection in animals with T2DM is not influenced by hyperglycemia and the capacity for exogenous cardioprotection by IPC is preserved. MGU and O-GlcNAc levels are increased by exogenously induced cardioprotection by IPC but not by endogenous cardioprotection in animals with T2DM reflecting different underlying mechanisms by exogenous and endogenous cardioprotection.

The Role of O-GlcNAcylation for Protection against Ischemia-Reperfusion Injury.

Ischemia reperfusion injury (IR injury) associated with ischemic heart disease contributes significantly to morbidity and mortality. O-linked ß-N-acetylglucosamine (O-GlcNAc) is a dynamic posttranslational modification that plays an important role in numerous biological processes, both in normal cell functions and disease. O-GlcNAc increases in response to stress. This increase mediates stress tolerance and cell survival, and is protective. Increasing O-GlcNAc is protective against IR injury. Experimental cellular and animal models, and also human studies, have demonstrated that protection against IR injury by ischemic preconditioning, and the more clinically applicable remote ischemic preconditioning, is associated with increases in O-GlcNAc levels. In this review we discuss how the principal mechanisms underlying tissue protection against IR injury and the associated immediate elevation of O-GlcNAc may involve attenuation of calcium overload, attenuation of mitochondrial permeability transition pore opening, reduction of endoplasmic reticulum stress, modification of inflammatory and heat shock responses, and interference with established cardioprotective pathways. O-GlcNAcylation seems to be an inherent adaptive cytoprotective response to IR injury that is activated by mechanical conditioning strategies.

Effects of hypoglycemia on myocardial susceptibility to ischemia-reperfusion injury and preconditioning in hearts from rats with and without type 2 diabetes.

BACKGROUND: Hypoglycemia is associated with increased mortality rate in patients with diabetes. The underlying mechanisms may involve reduced myocardial tolerance to ischemia and reperfusion (IR) or reduced capacity for ischemic preconditioning (IPC). As IPC is associated with increased myocardial glucose uptake (MGU) during reperfusion, cardioprotection is linked to glucose metabolism possibly by O-linked ß-N-acetylglucosamine (O-GlcNAc). We aimed to investigate the impact of hypoglycemia in hearts from animals with diabetes on myocardial IR tolerance, on the efficacy of IPC and whether modulations of MGU and O-GlcNAc levels are involved in the underlying mechanisms. METHODS: In a Langendorff model using diabetic ZDF (fa/fa) and non-diabetic (fa/+) rats (n = 6-7 in each group) infarct size (IS) was evaluated after 40 min of global ischemia and 120 min reperfusion during hypoglycemia [(glucose) = 3 mmol/l] and normoglycemia [(glucose) = 11 mmol/l]. Myocardial glucose uptake and O-GlcNAc levels were evaluated during reperfusion. IPC was induced by 2 × 5 min of global ischemia prior to index ischemia. RESULTS: IS increased in hearts from animals with (p < 0.01) and without (p < 0.01) diabetes during hypoglycemia compared to normoglycemia. IPC reduced IS during normoglycemia in both animals with (p < 0.01) and without (p < 0.01) diabetes. During hypoglycemia, however, IPC only reduced IS in hearts from animals with diabetes (p < 0.05). IPC increased MGU during reperfusion and O-GlcNAc levels in animals with diabetes during hypo- (MGU: p < 0.05, O-GlcNAc: p < 0.05) and normoglycemia (MGU: p < 0.01, O-GlcNAc: p < 0.05) and in animals without diabetes only during normoglycemia (MGU: p < 0.05, O-GlcNAc: p < 0.01). CONCLUSIONS: Hypoglycemia increases myocardial susceptibility to IR injury in hearts from animals with and without diabetes. In contrast to hearts from animals without diabetes, the hearts from animals with diabetes are amenable to cardioprotection during hypoglycemia. In parallel with IPC induced cardioprotection, MGU and O-GlcNAc levels increase suggesting that increased MGU and O-GlcNAc levels are involved in the mechanisms of IPC.

Short-Chain Fatty Acid Butyrate Is an Inotropic Agent With Vasorelaxant and Cardioprotective Properties.

