Medical treatment of myocardial ischemia in coronary artery disease: effect of drug regime and irregular dosing in the CAPE II trial

Overcoming Compensatory Mechanisms toward Chronic Drug Administration to Ensure Long-Term, Sustainable Beneficial Effects

Chronic administration of drugs leads to the activation of compensatory mechanisms that may inhibit some of their activity and induce unwanted toxicity. These mechanisms are an obstacle for maintaining a sustainable effect for many chronic medications. Pathways that adapt to the burden induced by chronic drugs, whether or not related to the underlying disease, can lead to a partial or complete loss of effect. Variability characterizes many biological systems and manifests itself as large intra- and inter-individual differences in the response to drugs. Circadian rhythm-based chronotherapy is further associated with variability in responses noted among patients. This paper reviews current knowledge regarding the loss of effect of chronic medications and the range of variabilities that have been described in responses and loss of responses. Establishment of a personalized platform for overcoming these prohibitive mechanisms is presented as a model for ensuring long-term sustained medication effects. This novel platform implements personalized variability signatures and individualized circadian rhythms for preventing and opposing the prohibitive effect of the compensatory mechanisms induced by chronic drug administration.

Effect of Perindopril / Amlodipine Fixed Combination on Ultrasound Characteristics of Ventricles of the Heart in Patients with Ischemic Heart Disease and Arterial Hypertension

In a group of 32 patients with combined ischemic heart disease (IHD) and arterial hypertension (AH) we studied dynamics of parameters of blood pressure and ECG 24-hour monitoring, as well as ultrasound structural and functional parameters of left and right ventricles during 3-month therapy with fixed dose combination of perindopril arginine (10.0 mg) and amlodipine (5.0 mg). The obtained results demonstrated significant positive effect of this combination on the geometry, structure and diastolic function of both left and right ventricles, as well as confirmed its high antiischemic and antihypertensive effects.

SEVERAL ASPECTS OF DILTIAZEM AND ORGANIC NITRATES USAGE IN VARIOUS SEVERITY STABLE ANGINA PATIENTS

Aim. To estimate the effectiveness of Diltiazem (Dlt) and its combination with nitrates in patients with ischemic heart disease (CHD) and arterial hypertension (AH) according to exercise tolerance by functional class (FC) of stable angina (StA).

Material and methods. 30 CHD male patients at the age of 58,8±7,5 with StA II FC (n=11), III FC (n=19) and 1–2 stage AH were included into open randomized placebo-controlled study. Drug therapy: Dlt 90–180 mg bid, isosorbide 5-mononitrate 50 mg qd, trinitrolong 2 mg bid or tid. Effectiveness of the regular drug intake was controlled by repeated exercise tolerance tests (ETT) by treadmill with the value of threshold effort time (ThT). Total duration of treatment was 4 weeks.

Results. At the beginning the ThT was 249,8±23,4 s for III FC and 368,6±14,4 s for II FC patients (p=0,0001). One dose of Dlt increased ThT in 5 hours to 387,3±37,5 s and 533,7±20,3 s in both groups, respectively (p=0,001), with the difference between groups being held. During regular Dlt intake the ThT in III FC angina patients reached 441,1±26,8 s, but in II FC patients in has not changed: 526,1±22,0 s. Additional nitrate intake to III FC group led to even more increase of ThT; in II FC patients there was no improvement. Combination therapy by Dlt and nitrates has not led to differences between III and II FC groups by achieved exercise tolerance. Hemodynamic parameters in both groups has not differ.

Conclusion. For patients with III FC stable angina it is recommended to prescribe Dlt with nitrates because of additional effectiveness of combination that might be linked to the influence on cardiac hemodynamics and to improvement of myocardium metabolism. In II FC stable angina Dlt alone reaches its maximum antiischemic effect so the addition of nitrates is not helpful.

[Patient adherence in antihypertensive treatment]

Hypertension is one of the most frequent chronic diseases as well as most important cardiovascular risk factors in developed countries. Blood pressure control to target levels can significantly decrease the risk for development of coronary artery disease, stroke, chronic renal disease and mortality. Adequately maintained blood pressure is very important in high risk patients. In the treatment of hypertension, life style therapy and drug treatment have essential roles. Further, patient adherence plays a significant part of the treatment, too. Importantly, about half of the patients only become adherent to antihypertensive therapy by the end of the first year treatment. Hence, non-adherence of patients is an important cause for resistant hypertension. Adherence is influenced by the complexity of drug regimen and characteristic of drug class, as well as age and gender of patients.

