Incidence of Sudden Cardiac Death and Life-Threatening Arrhythmias in Clinically Manifest Cardiac Sarcoidosis With and Without Current Indications for an Implantable Cardioverter Defibrillator.

BACKGROUND: Cardiac sarcoidosis (CS) predisposes to sudden cardiac death (SCD). Guidelines for implantable cardioverter defibrillators (ICDs) in CS have been issued by the Heart Rhythm Society in 2014 and the American College of Cardiology/American Heart Association/Heart Rhythm Society consortium in 2017. How well they discriminate high from low risk remains unknown. METHODS: We analyzed the data of 398 patients with CS detected in Finland from 1988 through 2017. All had clinical cardiac manifestations. Histological diagnosis was myocardial in 193 patients (definite CS) and extracardiac in 205 (probable CS). Patients with and without Class I or IIa ICD indications at presentation were identified, and subsequent occurrences of SCD (fatal or aborted) and sustained ventricular tachycardia were recorded, as were ICD indications emerging first on follow-up. RESULTS: Over a median of 4.8 years, 41 patients (10.3%) had fatal (n=8) or aborted (n=33) SCD, and 98 (24.6%) experienced SCD or sustained ventricular tachycardia as the first event. By the Heart Rhythm Society guideline, Class I or IIa ICD indications were present in 339 patients (85%) and absent in 59 (15%), of whom 264 (78%) and 30 (51%), respectively, received an ICD. Cumulative 5-year incidence of SCD was 10.7% (95% CI, 7.4%-15.4%) in patients with ICD indications versus 4.8% (95% CI, 1.2%-19.1%) in those without (χ2=1.834, P=0.176). The corresponding rates of SCD were 13.8% (95% CI, 9.1%-21.0%) versus 6.3% (95% CI, 0.7%-54.0%; χ2=0.814, P=0.367) in definite CS and 7.6% (95% CI, 3.8%-15.1%) versus 3.3% (95% CI, 0.5%-22.9%; χ2=0.680, P=0.410) in probable CS. In multivariable regression analysis, SCD was predicted by definite histological diagnosis (P=0.033) but not by Class I or IIa ICD indications (P=0.210). In patients without ICD indications at presentation, 5-year incidence of SCD, sustained ventricular tachycardia, and emerging Class I or IIa indications was 53% (95% CI, 40%-71%). By the American College of Cardiology/American Heart Association/Heart Rhythm Society guideline, all patients with complete data (n=245) had Class I or IIa indications for ICD implantation. CONCLUSIONS: Current ICD guidelines fail to distinguish a truly low-risk group of patients with clinically manifest CS, the 5-year risk of SCD approaching 5% despite absent ICD indications. Further research is needed on prognostic factors, including the role of diagnostic histology. Meanwhile, all patients with CS presenting with clinical cardiac manifestations should be considered for an ICD implantation.

Percutaneous coronary intervention with drug-coated balloon-only strategy combined with single antiplatelet treatment in patients at high bleeding risk: Single center experience of a novel concept.

OBJECTIVES: At least 1 month of dual antiplatelet therapy is required after coronary stenting. The aim of this all-comers retrospective registry study was to assess the efficacy and safety of percutaneous coronary intervention (PCI) using drug-coated balloon (DCB) with single antiplatelet treatment (SAPT). METHODS: Between 2011 and 2020, 232 PCIs were performed in 172 patients using the DCB-only strategy and discharged with SAPT. RESULTS: The mean age of the patients was 75 ± 11 years and 59% were male. The clinical presentation was stable coronary artery disease (CAD) in 42% of the patients and acute coronary syndrome (ACS) in 58%. The lesions were mainly de novo (96%). The majority (58%) of treated lesions were in large coronary arteries (≥3.0 mm). Most (87%) of the patients were at high bleeding risk (HBR) with at least one major or two minor Academic Research Consortium (ARC) risk factors for bleeding. Periprocedural DAPT was used in 49% of the patients. The 12-month major adverse cardiac events (MACE, the composition of cardiovascular death, nonfatal myocardial infarction, and target-lesion revascularization) rate was 1.4% in stable CAD and 7.1% in ACS. The 12-month all-cause mortality after DBC only + SAPT strategy was 4.1% in stable CAD and 12.1% in ACS. The rate of ischemia-driven target lesion revascularisation (TLR) was 0% in stable CAD and 3.0% in ACS at 12 months. The 12-month rate of significant bleeding (BARC type 2-5) was 10.5%. There were no acute or subacute vessel closures. CONCLUSIONS: Despite the aged patient population with comorbidities, the TLR, MACE, and bleeding rates were low with DCB-only PCI combined with SAPT. This novel approach could reduce the post-PCI bleeding risk in patients with CAD and HBR compared to stenting.

