Long-term nitrate use in chronic coronary artery disease: need for a randomized controlled trial

Chronic nitrate therapy is associated with different presentation and evolution of acute coronary syndromes: insights from 52,693 patients in the Global Registry of Acute Coronary Events

AIMS

Brief episode(s) of ischaemia may increase cardiac tolerance to a subsequent major ischaemic insult ('preconditioning'). Nitrates can pharmacologically mimic ischaemic preconditioning in animals. In this study, we investigated whether antecedent nitrate therapy affords protection toward acute ischaemic events using data from the Global Registry of Acute Coronary Events.

METHODS AND RESULTS

The dataset comprised 52,693 patients from 123 centres in 14 countries: 42,138 (80%) were nitrate-naïve and 10,555 (20%) were on chronic nitrates at admission. In nitrate-naïve patients, admission diagnosis was ST-segment elevation myocardial infarction (STEMI) in 41%, whereas 59% presented with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). In contrast, only 18% nitrate users showed STEMI, whereas 82% presented with NSTE-ACS. Thus, among nitrate users clinical presentation was tilted toward NSTE-ACS by more than four-fold, STEMI occurring in less than one of five patients (P < 0.0001). After adjustment (age, sex, medical history, prior therapy, revascularization, previous angina), chronic nitrate use remained independent predictor of NSTE-ACS (OR 1.36; 95% CI 1.26-1.46; P < 0.0001). Furthermore, regardless of presentation, within both STEMI and NSTEMI populations, antecedent nitrate use was associated with significantly lower levels of CK-MB and troponin (P < 0.0001 for all).

CONCLUSION

In this large multinational registry, chronic nitrate use was associated with a shift away from STEMI in favour of NSTE-ACS and with less release of markers of cardiac necrosis. These findings suggest that in nitrate users acute coronary events may develop to a smaller extent. Randomized, placebo-controlled trials are warranted to establish whether nitrate therapy may pharmacologically precondition the heart toward ischaemic episodes.

Continuous long-term dosing with oral slow-release isosorbide dinitrate does not reduce incidence of cardiac events in patients with healed myocardial infarction

BACKGROUND

In the short term, isosorbide dinitrate (ISDN) is considered to be therapeutically effective. The long-term effects of treatment with slow-release ISDN are less clear.

HYPOTHESIS

The study was undertaken to investigate the effects of continuous, long-term dosing with oral slow-release ISDN on the incidence of cardiac events in patients with healed myocardial infarction (MI). The study was carried out in accordance with the intention-to-treat principle.

METHODS

In all, 1.102 in- and outpatients, of either gender, with healed MI were randomly divided into groups treated with ISDN (n = 470) and not treated with ISDN (n = 632). Patients in the ISDN group received a continuous regimen of 20 mg of oral, long-acting ISDN three times a day, after meals. The mean observation period was 15.0 +/- 18.5 months. The primary endpoints were nonfatal and fatal recurrent MI, death from congestive heart failure, and sudden death.

RESULTS

There were no significant differences in the baseline characteristics of the patients in the ISDN and no-treatment groups; nevertheless, significantly more patients in the ISDN group experienced cardiac events. In the ISDN group, 35 patients (7.4%) experienced cardiac events during the observation period, versus only 28 patients (4.4%) in the no-treatment group (p < 0.05; odds ratio 1.74; 95% confidence interval 1.04-2.90).

CONCLUSION

Continuous long-term dosing with oral, slow-release ISDN does not reduce and probably increases the incidence of cardiac events among patients with healed MI.

Determinants of coronary events in patients with stable angina: results from the impact of nicorandil in angina study

BACKGROUND

IONA was a randomized trial of nicorandil (20 mg twice daily) versus placebo in 5126 patients with stable angina of effort. We present the characteristics as measured at baseline that were found to be associated with increased risk of major outcomes.

METHODS

The primary end point of the study was coronary heart disease death, nonfatal myocardial infarction (MI), or unplanned hospitalization for cardiac chest pain. The secondary outcome excluded the softer outcome of unplanned hospitalization for chest pain. Potential prognostic factors included nicorandil treatment, sex, smoking, severity of angina (Canadian Cardiovascular Society [CCS] grading), previous MI, coronary artery bypass graft/percutaneous transluminal coronary angioplasty (CABG/PTCA), left ventricular dysfunction, left ventricular hypertrophy (LVH) on electrocardiography (ECG), histories of diabetes or hypertension, baseline cardiovascular drugs, age, blood pressures, heart rate, height, weight, and body mass index.

RESULTS

A total of 5047 patients had complete baseline information. There were 724 primary outcomes and 240 secondary outcomes. The strongest determinants of the hard secondary end point were CCS score (hazards ratio [HR] 2.25, 95% confidence intervals [CI] 1.50-3.38) for grades III and IV versus grade I, age (HR 1.23, 95% CI 1.13-1.33) for 5-year risk, and previous MI (HR 2.05, 95% CI 1.48-2.85). The results for the primary outcome were similar, with stronger associations with LVH on ECG and smoking, and a weaker association with age.

CONCLUSIONS

We present models of risk factors for coronary outcomes in a population with angina of effort. The strongest risk factors were the CCS score and previous MI.