The clinical significance of continuous ECG (ambulatory ECG or Holter) monitoring of the ST-segment to evaluate ischemia: a review

Silent ischemia is a common manifestation of coronary artery disease (CAD). Continuous ECG (cECG) monitoring is an effective tool for assessing the frequency and duration of silent ischemic episodes for patients with CAD and for risk stratifying asymptomatic patients or those after an acute coronary syndrome by identifying those at increased risk for future cardiovascular events or death. cECG also allows monitoring of the effectiveness of therapy in patients with CAD. Treatment strategies targeted toward the elimination of silent ischemia have shown that revascularization was better than medical therapy in eliminating silent ischemia, but large scale, prospective studies targeting silent ischemia as a treatment endpoint are still lacking. Future research is warranted to study the effects of newer medical agents or the selected use of revascularization in those patients with persistent silent ischemia despite current medical regiments.

Emotional stressors trigger cardiovascular events

AIMS

To describe the relation between emotional stress and cardiovascular events, and review the literature on the cardiovascular effects of emotional stress, in order to describe the relation, the underlying pathophysiology, and potential therapeutic implications.

MATERIALS AND METHODS

Targeted PUBMED searches were conducted to supplement the authors' existing database on this topic.

RESULTS

Cardiovascular events are a major cause of morbidity and mortality in the developed world. Cardiovascular events can be triggered by acute mental stress caused by events such as an earthquake, a televised high-drama soccer game, job strain or the death of a loved one. Acute mental stress increases sympathetic output, impairs endothelial function and creates a hypercoagulable state. These changes have the potential to rupture vulnerable plaque and precipitate intraluminal thrombosis, resulting in myocardial infarction or sudden death.

CONCLUSION

Therapies targeting this pathway can potentially prevent acute mental stressors from initiating plaque rupture. Limited evidence suggests that appropriately timed administration of beta-blockers, statins and aspirin might reduce the incidence of triggered myocardial infarctions. Stress management and transcendental meditation warrant further study.

Silent ischemia: clinical relevance

Myocardial ischemia can occur without overt symptoms. In fact, asymptomatic (or silent) ST-segment depression during ambulatory electrocardiogram monitoring occurs more often than symptomatic ST-segment depression in patients with coronary artery disease. Initial studies documented that silent ischemia provided independent prediction of adverse outcomes in patients with known and unknown coronary artery disease. The ACIP (Asymptomatic Cardiac Ischemia Pilot Study) enrolled patients in the 1990s and found that revascularization was better than medical therapy in reducing silent ischemic episodes and possibly cardiovascular (CV) events. However, the more recent COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial found similar CV event rates between patients treated with optimal medical therapy alone and those treated with optimal medical therapy plus percutaneous revascularization. Therefore, in the current era, medical therapy appears to be as effective as revascularization in suppressing symptomatic ischemia and preventing CV events. COURAGE was not designed to evaluate changes in the frequency of silent ischemia. Therefore, silent ischemia may persist despite current-era treatment and might still identify patients with increased risk of CV events. Also, silent ischemia is likely to occur frequently in heart transplant patients with denervated hearts and coronary allograft vasculopathy, and future study aimed at improving the management of silent ischemia in this population is warranted. Additionally, future research is warranted to study the effect of newer medical therapies such as ranolazine or selected use of revascularization (for example, guided by fractional flow reserve) in those patients with persistent silent ischemia despite optimal current-era medical therapy.

Non-ST elevation myocardial infarction: a new pathophysiological concept could solve the contradiction between accepted cause and clinical observations

Non-ST elevation myocardial infarction (NSTEMI) and ST elevation infarction have many differences in their appearance and prognosis. A comprehensive search made us form a new hypothesis that a further cause also existsin NSTEMI: an acute, critical increase in the already existing high microvascular resistance in addition to the subtotal coronary artery occlusion. Various findings and studies can be interpreted only by our hypothesis: hemodynamic findings, ECG changes, autopsy reports and clinical observations (different long-time prognosis and different result of acute revascularization therapy in NSTEMI, similarities of NSTEMI with other clinical symptoms where increased microvascular resistance can be supposed without coronary artery disease).