Drug-coated balloon for treatment of de-novo coronary artery lesions in patients with high bleeding risk (DEBUT): a single-blind, randomised, non-inferiority trial.

BACKGROUND: The optimal technique of percutaneous coronary intervention in patients at high bleeding risk is not known. The hypothesis of the DEBUT trial was that percutaneous coronary intervention with drug-coated balloons is non-inferior to percutaneous coronary intervention with bare-metal stents for this population. METHODS: The DEBUT trial is a randomised, single-blind non-inferiority trial done at five sites in Finland. Patients were eligible if they had an ischaemic de-novo lesion in a coronary artery or bypass graft that could be treated with drug-coated balloons, at least one risk factor for bleeding, and a reference vessel diameter of 2·5-4·0 mm. Those with myocardial infarction with ST-elevation, bifurcation lesions needing a two-stent technique, in-stent restenosis, and flow-limiting dissection or substantial recoil (>30%) of the target lesion after predilation were excluded. After successful predilation of the target lesion, patients were randomly assigned (1:1), by use of a computer-generated random sequence, to percutaneous coronary intervention with a balloon coated with paclitaxel and iopromide or a bare-metal stent. The primary outcome was major adverse cardiac events at 9 months. Non-inferiority was shown if the absolute risk difference was no more than 3%. All prespecified analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01781546. FINDINGS: Between May 22, 2013, and Jan 16, 2017, 220 patients were recruited for the study and 208 patients were assigned to percutaneous coronary intervention with drug-coated balloon (n=102) or bare metal stent (n=106). At 9 months, major adverse cardiac events had occurred in one patient (1%) in the drug-coated balloon group and in 15 patients (14%) in the bare-metal stent group (absolute risk difference -13·2 percentage points [95% CI -6·2 to -21·1], risk ratio 0·07 [95% CI 0·01 to 0·52]; p<0·00001 for non-inferiority and p=0·00034 for superiority). Two definitive stent thrombosis events occurred in the bare metal stent group but no acute vessel closures in the drug-coated balloon group. INTERPRETATIONS: Percutaneous coronary intervention with drug-coated balloon was superior to bare-metal stents in patients at bleeding risk. The drug-coated balloon-only coronary intervention is a novel strategy to treat this difficult patient population. Comparison of this approach to the new generation drug-eluting stents is warranted in the future. FUNDING: B Braun Medical AG, AstraZeneca, and Competitive State Research Funding of the Kuopio University Hospital Catchment Area.

Sudden death in cardiac sarcoidosis: an analysis of nationwide clinical and cause-of-death registries.

