Is TAVI superior to surgery in high-risk patients? Insight into the concept of individual risk assessment

The prevalence of aortic valve stenosis (AS) is growing in developed countries because its prevalence increases with age. A growing number of elderly patients are currently referred to specialized centres to be evaluated for potential therapeutic strategies. Indeed, two techniques are nowadays able to treat high-risk AS patients: TAVI and surgical replacement (AVR). It is the purpose of the present review to summarize current knowledge on safety and efficacy of AVR and TAVI in high-risk patients; to focus on some aspects of recently published guidelines; to emphasize the growing importance of pre-operative individual risk assessment, which is considered the real crucial point for patient selection and trial's comparisons. Indeed, it is worth of noting that currently adopted risk-scores do not show satisfactory performances. Accordingly, it becomes of utmost importance to investigate several baseline but still neglected patients' characteristics (e.g. frailty, functional status, co-morbid conditions, etc.), as well as their pathogenetic relationships with interventional results and follow-up prognosis. All these items are emphasized in the present review. Finally, we have tried to anticipate future scenarios in terms of both ongoing clinical trials and improvements of risk-scores.

Tobacco smoke affects expression of peroxisome proliferator-activated receptor-gamma in monocyte/macrophages of patients with coronary heart disease

BACKGROUND AND PURPOSE

Tobacco smoke represents a relevant risk factor for coronary heart disease (CHD). Although peroxisome proliferator-activated receptor (PPAR)gamma activation reduces inflammation and atherosclerosis, expression of PPARgamma in cells and its modulation by smoking are poorly investigated. We previously reported that monocyte/macrophages from healthy smokers exhibited an enhanced constitutive expression of PPARgamma. Here, we evaluated PPARgamma expression and basal cytokine release in monocytes and monocyte-derived macrophages (MDMs) from 85 CHD patients, classified by their smoking habit (smokers, non-smokers and ex-smokers), and assessed the role of PPARgamma ligands in this context.

EXPERIMENTAL APPROACH

PPARgamma protein was detected by Western blot and semi-quantified by PPARgamma/beta-actin ratio; cytokine release was measured by elisa and nuclear factor-kappaB (NF-kappaB) translocation by electrophoretic mobility shift assays.

KEY RESULTS

As compared to the other groups, MDMs from smoker CHD patients exhibited a reduced PPARgamma/beta-actin ratio and an increased spontaneous release of tumour necrosis factor-alpha (TNF-alpha) and interleukin-6, but with no major variations in monocytes. In cells from selected CHD patients, rosiglitazone inhibited TNF-alpha release and NF-kappaB translocation induced by phorbol-12-myristate 13-acetate. The selective PPARgamma antagonist GW9662 reversed these effects, with some variations related to smoking habit.

CONCLUSIONS AND IMPLICATIONS

In CHD patients, exposure to tobacco smoke profoundly affected PPARgamma expression, and this was related to levels of secretion of pro-inflammatory cytokines. MDMs from CHD smokers showed the lowest PPARgamma expression and released more inflammatory cytokines. Moreover, rosiglitazone's ability to inhibit cytokine release and its reversal by GW9662 clearly indicated PPARgamma involvement in these changes in CHD patients.

A novel activity for substance P: stimulation of peroxisome proliferator-activated receptor-gamma protein expression in human monocytes and macrophages

BACKGROUND AND PURPOSE

Substance P (SP) and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) play important roles in different inflammatory conditions and are both expressed in human monocytes and macrophages. However, it is not known whether or not they interact. This study was undertaken to evaluate the effects of SP on PPAR-gamma protein expression in monocytes and macrophages (MDMs: monocyte-derived macrophages) from healthy smokers and non-smokers.

EXPERIMENTAL APPROACH

PPAR-gamma protein was detected by western blot and quantified by calculating the ratio between PPAR-gamma and beta-actin protein expression. Constitutive tachykinin NK(1) receptor expression in monocytes and MDMs from healthy smokers and non-smokers was evaluated by western blot. Cytokine release was evaluated by ELISA.

KEY RESULTS

In the concentration range 10(-10)-10(-6) M, SP stimulated PPAR-gamma protein expression in monocytes and MDMs, being more effective in cells from healthy smokers. Moreover, in these cells there was a constitutively increased expression of NK(1) receptors. SP-induced expression of the PPAR-gamma protein was receptor-mediated, as it was reproduced by the NK(1) selective agonist [Sar(9)Met(O(2))(11)]SP and reversed by the competitive NK(1) antagonist GR71251. SP-induced maximal effects were similar to those evoked by 15-deoxy-Delta(12,14)-prostaglandin J(2); an endogenous PPAR-gamma agonist, and were significantly reduced by a PPAR-gamma antagonist. NK(1) and PPAR-gamma agonists exerted opposite effects on TNF-alpha release from monocytes and MDMs.

