Optimal control of myocardial ischaemia: the benefit of a fixed combination of atenolol and nifedipine in patients with chronic stable angina

Efficacy of monotherapy compared with combined antianginal drugs in the treatment of chronic stable angina pectoris: a meta-analysis

OBJECTIVE

To determine the relative efficacy of antianginal drugs administered as monotherapy or in combination in patients with chronic stable angina.

METHODS

A meta-analysis was performed on randomized trials, published in English between 1980 and 1999, that directly compared combined treatment and monotherapy. Twenty-two articles were included, all on the comparison of -blocker monotherapies to their combination with a calcium antagonist and 10 on the comparison of calcium antagonist monotherapies to their combination with a -blocker.

RESULTS

Time to 1 mm ST-segment depression, total exercise duration and time to onset of anginal pain were significantly increased with the combined therapy compared to -blocker alone (by 8, 5 and 12%, respectively). Only time to 1 mm ST-segment depression was significantly increased with the combined therapy compared to calcium antagonist alone (by 9%). For all these parameters, the adjusted differences were significant only within 6 h following drug intake and were not significant after 6 h. No analysis of safety data could be performed.

CONCLUSION

As far as exercise testing is concerned, the combination of a calcium antagonist and a -blocker is statistically more effective than either monotherapy. Further studies are needed to confirm the higher efficacy after the first 6 h following drug intake.

Prognostic significance of transient ischemic episodes: response to treatment shows improved prognosis. Results of the Total Ischemic Burden Bisoprolol Study (TIBBs) follow-up

OBJECTIVES

The Total Ischemic Burden Bisoprolol Study (TIBBS) follow-up examined cardiac event rates in relation to transient ischemia and its treatment.

BACKGROUND

It is unclear whether transient ischemia on the ambulatory electrocardiogram has prognostic implications in stable angina and whether medical treatment can improve the prognosis.

METHODS

The TIBBS trial was an 8-week, randomized, controlled comparison of the effects of bisoprolol and nifedipine on transient ischemic episodes in patients with stable angina pectoris. Of the 545 patients screened, 520 (95.4%) could be followed up. Rates of cardiac and noncardiac death, nonfatal acute myocardial infarction, hospital admission for unstable angina and need for coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty were recorded.

RESULTS

A total of 145 events occurred in 120 (23.1%) of 520 patients. Patients with more than six episodes had an event rate of 32.5% compared with 25.0% for patients with two to six episodes and 13.2% for patients with less than two episodes (p < 0.001). Hard events (death, acute myocardial infarction, hospital admission for unstable angina pectoris) were more frequent in patients with two or more ischemic episodes (12.2% vs. 4.7%, p = 0.0049). Patients with a 100% response rate of transient ischemic episodes during the TIBBS trial had a 17.5% event rate at 1 year compared with 32.3% for non-100% responders (p = 0.008). Patients receiving bisoprolol during the TIBBS tria had a lower event rate (22.1%) at 1 year than patients randomized to nifedipine (33.1%, p = 0.033).

CONCLUSIONS

In patients with stable angina pectoris, frequent episodes of transient ischemia are a marker for an increased event rate. A 100% response to medical treatment reduces the event rate. The greater reduction of ischemia with bisoprolol than nifedipine during the TIBBS trial translated into an improved outcome at 1 year.

Contemporary approaches in medical management of patients with stable coronary artery disease

CAD continues to be the principal cause of mortality in the United States, and the largest group of patients with CAD are those with stable angina. Among this group of patients, the most common manifestation of CAD is presence of transient episodes of myocardial ischemia. The presence of transient ischemia and not the severity of angina has been found to be associated with poor clinical outcome in patients with stable CAD. As part of a global treatment strategy for patients with stable CAD, changes in lifestyle and modification of coronary risk factors should be emphasized as an integral part of treatment. Conventional antianginal therapy is quite effective in controlling anginal attacks. Currently, several drugs and therapeutic strategies are available for the treatment of patients with angina (see Table 5). Nitrates are highly effective antianginal drugs with complex beneficial actions in patients with CAD, but their usefulness is limited by development of tolerance during long-term use. When clinically indicated, the use of nitrates should be supplemented with another longer-acting antianginal drug, such as a beta-blocker or a calcium channel blocker. Based on the available data, beta-blockers, when tolerated, seem to be the most effective antianginal drugs for most patients with stable CAD. Beta-blockers are also the most effective anti-ischemic drugs that reduce the magnitude of myocardial ischemia detected during routine daily activities. Calcium channel blockers are also effective vasodilators and good antianginal drugs. The clinician should become familiar with the different actions that this heterogeneous group of drugs has on the heart and vessels. This knowledge allows the clinician to choose the appropriate combination of different antianginal drugs for patients on an individualized basis. It is also critical to develop the treatment strategy by carefully taking into account other associated medical conditions that are frequently encountered in patients with CAD.

Medical treatment to reduce total ischemic burden: total ischemic burden bisoprolol study (TIBBS), a multicenter trial comparing bisoprolol and nifedipine. The TIBBS Investigators

OBJECTIVES

We compared the effects of bisoprolol on transient myocardial ischemia with those of nifedipine in patients with chronic stable angina.

BACKGROUND

Both beta-adrenergic blocking agents and calcium antagonists reduce transient ischemic episodes, but comparisons of these agents have been made in only a few larger studies.