AIMS: The present study was done to assess the role of sudden cardiac death (SCD) among the presenting manifestations of and fatalities from cardiac sarcoidosis (CS). METHODS AND RESULTS: We analysed altogether 351 cases of CS presenting from year 1998 through 2015 in Finland. There were 262 patients with a clinical diagnosis and treatment of CS, 27 patients with an initial lifetime diagnosis of giant cell myocarditis that was later converted to CS, and 62 cases detected at autopsy and identified by screening >820 000 death certificates from the national cause-of-death registry. The total case series comprised 253 females and 98 males aged on average 52 years at presentation. High-grade atrioventricular block was the most common first sign of CS (n = 147, 42%) followed by heart failure (n = 58, 17%), unexpected fatal (n = 38) or aborted (n = 12) SCD (14%), and sustained ventricular tachycardia (n = 48, 14%). Severe coronary artery disease was found at autopsy concomitant with CS in four of the 38 cases presenting with fatal SCD. Of all deaths recorded till the end of 2015, 64% (n = 54/84) were unexpected SCDs from CS that had either been silent during life or defied all attempts at diagnosis. The Kaplan-Meier estimate (95% CI) of survival from symptom onset was 85% (80-90%) at 5 years and 76% (68-84%) at 10 years. CONCLUSION: Together fatal and aborted SCD constitute 14% of the presenting manifestations of CS. Nearly two-thirds of all fatalities from CS are caused by undiagnosed granulomas in the heart.

Percutaneous coronary intervention with drug-coated balloon-only strategy in stable coronary artery disease and in acute coronary syndromes: An all-comers registry study.

OBJECTIVES: The aim of this single center all-comers retrospective registry study was to assess the efficacy and safety of percutaneous coronary intervention (PCI) using drug-coated balloon (DCB) in de novo lesions including large proximal coronary arteries. METHODS: A total of 487 PCIs were performed using paclitaxel-coated DCB in 562 de novo lesions with the possibility for bailout stenting in a patient population presenting with stable coronary artery disease (CAD) or acute coronary syndrome (ACS). Half of the patients had at least one risk factor for bleeding. All of the treated lesions were de novo and 60% of DCBs used were ≥ 3.0 mm in diameter. The median follow-up time was 18 months for MACE and 60 months for survival. RESULTS: The total mortality after DBC only strategy was 2.3 and 9.3% at 12 months in stable CAD and ACS, respectively. The 12-month MACE rate was 7.1 and 12% in stable CAD and ACS. The rate of ischemia-driven target lesion revascularization was only 1.4% in stable CAD and 2.8% after ACS at 12 months. Median duration of DAPT was one month. The 12 month rate of significant bleeding (Bleeding Academic Research Consortium types 2-5) was 5.9%. Acute vessel closure occurred only in one case (0.2%) after DCB treatment. Bailout stenting was used in 12% of lesions. CONCLUSIONS: PCI using DCB-only strategy with the possibility for provisional stenting is a safe and efficient in de novo coronary artery lesions in both stable CAD and ACS. This strategy may be useful especially in patients with high bleeding risk.

Adenoviral intramyocardial VEGF-DΔNΔC gene transfer increases myocardial perfusion reserve in refractory angina patients: a phase I/IIa study with 1-year follow-up.

AIMS: We evaluated for the first time the effects of angiogenic and lymphangiogenic AdVEGF-DΔNΔC gene therapy in patients with refractory angina. METHODS AND RESULTS: Thirty patients were randomized to AdVEGF-DΔNΔC (AdVEGF-D) or placebo (control) groups. Electromechanical NOGA mapping and radiowater PET were used to identify hibernating viable myocardium where treatment was targeted. Safety, severity of symptoms, quality of life, lipoprotein(a) [Lp(a)] and routine clinical chemistry were measured. Myocardial perfusion reserve (MPR) was assessed with radiowater PET at baseline and after 3- and 12-months follow-up. Treatment was well tolerated. Myocardial perfusion reserve increased significantly in the treated area in the AdVEGF-D group compared with baseline (1.00 ± 0.36) at 3 months (1.31 ± 0.46, P = 0.045) and 12 months (1.44 ± 0.48, P = 0.009) whereas MPR in the reference area tended to decrease (2.05 ± 0.69, 1.76 ± 0.62, and 1.87 ± 0.69; baseline, 3 and 12 months, respectively, P = 0.551). Myocardial perfusion reserve in the control group showed no significant change from baseline to 3 and 12 months (1.26 ± 0.37, 1.57 ± 0.55, and 1.48 ± 0.48; respectively, P = 0.690). No major changes were found in clinical chemistry but anti-adenovirus antibodies increased in 54% of the treated patients compared with baseline. AdVEGF-D patients in the highest Lp(a) tertile at baseline showed the best response to therapy (MPR 0.94 ± 0.32 and 1.76 ± 0.41 baseline and 12 months, respectively, P = 0.023). CONCLUSION: AdVEGF-DΔNΔC gene therapy was safe, feasible, and well tolerated. Myocardial perfusion increased at 1 year in the treated areas with impaired MPR at baseline. Plasma Lp(a) may be a potential biomarker to identify patients that may have the greatest benefit with this therapy.