CONCLUSIONS AND IMPLICATIONS

Enhancement of PPAR-gamma protein expression represents a novel activity for SP, which could contribute to a range of chronic inflammatory disorders.

The role of nitric oxide in the peripheral vasoconstriction caused by human placental lactogen in anaesthetized pigs

Regional intra-arterial infusion of human placental lactogen in anaesthetized pigs has been shown to cause coronary, renal and iliac vasoconstriction by antagonizing the vasodilatory effects of beta2-adrenergic receptors. Since nitric oxide is known to modulate or mediate beta2-adrenergic effects, the present study was planned in the same experimental model to determine the role of nitric oxide in the above vascular responses to human placental lactogen. In eight pigs anaesthetized with sodium pentobarbitone, changes in anterior descending coronary, left renal and left internal iliac blood flow caused by intra-arterial infusion of human placental lactogen at constant heart rate and arterial blood pressure were assessed using electromagnetic flowmeters. Intra-arterial infusion of the human placental lactogen caused decreases in coronary, renal and iliac blood flow which, respectively, averaged 16.7, 8.1 and 12.2% of the baseline values. The role of nitric oxide in this response was studied in the same pigs by repeating the experiments, after measured blood flows had returned to baseline values, following intra-arterial administration of N(omega)-nitro-L-arginine methyl ester (L-NAME). The subsequent intra-arterial infusion of human placental lactogen did not cause any significant changes in measured blood flows, even when performed after reversing the increase in arterial blood pressure and coronary, renal and iliac resistance caused by L-NAME with continuous intravenous infusion of papaverine. These results indicate that the coronary, renal and iliac vasoconstriction caused by human placental lactogen, known to involve antagonism of beta2-adrenergic vasodilatory effects, was mediated by inhibition of nitric oxide release.

Human Placental Lactogen Decreases Regional Blood Flow in Anesthetized Pigs

In 22 pigs anesthetized with sodium pentobarbitone, changes in blood flow caused by infusion of human placental lactogen into the left renal, external iliac, and anterior descending coronary arteries were assessed using electromagnetic flowmeters. In 17 pigs, infusion of human placental lactogen whilst keeping the heart rate and arterial pressure constant decreased coronary, renal and iliac flow. In 5 additional pigs, increasing the dose of human placental lactogen produced a dose-related decrease in regional blood flow. The mechanisms of the above response were studied in 15 of the 17 pigs by repeating the experiment of infusion. The human placental lactogen-induced decrease in regional blood flow was not affected by blockade of cholinergic receptors (5 pigs) or of alpha-adrenergic receptors (5 pigs), but it was abolished by blockade of beta2-adrenergic receptors (5 pigs). The present study showed that intra-arterial infusion of human placental lactogen primarily decreased coronary, renal and iliac blood flow. The mechanism of this response was shown to be due to the inhibition of a vasodilatory beta2-adrenergic receptor-mediated effect.

Tissue plasminogen activator antigen is strongly associated with myocardial infarction in young women

Women who develop acute myocardial infarction (AMI) at a young age have fewer classical risk factors and less coronary stenosis than older women. In this rare population, it is plausible that a heightened hemostatic system may play an important mechanistic role in thrombus formation and in the development of AMI. We chose to investigate whether or not there is an association between premature AMI and the plasma concentrations of five hemostatic measurements that had been previously established as risk factors for AMI, and of the inflammation marker C-reactive protein (CRP). Women who had survived AMI at the age of 45 years or less (n = 141) were drawn from those admitted to 125 Italian coronary care units over a 3-year period. In them, and in an equal number of controls, plasma levels of immunoreactive tissue plasminogen activator (tPA), plasminogen activation inhibitor 1 (PAI-1), von Willebrand factor (VWF), fibrinogen, D-dimer and CRP were measured. Higher levels of VWF, fibrinogen, CRP and tPA were associated with AMI. After adjustment for both classical and hemostatic risk factors, only tPA maintained an independent association with AMI: the odds ratios (taken as an index of relative risk) for tPA values in the middle and higher tertiles were 2.86 (CI 1.63-5.02) and 8.18 (CI 2.66-25.20), respectively. In conclusion, there is a strong association between non-fatal AMI and increased plasma levels of tPA antigen. This finding is thought to be the expression of a reduced rather than enhanced fibrinolytic activity.