In terms of predisposing and triggering factors, associations with migraines, pregnancy, hypertension, genetic susceptibility, connective tissue disease, and fibromuscular dysplasia can be identified, with FMD being the most prevalent, seen in up to 85% of SCAD cases. Triggering factors still under study include emotional disorders, physical exertion, sexual hormones, Valsalva maneuvers, and certain drugs like hormone replacement therapy, cocaine, amphetamines, and methamphetamines [5]. Diagnosis can be reached through clinical suspicion (young women with low cardiovascular risk presenting with acute coronary syndrome) and targeted imaging studies, with coronary angiography currently remaining the method of choice. Coronary dissections can be angiographically classified into three types: Type 1, where a dissection flap with two or more radiolucent lumens can be visualized; Type 2, seen as soft, diffuse narrowing similar to coronary vasospasm; and Type 3, characterized by focal or tubular narrowing similar to an atherosclerotic plaque lesion. Type 2 is the most frequent, followed by Type 1 and Type 3. TIMI 2-3 flow is achieved in more than 50% of cases during diagnostic angiography [6].

Additionally, new invasive diagnostic and therapeutic tools are available today, such as intravascular imaging techniques and optical coherence tomography, which show promising results in appropriately selected patients. The recommended first-line treatment is conservative in the majority of cases, prioritizing invasive treatment with coronary angioplasty for clinically unstable patients [7,8].

CLINICAL CASES

Case 1: A 59-year-old woman with a history of dyslipidemia treated with atorvastatin, no other cardiovascular risk factors, presented to the institution 24 hours after experiencing Class IV angina for 30 minutes. At the time of assessment in the emergency department, the patient was asymptomatic, hemodynamically stable, with no pathologic findings on the electrocardiogram but elevated biomarkers (CPK 1821/2110U/L and TSH 583/619pg/mL). The echocardiogram was normal, and coronary angiography showed 70% obstruction in the proximal and middle thirds of the second lateral ventricular artery of the circumflex artery, with a radiolucent image consistent with a dissection flap (Figure 1A-B).

Conservative treatment was chosen. After five days of hospitalization with a favorable evolution and tolerance to the treatment, the patient was discharged for outpatient follow-up with double antiplatelet therapy (aspirin 100mg/day and clopidogrel 75mg/day), statins (atorvastatin 40mg/day), and betablockers (bisoprolol 2.5mg/day).

Case 2: A 52-year-old woman diagnosed with essential hypertension at age 50, with no other significant history, presented to the emergency department after experiencing Class IV angina for 20 min. At the time of assessment in the emergency room, the patient was asymptomatic, hypertensive, with acute subepicardial injury noted on the electrocardiogram in leads II-III-aVF, prompting an urgent coronary angiography. This revealed soft, diffuse stenosis from the mid-third of the right coronary artery to the mid-third of the posterior descending artery (Figure 2A-B). Intracoronary nitroglycerin infusion was performed without angiographic changes after infusion. Given the patient’s asymptomatic state at the time of study, hemodynamic stability, and TIMI 2 antegrade flow, conservative treatment was prioritized, optimizing medical treatment. Elevated biomarkers were observed in laboratory tests (TSH 850-911pg/ml and CPK 1800/2115U/L), with an echocardiogram showing preserved ejection fraction without significant segmental motility disorders. After 24 hours of hospitalization in the coronary unit, the patient presented with refractory angina, prompting a decision to perform a percutaneous reintervention guided by intravascular ultrasound (IVUS), which revealed an image compatible with a dissection flap and coronary intramural hematoma at the level of the right coronary artery (Figure 3). Finally, angioplasty was performed with the placement of a paclitaxel-eluting stent from the mid-third of the posterior descending artery to the mid-third of the right coronary artery, achieving a successful angiographic outcome (Figures 4 & Figure 5). After five days of hospitalization, with favorable evolution, the patient was discharged with established therapy including dual antiplatelet therapy (aspirin and clopidogrel), beta- blockers (bisoprolol 5 mg/day), and antihypertensive therapy (losartan 50 mg/day).