BACKGROUND: The heart can metabolize the microbiota-derived short-chain fatty acid butyrate. Butyrate may have beneficial effects in heart failure, but the underlying mechanisms are unknown. We tested the hypothesis that butyrate elevates cardiac output by mechanisms involving direct stimulation of cardiac contractility and vasorelaxation in rats. METHODS AND RESULTS: We examined the effects of butyrate on (1) in vivo hemodynamics using parallel echocardiographic and invasive blood pressure measurements, (2) isolated perfused hearts in Langendorff systems under physiological conditions and after ischemia and reperfusion, and (3) isolated coronary arteries mounted in isometric wire myographs. We tested Na-butyrate added to injection solutions or physiological buffers and compared its effects with equimolar doses of NaCl. Butyrate at plasma concentrations of 0.56 mM increased cardiac output by 48.8±14.9%, stroke volume by 38.5±12.1%, and left ventricular ejection fraction by 39.6±6.2%, and lowered systemic vascular resistance by 33.5±6.4% without affecting blood pressure or heart rate in vivo. In the range between 0.1 and 5 mM, butyrate increased left ventricular systolic pressure by up to 23.7±3.4% in isolated perfused hearts and by 9.4±2.9% following ischemia and reperfusion, while reducing myocardial infarct size by 81.7±16.9%. Butyrate relaxed isolated coronary septal arteries concentration dependently with an EC50=0.57 mM (95% CI, 0.23-1.44). CONCLUSIONS: We conclude that butyrate elevates cardiac output through mechanisms involving increased cardiac contractility and vasorelaxation. This effect of butyrate was not associated with adverse myocardial injury in damaged hearts exposed to ischemia and reperfusion.

Aldehyde dehydrogenase-2 inhibition blocks remote preconditioning in experimental and human models.

Mitochondrial aldehyde dehydrogenase-2 (ALDH-2) is involved in preconditioning pathways, but its role in remote ischaemic preconditioning (rIPC) is unknown. We investigated its role in animal and human models of rIPC. (i) In a rabbit model of myocardial infarction, rIPC alone reduced infarct size [69 ± 5.8 % (n = 11) to 40 ± 6.5 % (n = 12), P = 0.019]. However, rIPC protection was lost after pre-treatment with the ALDH-2 inhibitor cyanamide (62 ± 7.6 % controls, n = 10, versus 61 ± 6.9 % rIPC after cyanamide, n = 10, P > 0.05). (ii) In a forearm plethysmography model of endothelial ischaemia-reperfusion injury, 24 individuals of Asian ethnic origin underwent combined rIPC and ischaemia-reperfusion (IR). 11 had wild-type (WT) enzyme and 13 carried the Glu504Lys (ALDH2*2) polymorphism (rendering ALDH-2 functionally inactive). In WT individuals, rIPC protected against impairment of response to acetylcholine (P = 0.9), but rIPC failed to protect carriers of Glu504Lys polymorphism (P = 0.004). (iii) In a second model of endothelial IR injury, 12 individuals participated in a double-blind placebo-controlled crossover study, receiving the ALDH-2 inhibitor disulfiram 600 mg od or placebo for 48 h prior to assessment of flow-mediated dilation (FMD) before and after combined rIPC and IR. With placebo, rIPC was effective with no difference in FMD before and after IR (6.18 ± 1.03 % and 4.76 ± 0.93 % P = 0.1), but disulfiram inhibited rIPC with a reduction in FMD after IR (7.87 ± 1.27 % and 3.05 ± 0.53 %, P = 0.001). This study demonstrates that ALDH-2 is involved in the rIPC pathway in three distinct rabbit and human models. This has potential implications for future clinical studies of remote conditioning.

Ischemic preconditioning increases myocardial O-GlcNAc glycosylation.

OBJECTIVES: Through the hexosamine biosynthetic pathway (HBP) proteins are modified by O-linked-ß-N-acetylglucosamine (O-GlcNAc), which acts as a stress sensor. Augmentation of O-GlcNAc confers cardioprotection against ischemia- reperfusion injury, but its role in ischemic preconditioning (IPC) is unknown. Azaserine and alloxan are unspecific blockers of the HBP and have been used to block the cardioprotective effects of O-GlcNAc. We hypothesized that IPC reduces infarct size and increases O-GlcNAc levels in hearts subjected to ischemia-reperfusion injury, and that these effects could be blocked by azaserine and alloxan. DESIGN: Isolated rat hearts subjected to 40 min global ischemia and 120 min reperfusion were randomized to control, IPC, IPC + azaserine or alloxan, or control + azaserine or alloxan. The effects on infarct size, hemodynamic recovery, myocardial O-GlcNAc levels, and HBP enzyme activities were determined. RESULTS: IPC reduced infarct size, increased O-GlcNAc levels, O-GlcNAc-transferase levels, and O-GlcNAc-transferase activity. Azaserine and alloxan did not block the effect of IPC on O-GlcNAc levels and O-GlcNAc-transferase activity. CONCLUSIONS: IPC increased O-GlcNAc levels though increased O-GlcNAc-transferase expression and activity. Azaserine and alloxan failed to block these effects presumably due to poor specificity and sensitivity of the blockers, and IPC-mediated cardioprotection may therefore still be dependent on O-GlcNAc.

