Symptoms as a Predictor of the Placebo-Controlled Efficacy of PCI in Stable Coronary Artery Disease

BACKGROUND

Placebo-controlled evidence from ORBITA-2 found that percutaneous cutaneous intervention (PCI) in stable coronary artery disease with little or no antianginal medication relieved angina, but residual symptoms persisted in many. The reason for this was unclear.

OBJECTIVES

; This ORBITA-2 secondary analysis investigates the relationship between presenting symptoms and disease severity (anatomic, non-invasive, and invasive ischemia) and the ability of symptoms to predict the placebo-controlled efficacy of PCI.

METHODS

Pre-randomization symptom severity and nature were assessed using the ORBITA smartphone application and symptom and quality of life questionnaires including the Rose angina questionnaire. Disease severity was assessed using quantitative coronary angiography (QCA), stress echocardiography, fractional flow reserve (FFR), and instantaneous wave-free ratio (iFR). Bayesian ordinal regression was used.

RESULTS

At pre-randomization, the median number of daily angina episodes was 0.8 (0.4-1.6), 64% had Rose angina, QCA diameter stenosis 61 (49-74), stress echocardiography score 1.0 (0.0-2.7), FFR 0.63 (0.49-0.75), and iFR 0.78 (0.55-0.87). There was little relationship between symptom severity and nature and disease severity: angina symptom score with QCA ordinal correlation coefficient 0.06 (95% CrI 0.00 to 0.08); stress echocardiography 0.09 (95% CrI 0.02 to 0.10); FFR 0.04 (95% CrI -0.03 to 0.07); and iFR 0.04 (95% CrI -0.01 to 0.07). However, Rose angina and guideline-based typical angina were strong predictors of placebo-controlled PCI efficacy (angina symptom score: OR 1.9, 95% CrI 1.6 to 2.1, Pr(Interaction)=99.9% and OR 1.8, 95% CrI 1.6 to 2.1, Pr(Interaction)=99.9%, respectively).

CONCLUSIONS

Although symptom severity and nature were poorly associated with disease severity, the nature of symptoms powerfully predicted the placebo-controlled efficacy of PCI.

A Placebo-Controlled Trial of Percutaneous Coronary Intervention for Stable Angina

BACKGROUND

Percutaneous coronary intervention (PCI) is frequently performed to reduce the symptoms of stable angina. Whether PCI relieves angina more than a placebo procedure in patients who are not receiving antianginal medication remains unknown.

METHODS

We conducted a double-blind, randomized, placebo-controlled trial of PCI in patients with stable angina. Patients stopped all antianginal medications and underwent a 2-week symptom assessment phase before randomization. Patients were then randomly assigned in a 1:1 ratio to undergo PCI or a placebo procedure and were followed for 12 weeks. The primary end point was the angina symptom score, which was calculated daily on the basis of the number of angina episodes that occurred on a given day, the number of antianginal medications prescribed on that day, and clinical events, including the occurrence of unblinding owing to unacceptable angina or acute coronary syndrome or death. Scores range from 0 to 79, with higher scores indicating worse health status with respect to angina.

RESULTS

A total of 301 patients underwent randomization: 151 to the PCI group and 150 to the placebo group. The mean (±SD) age was 64±9 years, and 79% were men. Ischemia was present in one cardiac territory in 242 patients (80%), in two territories in 52 patients (17%), and in three territories in 7 patients (2%). In the target vessels, the median fractional flow reserve was 0.63 (interquartile range, 0.49 to 0.75), and the median instantaneous wave-free ratio was 0.78 (interquartile range, 0.55 to 0.87). At the 12-week follow-up, the mean angina symptom score was 2.9 in the PCI group and 5.6 in the placebo group (odds ratio, 2.21; 95% confidence interval, 1.41 to 3.47; P<0.001). One patient in the placebo group had unacceptable angina leading to unblinding. Acute coronary syndromes occurred in 4 patients in the PCI group and in 6 patients in the placebo group.

CONCLUSIONS

Among patients with stable angina who were receiving little or no antianginal medication and had objective evidence of ischemia, PCI resulted in a lower angina symptom score than a placebo procedure, indicating a better health status with respect to angina. (Funded by the National Institute for Health and Care Research Imperial Biomedical Research Centre and others; ORBITA-2 ClinicalTrials.gov number, NCT03742050.).

Revascularisation or medical therapy in elderly patients with acute anginal syndromes: the RINCAL randomised trial

BACKGROUND

Historically the elderly have been under-represented in non-ST-elevation myocardial infarction (NSTEMI) management trials.

AIMS

The aim of this trial was to demonstrate that an intervention-guided strategy is superior to optimal medical therapy (OMT) alone for treating NSTEMI in elderly individuals.