Percutaneous Coronary Intervention of Complex Calcified Lesions With Drug-Coated Balloon After Rotational Atherectomy.

OBJECTIVES: We investigated the safety and efficacy of PCI using drug-coated balloon (DCB) after rotational atherectomy (rotablation) in a retrospective single center study in patients with calcified de novo coronary lesions. The majority of patients had an increased risk for bleeding. BACKGROUND: DCB has been effective in the treatment of in-stent restenosis, small vessels, and bifurcations. DCB enables short one month dual antiplatelet treatment. No published data exist on the use of DCB after rotablation. METHODS: 82 PCIs were performed in 65 patients (mean age 72 ± 10 years) using rotablation followed by DCB treatment. The median follow-up time was 17 months. 82% of the patients had at least one risk factor for bleeding such as oral anticoagulation. 32% had an acute coronary syndrome. Median duration of dual antiplatelet treatment was 1 month. RESULTS: MACE (the composite of cardiovascular death, ischemia-driven target-lesion revascularization [TLR] or non-fatal myocardial infarction) occurred in 14% and 20% of the patients at 12 and 24 months, respectively. The rate of ischemia-driven TLR was 1.5% at 12 months and 3.0% at 24 months. No acute closure of the treated vessel occurred. Bailout stenting was needed in 10% of the PCIs. The incidence of significant bleeding was 9% at 12 months. CONCLUSIONS: This is the first study to show that PCI using DCB after preparation of calcified lesions with rotablation is safe and effective. This novel strategy may be considered especially in patients with a bleeding risk such as those using an oral anticoagulant.

Ultrasound imaging with bolus delivered contrast agent for the detection of angiogenesis and blood flow irregularities.

Highly increased blood flow and vascularity after angiogenic gene therapy have raised concerns of shunting and hemangioma-like blood pool formation that might decrease effective perfusion and ruin the beneficial effects of the therapy. Contrast enhanced ultrasound is a promising noninvasive tool for studying skeletal muscle perfusion. The objectives of the present study were to test bolus and infusion administrations of ultrasound microbubble contrast media in imaging vascular growth in skeletal muscle and assess the functionality of vessels grown with angiogenic gene therapy. Contrast enhanced ultrasound was used to study changes in skeletal muscle perfusion in normal and gene-transduced rabbit hindlimbs 6 days after gene transfer. Adenoviral gene transfer of VEGF (10e(9)-10e(11) viral particles) or ß-galactosidase control gene (10e(11) viral particles) was done under anesthesia and induced up to 16-fold increases in relative tissue perfusion. Contrast intensity versus time curves were plotted and analyzed for contrast kinetics. Bolus administration of the contrast media was highly feasible in analyzing skeletal muscle blood flow and its kinetics. Maximal signal intensity of the bolus signal reflected relative changes in both blood flow and volume equally to the infusion method. Flow irregularities were detected after angiogenic gene therapy. In conclusion, bolus delivery of ultrasound contrast agent is highly feasible for the relative analysis of both quantity and quality of blood flow after angiogenic gene therapy. The kinetics of blood flow can and should be studied more extensively in both preclinical and clinical trials of angiogenic gene therapy since there is increasing evidence of flow irregularities in angiogenic vessels.

HIF-1α and HIF-2α induce angiogenesis and improve muscle energy recovery.