Real-World Experience with Cangrelor as Adjuvant to Percutaneous Coronary Intervention: A Single-Centre Observational Study.

Background: Reversible P2Y12 inhibition can be obtained with cangrelor administered intravenously. More experience with cangrelor use in acute PCI with unknown bleeding risk is needed. Objectives: To describe real-world use of cangrelor including patient and procedure characteristics and patient outcomes. Methods: We performed a single-centre, retrospective, and observational study including all patients treated with cangrelor in relation to percutaneous coronary intervention at Aarhus University Hospital during the years 2016, 2017, and 2018. We recorded procedure indication and priority, the indications for cangrelor use, and patient outcomes within the first 48 hours after initiation of cangrelor treatment. Results: We treated 991 patients with cangrelor in the study period. Of these, 869 (87.7%) had an acute procedure priority. Among acute procedures, patients were mainly treated for STEMI (n = 723) and the remaining were treated for cardiac arrest and acute heart failure. Use of oral P2Y12 inhibitors prior to percutaneous coronary intervention was rare. Fatal bleeding events (n = 6) were only observed among patients undergoing acute procedures. Stent thrombosis was observed in two patients receiving acute treatment for STEMI. Thus, cangrelor can be used in relation to PCI under acute circumstances with advantages in terms of clinical management. The benefits and risks, in terms of patient outcomes, should ideally be assessed in randomized trials.

Dual-therapy CD34 antibody-covered sirolimus-eluting COMBO stents versus sirolimus-eluting Orsiro stents in patients treated with percutaneous coronary intervention: the three-year outcomes of the SORT OUT X randomised clinical trial.

BACKGROUND: Target lesion failure (TLF) remains an issue with contemporary drug-eluting stents. The dual-therapy sirolimus-eluting and CD34 antibody-coated COMBO stent (DTS) was designed to improve early healing. AIMS: We aimed to compare the 3-year outcomes of the DTS and the sirolimus-eluting Orsiro stent (SES) in all-comer patients treated with percutaneous coronary intervention. METHODS: The SORT OUT X trial is a prospective multicentre randomised clinical trial with a registry-based follow-up comparing DTS and SES. The primary endpoint, TLF, is a composite of cardiac death, myocardial infarction or target lesion revascularisation (TLR). RESULTS: A total of 3,146 patients were randomised to treatment with the DTS (1,578 patients) or the SES (1,568 patients). At 3 years, an intention-to-treat analysis showed that 155 patients (9.8%) who were assigned the DTS and 118 patients (7.5%) who were assigned the SES met the primary endpoint (incidence rate ratio for TLF=1.33, 95% confidence interval: 1.04-1.70; p=0.02). This difference was caused by a significantly higher TLF rate in the DTS group compared to the SES group within the first year, which was mainly explained by a higher incidence of TLR in the DTS group compared to the SES group. Of note, the TLF rates were almost identical from 1 year to 3 years in both stent groups. CONCLUSIONS: At 3 years, the SES was superior to the DTS, mainly because the DTS was associated with an increased risk of TLF within the first year but not from 1 to 3 years. CLINICALTRIALS: gov: NCT03216733.

Release of a humoral circulating cardioprotective factor by remote ischemic preconditioning is dependent on preserved neural pathways in diabetic patients.

Efficacy of ischemic preconditioning is decreased in animal models of type 2 diabetes mellitus while the responses in humans with diabetes are contradictory. It is unknown whether attenuation is related to decreased release of a mediating humoral cardioprotective factor or reduced ability to respond in the target tissue. The aim of the present study was to investigate the release and effect of a circulating cardioprotective factor in type 2 diabetes mellitus patients. Blood samples were drawn from nine non-diabetic subjects, eight diabetic patients without peripheral neuropathy, and eight diabetic patients with peripheral neuropathy before (control) and after a remote ischemic preconditioning (rIPC) stimulus. Blood samples were dialyzed against Krebs-Henseleit buffer and the cardioprotective effects of the dialysates were tested in rabbit hearts mounted on a Langendorff model and subjected to 30-min global ischemia and 120-min reperfusion. rIPC dialysate from non-diabetic and diabetic subjects without peripheral neuropathy reduced infarct size and improved hemodynamic recovery compared to control dialysate from non-diabetic and diabetic subjects. However, in the subgroup of diabetic patients with neuropathy the cardioprotective effect was attenuated. These findings indicate that the release mechanism involves neural pathways.