DISCUSSION

In the diagnostic approach of patients with acute coronary syndrome, the role of coronary angiography as a non-invasive method has been proposed, being used in the 'Triple rule-out' in multiple healthcare centers worldwide. However, some studies suggest that its usefulness in ACS is not entirely satisfactory, as while its diagnostic utility is high for abrupt luminal stenosis and intramural hematoma, it provides little diagnostic yield for visualizing the coronary dissection flap, which is likely due to the limited diagnostic resolution power in small and medium-caliber vessels [9].

Intracoronary imaging techniques such as IVUS or optical coherence tomography (OCT) play an increasingly important role in hemodynamics laboratories. However, when it comes to spontaneous coronary dissection, it deserves special mention with certain advantages and disadvantages: The diagnostic and therapeutic importance lies in the high diagnostic accuracy that allows for a definitive diagnosis of SCAD, with identification of the dissection flap and differentiation between true and false arterial lumens. It also provides a higher therapeutic success rate by allowing the proper positioning and expansion of the stent to be confirmed. On the other hand, the disadvantages of these invasive imaging methods include their high cost and limited availability, as well as a higher risk of dissection extension associated with the procedure, whether by guide catheter, coronary wire, imaging catheter, or hydraulic extension in the case of OCT. This is especially true for patients who tend to have a high predisposition to spontaneous dissection due to the association with connective tissue disease and fibromuscular dysplasia [10].

Therefore, for diagnostic purposes, the recommendations from the latest European, Canadian, and American guidelines advise continuing intracoronary imaging studies only in special situations where angiographic images are compatible with type 2 and 3 coronary dissections [8,11,12]. In general, mortality and survival free of major adverse cardiovascular events (MACE) are greater than 85% when analyzing all patients with spontaneous coronary dissection, with spontaneous resolution in follow-up at six months after conservative treatment [13]. However, when analyzing subgroups of patients who present with acute myocardial infarction associated with spontaneous coronary dissection, they appear to have a higher risk of in-hospital mortality compared to women who are hospitalized for acute coronary syndrome without evidence of SCAD [14]. Invasive treatment at the time of angiographic diagnosis was associated with a higher percentage of in-hospital events (a combination of mortality, MI, stroke, cardiogenic shock, and stent thrombosis) and a higher need for revascularization during the 30-day follow-up [13]. It was even found that coronary dissection propagation occurred in 32% of patients who underwent interventional treatment [8].

When analyzing predictors of spontaneous coronary dissection progression, the presence of intramural hematoma, involvement of multiple vessels, and obstruction greater than 80% were found to be statistically significant [14]. For this reason, the latest clinical practice guidelines recommend, after the angiographic diagnosis of SCAD, to assess the degree of myocardial perfusion according to the "TIMI" classification and the clinical presentation to determine conservative medical treatment in patients with TIMI 2-3 flow and hemodynamic stability, percutaneous coronary intervention in patients with hemodynamic instability and TIMI 0-1 flow, or myocardial revascularization surgery in experienced centers [15-19]. The clinical practice guidelines recommend conservative medical treatment for patients with TIMI 2-3 flow and hemodynamic stability and percutaneous coronary intervention for those with TIMI flow 0-1 and hemodynamic instability or coronary artery bypass surgery in specialized centers [14,17-19].

CONCLUSION

SCAD is an important cause of myocardial infarction in young women with low cardiovascular risk, and it is a pathophysiological entity distinct from atherosclerotic myocardial infarction. To date, the predisposing and triggering factors for this clinical entity are still under study, although the strong association with connective tissue disease and fibromuscular dysplasia should be considered. The diagnostic method of choice initially remains coronary angiography, with intracoronary imaging suggested as a diagnostic and therapeutic complement only in selected cases. It is preferred, whenever possible, to prioritize conservative medical treatment, particularly when the dissection does not significantly compromise blood flow or cardiac function, due to the high percentage of spontaneous resolution in follow-up, and the high percentage of in-hospital complications and complications after invasive treatment. However, in special situations, such as hemodynamic instability and TIMI 0-1 coronary flow, invasive coronary treatment is preferred.

Patients with SCAD should be closely monitored due to the possibility of recurrence of dissection or long-term complications. While we await large-scale studies that strongly support the use of dual antiplatelet therapy, antihypertensives, and beta-blockers in SCAD patients, following the current acute coronary syndrome clinical practice guidelines, we consider this treatment approach appropriate.