Evaluating effects of treatment in subgroups of patients within a clinical trial: the case of non-Q-wave myocardial infarction and beta blockers

Heart Failure Complicating Acute Mtyocardial Infarction

Factors predisposing the older person with acute myocardial infarction (MI) to develop heart failure (HF) include an increased prevalence of MI, multivessel coronary artery disease, decreased left ventricular (LV) contractile reserve, impairment of LV diastolic relaxation, increased hypertension, LV hypertrophy, diabetes mellitus, valvular heart disease, and renal insufficiency. HF associated with acute MI should be treated with a loop diuretic. The use of nitrates, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, aldosterone antagonists, beta-blockers, digoxin, and positive inotropic drugs; treatment of arrhythmias and mechanical complications; and indications for use of implantable cardioverter-defibrillators and cardiac resynchronization is discussed.

Current role of beta-blockers in the treatment of hypertension

IMPORTANCE OF THE FIELD

It is important to know which patients with hypertension will benefit from beta-blocker therapy and which beta-blockers should be used in the treatment of hypertension to reduce cardiovascular events and mortality.

AREAS COVERED IN THIS REVIEW

Studies between 1981 and 2009 using a Medline search are reported. Beta-blockers should be used to treat hypertension in patients with previous myocardial infarction, acute coronary syndromes, angina pectoris, congestive heart failure, ventricular arrhythmias, supraventricular tachyarrhythmias, diabetes mellitus, after coronary artery bypass graft surgery, and in patients who are pregnant, have thyrotoxicosis, glaucoma, migraine, essential tremor, perioperative hypertension, or an excessive blood pressure response after exercise.

WHAT THE READER WILL GAIN

The use of beta-blockers as first-line therapy in patients with primary hypertension has been controversial. However, the 2009 guidelines of the European Society of Hypertension state that large-scale meta-analyses of available data confirm that diuretics, beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and calcium channel blockers do not significantly differ in their ability to lower blood pressure and to exert cardiovascular protection both in elderly and in younger patients.

TAKE HOME MESSAGE

The key message of this paper is that atenolol should not be used as an antihypertensive drug and that the degree of reduction of mortality, myocardial infarction, stroke and congestive heart failure by antihypertensive therapy is dependent on the degree of lowering of aortic blood pressure. Newer vasodilator beta-blockers such as carvedilol and nebivolol may be more effective in reducing cardiovascular events than traditional beta-blockers, but this needs to be investigated by controlled clinical trials.

Heart Failure–Complicating Acute Myocardial Infarction

This article addresses issues related to acute myocardial infarction (MI) complicated by heart failure, particularly in elderly patients. Findings have shown that acute MI complicated by congestive heart failure (CHF) is associated with a high mortality, and that women with acute MI are more likely to be older and to develop CHF than men with acute MI. In general, management of CHF complicating acute MI is similar in older and younger patients. Actions discussed include hemodynamic monitoring; the administration of oxygen; and the use of morphine, diuretics, nitroglycerin, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, spironolactone, beta-blockers, calcium channel blockers, magnesium, digoxin, and positive inotropic drugs. The article also discusses measures for treating arrhythmias and for diagnosing mechanical complications.

Heart-Failure–Complicating Acute Myocardial Infarction

This article addresses issues related to acute myocardial infarction(MI) complicated by heart failure, particularly in elderly patients. Findings have shown that acute MI complicated by congestive heart failure (CHF) is associated with a high mortality, and that women with acute MI are more likely to be older and to develop CHF than men with acute MI. In general, management of CHF-complicating acute MI is similar in older and younger patients. Actions discussed include hemodynamic monitoring; the administration of oxygen; and the use of morphine, diuretics, nitroglycerin,angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, spironolactone, beta-blockers, calcium channel blockers, magnesium, digoxin, and positive inotropic drugs. The article also discusses measures for treating arrhythmias and for diagnosing mechanical complications.