Two case reports of transcatheter valve-in-valve implantation of Sapien 3 and MyVal in degenerated biological tricuspid prosthesis valves.

Background: Patients with severe tricuspid valve stenosis or dysfunction following degeneration of biological valve prosthesis in tricuspid position are complex, have substantial comorbidity, and very high surgical risk. Case summary: We report two cases with transcatheter tricuspid valve-in-valve implantation in patients with degenerated tricuspid bioprosthesis with transfemoral and transjugular access with Sapien 3 valve and MyVal, respectively. Discussion: In patients with high surgical risk, transcatheter tricuspid valve implantation is a good alternative. Careful consideration of optimal access site, device size, and delivery system is paramount. This case report demonstrates technically feasible and safe transcatheter valve-in-valve implantantion in tricuspid position and highlights the importance of meticulous procedure planning.

Association of Age With the Diagnostic Value of Coronary Artery Calcium Score for Ruling Out Coronary Stenosis in Symptomatic Patients.

Importance: The diagnostic value is unclear of a 0 coronary artery calcium (CAC) score to rule out obstructive coronary artery disease (CAD) and near-term clinical events across different age groups. Objective: To assess the diagnostic value of a CAC score of 0 for reducing the likelihood of obstructive CAD and to assess the implications of such a CAC score and obstructive CAD across different age groups. Design, Setting, and Participants: This cohort study obtained data from the Western Denmark Heart Registry and had a median follow-up time of 4.3 years. Included patients were aged 18 years or older who underwent computed tomography angiography (CTA) between January 1, 2008, and December 31, 2017, because of symptoms that were suggestive of CAD. Data analysis was performed from April 5 to July 7, 2021. Exposures: Obstructive CAD, which was defined as 50% or more luminal stenosis. Main Outcomes and Measures: Proportion of individuals with obstructive CAD who had a CAC score of 0. Risk-adjusted diagnostic likelihood ratios were used to assess the diagnostic value of a CAC score of 0 for reducing the likelihood of obstructive CAD beyond clinical variables. Risk factors associated with myocardial infarction and death were estimated. Results: A total of 23 759 symptomatic patients, of whom 12 771 (54%) had a CAC score of 0, were included. This cohort had a median (IQR) age of 58 (49-65) years and was primarily composed of women (13 160 [55%]). Overall, the prevalence of obstructive CAD was relatively low across all age groups, ranging from 3% (39 of 1278 patients) in those who were younger than 40 years to 8% (52 of 619) among those who were 70 years or older. In patients with obstructive CAD, 14% (725 of 5043) had a CAC score of 0, and the prevalence varied across age groups from 58% (39 of 68) among those who were younger than 40 years, 34% (192 of 562) among those aged 40 to 49 years, 18% (268 of 1486) among those aged 50 to 59 years, 9% (174 of 1963) among those aged 60 to 69 years, to 5% (52 of 964) among those who were 70 years or older. The added diagnostic value of a CAC score of 0 decreased at a younger age, with a risk factor-adjusted diagnostic likelihood ratio of a CAC score of 0 ranging from 0.68 (approximately 32% lower likelihood of obstructive CAD than expected) in those who were younger than 40 years to 0.18 (approximately 82% lower likelihood than expected) in those who were 70 years or older. The presence of obstructive vs nonobstructive CAD among those with a CAC score of 0 was associated with a multivariable adjusted hazard ratio of 1.51 (95% CI, 0.98-2.33) for myocardial infarction and all-cause death; however, this hazard ratio varied from 1.80 (95% CI, 1.02-3.19) in those who were younger than 60 years to 1.24 (95% CI, 0.64-2.39) in those who were 60 years or older. Conclusions and Relevance: This cohort study found that the diagnostic value of a CAC score of 0 to rule out obstructive CAD beyond clinical variables was dependent on age, with the added diagnostic value being smaller for younger patients. In symptomatic patients who were younger than 60 years, a sizable proportion of obstructive CAD occurred among those without CAC and was associated with an increased risk of myocardial infarction and all-cause death.

Influence of strain, age, origin, and anesthesia on the cardioprotective efficacy by local and remote ischemic conditioning in an ex vivo rat model.