METHODS

The Total Ischemic Burden Bisoprolol Study (TIBBS) was a randomized double-blind controlled study with two parallel groups; 330 patients from 30 centers in seven European countries with stable angina pectoris, a positive exercise test and more than two transient ischemic episodes during 48 h of Holter monitoring (central evaluation) were included. Of these patients 161 were randomized to receive bisoprolol and 169 to receive nifedipine slow release. There were two treatment phases of 4 weeks each, with 48-h Holter monitoring after each phase. During phase 1, patients received either 10 mg of bisoprolol daily or 2 x 20 mg of nifedipine slow release. During phase 2, they received either 20 mg of bisoprolol daily or 2 x 40 mg of nifedipine slow release.

RESULTS

In phase 1 of the trial, 4 weeks of bisoprolol therapy (10 mg daily) reduced the mean [+/- SD] number of transient ischemic episodes from 8.1 +/- 0.6 to 3.2 +/- 0.4/48 h. Nifedipine (2 x 20 mg) reduced transient ischemic episodes from 8.3 +/- 0.5 to 5.9 +/- 0.4/48 h. Total duration of ischemia was reduced from 99.3 +/- 10.1 to 31.9 +/- 5.5 min/48 h with bisoprolol and from 101 +/- 9.1 to 72.6 +/- 8.1 min/48 h with nifedipine. Reductions were statistically significant for both drugs; the difference between bisoprolol and nifedipine was also significant (p < 0.0001). Bisoprolol reduced the heart rate at onset of episodes by 13.7 +/- 1.4 beats/min from a baseline value of 99.5 +/- 1.2 beats/min (p < 0.001). Heart rate was unchanged with nifedipine. Bisoprolol had significantly higher responder rates than nifedipine. Doubling of the dose in phase 2 of the trial had small additive effects. Only bisoprolol showed a marked circadian effect by reducing the morning peak of transient ischemic episodes (by 68% at peak time, 8:00 to 8:59 AM).

CONCLUSIONS

Both bisoprolol and nifedipine reduced the number and duration of transient ischemic episodes in patients with chronic stable angina. Bisoprolol was significantly more effective than nifedipine in both doses tested and reduced the morning peak of ischemic activity.

Comparison of the efficacy of atenolol and its combination with slow-release nifedipine in chronic stable angina

There is still uncertainty of whether combined therapy with a beta-blocker and calcium-channel antagonist provides additive or synergistic clinical benefits in most patients with stable angina pectoris. The comparative antianginal effect of atenolol 50 mg and atenolol 50 mg and slow release nifedipine (20 mg) twice a day was assessed in 27 patients with chronic stable angina in a randomized, double-blind, crossover study. After a 4 week run-in period on atenolol, patients were randomly allocated to receive either atenolol alone or its combination with nifedipine and then crossed over to the alternative treatment for a further 4 weeks. Symptom-limited exercise treadmill tests were performed according to the Naughton protocol. The major endpoints in this study were (a) exercise time to pain; (b) exercise time to > or = 1 mm ST depression; (c) total exercise time; (d) maximal ST-segment depression; (e) number of anginal attacks; and (f) nitrate consumption. The preexercise systolic blood pressure was lower on the combination treatment than on atenolol alone, but heart rate was lower on atenolol compared with the combination treatment. There was no difference in the systolic blood pressure at the onset of pain or at 1 mm ST depression, while heart rate was lower on both occasions with atenolol compared to the combination treatment. There was no difference between the two treatments in terms of the rate-pressure product at the onset of pain or at 1 mm ST depression. Twice as many patients experienced pain later with the combination treatment than with atenolol alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Silent myocardial ischemia

The documentation of abnormalities related to myocardial ischemia, whether symptomatic or silent, is of central importance. Whenever this information is available, it should be used in the overall assessment of the patient at risk for adverse outcome. The level of concern for treatment of CAD should be based on the risk implications associated with the ischemia-related abnormalities detected during objective testing rather than on the presence or absence of pain. The exercise stress test is still the single most useful test to begin the evaluation of a patient with an analyzable ST segment. In persons suspected of having CAD, the detection of ischemic-type ST-segment depression, at a low workload (e.g., < 120 beats/min or < 6.5 METS) of > 2 mm magnitude or persisting for more than 6 min implies high risk for adverse outcome. Asymptomatic ischemia during everyday activities, detected by Holter monitoring, in the high-risk patient, most probably adds additional risk beyond the risk of an abnormal stress test alone. Left ventricular imaging by two-dimensional echocardiography, RNA, angiogram, vest, etc, showing an ejection fraction > or = 40%, reversible wall motion abnormalities in multiple regions and redistribution defects or a failure to increase ejection fraction during exercise even if the patient remains asymptomatic, also imply high risk. The presence of any of these abnormal findings, regardless of symptoms, should therefore prompt as high a degree of concern as with ischemia-related signals associated with pain. Thus any therapy chosen should be directed toward elimination of transient ischemia, not just relief of symptoms that may or may not be ischemia related. If this course is chosen, the efficacy of the therapeutic regimen and possible progression of CAD should be assessed with follow-up testing for ischemia. We believe that risk factor modification and aspirin should be considered for most, if not all, patients in whom ischemia, silent or symptomatic, is suspected or detected. If symptoms or ischemia suggesting low risk is present, anti-ischemic medical therapy may be considered, but follow-up is advised. If a high-risk ischemic signal, even without symptoms, is detected, medical therapy should be used to attempt to modify the signal. If the ischemic signal suggesting high risk persists despite medical therapy, revascularization should be considered. Until additional data from large clinical trials are available, this approach appears to have the greatest likelihood of modifying the adverse outcome of CAD.