Treatment after myocardial infarction

Persons after myocardial infarction (MI) should have their modifiable coronary artery risk factors intensively treated. Hypertension should be treated with beta blockers and angiotensin-converting enzyme (ACE) inhibitors. The blood pressure should be reduced to <140/90 mmHg and to <130/80 mmHg in persons with diabetes or renal insufficiency. The serum low-density lipoprotein cholesterol should be reduced to <70 mg/dl with statins if necessary. Diabetics should have their hemoglobin A1c reduced to <7.0%. Aspirin or clopidogrel, beta blockers, and ACE inhibitors should be given indefinitely unless contraindications exist to the use of these drugs. Long-acting nitrates are effective antianginal and antiischemic drugs. Postinfarction patients at very high risk for sudden cardiac death should have an implantable cardioverter-defibrillator. The two indications for coronary revascularization are prolongation of life and relief of unacceptable symptoms despite optimal medical management.

Management of the Elderly Person After Myocardial Infarction

Elderly persons after myocardial infarction should have their modifiable coronary artery risk factors intensively treated. Hypertension should be treated with beta blockers and angiotensin-converting enzyme inhibitors. The blood pressure should be reduced to &lt;140/85 mmHg and to ≥130/80 mmHg in persons with diabetes or renal insufficiency. The serum low-density lipoprotein cholesterol should be reduced to &lt;100 mg/dl with statins if necessary. Aspirin or clopidogrel, beta blockers, and angiotensin-converting enzyme inhibitors should be given indefinitely unless contraindications exist to the use of these drugs. Long-acting nitrates are effective antianginal and antiischemic drugs. There are no Class I indications for the use of calcium channel blockers after myocardial infarction. Postinfarction patients should not receive Class I antiarrhythmic drugs, sotalol, or amiodarone. An automatic implantable cardioverter-defibrillator should be implanted in postinfarction patients at very high risk for sudden cardiac death. Hormonal therapy should not be used in postmenopausal women after myocardial infarction. The two indications for coronary revascularization are prolongation of life and relief of unacceptable symptoms despite optimal medical management.

Cardiovascular medications taken by patients aged >or=70 years hospitalized for acute coronary syndromes before hospitalization and at hospital discharge

A prospective study was performed in 177 patients, mean age 78+/-6 years, hospitalized with acute coronary syndromes. Obstructive coronary artery disease was documented by coronary angiography in 154 of 177 patients (87%). Coronary revascularization was performed in 96 of 177 patients (54%). Five of 177 patients (3%) died during hospitalization. Compared to use before hospitalization, at hospital discharge the use of aspirin increased from 43% to 84% (p<0.001), the use of clopidogrel increased from 21% to 54% (p<0.001), the use of beta blockers increased from 38% to 76% (p<0.001), the use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers increased from 42% to 70% (p<0.001), the use of long-acting nitrates increased from 15% to 31% (p<0.001), and the use of calcium channel blockers decreased from 28% to 23% (p=NS). Dyslipidemia was present in 62% of the 177 patients. The use of statins increased from 34% before hospitalization to 63% at hospital discharge (p<0.001).

Drug treatment of elderly patients with acute myocardial infarction: practical recommendations

Aspirin (acetylsalicylic acid) should be administered to patients on day 1 of an acute myocardial infarction (MI) and continued indefinitely. Early intravenous beta-blockade should be used during acute MI. beta-blockers should be continued indefinitely. Angiotensin-converting enzyme (ACE) inhibitors should be used in patients with acute MI with ST-segment elevation in two or more anterior precordial leads. ACE inhibitors should be used during and after acute MI in patients with chronic heart failure (CHF) or with a left ventricular ejection fraction < or =40%. There are no class I indications for using calcium channel antagonists during and after acute MI. Intravenous heparin should be used in patients with acute MI undergoing coronary revascularisation and in patients at high risk for systemic embolisation. Enoxaparin should be used in patients with non-Q-wave MI. Thrombolytic therapy should be considered in patients with acute MI with ST-segment elevation in contiguous leads of a 12-lead electrocardiogram or with left bundle branch block. Platelet glycoprotein IIb/IIIa inhibitors should be administered intravenously as an adjunct to heparin and aspirin in patients with non-Q-wave MI. Intravenous nitroglycerin should be used: (i) for the first 24 to 48 hours in patients with acute MI and CHF, large anterior MI, persistent ischaemia or hypertension; and (ii) continued beyond 48 hours in patients with recurrent angina pectoris or persistent pulmonary congestion. Long-acting nitrates should be given after MI, along with beta-blockers, to patients with angina pectoris. There are no class I indications for using intravenous magnesium during acute MI. The routine use of antiarrhythmic drugs other than beta-blockers during and after acute MI is not recommended.

