Myocardial infarction in young patients.

Myocardial infarction in persons under the age of 45 years accounts for 6% to 10% of all myocardial infarctions in the United States. In this age group, it is predominantly a disease of men. Important risk factors include a family history of myocardial infarction before age 55 years, hyperlipidemia, smoking, and obesity. Unlike older patients, approximately half of young patients have single-vessel coronary disease, and in up to 20%, the cause is not related to atherosclerosis. Coronary angiography may be warranted in young patients with myocardial infarction to define the anatomy of the disease and to permit optimal management.     

Myocardial infarction in young subjects

The annual incidence of myocardial infarction (MI) before 40 years of age is 10 times less frequent than that in patients of all ages, and 10 times less frequent in women than men. The severity and extensiveness of lesions demonstrated by coronary arteriography are significantly less in a young patient with an infarction than an elderly patient. Significant isolated coronary artery stenosis is encountered 10 times more frequently before age 35 than after age 50; 15 percent of young patients have no significant stenosis and 8 to 14 percent have entirely normal coronary artery circulation, depending on the study. There appears, then, to be two pathogenetically distinct varieties of MI in the young patient: approximately one-half of cases exhibit multiple sclerosis seen with typical coronary artery atherosclerotic disease; the remainder, which are almost specific for young patients, represent a single obstruction due most often to the rapid development of a thrombosis on an otherwise normal vascular tree. Coronary artery spasm resulting in complete arterial occlusion is certainly involved, nevertheless its frequency must be further defined.     

Myocardial infarction in young women

This study of 24 women under age 40 years with myocardial infarction demonstrates that even in young women myocardial infarction is most commonly due to coronary atherosclerotic heart disease. Other causes of coronary occlusion were documented in 17 percent of these patients, indicating that these lesser causes of myocardial infarction are more common in young women than in older persons or in young men. In those patients with coronary atherosclerosis one or more significant risk factors could usually, but not always, be documented. The clinical manifestation of the coronary occlusion in the study group was not unlike its manifestation in groups of different ages or sex, or both.     

Myocardial infarction before age 36: Risk factor and arteriographic analysis

One-hundred twenty consecutive patients who were 35 years of age or younger underwent coronary arteriography after clinical myocardial infarction. Ninety-two percent were men. Four distinct subgroups were identified: Ninety-four patients (78 percent) had significant coronary artery disease (greater than 50 percent diameter narrowing of at least one major coronary artery), 20 (17 percent) had normal coronary arteries, 5 (4 percent) had major coronary arterial anomalies and 1 patient had coronary arteritis. Of the patients with obstructive coronary disease, risk factors were smoking in 89 percent, positive family history of coronary artery disease in 48 percent, hypertension in 21 percent and a history of lipid abnormality in 20 percent. Risk factors were distinctly less frequent in the groups without coronary atherosclerosis. In the group with coronary artery disease, the prevalence rate of one, two and three vessel disease was 32, 26 and 42 percent, respectively. Coronary arterial anomalies included anomalous origin of the left coronary artery from the pulmonary artery (three patients) and single right and single left coronary artery (one patient each).It is concluded that myocardial infarction before age 36 is a disease of men who smoke and who often have a family history of premature coronary artery disease. Twenty-two percent of patients will have normal coronary arteries, coronary arterial anomalies or coronary vasculitis. Coronary arteriography should be considered for patients who sustain a myocardial infarction before age 36 for purposes of diagnosis, management and prognosis.     

Myocardial infarction in the young. Angiographic features and risk factor analysis of patients with myocardial infarction at or before the age of 35 years