Therapeutic potential of nitric oxide donors in the prevention and treatment of atherosclerosis

Well-known risk factors for atherosclerosis include hypercholesterolaemia, hypertension, diabetes, and smoking. These conditions are associated with endothelial dysfunction, which itself is associated with reduced endothelial generation of nitric oxide (NO). This is an overview of the implications of NO generation in atherosclerosis and of the potential therapeutic benefit of drugs which donate NO, such as organic nitrates, nicorandil, and sydnonimines, or those which increase the availability of endogenous NO, such as statins, angiotensin-converting enzyme inhibitors, L-arginine, and tetrahydrobiopterin.

Long-term treatment with the NO-donor molsidomine reduces circulating ICAM-1 levels in patients with stable angina

Recent clinical evidence has indicated that the severity of atherosclerosis is correlated with the level of soluble ICAM-1 (sICAM-1). Nitric oxide (NO) donors are used to treat patients with stable angina pectoris, and the aim of this study was to investigate the short- and long-term effect of molsidomine on the level of this circulating biochemical marker of endothelial function. We included 172 patients and examined the effect of the NO donor treatment on angina related parameters and on sICAM-1 levels after a 4-week- and a 1-year treatment period. After 4 weeks, angina attacks and sublingual (s.l.) isosorbide dinitrate tablet (ISDN) consumption frequency was significantly (p<0.0001) reduced without altering sICAM-1 levels when compared to the baseline values. The anti-anginal effect of molsidomine 16 mg once a day (o.a.d.) was sustained (s.l. ISDN consumption) or improved (angina attacks frequency; p<0.002) during the following year and a significant decrease in sICAM-1 levels (p<0.0001) was observed. When the sICAM-1 changes during the 1-year treatment period were distributed in four categories (quartiles of the distribution), it was demonstrated that the decrease in s.l. ISDN consumption between the start and the end, was most pronounced in the group with the largest sICAM-1 decrease (fourth quartile of distribution; p=0.038). In conclusion, the reduction in the pro-inflammatory marker sICAM-1 after 1-year daily treatment with molsidomine may indicate that this NO donor besides its anti-anginal function, promotes a less activated state of the endothelium in patients with stable angina.

Improved prognosis of patients presenting with clinical markers of spontaneous reperfusion during acute myocardial infarction

OBJECTIVE

To describe the clinical features, management, and prognosis of patients presenting with clinical markers of spontaneous reperfusion (SR) during acute myocardial infarction (AMI).

DESIGN

Cohort study.

SETTING

National registry of 26 coronary care units.

PATIENTS

2382 consecutive patients with AMI.

MAIN OUTCOME MEASURES

Patient characteristics, management, and mortality.

RESULTS

The incidence of SR was 4% of patients (n = 98) compared with thrombolytic treatment (n = 1163, 49%), primary angioplasty (n = 102, 4%), and non-reperfusion (n = 1019, 43%). SR patients were more likely to develop less or no myocardial damage as indicated by a higher percentage of non-Q wave AMI (58% v 32%, 47%, and 44%, respectively, p < 0.0001), aborted AMI (25% v 9%, 8%, and 12%, p < 0.001), and lower peak creatine kinase (503 v 1384, 1519, and 751 IU, p < 0.0001). SR patients, however, were more likely to develop recurrent ischaemic events (35% v 17%, 12%, and 16%, respectively; p < 0.001) and subsequently were more likely to be referred to coronary angiography (67%), angioplasty (41%), or bypass surgery (16%, p < 0.001). Mortality at 30 days (1% v 8%, 7%, and 13%, respectively, p < 0.0001) and one year (6% v 11%, 12%, and 19%, p < 0.0001) was significantly lower for SR patients than for the other subgroups. By multivariate analysis, SR remained a strong determinant of 30 day survival (odds ratio (OR) 0.16, 95% confidence interval (CI) 0.01 to 0.74). At one year, the association between SR and survival decreased (OR 0.49, 95% CI 0.18 to 1.13).

CONCLUSIONS

Clinical markers of SR are associated with greater myocardial salvage and favourable prognosis. The vulnerability of SR patients to recurrent ischaemic events suggests that they need close surveillance and may benefit from early intervention.

Nitrate tolerance does not increase production of peroxynitrite in the heart

Clinical studies have suggested that long-term nitrate treatment does not improve and may even worsen cardiovascular mortality, and the possible role of nitrate tolerance has been suspected. Nitrate tolerance has been recently shown to increase vascular superoxide and peroxynitrite production leading to vascular dysfunction. Nevertheless, nitrates exert direct cardiac effects independent from their vascular actions. Therefore, we investigated whether in vivo nitroglycerin treatment leading to vascular nitrate tolerance increases cardiac formation of nitric oxide (NO), reactive oxygen species, and peroxynitrite, thereby leading to cardiac dysfunction. Nitrate tolerance increased bioavailability of NO in the heart without increasing formation of reactive oxygen species. Despite elevated myocardial NO, neither cardiac markers of peroxynitrite formation nor cardiac mechanical function were affected by nitroglycerin treatment. However, serum free nitrotyrosine, a marker for systemic peroxynitrite formation, was significantly elevated in nitroglycerin-treated animals. This is the first demonstration that, although the systemic effects of nitroglycerin may be deleterious due to enhancement of extracardiac peroxynitrite formation, nitroglycerin does not result in oxidative damage in the heart.