Beta-blockers for hypertension

BACKGROUND

Two recent systematic reviews found first-line beta-blockers to be less effective in reducing the incidence of stroke and the combined endpoint of stroke, myocardial infarction, and death compared to all other antihypertensive drugs taken together. However, beta-blockers might be better or worse than a specific class of drugs for a particular outcome measure so that comparing beta-blockers with all other classes taken together could be misleading. In addition, these systematic reviews did not assess the tolerability of beta-blockers relative to other antihypertensive medications. We thus undertook this review to re-assess the place of beta-blockade as first-line therapy for hypertension relative to each of the other major classes of antihypertensive drugs.

OBJECTIVES

To quantify the effectiveness and safety of beta-blockers on morbidity and mortality endpoints in adults with hypertension.

SEARCH STRATEGY

We searched eligible studies up to June 2006 in the Cochrane Controlled Trials Register, Medline, Embase, and reference lists of previous reviews, and by contacting hypertension experts.

SELECTION CRITERIA

We selected randomised controlled trials which assessed the effectiveness of beta-blockers compared to placebo, no therapy or other drug classes, as monotherapy or first-line therapy for hypertension, on mortality and morbidity endpoints in men and non-pregnant women aged 18 years or older.

DATA COLLECTION AND ANALYSIS

At least two authors independently applied study selection criteria, assessed study quality, and extracted data; with differences resolved by consensus. We expressed study results as relative risks (RR) with 95% confidence intervals (CI) and conducted quantitative analyses with trial participants in groups to which they were randomly allocated, regardless of which or how much treatment they actually received. In the absence of significant heterogeneity between studies (p>0.1), we performed meta-analysis using a fixed effects method. Otherwise, we used the random effects method and investigated the cause of heterogeneity by stratified analysis. In addition, we used the Higgins statistic (I(2)) to quantify the amount of between-study variability in effect attributable to true heterogeneity rather than chance.

MAIN RESULTS

Thirteen randomised controlled trials (N=91,561 participants), which met our inclusion criteria, compared beta-blockers to placebo or no treatment (4 trials with 23,613 participants), diuretics (5 trials with 18,241 participants), calcium-channel blockers (CCBs: 4 trials with 44,825 participants), and renin-angiotensin system (RAS) inhibitors (3 trials with 10,828 participants). The risk of all-cause mortality was not different between first-line beta-blockers and placebo (RR 0.99, 95%CI 0.88 to 1.11, I(2)=0%), diuretics or RAS inhibitors, but was higher for beta-blockers compared to CCBs (RR 1.07, 95%CI 1.00 to 1.14, I(2)=2.2%; ARI=0.5%, NNH=200). The risk of total cardiovascular disease (CVD) was lower for first-line beta-blockers compared to placebo (RR 0.88, 95%CI 0.79 to 0.97, I(2)=21.4%, ARR=0.7%, NNT=140). This is primarily a reflection of the significant decrease in stroke (RR 0.80, 95%CI 0.66 to 0.96; I(2)=0%; ARR=0.5%, NNT=200); coronary heart disease (CHD) risk was not significantly different between beta-blockers and placebo. The effect of beta-blockers on CVD was significantly worse than that of CCBs (RR 1.18, 95%CI 1.08 to 1.29, I(2)=0%; ARI=1.3%, NNH=80), but was not significantly different from that of diuretics or RAS inhibitors. Increased total CVD was due to an increase in stroke compared to CCBs (RR 1.24, 95%CI 1.11 to 1.40, I(2)=0%; ARI=0.6%, NNH=180). There was also an increase in stroke with beta-blockers as compared to RAS inhibitors (RR 1.30, 95%CI 1.11 to 1.53, I(2)=29.1%; ARI=1.5%, NNH=65). CHD was not significantly different between beta-blockers and diuretics or CCBs or RAS inhibitors. In addition, patients on beta-blockers were more likely to discontinue treatment due to side effects than those on diuretics (RR 1.86, 95%CI 1.39 to 2.50, I(2)=78.2%, ARI=6.4% NNH=16) and RAS inhibitors (RR 1.41, 95%CI 1.29 to 1.54, I(2)=12.1%; ARI=5.5%, NNH=18), but there was no significant difference with CCBs.