We reviewed the records of 2,400 consecutive patients undergoing cardiac catheterization at USAF Medical Center Keesler between 1978 and 1984 and found 35 patients (1.5 percent of all cardiac catheterizations) aged 35 years or less (mean age, 32 years) who underwent cardiac catheterization after myocardial infarction. These 35 patients (group 1) were compared to a randomly selected group of 100 patients (group 2) aged 55 years or greater who underwent cardiac catheterization for evaluation of coronary artery disease during the same period. The two groups were compared in terms of angiographic features and risk factors for coronary artery disease. The patients in group 1 had a higher proportion of normal coronary arteries (14 percent [5 patients] vs 0; p less than 0.01) and single-vessel disease compared to group 2, while the incidence of three-vessel disease was much less (14 percent [5] vs 47 percent; p less than 0.001). Involvement of the left main coronary artery was uncommon in group 1 (3 percent [1] vs 15 percent in group 2; p less than 0.01). Risk factor analysis revealed smoking to be the most common risk factor in both groups (89 percent [31] in group 1 and 91 percent in group 2). Hypertension (28 percent [10] vs 48 percent; p less than 0.05) and diabetes (3 percent [1] vs 23 percent; p less than 0.01) were more common in group 2. Importantly, of 19 patients in group 1 who underwent cardiac catheterization for prognosis despite being asymptomatic and able to reach at least stage 4 on a Bruce protocol exercise test, none was found to have residual surgically correctable disease.     

Myocardial infarction in the young adult

CAD in young male adults below the age of 40 years has generally been found to be associated with the usual risk factors associated with CAD. In a lesser number of young adults, MIs may be related to cocaine use. Sympathomimetic effects and increase in myocardial oxygen demand are factors considered responsible for acute MI in cocaine-abusing patients. In young adults who are asymptomatic following an acute MI and who are able to pass treadmill exercise stress tests at levels of Bruce stage 4 have been shown to have normal coronary arteriograms. Thus this subset should not require routine coronary angiograms following an acute MI.     

Myocardial infarction in young Indian patients: risk factors and coronary arteriographic profile

One hundred four patients (101 men, three women), under 40 years of age, with myocardial infarction (MI), underwent coronary arteriography. Eighty patients had significant obstructive coronary artery disease (CAD) (group 1), 23 had normal coronary arteries (group 2), and one patient had coronary ostial stenosis as a result of nonspecific aortoarteritis (group 3). Coronary risk factors in group 1 included smoking (76.2%), hypercholesterolemia (36.3%), hypertension (32.5%), positive family history (28.7%), and diabetes mellitus (5%). Multiple risk factors were frequent (56.2%). Smoking was common (p less than 0.01) and diabetes mellitus less frequent (p less than 0.05) as compared to older (greater than 40 years) patients with MI and arteriographically proved CAD. The frequency of one-, two-, and three-vessel disease was 33.7%, 26.2%, and 40%, respectively, in group 1. Group 2 patients were almost devoid of coronary risk factors. The only group 3 patient had left coronary ostial stenosis with no risk factors. Similar to their counterparts in developed countries, young Indian patients with MI and obstructive CAD have a high frequency of coronary risk factors, especially smoking and severe multiple-vessel disease. Since normal coronary arteriograms are also frequent in this setting, a detailed evaluation is recommended for purposes of prognosis and management.     

Myocardial infarction in the young: a sex-based comparison

A relative paucity of information concerns the natural history, clinical features and coronary anatomy in young patients with acute myocardial infarction. In particular, there is a dearth of data relating to sex differences in young patients. The objective was to evaluate whether or not there are correlations between the clinical characteristics and the extent and localization of coronary artery lesions in young men compared with young women. The study population consisted of 1646 young patients (87% men, 13% women; mean age 39+/-5 years) with a first acute myocardial infarction admitted to one of the 125 coronary care units of Italy in a period of 3 years. Clinical data were collected. All patients underwent coronary angiography during hospitalization. Smoking, hypercholesterolemia and obesity were significantly more prevalent in men than in women; physical inactivity was significantly more prevalent among women. Hemodynamically significant coronary stenosis occurred in 82% of patients and were more frequent in men than in women (P<0.05). Women more frequently had single-vessel disease and no coronary lesions at all (58 vs. 47% and 24 vs. 9% women vs. men respectively, both P<0.05). Men more frequently had multivessel disease (38 vs. 13%, P<0.05). Significant stenosis mainly affected the left anterior descending artery (52%) with no gender-related difference; men more likely had lesions of the left circumflex or right coronary artery (P<0.05). In conclusion, young patients with a first acute myocardial infarction risk factors profile and extent of coronary artery lesions were significantly different between sexes.     

