Acute myocardial infarction with angiographically normal coronary arteries

Coronary Embolism and Myocardial Infarction: A Scoping Study

Coronary embolism is a cause of acute myocardial infarction (AMI)in which obstructive foci enter the coronary circulation, block normal blood flow and precipitate ischemia. Precise studies focusing on patient population affected, pathophysiological mechanisms, and treatment strategies are scanty, in spite of a reported prevalence estimated at 2.9%. As the understanding of myocardial infarction without evidence of coronary artery disease continues to grow, an in-depth review of this previously seldomly reported subtype of coronary ischemia was in order. Patients suffering coronary embolism are 15 to 20 years younger than traditional AMI patients with a slight predominance towards male sex, which resembles the gender data of the populations affected by non-traditional myocardial infarction in published reports. While the expected prevalence rate of cardiovascular disease risk factors such as hypertension and hyperlipidemia are present, this population also has a relatively high prevalence of atrial fibrillation and valve pathology, especially endocarditis. Initial presentation is indistinguishable from other causes of myocardial infarction however fever is commonly present, when endocarditis with valvular involvement is the primary cause of the coronary embolism. Mechanical thrombectomy is the mainstay of treatment, followed by percutaneous coronary intervention. Mortality is the highest in patients who do not receive targeted treatment for the coronary embolism, particularly if only antimicrobial agents or anticoagulation without thrombolytic agents are employed. The unique features of coronary embolism highlighted in this historical study justify further examination in contemporary patient populations.

Characteristics and Long-Term Prognosis of Patients ≤35 Years of Age with ST Segment Elevation Myocardial Infarction and "Normal or Near Normal" Coronary Arteries

There are scarce data regarding risk factors and prognosis of patients with premature ST segment elevation myocardial infarction (STEMI) and "normal or near normal" coronary arteries (N/NNCAs). We compared the characteristics and long-term prognosis of patients with premature STEMI and N/NNCAs with their counterparts with significant coronary artery disease (CAD). We recruited 330 patients who had STEMI ≤35 years of age and 167 age- and gender-matched controls. All patients underwent coronary angiography. Coronary arteries with no lesions or lesions causing <30% reduction in lumen diameter were defined as N/NNCAs, whereas narrowings causing ≥50% diameter reduction formed the significant CAD group. Lipid profile, homocysteine levels, and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism were determined. Sixty patients (18%) had N/NNCAs. Patients with N/NNCAs had lower low-density lipoprotein-cholesterol and higher high-density lipoprotein-cholesterol levels, higher homocysteine levels, and higher prevalence of MTHFR TT genotype (34.6 vs 18%, p = 0.008) compared with patients with significant CAD. After a median follow-up of 8 years, cardiovascular events occurred in 105 (36%) of 291 patients with available follow-up data. Significant CAD was associated with higher risk for recurrent cardiovascular events after adjustment for traditional risk factors (hazard ratio 2.095, 95% confidence interval 1.088 to 3.664, p = 0.022) and additional adjustment for the left ventricular ejection fraction, reperfusion therapy, and persistent smoking (hazard ratio 1.869, 95% confidence interval 1.007 to 3.468, p = 0.041). In conclusion, patients with premature STEMI and N/NNCAs have fewer lipid abnormalities, higher homocysteine levels and prevalence of MTHFR TT genotype, and better long-term prognosis compared with their counterparts with significant CAD.

Acute ST elevation myocardial infarction with angiographically normal coronary arteries: causes and outcomes

A minority of patients presenting with ST elevation myocardial infarction (STEMI) have angiographically normal coronary arteries. We aimed to assess its incidence, identify possible aetiologies and determine long-term prognosis. We retrospectively analysed 714 consecutive patients presenting with STEMI over a 10-year period (1995 to 2005), and identified 41 patients with angiographically normal coronary arteries. Mean age was 44+/-15 years; the majority were male. Specific diagnoses were made in 13/41 (32%) patients, including peri-myocarditis (11/41) and Takotsubo cardiomyopathy (2/41). No specific diagnosis was made in the remainder and these were considered cryptogenic AMI's. At a mean follow-up of 44+/-30 months, 1 patient with cryptogenic AMI had a non-cardiovascular death and 1 patient required pacing. In conclusion, there is a small but definite incidence of angiographically normal coronary arteries in patients presenting with STEMI. While the eventual aetiology remains uncertain in most patients, long-term outcomes appear favourable.

Myocardial infarction with normal coronary arteries: a conundrum with multiple aetiologies and variable prognosis: an update

The existence of myocardial infarction despite angiographically normal coronary arteries was recognized more than 30 years ago. Since then, various series of such patients have been described, but the aetiology and pathogenesis of the condition are still a source of debate. Evidence exists for a role of coronary vasospasm, thrombosis, embolization and inflammation, per se or combined, in determining the occurrence of myocardial infarction in the presence of angiographically normal coronary arteries. Endothelial dysfunction, possibly superimposed to nonangiographically evident atherosclerosis, may be an underlying common feature predisposing to the acute event. Additionally, myocarditis may explain some of these occurrences. Myocardial infarction with normal coronary arteries is therefore likely the result of multiple pathogenetic mechanisms. Although most reports emphasize the good prognosis of this condition, in general much better than myocardial infarction with coronary artery disease, prognosis is likely variable according to the underlying mechanism. This review summarizes current knowledge on this condition and examines areas of recent progress.

Peripartum myocardial ischemia: a review of Canadian deliveries from 1970 to 1998

OBJECTIVE

The purpose of this study was to evaluate the incidence of peripartum myocardial ischemia in Canada.

STUDY DESIGN

We identified the cohort of women who were admitted to Canadian hospitals for delivery between 1970 and 1998 to calculate the incidence rate and to evaluate potential risk factors.

RESULTS

One hundred fourteen of 10,032,375 women delivered in Canadian hospitals between 1970 and 1998 had peripartum myocardial ischemia recorded as a discharge diagnosis. The overall crude incidence rate was 1.1 (95% confidence interval 0.93, 1.37) women with peripartum myocardial ischemia per 100,000 women delivering per year as noted in the Canadian Hospital Morbidity database. Rates did not increase over time but increased with maternal age. Identified risk factors were diabetes mellitus, hyperlipidemia, and chronic heart disease. The case fatality rate among women with the disease was 1.8%.

CONCLUSION

The incidence of peripartum myocardial ischemia did not increase between 1970 and 1998 in Canada, despite an aging cohort with more prevalent medical comorbidities. Maternal mortality from this event is lower than previously described.