METHODS

Patients (≥80 years, chest pain, ischaemic ECG, and elevated troponin) were randomised 1:1 to an intervention-guided strategy plus OMT versus OMT alone. The primary endpoint was a composite of all-cause mortality and non-fatal myocardial reinfarction at 1 year. Ethics approval was obtained by the institutional review board of every recruiting centre.

RESULTS

From May 2014 to September 2018, 251 patients (n=125 invasive vs n=126 conservative) were enrolled. Almost 50% of participants were female. The trial was terminated prematurely due to slow recruitment. A Kaplan-Meier estimate of event-free survival revealed no difference in the primary endpoint at 1 year (invasive 18.5% [23/124] vs conservative 22.2% [28/126]; p=0.39). No significant difference persisted after Cox proportional hazards regression analysis (hazard ratio 0.79, 95% confidence interval 0.45-1.35; p=0.39). There was greater freedom from angina at 3 months (p<0.001) after early intervention but this was similar at 1 year. Both non-fatal reinfarction (invasive 9.7% [12/124] vs conservative 14.3% [18/126]; p=0.22) and unplanned revascularisation (invasive 1.6% [2/124] vs conservative 6.4% [8/126]; p=0.10) occurred more frequently in the OMT alone cohort.

CONCLUSIONS

An intervention-guided strategy was not superior to OMT alone to treat very elderly NSTEMI patients. The trial was underpowered to demonstrate this definitively. Early intervention resulted in fewer cases of reinfarction and unplanned revascularisation but did not improve survival.

Prognostic benefit of transcatheter aortic valve implantation compared with medical therapy in patients with inoperable aortic stenosis

OBJECTIVES

To compare survival in patients with inoperable aortic stenosis who undergo transcatheter aortic valve implantation against those managed medically.

BACKGROUND

Without surgical correction, survival of patients with severe symptomatic aortic stenosis is poor. It is unknown whether patients undergoing transcatheter aortic valve implantation (TAVI) have a better prognosis than similar patients who are treated with medical management.

METHODS

Survival rates were compared in consecutive patients with severe symptomatic aortic stenosis who either underwent TAVI or continued on medical management following multidisciplinary team assessment. All patients had been turned down, or considered at unacceptably high risk, for conventional aortic valve surgery. Patients were reviewed in clinic or by telephone six monthly. Mortality data was obtained from the United Kingdom Office of National Statistics.

RESULTS

The study group included 85 patients aged 81 +/- 7 years (range 62-94), of whom 48 were male. Thirty eight patients underwent TAVI while 47 patients were deemed unsuitable based on echocardiographic, angiographic, or clinical criteria and remained on medical therapy. The calculated EuroSCORE for the TAVI group was 11 +/- 2 and for the medical group 9 +/- 2 (P < 0.001). TAVI-related procedural mortality was 2.6%, and 30-day mortality was 5.2%. Among the medically-treated patients, 14 (30%) underwent palliative balloon aortic valvuloplasty, with a trend toward improved survival (P = 0.06). During overall follow-up of 215 +/- 115 days there were a total of 18 deaths; TAVI N = 5 (13%); Medical N = 13 (28%) (P = 0.04).

CONCLUSIONS

Patients with severe aortic valve disease who are not suitable for surgical aortic valve replacement have an improved prognosis if treated with transcatheter aortic valve implantation rather than continuing on medical management alone.

Tomato root growth, gravitropism, and lateral development: correlation with auxin transport

Tomato (Lycopersicon esculentum, Mill.) roots were analyzed during growth on agar plates. Growth of these roots was inhibited by the auxin transport inhibitors naphthylphthalamic acid (NPA) and semicarbazone derivative I (SCB-1). The effect of auxin transport inhibitors on root gravitropism was analyzed by measurement of the angle of gravitropic curvature after the roots were reoriented 90 degrees from the vertical. NPA and SCB-1 abolished both the response of these roots to gravity and the formation of lateral roots, with SCB-1 being the more effective at inhibition. Auxins also inhibited root growth. Both auxins tested has a slight effect on the gravity response, but this effect is probably indirect, since auxins reduced the growth rate. Auxins also stimulated lateral root growth at concentration where primary root growth was inhibited. When roots were treated with both IAA and NPA simultaneously, a cumulative inhibition of root growth was found. When both compounds were applied together, analysis of gravitropism and lateral root formation indicated that the dominant effect was exerted by auxin transport inhibitors. Together, these data suggest a model for the role of auxin transport in controlling both primary and lateral root growth.