AUTHORS' CONCLUSIONS

The available evidence does not support the use of beta-blockers as first-line drugs in the treatment of hypertension. This conclusion is based on the relatively weak effect of beta-blockers to reduce stroke and the absence of an effect on coronary heart disease when compared to placebo or no treatment. More importantly, it is based on the trend towards worse outcomes in comparison with calcium-channel blockers, renin-angiotensin system inhibitors, and thiazide diuretics. Most of the evidence for these conclusions comes from trials where atenolol was the beta-blocker used (75% of beta-blocker participants in this review). However, it is not known at present whether beta-blockers have differential effects on younger and elderly patients or whether there are differences between the different sub-types of beta-blockers.

Diazoxide-induced respiratory inhibition - a putative mitochondrial K(ATP) channel independent mechanism of pharmacological preconditioning

The ischemic preconditioning biological phenomenon has been explored to identify putative pharmacologic agents to mimic this cytoprotective program against cellular ischemic injury. Diazoxide administration confers this cytoprotection, however, whether this is via direct activation of the putative mitochondrial K(ATP) (mK(ATP)) channel which was originally proposed has been questioned. Here, we present data supporting an alternate hypothesis evoking mitochondrial respiratory inhibition rather than mK(ATP) channel activation, as a mediating event in the diazoxide-activated cytoprotective program. Mitochondrial respiration and reactive oxygen species (ROS) production was measured in digitonin-permeabilized C2C12 myotubes, allowing for the modulation of mK(ATP) conductance by changing the potassium concentration of the medium (0-130 mM). Diazoxide dose-dependently attenuated succinate-supported respiration, an effect that was independent of mK(ATP) channel conductance. Similarly, 5-hydroxydecanoate (5-HD), a putative mK(ATP) channel blocker, released diazoxide-induced respiratory inhibition independently of potassium concentration. Since diazoxide-induced cytoprotection and respiratory inhibition are both integrally linked to ROS generation we repeated above experiments following ROS generation using DCF fluorescence. Cytoprotective doses of diazoxide increased ROS generation independently of potassium concentration and 5-HD inhibited ROS production under the same conditions. Collectively these data support the hypothesis that diazoxide-mediated cytoprotection is independent of the conductance of the mK(ATP) channel and rather implicate mitochondrial respiratory inhibition-triggered ROS signaling.

Free Fatty Acid Depletion Acutely Decreases Cardiac Work and Efficiency in Cardiomyopathic Heart Failure

Background— Metabolic modulators that enhance myocardial glucose metabolism by inhibiting free fatty acid (FFA) metabolism may improve cardiac function in heart failure patients. We studied the effect of acute FFA withdrawal on cardiac function in patients with heart failure caused by idiopathic dilated cardiomyopathy (IDCM).

Methods and Results— Eighteen fasting nondiabetic patients with IDCM (14 men, 4 women, aged 58.8±8.0 years, ejection fraction 33±8.8%) and 8 matched healthy controls underwent examination of myocardial perfusion and oxidative and FFA metabolism, before and after acute reduction of serum FFA concentrations by acipimox, an inhibitor of lipolysis. Metabolism was monitored by positron emission tomography and [ 15 O]H 2 O, [ 11 C]acetate, and [ 11 C]palmitate. Left ventricular function and myocardial work were echocardiographically measured, and efficiency of forward work was calculated. Acipimox decreased myocardial FFA uptake by >80% in both groups. Rate–pressure product and myocardial perfusion remained unchanged, whereas stroke volume decreased similarly in both groups. In the healthy controls, reduced cardiac work was accompanied by decreased oxidative metabolism (from 0.071±0.019 to 0.055±0.016 min −1 , P <0.01). In IDCM patients, cardiac work fell, whereas oxidative metabolism remained unchanged and efficiency fell (from 35.4±12.6 to 31.6±13.3 mm Hg · L · g −1 , P <0.05).