Treatment of the elderly post-myocardial infarction patient

Coronary risk factors should be modified in older persons after myocardial infarction (MI). Aspirin 160-325 mg daily and beta blockers should be administered indefinitely. Anticoagulants should be administered post-MI to patients unable to tolerate daily aspirin, to those with persistent atrial fibrillation, and to those with left ventricular thrombus. Nitrates, along with beta blockers, should be used to treat angina pectoris. Angiotensin-converting enzyme inhibitors should be administered after MI to patients who have congestive heart failure, an anterior MI, or a left ventricular ejection fraction of at or below 40%. There are no class I indications for the use of calcium channel blockers after MI. Complex ventricular arrhythmias should be treated with beta blockers. Persons with life-threatening ventricular tachycardia or ventricular fibrillation or who are at very high risk for sudden cardiac death after MI should receive an automatic implantable cardioverter-defibrillator. There are no class I indications for the use of hormonal therapy in postmenopausal women after MI. Indications for coronary revascularization after MI in older individuals are prolongation of life and relief of unacceptable symptoms despite optimal medical management.

Heart failure complicating acute myocardial infarction

Older people with congestive heart failure associated with acute myocardial infarction should be treated with loop diuretic therapy. Class I indications for the use of early intravenous beta blockade in patients with acute myocardial infarction are patients without a contraindication to beta blockers who can be treated within 12 hours of onset of myocardial infarction; patients with continuing or recurrent ischemic pain; and patients with tachyarrythmias, such as atrial fibrillation with a rapid ventricular rate. Class I indications for the use of angiotensin-converting enzyme inhibitors during acute myocardial infarction are (1) patients within the first 24 hours of onset of a suspected acute myocardial infarction with ST segment elevation in two or more anterior precordial leads or with clinical heart failure in the absence of significant hypotension or contraindications to the use of angiotensin-converting enzyme inhibitors, (2) patients with myocardial infarction and a left ventricular ejection fraction of less then 40%, (3) and patients with clinical heart failure on the basis of systolic pump dysfunction during and after convalescence from acute myocardial infarction. No class I indications exist for using calcium channel blockers or magnesium during acute myocardial infarction.

Beta-blockers, angiotensin-converting enzyme inhibitors, and calcium antagonists in treatment of elderly patients with acute myocardial infarction

Administration of beta-blockers reduces mortality among old persons during and after acute myocardial infarction. The American College of Cardiology/American Heart Association guidelines recommend that persons without contraindications to use of beta-blockers should be administered beta-blockers within a few days of myocardial infarction (if administration is not initiated acutely) and that their administration should be continued indefinitely. These guidelines also recommend the use of angiotensin converting enzyme inhibitors in treating persons within the first 24 h of suspected onset of acute myocardial infarction with ST-segment elevation in two or more anterior precordial leads or with congestive heart failure in the absence of significant hypotension or other contraindications to use of ACE inhibitors; and persons during and after convalescence from acute myocardial infarction with congestive heart failure associated with an abnormal left ventricular ejection fraction (LVEF) or with asymptomatic left ventricular systolic dysfunction with a LVEF < 40%. These guidelines state that there are no class I indications for using calcium antagonists after myocardial infarction. If patients have persistent angina pectoris after myocardial infarction despite treatment with beta-blockers and nitrates or hypertension inadequately controlled by other drugs, administration of a nondihydropyridine calcium antagonist such as verapamil or diltiazem should be added to the therapeutic regimen if the LVEF is normal. If the LVEF is abnormal, administration of amlodipine or felodipine should be added to the therapeutic regimen.

