Cardiovascular disease Silent MI Prevalence and prognosis in older patients diagnosed by routine electrocardiograms Wilbert S Aronow MD Older men and women with coronary artery disease and silent myocardial ischemia detected by 24 hour ambulatory electrocardiograms ECGs have a higher incidence of new coronary events than those with no silent ischemia The prevalence of clinically unrecognized MI detected by routine ECGs in older persons varies from 21 to 68 Atypical symptoms associated with acute MI in older persons include dyspnea and neurologic and GI symptoms as well as chest pain Older persons with clinically unrecognized MI have a similar or higher incidence of new coronary events and mortality compared with those with recognized MI which suggests that an aggressive diagnostic and therapeutic approach may be beneficial in these patients Aronow WS Silent MI Prevalence and prognosis in older patients diagnosed by routine electrocardiograms Geriatrics 2003 58 Jan 24 40 Key words MI Myocardial ischemia Silent ischemia ECGs Q wave A s heart disease continues to be the 1 cause of death in the United States primary and secondary prevention efforts warrant renewed attention Silent myocardial ischemia and silent MI once believed relatively rare are now recognized to affect anywhere from 21 to 68 of older adults with coronary artery disease CAD or nearly 3 million Americans These risk factors increase the incidence of new coronary events and death in older adults and require aggressive Dr Aronow is clinical professor of medicine department of medicine cardiology and geriatrics divisions New York Medical College Valhalla NY and adjunct professor of geriatrics and adult development Mount Sinai School of Medicine New York NY Disclosure The author has no real or apparent conflicts of interest relating to the content presented here 24 Geriatrics pharmacologic treatment when discovered The evidence supports periodic routine ECGs in all adults age 60 but particularly before and after surgery This article reviews the epidemiology diagnosis and treatment of silent ischemia and silent MI in older adults Editor s note See pages 57 and 58 for a patient Action Plan for handling heart attacks Silent myocardial ischemia Silent or asymptomatic myocardial ischemia may affect 33 to 49 of older Americans with CAD 1 2 Silent myocardial ischemia is defined as horizontal or downsloping ST segment depression of 1 0 mm or more below the level at rest at 80 milliseconds after the J point lasting for 1 0 minute or longer and unassociated with anginal symptoms detected by 24 hour ambulatory ECGs The reason for the frequent absence January 2003 Volume 58 Number 1 of chest pain in older patients with CAD is unclear Speculations include 3 cognitive impairment with inability to verbalize a sensation of pain myocardial collateral circulation related to gradual progressive coronary artery narrowing a reduced sensitivity to pain because of aging changes such as systemic or localized autonomic dysfunction Ambepitiya et al compared the time delay between the onset of 1 mm of ECG ST segment depression and the onset of angina pectoris during exercise stress testing Significantly the mean delay was 49 seconds in patients aged 70 82 compared with 30 seconds in patients aged 42 59 4 The investigators postulated that the delay in perception of myocardial ischemia in older patients involved peripheral mechanisms such as changes in the myocardial autonomic nerve endings with blunting of the perception of ischemic pain as well as changes in central mechanisms In the older patient population vague symptoms such as unexplained dyspnea neurologic symptoms or GI symptoms warrant follow up with an ECG Prognosis of silent ischemia Older patients with silent myocardial ischemia are twice as likely to have new coronary events than older patients with no myocardial ischemia 1 2 At 45month follow up of 395 men mean age 80 and at 47 month follow up of 771 women mean age 81 with CAD silent myocardial ischemia increased the incidence of new coronary events sudden coronary death or MI 2 1 times in men and 2 1 times in women 1 In another study at 43 month follow up of 39 men mean age 68 with coronary artery disease silent myocardial ischemia increased the incidence of new coronary events 16 0 times 2 Reduction of silent myocardial ischemia in older men and women with heart disease by beta blocker therapy with propranolol significantly reduced the incidence of sudden cardiac death total cardiac death and total mortality 4 Prevalence of unrecognized MI As with myocardial ischemia some patients with MI may be completely asymptomatic or the symptoms may be so vague that they are unrecognized by the patient or physician as an acute MI Figure 1 shows the percent of Qwave MIs in the Framingham Heart Study that were clinically unrecognized but diagnosed by routine ECGs in different age groups of men and of women aged 45 94 6 Table 1 shows the percent 22 to 68 of MIs that were clinically unrecognized in older patients but diagnosed by routine ECGs in other studies 7 14 In a prospective study ECGs and MB isoenzymes of serum creatine kinase were obtained at the time of chest pain sudden dyspnea new neurologic symptoms and GI symptoms in 110 older patients mean age 82 9 Chest pain was defined as pain tightness pressure or discomfort in the chest Neurologic symptoms as the presenting symptom of MI included syncope stroke transient cerebral ischemic attack faintness and acute confusion GI symptoms as the presenting symptom of MI included epigastric distress nausea and vomiting Of 110 Q wave or non Q wave MIs 23 21 were clinically unrecognized Two of the clinically unrecognized MIs 2 occurred during surgery 9 In the largest prospective study involving 4 315 patients age 50 and older undergoing major elective non cardiac surgery history of ischemic heart disease as evidenced by Q waves on the ECG or clinical history of MI was 1 of 6 inde Silent myocardial ischemia and silent MI once believed relatively rare are now recognized to affect 21 to 68 of older adults with coronary artery disease or nearly 3 0 million Americans Illustration for Geriatrics by Sally Cummings pendent predictors of major cardiac complications 15 These data indicate the importance of obtaining an ECG routinely before and after surgery and of obtaining a periodic routine ECG in older patients Exercise stress testing All older patients with silent MI should have an exercise stress test
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