Conclusions— Acutely decreased serum FFA depresses cardiac work. In healthy hearts, this is accompanied by parallel decrease in oxidative metabolism, and myocardial efficiency is preserved. In failing hearts, FFA depletion did not downregulate oxidative metabolism, and myocardial efficiency deteriorated. Thus, failing hearts are unexpectedly more dependent than healthy hearts on FFA availability. We propose that both glucose and fatty acid oxidation are required for optimal function of the failing heart.

How strong is the evidence for use of beta-blockers as first-line therapy for hypertension? Systematic review and meta-analysis

OBJECTIVE

To quantify the effect of first-line antihypertensive treatment with beta-blockers on mortality, morbidity and withdrawal rates, compared with the other main classes of antihypertensive agents.

METHODS

We identified eligible trials by searching the Cochrane Controlled Trials Register, Medline, Embase, reference lists of previous reviews, and contacting researchers. We extracted data independently in duplicate and conducted meta-analysis by analysing trial participants in groups to which they were randomized, regardless of subsequent treatment actually received.

RESULTS

Thirteen trials with 91,561 participants, meeting inclusion criteria, compared beta-blockers to placebo (four trials; n = 23,613), diuretics (five trials; n = 18,241), calcium-channel blockers (CCBs) (four trials; n = 44,825), and renin-angiotensin system (RAS) inhibitors, namely angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (three trials; n = 10,828). Compared to placebo, beta-blockers reduced the risk of stroke (relative risk 0.80; 95% confidence interval 0.66-0.96) with a marginal fall in total cardiovascular events (0.88, 0.79-0.97), but did not affect all-cause mortality (0.99, 0.88-1.11), coronary heart disease (0.93, 0.81-1.07) or cardiovascular mortality (0.93, 0.80-1.09). The effect on stroke was less than that of CCBs (1.24, 1.11-1.40) and RAS inhibitors (1.30, 1.11-1.53), and that on total cardiovascular events less than that of CCBs (1.18, 1.08-1.29). In addition, patients on beta-blockers were more likely to discontinue treatment than those on diuretics (1.80; 1.33-2.42) or RAS inhibitors (1.41; 1.29-1.54).

CONCLUSION

Beta-blockers are inferior to CCBs and to RAS inhibitors for reducing several important hard end points. Compared with diuretics, they had similar outcomes, but were less well tolerated. Hence beta-blockers are generally suboptimal first-line antihypertensive drugs.

Cardiovascular disease prevention with a multidrug regimen in the developing world: a cost-effectiveness analysis

BACKGROUND

Cardiovascular disease is the leading cause of death, with 80% of cases occurring in developing countries. We therefore aimed to establish whether use of evidence-based multidrug regimens for patients at high risk for cardiovascular disease would be cost-effective in low-income and middle-income countries.

METHODS

We used a Markov model to do a cost-effectiveness analysis with two combination regimens. For primary prevention, we used aspirin, a calcium-channel blocker, an angiotensin-converting-enzyme inhibitor, and a statin, and assessed them in four groups with different thresholds of absolute risks for cardiovascular disease. For secondary prevention, we assessed the same combination of drugs in one group, but substituted a beta blocker for the calcium-channel blocker. To compare strategies, we report incremental cost-effectiveness ratios (ICER), in US dollars per quality-adjusted life-year (QALY).

FINDINGS

We recorded that preventive strategies could result in a 2-year gain in life expectancy. Across six developing World Bank regions, primary prevention yielded ICERs of US746-890 dollars/QALY gained for patients with a 10-year absolute risk of cardiovascular disease greater than 25%, and 1039-1221 dollars/QALY gained for those with an absolute risk greater than 5%. ICERs for secondary prevention ranged from 306 dollars/QALY to 388 dollars/QALY gained.

INTERPRETATION

Regimens of aspirin, two blood-pressure drugs, and a statin could halve the risk of death from cardiovascular disease in high-risk patients. This approach is cost-effective according to WHO recommendations, and is robust across several estimates of drug efficacy and of treatment cost. Developing countries should encourage the use of these inexpensive drugs that are currently available for both primary and secondary prevention.