Myocardial infarction associated with exercise in young men

Three male patients age 17, 23 and 27 years developed chest pain during, or in one case, immediately after competitive sport. In all cases myocardial infarction was diagnosed by standard criteria or the diagnosis was made on the basis of indium-111 antimyosin imaging, contrast ventriculogram and thallium scan. Coronary arteriography was normal in two and a blocked right coronary artery was found in one. Exercise-related myocardial infarction can occur in young men and chest pain during exercise in this age-group may not always be innocent.     

Myocardial infarction in young adults: Risk factors and natural history

The risk factors and clinical course of 165 patients under 40 years of age (mean age 35) having an initial myocardial infarction (MI) (Group I) were compared to 100 patients over 40 (mean age 50) (Group II). Six risk factors were analyzed: smoking 20 pack-years, hyperlipidemia, hypertension, family history of ischemic disease, diabetes mellitus, and obesity. Only two patients in Group I and six patients in Group II had no risk factors, but the mean number of risk factors in Group I (3) differed from Group II (2) (p< 0.05). Group I had only 18% of patients without either obesity, hyperlipidemia, hypertension, or diabetes mellitus as risk factors while Group II had 41 patients with similar findings (p< 0.001). Group I had hyperlipidemia, obesity, and family history more commonly than did Group II while hypertension was more frequent in the older patients. A prior history of angina was present in nearly half of Group I and II but physical exertion just prior to MI was more common in Group I (32%) than in Group II (20%) (p < 0.05). Death at the time of MI was more frequent in Group II (p < 0.001) but congestive failure occurred in 17% of both groups. On follow-up, 45% of both groups had no complications, and the rates of subsequent MI and angina pectoris were similar in both groups. However, late death was less frequent in Group I than in Group II. Patients under 40 with myocardial infarction have more risk factors than those over 40 which may play some role in pathophysiology of young myocardial infarction. Physical exertion at the time of myocardial infarction is more common in younger patients. The complication rate is similar in both young and older myocardial infarction patients but the mortality rate, both early and late, is lower in young myocardial infarction patients.     

Myocardial infarction in young vs old male rats: pathophysiologic changes

Young (90 days) and old (15 months) male, Sprague-Dawley rats were subjected to an acute and massive myocardial infarct by giving them two injections of a large dose of isoproterenol. The animals were autopsied at sequential time intervals to ascertain the similarities or dissimilarities in the pathophysiologic events which attend acute myocardial infarction and repair in young vs old rats. Although the signs and severity of hypotensive shock appeared to be equal, mortality was higher in the old rats, especially during the acute necrosis phase. The older rats also manifested more severe and persistent congestive heart failure, i.e., hydrothorax. Serum enzymes (CPK, SGOT, SGPT, and LDH), lipids (triglycerides, free fatty acids, and cholesterol), glucose, and BUN levels manifested a dynamic rise and fall concomitant with the induced myocardial necrosis and repair phases with distinct differences in these metabolic changes between young and old rats. Despite initially higher circulating levels of corticosterone in the old vs young rats, the older animals manifested little or no increase in circulating corticosterone levels during the acute stress of myocardial infarction. This apparent lack of adrenocortical responsiveness was accentuated by the concomitant finding of greatly hypertrophied, hemorrhagic, and lipid-depleted adrenal glands in the old rats vs a dynamic increase in circulating corticosterone levels and alterations in the weight of adrenal and thymus glands of the young rats. During the myocardial repair phase, the young rats manifested extensive endocardial fibrosis whereas the old rats displayed little or no endocardial fibrosis but copous and persistent myocardial edema and ground substance in keeping with their higher concentration of cardiac hexosamine. The pathophysiologic course of events which attends myocardial necrosis and repair is quite different in young vs old rats and may be related to the degree of responsiveness of the pituitary-adrenal axis which changes with age.     