OBJECTIVE

Despite similarities in the underlying pathologic mechanism non-ST elevation myocardial infarction(NSTEMI) and ST elevation infarction (STEMI) have many differences in their clinical presentation and prognosis.

METHOD

A systematic review of the literature about NSTEMI and the blood supply of the myocardium made us form a hypothesis that a further cause also exists in addition to the accepted cause of NSTEMI (subtotal coronaryartery occlusion): an acute, critical increase in an already existing high intramyocardial microvascular resistance.

EVIDENCE

Knowledge about microcirculation disturbances in ischemic heart disease and development of microcirculation damage can be fitted in our hypothesis. Various findings and studies can be interpreted only by our hypothesis: hemodynamic findings, ECG changes, autopsy reports and clinical observations about NSTEMI. The latest ones involve the different long-time prognosis and different result of acute revascularization therapy in STEMI and NSTEMI. Regarding the repolarization changes on the ECG NSTEMI shows similarities with other clinical symptoms where increased intramyocardial microvascular resistance can be supposed without coronary artery disease: false positive exercise stress test, supraventricular tachycardia, left ventricular strain and conduction disturbances.

CONCLUSION

The acute treatment of NSTEMI should aim to improve the blood inflow to the stiff myocardiumand/or impaired microvascular system and decrease the high microvascular resistance.

Potent anti-ischaemic effects of statins in chronic stable angina: incremental benefit beyond lipid lowering?

Aims

The DoUble-blind Atorvastatin AmLodipine (DUAAL) trial investigated whether atorvastatin decreases ischaemia by a vascular benefit, independent of low-density lipoprotein cholesterol lowering, in patients with coronary artery disease (CAD), both alone and in combination with the traditional anti-anginal therapy, amlodipine.

Methods and results

Randomized, double-blind, parallel-group, multicountry trial (2 weeks run-in and 24 weeks active therapy) comparing three treatments: amlodipine, atorvastatin, and amlodipine + atorvastatin; in 311 patients (78% male; mean age 62 years) with stable angina (≥2 attacks/week), CAD history, ≥3 transient myocardial ischaemia (TMI) episodes, and/or ≥15 min ischaemia on 48 h ambulatory electrocardiographic (AECG) monitoring. Efficacy variables were change in TMI by AECG, exercise ischaemia, angina diary data, and inflammatory biomarkers at Week 26. There was a comparable, highly significant decrease in TMI with amlodipine and atorvastatin, but no additional benefit for the combination. More than 50% of patients became TMI-free in all three groups and this was accompanied by a comparable, marked reduction in angina and nitroglycerin consumption. High-sensitivity C-reactive protein fell by 40% in patients receiving atorvastatin but there was no change with amlodipine. Adverse events were comparable among groups.

Conclusion

Atorvastatin was as potent an anti-ischaemic agent as amlodipine. Future studies of combination therapies will be instructive.

Clinical trial registration information: National clinical trial number: NCT00159718, protocol number A0531031 listed on http://clinicaltrials.gov/.

Silent myocardial ischaemia: clinical relevance and treatment

Transient myocardial ischaemia in the absence of chest pain ('silent ischaemia') commonly occurs in patients with coronary artery disease (CAD) and has important prognostic implications. However, doubts exist as to whether and how silent ischaemia should be managed. In the present article we review current knowledge regarding silent ischaemia and the role of recently developed drugs that may be effective to control its occurrence. Since the description in the 1770s of the syndrome of 'angina pectoris' by William Heberden, the importance of chest pain for the diagnosis of CAD has remained un-abated. However, several decades ago it became apparent that both myocardial infarctions and transient episodes of myocardial ischaemia could occur in the absence of chest pain. Indeed, a large proportion of patients with CAD have both silent and painful myocardial ischaemia as a manifestation of CAD. Whether the presence of asymptomatic ischaemic electrocardiographic changes in patients with CAD has prognostic importance and whether it needs medical or surgical treatment has been a matter of speculation for several decades.

Subgroup analyses in therapeutic cardiovascular clinical trials: are most of them misleading?

BACKGROUND

Treatment decisions in clinical cardiology are directed by results from randomized clinical trials (RCTs). We studied the appropriateness of the use and interpretation of subgroup analysis in current therapeutic cardiovascular RCTs.