Ceramide attenuates hypoxic cell death via reactive oxygen species signaling

We have previously demonstrated that tumor necrosis factor alpha (TNFalpha), a cytokine known to be induced by ischemia, independently promotes preconditioning in part via ceramide generation. As reactive oxygen species (ROS) signaling is evoked by ischemic preconditioning, by TNFalpha and by ceramide we reasoned that ceramide-induced preconditioning is ROS-mediated. Fibroblastic L-cells were subjected to 8 hours simulated ischemia and were preconditioned by pretreatment with cell permeable c2 ceramide (1 microM) with or without the antioxidant N-mercaptopropionyl glycine (MPG; 1 mM). Pretreatment with ceramide reduced lactate dehydrogenase release at the end of the simulated ischemia but this cytoprotective effect was lost in the presence of MPG. Concurrent temporal ROS generation was measured using confocal microscopy on cells stained with dichlorofluorescein diacetate (DCF-DA). Ceramide increased ROS production after 30 minutes and this induction was decreased by MPG. Incubation of ceramide with cyclooxygenase-2 inhibitor, NS 398 (10 microM), or with a mitochondrial respiratory chain inhibitor, rotenone (10 microM) reduced the cytoprotective effect of ceramide in parallel with a partial diminution in ROS generation. In contrast, inhibition of other ROS-producing systems including nitric oxide synthase, xanthine oxidase, or NADPH oxidase failed to modulate ceramide-induced cytoprotection. Collectively, these data demonstrate that ceramide induces a cell survival program through ROS signaling activated, in part, via cyclooxygenase and the mitochondrial respiratory chain.

Adverse effects of free fatty acid associated with increased oxidative stress in postischemic isolated rat hearts

The mechanisms of the adverse effects of free fatty acids on the ischemic-reperfused myocardium are not fully understood. Long-chain fatty acids, including palmitate, uncouple oxidative phosphorylation and should therefore promote the formation of oxygen-derived free radicals, with consequent adverse effects. Conversely, the antianginal agent trimetazidine (TMZ), known to inhibit cardiac fatty acid oxidation, could hypothetically lessen the formation of reactive oxygen species (ROS) and thus improve reperfusion mechanical function. Isolated perfused rat hearts underwent 30 min of total global ischemia followed by 30 min of reperfusion. Hearts were perfused with glucose 5.5 mmol/l or palmitate 1.5 mmol/l with or without TMZ (100 micromol/l). Ascorbyl free radical (AFR) release during perfusion periods was measured by electron spin resonance as a marker of oxidative stress. Post-ischemic recovery in the palmitate group of heart was lower than in the glucose group with a marked rise in diastolic tension and reduction in left ventricular developed pressure (Glucose: 85 +/- 11 mmHg; Palmitate: 10 +/- 6 mmHg; p < 0.001). TMZ decreased diastolic tension in both glucose- and in palmitate-perfused hearts. Release of AFR within the first minute of reperfusion was greater in palmitate-perfused hearts and in hearts perfused with either substrate, this marker of oxidative stress was decreased by TMZ (expressed in arbitrary units/ml; respectively: 8.49 +/- 1.24 vs. 1.06 +/- 0.70 p < 0.05; 12.47 +/- 2.49 vs. 3.37 +/- 1.29 p < 0.05). Palmitate increased the formation of ROS and reperfusion contracture. TMZ, a potential inhibitor of palmitate-induced mitochondrial uncoupling, decreased the formation of free radicals and improved postischemic mechanical dysfunction. The novel conclusion is that adverse effects of fatty acids on ischemic-reperfusion injury may be mediated, at least in part, by oxygen-derived free radicals.

Cardiologists are living through exciting times. The example of postconditioning to protect the human heart during revascularization

The exciting work the group of Jennings, published in Circulation in 1986, has established a new and powerful form of cardioprotection, whereby exposure to short bouts of repeated ischemia interspersed by reperfusion protects from a subsequent prolonged and potentially very serious major ischemic attack. Similar protection by postconditioning can be achieved by short bursts of ischemia just after the onset of mechanical reperfusion in acute myocardial infarction. Of interest, it has taken almost 20 years of intense work to bring all the important preconditioning ideas to clinical reality in the form of postconditioning. Once cardiologists are fully awoken to the idea of attacking reperfusion induced myocardial cell death, then this area will be set to develop as a major and novel target in the therapy of acute myocardial infarction.

