The occurrence of Type 1 myocardial infarction and SCM simultaneously is rare but has previously been reported in the literature (1). However, we believe this is the first report of a simultaneous diagnosis of Type I MI and SCM complicated by a VF arrest.
It is unclear whether the acute coronary syndrome precipitated SCM or the other way around, the so-called chicken-and-egg dilemma. The clinical relevance of the dilemma is how to proceed with sudden death risk stratification and to determine whether a secondary prevention ICD is indicated.
The existing guidelines are clear that ventricular arrhythmias occurring within a 48-hour window of an MI fall within a reversible category, and an ICD is generally not indicated, especially when there has been adequate revascularization (2). However, it remains controversial as to whether a ventricular arrhythmia arrest in the context of SCM falls within the same reversible category. While the LV systolic function generally tends to recover over time, the risk of cardiomyopathy recurrence has been reported as high as 26% (3). Furthermore, ventricular arrhythmias complicate stress cardiomyopathy in 3.4% in the largest meta-analysis of case reports cases (4), and in a more contemporary large series, this figure was closer to 10% (5).
Current guidelines do not specifically address the management of ventricular arrhythmias complicating SCM and specifically whether an implantable cardioverter-defibrillator (ICD) is indicated. While this unique cardiomyopathy is considered reversible, the risk of recurrence and ventricular arrhythmia are considered relatively high, as outlined above. Given the evidence gap, we factored in several variables in our decision to ultimately implant the defibrillator. These variables include our patient’s life expectancy, the relatively high risk of ventricular arrhythmia associated with SCM, and the presence of LGE on CMR.
The most common mechanism of death in patients presenting with SCM is sudden death (4). Moreover, the presence of ventricular arrhythmias during the index admission increases the risk of mortality substantially and is perhaps the most important variable with a Hazard Ratio (HR) of 5, p < 0.001 (5). Other factors that should be considered include ECG parameters such as prolonged PR, QTc, and R-R intervals (6).
Cardiac Magnetic Resonance (CMR) imaging can also play a role in risk stratification. Typically, the hallmark of SCM in the vast majority of cases on CMR has been the absence of scar and the presence of myocardial edema in the mid to apical LV cavity (7). However, in what is likely the largest prospective study on the topic, scar or focal LGE was observed to some extent in up to 9% of patients (22/199) (8). While there was no evidence in this study that LGE was associated with mortality, other subsequent studies have provided contradicting evidence. In a single-center study by Steirmaier and colleagues (5) of 178 patients with SCM, subtle LGE was more common in patients developing any arrhythmia (including VT/VF) than those without (33% vs. 7.2%, p = 0.04). While the distribution of LGE (basal lateral LV) was unusual for Takutsubo in our patient, it nevertheless factored into our decision-making.
The DANISH study reports that the risk of sudden death in a non-ischemic cardiomyopathy population was approximately 8.2% over the course of a 5-year follow-up and significantly reduced with an ICD to 4.3% (HR 0.5, 95% CI 0.31–0.82) (9). This risk of SCD in an all-comer non-ischemic cardiomyopathy population is considered high and certainly merits consideration of an ICD. The risk of SCD in SCM is similarly high and can approach 10%; by the same token, implantation of a defibrillator should, therefore, be seriously considered, and especially if the presentation is complicated by ventricular arrhythmia.