BACKGROUND: Cardiovascular patients suffer from reduced blood flow leading to ischaemia and impaired tissue metabolism. Unfortunately, an increasing group of elderly patients cannot be treated with current revascularization methods. Thus, new treatment strategies are urgently needed. Hypoxia-inducible factors (HIFs) upregulate the expression of angiogenic mediators together with genes involved in energy metabolism and recovery of ischaemic tissues. Especially, HIF-2α is a novel factor, and only limited information is available about its therapeutic potential. METHODS: Gene transfers with adenoviral HIF-1α and HIF-2α were performed into the mouse heart and rabbit ischaemic hindlimbs. Angiogenesis was evaluated by histology. Left ventricle function was analysed with echocardiography. Perfusion in rabbit skeletal muscles and energy recovery after electrical stimulation-induced exercise were measured with ultrasound and (31)P-magnetic resonance spectroscopy ((31)P-MRS), respectively. RESULTS: HIF-1α and HIF-2α gene transfers increased capillary size up to fivefold in myocardium and ischaemic skeletal muscles. Perfusion in skeletal muscles was increased by fourfold without oedema. Especially, AdHIF-1α enhanced the recovery of ischaemic muscles from electrical stimulation-induced energy depletion. Special characteristic of HIF-2α gene transfer was a strong capillary growth in muscle connective tissue and that HIF-2α gene transfer maintained left ventricle function. CONCLUSIONS: We conclude that both AdHIF-1α and AdHIF-2α gene transfers induced beneficial angiogenesis in vivo. Transient moderate increases in angiogenesis improved energy recovery after exercise in ischaemic muscles. This study shows for the first time that a moderate increase in angiogenesis is enough to improve tissue energy metabolism, which is potentially a very useful feature for cardiovascular gene therapy.

The bottleneck stent model for chronic myocardial ischemia and heart failure in pigs.

A large animal model of chronic myocardial ischemia and heart failure is crucial for the development of novel therapeutic approaches. In this study we developed a novel percutaneous one- and two-vessel model for chronic myocardial ischemia using a stent coated with a polytetrafluoroethylene tube formed in a bottleneck shape. The bottleneck stent was implanted in the proximal left anterior descending (LAD) or proximal circumflex artery (LCX), or in both proximal LCX and mid LAD 1 wk later (2-vessel model), and pigs were followed for 4-5 wk. Ejection fraction (EF), infarct size, collateral growth, and myocardial perfusion were assessed. Pigs were given antiarrhythmic medication to prevent sudden death. The occlusion time of the bottleneck stent and the timing of myocardial infarction could be modulated by the duration of antiplatelet medication. Fractional flow reserve measurements and positron emission tomography imaging showed severe ischemia after bottleneck stenting covering over 50% of the left ventricle in the proximal LAD model. Complete coronary occlusion was necessary for significant collateral growth, which mostly had occurred already during the first wk after the stent occlusion. Dynamic and competitive collateral growth patterns were observed. EF declined from 64 to 41% in the LCX model and to 44% in the LAD model 4 wk after stenting with 12 and 21% infarcted left ventricle in the LCX and LAD models, respectively. The mortality was 32 and 37% in the LCX and LAD models but very (71%) high in the two-vessel disease model. The implantation of a novel bottleneck stent in the proximal LAD or LCX is a novel porcine model of reversible myocardial ischemia (open stent) and ischemic heart failure (occluded stent) and is feasible for the development of new therapeutic approaches.

Drug-coated balloon-only strategy for percutaneous coronary intervention of de novo left main coronary artery disease: the importance of proper lesion preparation.

This retrospective single-center registry study included all consecutive patients who underwent percutaneous coronary intervention (PCI) for a de novo left main coronary artery lesion using drug coated-balloon (DCB)-only strategy between August 2011 and December 2018. To best of our knowledge, no previous studies of DCB-only strategy of treating de novo left main coronary artery disease, exist. The primary endpoint was major adverse cardiovascular events (MACEs) including cardiac death, non-fatal myocardial infarction, and target lesion revascularization (TLR). The cohort was divided into two groups depending on weather the lesion preparation was done according to the international consensus group guidelines. Sixty-six patients (mean age 75±8.6, 72% male), 52% of whom had acute coronary syndrome, underwent left main PCI with the DCB-only strategy. No procedural mortality and no acute closures of the treated left main occurred. At 12 months, MACE and TLR occurred in 24% and 6% of the whole cohort, respectively. If the lesion preparation was done according to the guidelines, the MACE and TLR rates were 21.2% and 1.9%. Left main PCI with the DCB only-strategy is safe leading to acceptable MACE and low TLR rates at one year, if the lesion preparation is done according to the guidelines.