METHODS

We reviewed main reports of phase 3 cardiovascular RCTs with at least 100 patients, published in 2002 and 2004, and from major journals (Circulation, J Am Coll Cardiol, Am Heart J, Am J Cardiol, N Engl J Med, Lancet, JAMA, BMJ, Ann Intern Med). Information on subgroups included prespecification, number, interaction test use, significant subgroups found, and emphasis on findings. We examined appropriateness of reporting and differences according to sample size, overall trial result, and CONSORT adoption.

RESULTS

We selected 63 RCTs, with a median of 496 (range 100-15,245) patients. Thirty-nine RCTs were reported with subgroup analyses and 26 with > 5 subgroups. No trial was specifically powered to detect subgroup effects, and only 14 RCTs were reported with fully prespecified subgroups. Only 11 RCTs were reported with interaction tests. Furthermore, 21 RCTs were reported with claims of significant subgroups and 15 with equal or more emphasis to subgroups than to the overall results. Subgroup analyses in large RCTs (> 500 patients) were reported more often than in small ones (24/30 vs 15/33, P = .005). No differences were found according to overall result (positive/negative) or CONSORT adoption.

CONCLUSIONS

Subgroup analyses in recent cardiovascular RCTs were reported with several shortcomings, including a lack of prespecification and testing of a large number of subgroups without the use of the statistically appropriate test for interaction. Reporting of subgroup analysis needs to be substantially improved because emphasis on these secondary results may mislead treatment decisions.

Synergism of atenolol and amlodipine on lowering and stabilizing blood pressure in spontaneously hypertensive rats

This study was designed to investigate the possible synergism of atenolol and amlodipine on lowering and stabilizing blood pressure (BP) in spontaneously hypertensive rats. Sixty-four spontaneously hypertensive rats were randomly divided into eight groups. They were given 0.8% carboxymethylcellulose sodium (control), atenolol (10 mg/kg), amlodipine (0.5, 1 and 2 mg/kg) and the combinations of atenolol and amlodipine (10 + 0.5, 10 + 1 and 10 + 2 mg/kg), respectively. The drugs were given via a catheter of gastric fistula. BP was recorded for 25 h from 1 h before drug administration to 24 h after administration, in conscious, freely moving rats. It was found that combination of atenolol and amlodipine significantly decreased BP and systolic BP variability. From probability sum analysis it was found that the combination of atenolol and amlodipine, in a proportion as 10 : 1, was the best one (q = 1.54). In conclusion, the present work clearly demonstrated that there is a synergistic effect between atenolol and amlodipine in lowering and stabilizing the BP. The synergistic effect is highest when the dose proportion of the two drugs is 10 : 1.

Contemporary management of silent ischemia: the role of ambulatory monitoring

Silent ischemia is highly prevalent among patients with ischemic heart disease and is associated with a poor prognosis in moderate/high risk outpatients who either exhibit exercise- or pharmacological-induced myocardial ischemia, or in those patients who demonstrate silent ischemia following an acute coronary syndrome. Pharmacotherapy, including beta-blockers, angiotensin-converting enzyme inhibitors, statins, calcium channel antagonists and antiplatelet agents, have all demonstrated a reduction in silent ischemia and an improvement in cardiac prognosis. The management of patients with ischemic heart disease is currently based on patients' report of anginal symptoms: documentation of silent ischemia, usually using ambulatory electrocardiography, is not incorporated into the routine management of coronary artery disease. Yet studies comparing ambulatory electrocardiography with exercise testing have shown these tests to be complementary. We review the evidence concerning the prognostic value of ambulatory electrocardiography for monitoring silent ischemia and the prognostic value of attenuating silent ischemia. Mitigation of silent ischemia improves cardiac prognosis and ambulatory electrocardiographic monitoring before and after treatment of silent ischemia can play a valuable role in the management of coronary artery disease.

Usefulness of ambulatory electrocardiographic monitoring for myocardial ischemia after coronary bypass

Cardiac patients with asymptomatic myocardial ischemia have a poor prognosis. Ambulatory electrocardiographic monitoring can help to ensure that these patients, who are unaware of their high-risk status, are relieved of residual myocardial ischemia in response to cardioprotective medication, and rendered as low cardiac risk.