Hypertension, hormones, and aging

The most rapidly growing segment of the United States population is the geriatric group, especially those above 75 years of age. Hypertension, diabetes mellitus, and dyslipidemia increase with advancing years in Westernized, industrialized societies such as the United States. These disorders contribute significantly to strokes and myocardial infarctions and associated morbidity and mortality in our elderly population. The increase in these chronic disease processes with aging is related, in part, to increasing obesity, reductions in physical activity, and medications that predispose to these conditions (ie, nonsteroidal inflammatory agents and hypertension). Hypertension in the elderly is characterized by high peripheral vascular resistance/reduced cardiac output, impaired baroflex sensitivity, relatively greater systolic pressures, increased blood pressure variability, and a propensity to salt sensitivity. Type 2 diabetes in the elderly is related to alterations in body composition (ie, increased central adiposity and decreased lean body mass) and to reduced physical activity. There is an increasing body of evidence that aggressive treatment of hypertension and dyslipidemia in the elderly results in comparable, if not greater, reductions in cardiovascular morbidity and mortality in the elderly as in younger counterparts.

Prevention of suboptimal beta-blocker treatment in patients with myocardial infarction

OBJECTIVE

To review the published data and clinical guidelines on the use of beta-blockers in myocardial infarctions (MIs) and contrast that with actual clinical practice.

DATA SOURCES

A MEDLINE search (January 1970-June 1999) was performed to identify all relevant articles. References from these articles were also evaluated for review if deemed important.

DATA SYNTHESIS

Intravenous and oral beta-blockers have been proven to improve outcomes in patients with MIs in numerous clinical trials. In current clinical practice, only 15% of MI patients receive intravenous beta-blockers and long-term beta-blocker therapy is used in <40% of patients without contraindications. However, they could be safely administered to 40% and 70% of these patients, respectively. Furthermore, most of these patients are receiving doses far below those found beneficial in clinical trials. Many of the real and perceived contraindications to beta-blockers are reviewed to allow the practitioner to identify patients who are incorrectly excluded from beta-blocker therapy. Also discussed are special clinical situations in which the benefits observed during clinical trials may not apply.

CONCLUSIONS

Beta-blockers are valuable drugs in the treatment of peri- and post-MI. In clinical practice, most patients are not treated or are inadequately treated with beta-blockers. Pharmacists should ensure that such patients actually have an absolute contraindication or unusual situation where therapy is not firmly indicated. Patients without absolute contraindications warrant titration to specific target doses or a target heart rate of 55-60 beats/min.

Management of older persons after myocardial infarction

OBJECTIVE

To review the management of the older person after myocardial infarction (MI).

DATA SOURCES

A computer-assisted search of the English language literature (MEDLINE database) followed by a manual search of the bibliographies of pertinent articles.

STUDY SELECTION

Studies on the management of persons after MI were screened for review. Studies in persons older than 60 years and recent studies were emphasized.

DATA EXTRACTION

Pertinent data were extracted from the reviewed articles. Emphasis was on studies involving older persons. Relevant articles were reviewed in depth.

DATA SYNTHESIS

Available data about therapy of persons after MI, including control of risk factors, use of aspirin and beta-blockers, and indications for use of angiotensin-converting enzyme inhibitors, long-term anticoagulant therapy, nitrates, calcium channel blockers, hormone replacement therapy, antiarrhythmic drugs, the automatic implantable cardioverter-defibrillator, and revascularization, with emphasis on studies involving older persons, were summarized.

CONCLUSIONS

Risk factors for coronary artery disease should be controlled after MI in older persons. A serum low-density lipoprotein (LDL) cholesterol >125 mg/dL after MI should be treated with lipid-lowering drug therapy to decrease the serum LDL cholesterol to <100 mg/dL. Aspirin in a dose of 160 mg to 325 mg daily should be given indefinitely. Indications for long-term anticoagulant therapy with warfarin after MI to maintain an international normalized ratio between 2.0 and 3.0 include secondary prevention of MI in persons unable to tolerate daily aspirin, persistent atrial fibrillation, and left ventricular thrombus. Beta-blockers should be given indefinitely. Angiotensin-converting enzyme inhibitors should be given to persons who have congestive heart failure, an anterior MI, or a left ventricular ejection fraction < or = 40%. Calcium channel blockers should not be used unless there is persistent angina pectoris despite beta-blockers and nitrates. Antiarrhythmic drugs other than beta-blockers should not be used. An automatic implantable cardioverter-defibrillator should be used in persons who have a history of ventricular fibrillation or serious sustained ventricular tachycardia or who are at very high risk for developing sudden cardiac death. Until data from the Heart Estrogen/ Progestin Replacement Study are available, use of an estrogen/progestin regimen is recommended in the treatment of postmenopausal women after MI unless they are at increased risk for developing breast cancer. The two indications for revascularization in older persons after MI are prolongation of life and relief of unacceptable symptoms despite optimal medical management.