Myocardial infarction in the young subject: a medium-term clinical and coronary angiographic study in 40 patients under 36 years of age. Comparison with coronary angiographic data of myocardial infarction in patients after 50 years of age

A series of 40 myocardial infarctions, occurring in patients under 36 years of age was studied retrospectively (Group I: mean age 31.3 years). The medium term results of coronary angiography in this group were compared with those of 60 myocardial infarctions after 50 years of age (Group II: mean age 56.6 years). Group I had a clear male predominance (92.5%), a high incidence of smoking (69%), hypercholesterolaemia (69%); myocardial infarction was the first manifestation of their disease in 54% and it was often extensive (42%). A comparative angiographic study between the two groups showed: 1) Less widespread lesions in Group I, as assessed by the number of main arteries stenosed (p less than 0.001), the coronary index (p less than 0.01) and the mean coronary score using Friesinger's method (p less than 0.01). 2) A higher incidence of subnormal coronary angiogrammes in Group I (absence of 50% stenosis) (15%) and of single vessel disease (40%): compared with Group II in which multivessel disease was observed in 86.5% of cases. 3) Collateral circulation was less common in Group I (p less than 0.01). On the other hand, a comparative study of regional and global left ventricular function showed no difference between the two groups. Two subgroups were distinguished in Group I: in one subgroup, multiple lesions similar to those found in Group II, suggestive of premature coronary atherosclerosis (52.5%); the other group (47.5%) presented unilocular lesions i.e. focal mono-arterial lesions compatible with other causes of infarction (thrombosis and/or spasm). These patients were younger (p less than 0.05) and had significantly fewer cardiovascular risk factors (p less than 0.01). Despite the fact that the coronary lesions were limited, the myocardial damage was comparable with the other groups as the collateral circulation was much less developed (p less than 0.02). These appearances were only observed in 3.5% of patients in Group II. The study of the angiographic outcomes of these two types of lesions should show a difference and could contribute to the understanding of their mechanisms.     

Myocardial infarction in young patients (< or =35 years of age) with systemic lupus erythematosus: a case report and clinical analysis of the literature

The present study aims to report a-20-year old girl with systemic lupus erythematosus (SLE) who developed myocardial infarction (MI) and also aims to review acute myocardial infarction (AMI) in young SLE cases (< or =35 years) reported in the literature. We conducted a comprehensive review of the English literature from 1975 to 2006 to analyse data on MI in SLE patients who had developed AMI either at 35 or earlier. In 32 English articles, we identified 49 SLE patients, plus our case, with AMI. They consist of 41 female and nine male patients, their mean age being 24 +/- 6.4 years (range of 5-35). Disease duration varied between 0 and 13 years. The lag time between the onset of the SLE manifestations and development of AMI was 7.7 +/- 5.4 year (range of 1 month to 20.5 years). We divided the patients into three subgroups according to their coronary involvement type (Group I: normal coronary artery or coronary thrombosis (n = 16); Group II: coronary aneurysm/arteritis (n = 12); Group III: coronary atherosclerosis (n = 22)). The lag time between the onset of the SLE manifestations and development of MI in the subgroups showed variations: Group I < Group II < Group III. Both prevalence of renal involvement and steroid therapy were higher in patients with coronary atherosclerosis than were in Group I. There were one or more risk factors for atherosclerosis in 39 SLE patients. AMI in young SLE patients may be seen, albeit rare. We suggest that clinicians should have a low threshold for cardiac evaluation in patients with SLE. Also, traditional risk factors could be managed through preventive measures.     

Myocardial infarction and primary thrombocytosis in a young man

We report the case of a 27-year-old male smoker with simultaneous myocardial infarction (MI) and acute peripheral ischaemia. At the time of his first hospitalization, the platelet count and the coronary angiogram were normal. Two years later, the patient presented again with a leg artery occlusion, followed, a few days later, by a recurrence of MI. At this time, the platelet count was high and the coronary angiogram revealed an occlusion of the right coronary artery. The diagnosis of primary thrombocytosis was made by bone marrow aspiration and biopsy. Different unusual mechanisms of MI in young people are discussed in this report.