Evidence for a Single Naphthylphthalamic Acid Binding Site on the Zucchini Plasma Membrane

The binding of [2,3,4,5,(n)-3H]N-1-napthylphthalamicacid ([3H]-NPA) to zucchini (Cucurbita pepo L.) plasma membranes was examined in detail using two different filtration assays and the results were rigorously analyzed by saturation curves, double-reciprocal plots, Scatchard plots, Hill plots, and the computer program Ligand (P.J. Munson, D. Rodbard [1980] Anal Biochem 107: 220-239). To facilitate these analyses, a new assay that allows rapid and quantitative analysis of [3H]NPA binding with high reproducibility and ease of manipulation has been developed. These detailed kinetic analyses indicate that only one binding site for [3H]NPA (Kd = 16 nM) was associated with the zucchini plasma membrane. Analysis of [3H]NPA dissociation by several auxin transport inhibitors revealed similar dissociation constants with both plasma and microsomal membrane. Collectively, these data indicate the presence of only one binding site for NPA associated with the zucchini plasma membrane.

Auxin transport and the interaction of phytotropins: probing the properties of a phytotropin binding protein

We have described the inhibition of polar auxin transport by several phytotropins including 1-N-naphthylphthalamic acid (NPA) and quercetin. Semicarbazones (substituted phenylsemicarbazones of 2-acetylarylcarboxylic acids) are inhibitors consistent with previously predicted general structural requirements for auxin transport inhibitors. The best semicarbazone derivative tested to date, hereafter called SCB-I, binds to the NPA binding protein with high affinity, K(b) = 4 nanomolar. Quantification of the binding of various phytotropins allows us to make some general statements concerning the structure/properties of the NPA binding protein. The data suggest that the ligand binding region of this protein is multifaceted, a conclusion supported by the chemical predictions of Katekar and Geissler ([1977] Plant Physiol 60: 826-829). Although the data do not allow us to make specific conclusions on the structure of the binding site, they do show that both NPA and SCB-I could each occupy two regions of the protein. At least one of these binding regions appears to be common for both inhibitors of auxin transport. We suggest that the diversity of the binding site structure reflects the possible existence of more than one type of natural ligand controlling the process of auxin transport.

The generation of singlet oxygen (o(2)) by the nitrodiphenyl ether herbicide oxyfluorfen is independent of photosynthesis

The mechanism of action of the p-nitrodiphenyl ether herbicides has remained ambiguous because of conflicting reports in the literature. The diphenyl ether herbicide oxyfluorfen causes a light induced consumption of oxygen which resembles the electron acceptor reaction of paraquat. However, this reaction is not linked to the transport of electrons through photosystem I. This conclusion is based on the observation that the rate of oxygen consumption, in the presence of oxyfluorfen, does not demonstrate a first order rate dependence on light intensity. Using the bleaching of N,N-dimethyl p-nitrosoaniline as a specific detector of singlet oxygen, we demonstrate that oxyfluorfen is a potent generator of this toxic radical. The production of singlet oxygen occurs in the presence of inhibitors of photosynthetic electron transport (oxyfluorfen at 10(-4) molar and paraquat) and also under temperature conditions (3 degrees C) which prevent electron transport. This light induced reaction results in oxygen consumption and is the primary cause of lethality for oxyfluorfen. The production of singlet oxygen occurs rapidly and at low herbicide concentrations (10(-9) molar). The reaction occurs without photosynthetic electron transport but does require an intact thylakoid membrane.

Amino Acid Metabolism of Lemna minor L. : II. Responses to Chlorsulfuron

Chlorsulfuron, an inhibitor of acetolactate synthase (EC 4.1.3.18) (TB Ray 1984 Plant Physiol 75: 827-831), markedly inhibited the growth of Lemna minor at concentrations of 10(-8) molar and above, but had no inhibitory effects on growth at 10(-9) molar. At growth inhibitory concentrations, chlorsulfuron caused a pronounced increase in total free amino acid levels within 24 hours. Valine, leucine, and isoleucine, however, became smaller percentages of the total free amino acid pool as the concentration of chlorsulfuron was increased. At concentrations of chlorsulfuron of 10(-8) molar and above, a new amino acid was accumulated in the free pool. This amino acid was identified as alpha-amino-n-butyrate by chemical ionization and electron impact gas chromatography-mass spectrometry. The amount of alpha-amino-n-butyrate increased from undetectable levels in untreated plants, to as high as 840 nanomoles per gram fresh weight (2.44% of the total free pool) in plants treated with 10(-4) molar chlorsulfuron for 24 hours. The accumulation of this amino acid was completely inhibited by methionine sulfoximine. Chlorsulfuron did not inhibit the methionine sulfoximine induced accumulations of valine, leucine, and isoleucine, supporting the idea that the accumulation of the branched-chain amino acids in methionine sulfoximine treated plants is the result of protein turnover rather than enhanced synthesis. Protein turnover may be primarily responsible for the failure to achieve complete depletion of valine, leucine, and isoleucine even at concentrations of chlorsulfuron some 10(4) times greater than that required to inhibit growth. Tracer studies with (15)N demonstrate that chlorsulfuron inhibits the incorporation of (15)N into valine, leucine, and isoleucine. The alpha-amino-n-butyrate accumulated in the presence of chlorsulfuron and [(15)N]H(4) (+) was heavily labeled with (15)N at early time points and appeared to be derived by transamination from a rapidly labeled amino acid such as glutamate or alanine. We propose that chlorsulfuron inhibition of acetolactate synthase may lead to accumulation of 2-oxobutyrate in the isoleucine branch of the pathway, and transamination of 2-oxobutyrate to alpha-amino-n-butyrate by a constitutive transaminase utilizing either glutamate or alanine as alpha-amino-N donors.