BACKGROUND: Local ischemic preconditioning (IPC) and remote ischemic conditioning (RIC) induced by brief periods of ischemia and reperfusion protect against ischemia-reperfusion injury. METHODS: We studied the sensitivity to IR-injury and the influence of strain, age, supplier, and anesthesia upon the efficacy of IPC and RIC in 7- and 16-weeks-old Sprague-Dawley and Wistar rats from three different suppliers. The influence of sedation with a hypnorm and midazolam mixture (rodent mixture) and pentobarbiturate was compared. RESULTS: IPC attenuated infarct size in both 7-weeks-old Sprague-Dawley (48.4 ± 17.7% vs. 20.3 ± 6.9, p < 0.001) and 7-weeks-old Wistar (55.6 ± 10.9% vs. 26.8 ± 5.0%, p < 0.001) rats. Infarct size was larger in 16-weeks-old Sprague-Dawley rats, however, IPC still lowered infarct size (78.8 ± 9.2% vs. 58.3 ± 12.3%, p < 0.01). RIC reduced infarct sizes in 7-weeks-old Sprague-Dawley (75.3 ± 11.8% vs. 58.6 ± 8.9%, p < 0.05), but not in 7-weeks-old Wistar rats (31.7 ± 17.6% and 24.0 ± 12.6%, p = 0.2). In 16-weeks-old Sprague-Dawley rats, RIC did not induce protection (76.4 ± 5.5% and 73.2 ± 14.7%, p = 0.6). However, RIC induced protection in 16-weeks-old Wistar rats (45.2 ± 8.5% vs. 14.7 ± 10.8%, p < 0.001). RIC did not reduce infarct size in 7-weeks-old Sprague-Dawley rats from Charles River (62.0 ± 13.5% and 69.4 ± 10.4% p = 0.3) or 16-weeks-old Wistar rats from Janvier (50.7 ± 11.3 and 49.2 ± 16.2, p = 0.8). There was no difference between sedation with rodent mixture or pentobarbiturate. CONCLUSION: The cardioprotective effect of IPC is consistent across rat strains independent of age, strain, and supplier. RIC seems to be less reproducible, but still yields protection across different rat strains. However, age, animal supplier, and anesthetics may modulate the sensitivity of IR-injury and the response to RIC.

Cardioprotective effect of combination therapy by mild hypothermia and local or remote ischemic preconditioning in isolated rat hearts.

A multitargeted strategy to treat the consequences of ischemia and reperfusion (IR) injury in acute myocardial infarction may add cardioprotection beyond reperfusion therapy alone. We investigated the cardioprotective effect of mild hypothermia combined with local ischemic preconditioning (IPC) or remote ischemic conditioning (RIC) on IR injury in isolated rat hearts. Moreover, we aimed to define the optimum timing of initiating hypothermia and evaluate underlying cardioprotective mechanisms. Compared to infarct size in normothermic controls (56 ± 4%), mild hypothermia during the entire or final 20 min of the ischemic period reduced infarct size (34 ± 2%, p < 0.01; 35 ± 5%, p < 0.01, respectively), while no reduction was seen when hypothermia was initiated at reperfusion (51 ± 4%, p = 0.90). In all groups with effect of mild hypothermia, IPC further reduced infarct size. In contrast, we found no additive effect on infarct size between hypothermic controls (20 ± 3%) and the combination of mild hypothermia and RIC (33 ± 4%, p = 0.09). Differences in temporal lactate dehydrogenase release patterns suggested an anti-ischemic effect by mild hypothermia, while IPC and RIC preferentially targeted reperfusion injury. In conclusion, additive underlying mechanisms seem to provide an additive effect of mild hypothermia and IPC, whereas the more clinically applicable RIC does not add cardioprotection beyond mild hypothermia.

Ischemic Heart Disease: An Update.

Ischemic heart disease is a dynamic process of atherosclerosis of the coronary arteries or functional alterations of coronary circulation that can be modified by lifestyle, pharmacological therapies, and revascularization. Such treatment may result in disease stabilization or regression. New terminology describes clinical presentations of Ischemic heart disease categorized as either acute coronary syndrome or chronic coronary syndrome. The reduction in prevalence of obstructive coronary artery disease in a symptomatic population causes a lower pretest probability and clinical likelihood of disease, influencing the diagnostic work-up. Noninvasive functional or anatomic imaging for myocardial ischemia is recommended as the initial test to diagnose coronary artery disease in symptomatic patients, where obstructive disease cannot be excluded by clinical assessment alone. Coronary computed tomography (CT) angiography has advanced and is first line in suitable patients, due to high rule-out power and further qualification of the diagnosis by functional assessment using noninvasive nuclear or magnetic resonance technology or CT-based fractional flow reserve (FFR-CT). Optimal medical treatment remains paramount, while FFR-guided myocardial revascularization in patients that are not responsive to antianginal treatment provides further symptom relieve as well as prognostic impact on prevention of spontaneous myocardial infarction.