Postinfarction use of beta-blockers in elderly patients

beta-Adrenoceptor antagonists (beta-blockers) reduce mortality and recurrent myocardial infarction (MI) in older patients after both Q-wave MI and non-Q-wave MI. The effects of beta-blockers are to: (i) reduce complex ventricular arrhythmias, including ventricular tachycardia; (ii) increase the ventricular fibrillation threshold; (iii) reduce myocardial ischaemia; (iv) decrease sympathetic tone; (v) markedly attenuate the circadian variation of complex ventricular arrhythmias: (vi) abolish the circadian variation of myocardial ischaemia; and (vii) abolish the circadian variation of sudden cardiac death or MI. beta-Blockers reduce mortality in patients with MI and complex ventricular arrhythmias. In addition, they are excellent antianginal agents. Older persons with hypertension who have had an MI should be treated initially with a beta-blocker. beta-Blockers reduce mortality in patients with: (i) diabetes mellitus who have had an MI; (ii) MI and congestive heart failure with an abnormal or normal left ventricular ejection fraction; and (iii) MI and an asymptomatic abnormal left ventricular ejection fraction. Severe congestive heart failure, severe peripheral arterial disease with threatening gangrene, greater than first degree atrioventricular block, hypotension, bradycardia, lung disease with bronchospasm, and bronchial asthma are contraindications to treatment with beta-blockers.

Beta-adrenergic blockers as cardioprotective agents

The evidence supporting and describing cardioprotective effects of beta-adrenergic blocker treatment is surveyed. Details of the many studies that individually and collectively document the ability of long-term and acute beta-blocker therapy to reduce overall mortality, sudden cardiovascular death, and nonfatal reinfarction in patients surviving or experiencing a myocardial infarction are described. A discussion of the mechanisms by which beta blockers probably and theoretically achieve these benefits includes the suggestion that they may reduce plaque rupture, thus indirectly inhibiting thrombosis. It is also suggested that, in the future, further cardioprotective benefits may accrue to the use of beta blockers in conjunction with thrombolysis and of beta blockers with a duration of action sustained throughout a full 24 hours.

Circadian distribution of onset of acute myocardial infarction in subgroups from analysis of 10,791 patients treated in a single center

A circadian variation of symptom onset in acute myocardial infarction (AMI) with an increased frequency in the late morning and possibly also in the evening has been found in several studies. It has been suggested that different circadian rhythms may exist in various subgroups of patients. This possibility was examined in a population of 10,791 patients collected between 1973 and 1987 in a continuously operating register of patients with AMI in Malmö, Sweden. In 6,763 patients (63%) in whom a distinct symptom onset could be established, symptom onset occurred with an increased frequency between 6:01 A.M. and 12:00 noon (30.6%) and between 6:01 P.M. and 12:00 midnight (26.9%). Similar bimodal circadian rhythms were seen in patients aged greater than 70 years (n = 2,923), less than or equal to 70 years (n = 3,840), men (n = 4,528), women (n = 2,235), smokers (n = 2,458), hypertensives (n = 1,999), diabetics (n = 653), patients with (n = 1,872) and without (n = 4,891) a history of previous AMI, and in patients with recent non-Q-wave AMI (n = 333). In 455 patients receiving cardioselective beta blockers the circadian distribution did not differ from a random, whereas in patients taking nonselective beta blockers or calcium antagonists significant bimodal rhythms were found. Statistically significant interactions were found between symptom onset and age dichotomized at 70 years, and between patients with and without a history of previous AMI. In a multivariate analysis only these variables age less than or equal to/greater than 70 years; +/- history of a previous AMI) were found to modify the circadian rhythm of symptom onset in the population.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictors of early morbidity and mortality after thrombolytic therapy of acute myocardial infarction. Analyses of patient subgroups in the Thrombolysis in Myocardial Infarction (TIMI) trial, phase II

BACKGROUND

Thrombolysis has altered treatment of acute myocardial infarction (AMI). Therefore, reevaluation of predictors of outcome and treatment strategies is appropriate.