Interaction of Herbicides and Quinone with the Q(B)-Protein of the Diuron-Resistant Chlamydomonas reinhardtii Mutant Dr2

We have used the diuron-resistant Dr2 mutant of Chlamydomonas reinhardtii which is altered in the 32 kilodalton Q(B)-protein at amino acid 219 (valine to isoleucine), to investigate the interactions of herbicides and plastoquinone with the 32 kilodalton Q(B)-protein. The data contained in this report demonstrate that the effects of this mutation are different from those of the more completely characterized mutant which confers extreme resistance to triazines in higher plants. The mutation in C. reinhardtii Dr2 confers only slight resistance to a number of inhibitors of photosynthetic electron transport. Extreme triazine resistance results from an increase in the binding constant of the herbicide with the 32 kilodalton Q(B)-protein, in contrast the diuron binding constant for chloroplasts isolated from wild-type (sensitive) Chlamydomonas and the resistant Dr2 are indistinguishable. We conclude that the altered structure in the 32 kilodalton Q(B)-protein of Dr2 does not directly affect the diuron binding site. This mutation appears to alter the steric properties of the binding protein in such a way that diuron and plastoquinone do not directly compete for binding. This steric perturbation confers mild resistance to other herbicidal inhibitors of photosynthesis and alters the kinetics of Q(A) to Q(B) electron transfer.

Amino Acid Metabolism of Lemna minor L. : I. Responses to Methionine Sulfoximine

When Lemna minor L. is supplied with the potent inhibitor of glutamine synthetase, methionine sulfoximine, rapid changes in free amino acid levels occur. Glutamine, glutamate, asparagine, aspartate, alanine, and serine levels decline concomitantly with ammonia accumulation. However, not all free amino acid pools deplete in response to this inhibitor. Several free amino acids including proline, valine, leucine, isoleucine, threonine, lysine, phenylalanine, tyrosine, histidine, and methionine exhibit severalfold accumulations within 24 hours of methionine sulfoximine treatment. To investigate whether these latter amino acid accumulations result from de novo synthesis via a methionine sulfoximine insensitive pathway of ammonia assimilation (e.g. glutamate dehydrogenase) or from protein turnover, fronds of Lemna minor were prelabeled with [(15)N]H(4) (+) prior to supplying the inhibitor. Analyses of the (15)N abundance of free amino acids suggest that protein turnover is the major source of these methionine sulfoximine induced amino acid accumulations. Thus, the pools of valine, leucine, isoleucine, proline, and threonine accumulated in response to the inhibitor in the presence of [(15)N]H(4) (+), are (14)N enriched and are not apparently derived from (15)N-labeled precursors. To account for the selective accumulation of amino acids, such as valine, leucine, isoleucine, proline, and threonine, it is necessary to envisage that these free amino acids are relatively poorly catabolized in vivo. The amino acids which deplete in response to methionine sulfoximine (i.e. glutamate, glutamine, alanine, aspartate, asparagine, and serine) are all presumably rapidly catabolized to ammonia, either in the photorespiratory pathway or by alternative routes.

Protein phosphorylation-induced State I-State II transitions are dependent on thylakoid membrane microviscosity

Incorporation of cholesterol hemisuccinate into thylakoid membranes decreased the membrane fluidity as measured by polarized fluorescence from 1,6-diphenyl-1,3,5-hexatriene. Increasing membrane viscosity in this manner did not inhibit the thylakoid membrane protein kinase. In contrast the effects of the protein phosphorylation on State I-State II transitions, which were observed in untreated membranes, were abolished. This observation is interpreted as indicating that protein phosphorylation-induced energy transfer changes are sensitive to membrane viscosity because they might require a lateral migration of the light-harvesting complex serving Photosystem II from grana to stromal lamellae. Cation effects on room- and low-temperature fluorescence emission properties and membrane adhesion were not abolished in these cholesterol hemisuccinate-treated membranes.