Ceramide-induced preconditioning involves reactive oxygen species

INTRODUCTION

Ceramide induces programmed cell death and it is thought to contribute to cardiac ischemia/reperfusion (I/R) injury. In contrast, we have demonstrated that administration of low doses of ceramide engenders cardiac preconditioning (PC). Ceramide is known to generate reactive oxygen species (ROS) in cells. Since mechanisms triggering the ceramide-induced cardioprotection remain unknown, we investigated the role of ROS in the genesis of this protective mechanism.

METHODS

Using an isolated Langendorff-perfused rat heart model, four groups (n > or = 6 in each group) were considered: Control hearts underwent 30 min index regional ischemia and 120 min of reperfusion. In the ceramide group, hearts were preconditioned with c2-ceramide 1 microM for 7 min followed by 10 min washout prior to the I/R insult. In additional groups, MPG (1 mM), a synthetic antioxidant was given for 15 min alone or bracketing the ceramide perfusion. In each group, infarct size was determined at the end of the reperfusion period and superoxide dismutases (CuZnSOD and MnSOD) and catalase activities were evaluated.

RESULTS

Ceramide preconditioning reduced the infarct/area at risk (I/AAR) ratio (8.3 +/- 1.1% for ceramide vs. 36.4 +/- 1.2% for control, p < 0.001). Perfusion with MPG abolished the preconditioning effect of ceramide (I/AAR ratio = 36.7 +/- 4.9%). Ceramide was also associated with a 29% and 38% increase in catalase and CuZnSOD activities, respectively, compared with control group.

CONCLUSION

Production of reactive oxygen species following ceramide preconditioning of the ischemic-reperfused heart appears to play a role in the cardioprotective effect of ceramide.

Cost-effectiveness analysis of hypertension guidelines in South Africa: absolute risk versus blood pressure level

BACKGROUND

Hypertension is responsible for more deaths worldwide than any other cardiovascular risk factor. Guidelines based on blood pressure level for initiation of treatment of hypertension may be too costly compared with an approach based on absolute cardiovascular disease (CVD) risk, especially in developing countries.

METHODS AND RESULTS

Using a Markov CVD model, we compared 6 strategies for initiation of drug treatment--2 different blood pressure levels (160/95 and 140/90 mm Hg) and 4 different levels of absolute CVD risk over 10 years (40%, 30%, 20%, and 15%)--with one of no treatment. We modeled a hypothetical cohort of all adults without CVD in South Africa, a multiethnic developing country, over 10 years. The incremental cost-effectiveness ratios for treating those with 10-year absolute risk for CVD >40%, 30%, 20%, and 15% were 700 dollars, 1600 dollars, 4900 dollars, and 11,000 dollars per quality-adjusted life-year gained, respectively. Strategies based on a target blood pressure level were both more expensive and less effective than treatment decisions based on the strategy that used absolute CVD risk of >15%. Sensitivity analysis of cost of treatments, prevalence estimates of risk factors, and benefits expected from treatment did not change the ranking of the strategies.

CONCLUSIONS

In South Africa, current guidelines based on blood pressure levels are both more expensive and less effective than guidelines based on absolute risk of cardiovascular disease. The use of quantitative risk-based guidelines for treatment of hypertension could free up major resources for other pressing needs, especially in developing countries.

Hypertension in sub-Saharan African populations

BACKGROUND

Hypertension in sub-Saharan Africa is a widespread problem of immense economic importance because of its high prevalence in urban areas, its frequent underdiagnosis, and the severity of its complications.

METHODS AND RESULTS

We searched PubMed and relevant journals for words in the title of this article. Among the major problems in making headway toward better detection and treatment are the limited resources of many African countries. Relatively recent environmental changes seem to be adverse. Mass migration from rural to periurban and urban areas probably accounts, at least in part, for the high incidence of hypertension in urban black Africans. In the remaining semirural areas, inroads in lifestyle changes associated with "civilization" may explain the apparently rising prevalence of hypertension. Overall, significant segments of the African population are still afflicted by severe poverty, famine, and civil strife, making the overall prevalence of hypertension difficult to determine. Black South Africans have a stroke rate twice as high as that of whites. Two lifestyle changes that are feasible and should help to stem the epidemic of hypertension in Africa are a decreased salt intake and decreased obesity, especially in women.