The effect of hydroxychloroquine on cholesterol metabolism in statin treated patients after myocardial infarction.

Background and aims: To evaluate the effect of hydroxychloroquine (HCQ) on serum and lipoprotein lipids and serum biomarkers of cholesterol synthesis and absorption in myocardial infarction patients with a high-dose statin. Methods: Myocardial infarction patients (n = 59) with a constant statin dose were randomized to receive hydroxychloroquine 300 mg (n = 31) or placebo (n = 28) daily for six months and followed up for one year. Results: Statin reduced total-c (-26 ± 22% in hydroxychloroquine and -28 ± 19% in placebo group, P = 0.931), LDL-c (-38 ± 26% vs. -44 ± 23%, respectively, P = 0.299), and cholesterol synthesis biomarkers zymostenol, desmosterol, and lathosterol ratios from baseline to one year (e.g., serum lathosterol ratio -17 ± 45% vs. -15 ± 41%, respectively, P < 0.001 for both, P = 0.623 between groups). Compensatorily, cholesterol absorption increased during the intervention (e.g., serum campesterol ratio 125 ± 90% vs. 113 ± 72%, respectively, P < 0.001 for both, P = 0.488 between groups). Hydroxychloroquine did not affect cholesterol concentrations or cholesterol absorption. It prevented the statin-induced increase in cholesterol precursor, desmosterol ratio, from six months to one year in the hydroxychloroquine group (P = 0.007 at one year compared to placebo). Conclusions: Combined with a high-dose statin, hydroxychloroquine had no additional effect on serum cholesterol concentration or cholesterol absorption. However, the findings suggest that hydroxychloroquine interferes with lanosterol synthesis, and thereafter, it temporarily interferes with the cholesterol synthesis pathway, best seen in halting the increase of the desmosterol ratio.Trial Registration ClinicalTrials.gov Identifier: NCT02648464.

Novel Technologies in the Detection of Atrial Fibrillation: Review of Literature and Comparison of Different Novel Technologies for Screening of Atrial Fibrillation.

Atrial fibrillation (AF) is globally the most common arrhythmia associated with significant morbidity and mortality. It impairs the quality of the patient's life, imposing a remarkable burden on public health, and the healthcare budget. The detection of AF is important in the decision to initiate anticoagulation therapy to prevent thromboembolic events. Nonetheless, AF detection is still a major clinical challenge as AF is often paroxysmal and asymptomatic. AF screening recommendations include opportunistic or systematic screening in patients ≥65 years of age or in those individuals with other characteristics pointing to an increased risk of stroke. The popularities of well-being and taking personal responsibility for one's own health are reflected in the continuous development and growth of mobile health technologies. These novel mobile health technologies could provide a cost-effective solution for AF screening and an additional opportunity to detect AF, particularly its paroxysmal and asymptomatic forms.

Baculovirus-mediated vascular endothelial growth factor-D(ΔNΔC) gene transfer induces angiogenesis in rabbit skeletal muscle.