METHODS AND RESULTS

Clinical variables collected prospectively for the 3,339 patients of the Thrombolysis in Myocardial Infarction II study were analyzed retrospectively to identify predictors of clinical events at 42 days and earlier and to identify subgroups in which an invasive or conservative strategy might be superior. Pulmonary edema/cardiogenic shock presented as the strongest independent correlate with death (relative risk, 6.0). In two subgroups, mortality differed between the invasive and conservative strategies: 1) Patients with versus without prior AMI had a higher mortality in the conservative strategy (11.5% versus 3.5%, p less than 0.001); in the invasive strategy, the mortality rates were similar (6.0% and 5.1%). 2) Patients with diabetes mellitus and no prior AMI had a higher mortality in the invasive than in the conservative strategy (14.8% versus 4.2%, p less than 0.001). Reinfarction was not independently correlated with baseline characteristics except with history of angina (relative risk, 1.9). Mortality was lower in current smokers and ex-smokers versus never-smokers (3.6% and 4.8% versus 8.0%, p less than 0.001). Current smokers had a lower risk profile (p less than 0.001), including age, pulmonary edema/cardiogenic shock, history of hypertension, and diabetes. The rate of reinfarction was lower in current smokers versus ex-smokers and never-smokers (4.6% versus 8.3% and 8.8%, p less than 0.001). "Not current smoker" was an independent correlate with reinfarction (relative risk, 1.9). The coronary anatomy did not differ among the current smokers, ex-smokers, and never-smokers.

CONCLUSIONS

The strong independent correlation of pulmonary edema/cardiogenic shock with death suggests that thrombolysis is not sufficient to improve survival in these patients. The higher mortality in patients with versus without prior AMI in the conservative strategy suggests that early catheterization and revascularization of these patients might be beneficial. Conversely, the higher mortality in diabetes without prior AMI in the invasive than in the conservative strategy suggests that early aggressive management might not be suitable in this subgroup except for clinical indications. Reinfarction was not predictable by clinical variables except by history of angina. The finding that "not current smoker" was an independent correlate with reinfarction was unexpected.

Increased risk of death and cardiac arrest from encainide and flecainide in patients after non-Q-wave acute myocardial infarction in the Cardiac Arrhythmia Suppression Trial. CAST Investigators

This report examines whether in the Cardiac Arrhythmia Suppression Trial death and cardiac arrest from encainide, flecainide and moricizine during the titration phase and from encainide and flecainide during the follow-up phase were related to presence (Q-wave acute myocardial infarction [Q-AMI]) or absence (non-Q-AMI) of pathologic Q waves. In all, 2,371 patients (70% with Q-AMI, 26% with non-Q-AMI, and 4% unknown) entered the titration phase, starting 117 +/- 163 days after index AMI and lasting for an average of 21 days. For the titration phase, no significant differences existed between Q-AMI and non-Q-AMI patients for death and cardiac arrest rate, ventricular premature complex suppression rate, and nonrandomization rate. A total of 1,498 patients entered the follow-up phase of an average of 10 months (starting 129 +/- 158 days after the index AMI), and were randomized to encainide or flecainide, or their matching placebos. In the placebo group, non-Q-AMI patients had a significantly lower rate of death and cardiac arrest than Q-AMI patients (1.0 and 4.6%, respectively; p = 0.04). Encainide and flecainide significantly elevated death and cardiac arrest rate in both non-Q-AMI patients (8.7%, p less than 0.01) and Q-AMI patients (7.8%, p = 0.04). The relative risk for encainide or flecainide over placebo in the non-Q-AMI patients was 8.7, which was significantly higher than 1.7 observed for the Q-AMI patients (p = 0.03). None of the baseline characteristics had any significant interaction with encainide or flecainide.(ABSTRACT TRUNCATED AT 250 WORDS)