CONCLUSIONS

Overall, differences from whites in etiology and therapeutic responses in sub-Saharan African populations are graded and overlapping rather than absolute. Further studies are needed on black Africans, who may (or may not) be genetically and environmentally different from black Americans and from each other in different parts of this vast continent.

Effect of losartan versus candesartan on uric acid, renal function, and fibrinogen in patients with hypertension and hyperuricemia associated with diuretics

BACKGROUND

Hyperuricemia may counter benefits of blood pressure (BP) reduction, although this is controversial.

METHODS

We examined the effects of candesartan and losartan on uric acid, creatinine, and fibrinogen. Patients with hypertension and serum uric acid > or = 0.42 mmol/L (7 mg/dL) associated with diuretics were randomized to receive losartan 50 to 100 mg or candesartan 8 to 16 mg for 24 weeks. At randomization and after 24 weeks, systolic and diastolic BP, serum uric acid, creatinine, and fibrinogen were measured.

RESULTS

A total of 59 patients were entered into the study (30 in the losartan and 29 in the candesartan group). Mean systolic and diastolic BP were reduced in the candesartan group, from 156 mm Hg at baseline to 132 mm Hg at 24 weeks, and from 90.9 to 80.8 mm Hg respectively, P < .0001), and in the losartan group from 150.3 to 132 mm Hg and from 89.6 to 77.6 respectively, P < 0001). Overall mean values of fibrinogen levels were again reduced from 4.39 g/L at baseline to 4.01 g/L at 24 weeks (P < .02). Mean values of serum uric acid in the losartan and candesartan groups were similar at baseline (0.44 and 0.46 mmol/L, respectively), but they were lower in the losartan group after 24 weeks (0.39 and 0.48 mmol/L, P = .01). Twelve patients (44%) in the candesartan group had a 10% increase in serum creatinine compared with four patients (14.2%) in the losartan group (P < .02).

CONCLUSIONS

Candesartan and losartan lowered BP, but only losartan reduced uric acid. The lowering of fibrinogen in both groups may explain the reduction in stroke with angiotensin receptor blockers. The effect of persistent hyperuricemia on renal function requires further study.

Controversies in ventricular remodelling

Ventricular remodelling describes structural changes in the left ventricle in response to chronic alterations in loading conditions, with three major patterns: concentric remodelling, when a pressure load leads to growth in cardiomyocyte thickness; eccentric hypertrophy, when a volume load produces myocyte lengthening; and myocardial infarction, an amalgam of patterns in which stretched and dilated infarcted tissue increases left-ventricular volume with a combined volume and pressure load on non-infarcted areas. Whether left-ventricular hypertrophy is adaptive or maladaptive is controversial, as suggested by patterns of signalling pathways, transgenic models, and clinical findings in aortic stenosis. The transition from apparently compensated hypertrophy to the failing heart indicates a changing balance between metalloproteinases and their inhibitors, effects of reactive oxygen species, and death-promoting and profibrotic neurohumoral responses. These processes are evasive therapeutic targets. Here, we discuss potential novel therapies for these disorders, including: sildenafil, an unexpected option for anti-transition therapy; surgery for increased sphericity caused by chronic volume overload of mitral regurgitation; an antifibrotic peptide to inhibit the fibrogenic effects of transforming growth factor beta; mechanical intervention in advanced heart failure; and stem-cell therapy.

Controversies in atrial fibrillation

Atrial fibrillation is the most common sustained cardiac arrhythmia, and contributes greatly to cardiovascular morbidity and mortality. Many aspects of the management of atrial fibrillation remain controversial. We address nine specific controversies in atrial fibrillation management, briefly focusing on the relations between mechanisms and therapy, the roles of rhythm and rate control, the definition of optimum rate control, the need for early cardioversion to prevent remodelling, the comparison of electrical with pharmacological cardioversion, the selection of patients for long-term oral anticoagulation, the roles of novel long-term anticoagulation approaches and ablation therapy, and the potential usefulness of upstream therapy targeting substrate development. The background of every controversy is reviewed and our opinions expressed. Here, we hope to inform physicians about the most important controversies in this specialty and stimulate investigators to address unresolved issues.