Differences in intrinsic aerobic capacity alters sensitivity to ischemia-reperfusion injury but not cardioprotective capacity by ischemic preconditioning in rats.

INTRODUCTION: Aerobic capacity is a strong predictor of cardiovascular mortality. Whether aerobic capacity influences myocardial ischemia and reperfusion (IR) injury is unknown. PURPOSE: To investigate the impact of intrinsic differences in aerobic capacity and the cardioprotective potential on IR injury. METHODS: We studied hearts from rats developed by selective breeding for high (HCR) or low (LCR) capacity for treadmill running. The rats were randomized to: (1) control, (2) local ischemic preconditioning (IPC) or (3) remote ischemic preconditioning (RIC) followed by 30 minutes of ischemia and 120 minutes of reperfusion in an isolated perfused heart model. The primary endpoint was infarct size. Secondary endpoints included uptake of labelled glucose, content of selected mitochondrial proteins in skeletal and cardiac muscle, and activation of AMP-activated kinase (AMPK). RESULTS: At baseline, running distance was 203±7 m in LCR vs 1905±51 m in HCR rats (p<0.01). Infarct size was significantly lower in LCR than in HCR controls (49±5% vs 68±5%, p = 0.04). IPC reduced infarct size by 47% in LCR (p<0.01) and by 31% in HCR rats (p = 0.01). RIC did not modulate infarct size (LCR: 52±5, p>0.99; HCR: 69±6%, p>0.99, respectively). Phosphorylaion of AMPK did not differ between LCR and HCR controls. IPC did not modulate cardiac phosphorylation of AMPK. Glucose uptake during reperfusion was similar in LCR and HCR rats. IPC increased glucose uptake during reperfusion in LCR animals (p = 0.02). Mitochondrial protein content in skeletal muscle was lower in LCR than in HCR (0.77±0.10 arbitrary units (AU) vs 1.09±0.07 AU, p = 0.02), but not in cardiac muscle. CONCLUSION: Aerobic capacity is associated with altered myocardial sensitivity to IR injury, but the cardioprotective effect of IPC is not. Glucose uptake, AMPK activation immediately prior to ischemia and basal mitochondrial protein content in the heart seem to be of minor importance as underlying mechanisms for the cardioprotective effects.

Influence of diabetes mellitus duration on the efficacy of ischemic preconditioning in a Zucker diabetic fatty rat model.

Augmented mortality and morbidity following an acute myocardial infarction in patients with diabetes mellitus Type 2 (T2DM) may be caused by increased sensitivity to ischemia reperfusion (IR) injury or altered activation of endogenous cardioprotective pathways modified by T2DM per se or ischemic preconditioning (IPC). We aimed to investigate, whether the duration of T2DM influences sensitivity against IR injury and the efficacy of IPC, and how myocardial glucose oxidation rate was involved. Male Zucker diabetic fatty rats (homozygote (fa/fa)) at ages 6-(prediabetic), 12- (onset diabetes) and 24-weeks of age (late diabetes) and their age-matched non-diabetic controls (heterozygote (fa/+) were subjected to IR injury in the Langendorff model and randomised to IPC stimulus or control. T2DM rats were endogenously protected at onset of diabetes, as infarct size was lower in 12-weeks T2DM animals than in 6- (35±2% vs 53±4%; P = 0.006) and 24-weeks animals (35±2% vs 72±4%; P<0.0001). IPC reduced infarct size in all groups irrespective of the presence of T2DM and its duration (32±3%; 20±2%; 36±4% respectively; (ANOVA P<0.0001). Compared to prediabetic rats, myocardial glucose oxidation rates were reduced during stabilisation and early reperfusion at onset of T2DM, but these animals retained the ability to increase oxidation rate in late reperfusion. Late diabetic rats had low glucose oxidation rates throughout stabilisation and reperfusion. Despite inherent differences in sensitivity to IR injury, the cardioprotective effect of IPC was preserved in our animal model of pre-, early and late stage T2DM and associated with adaptations to myocardial glucose oxidation capacity.