BACKGROUND: Occluded arteries and ischemic tissues cannot always be treated by angioplasty, stenting or by-pass-surgery. Under such circumstances, viral gene therapy may be useful in inducing increased blood supply to ischemic area. There is evidence of improved blood flow in ischemic skeletal muscle and myocardium in both animal and human studies using adenoviral vascular endothelial growth factor (VEGF) gene therapy. However, the expression is transient and repeated gene transfers with the same vector are inefficient due to immune responses. METHODS: Different baculoviral vectors pseudotyped with or without vesicular stomatitis virus glycoprotein (VSV-G) and/or carrying woodchuck hepatitis virus post-transcriptional regulatory element (Wpre) were tested both in vitro and in vivo. VEGF-D(ΔNΔC) was used as therapeutic transgene and lacZ as a control. In vivo efficacy was evaluated as capillary enlargement and transgene expression in New Zealand White (NZW) rabbit skeletal muscle. RESULTS: A statistically significant capillary enlargement was detected 6 days after gene transfer in transduced areas compared to the control gene transfers with baculovirus and adenovirus encoding ß-galactosidase (lacZ). Substantially improved gene transfer efficiency was achieved with a modified baculovirus pseudotyped with VSV-G and carrying Wpre. Dose escalation experiments revealed that either too large volume or too many virus particles caused inflammation and necrosis in the target tissue, whereas 10(9) plaque forming units injected in multiple aliquots resulted in transgene expression with only mild immune reactions. CONCLUSIONS: We show the first evidence of biologically significant baculoviral gene transfer in skeletal muscle of NZW rabbits using VEGF-D(ΔNΔC) as a therapeutic transgene.

VEGF-B is dispensable for blood vessel growth but critical for their survival, and VEGF-B targeting inhibits pathological angiogenesis.

VEGF-B, a homolog of VEGF discovered a long time ago, has not been considered an important target in antiangiogenic therapy. Instead, it has received little attention from the field. In this study, using different animal models and multiple types of vascular cells, we revealed that although VEGF-B is dispensable for blood vessel growth, it is critical for their survival. Importantly, the survival effect of VEGF-B is not only on vascular endothelial cells, but also on pericytes, smooth muscle cells, and vascular stem/progenitor cells. In vivo, VEGF-B targeting inhibited both choroidal and retinal neovascularization. Mechanistically, we found that the vascular survival effect of VEGF-B is achieved by regulating the expression of many vascular prosurvival genes via both NP-1 and VEGFR-1. Our work thus indicates that the function of VEGF-B in the vascular system is to act as a "survival," rather than an "angiogenic" factor and that VEGF-B inhibition may offer new therapeutic opportunities to treat neovascular diseases.

Capillary enlargement, not sprouting angiogenesis, determines beneficial therapeutic effects and side effects of angiogenic gene therapy.

AIMS: Currently, it is still unclear which mechanisms drive metabolic benefits after angiogenic gene therapy. The side-effect profile of efficient angiogenic gene therapy is also currently incompletely understood. In this study, the effects of increasing doses of adenoviral (Ad) vascular endothelial growth factor-A (VEGF-A) were evaluated on vascular growth, metabolic benefits, and systemic side effects. METHODS AND RESULTS: Adenoviral vascular endothelial growth factor-A or AdLacZ control was injected intramuscularly (10(9)-10(11) vp/mL) or intra-arterially (5 × 10(11) vp/mL) into rabbit (n = 102) hindlimb muscles and examined 6 or 14 days later. Blood flow, tissue oedema, metabolic benefits, and the structure of angiogenic vessels were assessed using ultrasound imaging, modified Miles assay, arterial blood gas and metabolite analyses, and light and confocal microscopy, respectively. Safety analyses included cardiac ultrasound, electrocardiograms, and blood and tissue samples. Sprouting angiogenesis was already induced with low AdVEGF-A concentrations, whereas higher concentrations were needed to reach efficient capillary enlargement and increases in target muscle perfusion. Interestingly, metabolic benefits, such as improved aerobic energy metabolism and decreased metabolic acidosis during exercise, after AdVEGF-A administration were highly correlated to the level of capillary enlargement but not to sprouting angiogenesis. Several systemic dose-dependent side effects, including transient increases in liver, kidney, and pancreatic enzymes, and signs of cardiac effects were observed. CONCLUSION: Efficient capillary enlargement leading to significant increases in tissue perfusion is needed to gain metabolic benefits after angiogenic gene therapy. However, the risk of systemic side effects can increase as the efficiency of angiogenic gene therapy is improved. Importantly, the unstable wall structure of the newly formed vessels seems not to compromise the metabolic benefits.