Controversies in hypertension

Hypertension remains the most common risk factor for cardiovascular morbidity and mortality. Its incidence is rising in both ageing and obese populations, but its control remains inadequate worldwide. We address several persisting controversies that may interfere with appropriate management of hypertension. They include: the reasons behind the increasing incidence of hypertension and the possible ways to slow the process, especially by lifestyle changes; the need for overall cardiovascular risk assessment; the major issues in the decision to institute drug therapy and the choice of drugs; and the importance of screening for various identifiable causes. We provide the background for these controversies, followed by some opinions on how to guide practitioners to offer more effective management of hypertension.

Controversies in stable coronary artery disease

Coronary heart disease is still highly prevalent worldwide, and stable angina pectoris is one of its more common presentations. Three major controversies are risk factor management, drug therapy, and intervention. As well as the major risk factors stated by the Framingham study and European guidelines, other factors include abdominal obesity, metabolic syndrome, and psychological stress. How should these additional factors be rated? With respect to drug therapy, apart from aspirin, all patients with stable angina should be assessed for statin treatment. Although statins will reduce coronary events by about one third in patients with vascular disease, the absolute benefit depends on the absolute risk. Non-controversially, all patients should be considered for angiotensin-converting-enzyme inhibitors. The concept that beta blockers are protective from future coronary events can be disputed. Percutaneous coronary intervention can relieve symptoms without extending lifespan beyond medical therapy. However, strong mortality data favour coronary-artery bypass grafting in individuals with triple-vessel or even double-vessel disease. Thus, effort angina needs comprehensive assessment, lifestyle changes, and treatment tailored to the individual patient.

Pharmacological Preconditioning With Tumor Necrosis Factor-α Activates Signal Transducer and Activator of Transcription-3 at Reperfusion Without Involving Classic Prosurvival Kinases (Akt and Extracellular Signal–Regulated Kinase)

Background— We previously reported that tumor necrosis-factor-α (TNF-α) can mimic classic ischemic preconditioning (IPC) in a dose- and time-dependent manner. Because TNF-α activates the signal transducer and activator of transcription-3 (STAT-3), we hypothesized that TNF-α–induced preconditioning requires phosphorylation of STAT-3 rather than involving the classic prosurvival kinases, Akt and extracellular signal–regulated kinase (Erk) 1/2, during early reperfusion.

Methods and Results— Isolated, ischemic/reperfused rat hearts were preconditioned by either IPC or low-dose TNF-α (0.5 ng/mL). Western blot analysis confirmed that IPC phosphorylated Akt and Erk 1/2 after 5 minutes of reperfusion (Akt increased by 34±6% and Erk, by 105±28% versus control; P <0.01). Phosphatidylinositol 3-kinase/Akt inhibition (wortmannin) or mitogen-activated protein kinase–Erk 1/2 kinase inhibition (PD-98059) during early reperfusion abolished the infarct-sparing effect of IPC. In contrast, TNF-α preconditioning did not phosphorylate these kinases (Akt increased by 7±7% and Erk, by 17±14% versus control; P =NS). Neither wortmannin nor PD-98059 inhibited TNF-α–mediated cardioprotection. However, TNF-α and IPC both phosphorylated STAT-3 and the proapoptotic protein Bcl-2 antagonist of cell death (BAD) (STAT-3 increased by 58±17% with TNF-α or by 68±12% with IPC; BAD increased by 75±8% with TNF-α or by 205±20% with IPC; P <0.01 versus control), thereby activating the former and inactivating the latter. The STAT-3 inhibitor AG 490 abolished cardioprotection and BAD phosphorylation with both preconditioning stimuli.

Conclusions— Activation of the classic prosurvival kinases (Akt and Erk 1/2) is not essential for TNF-α–induced preconditioning in the early reperfusion phase. We show the existence of an alternative protective pathway that involves STAT-3 activation specifically at reperfusion in response to both TNF-α and classic IPC. This novel prosurvival pathway may have potential therapeutic significance.