Prognostic Role of CMR and Conventional Risk Factors in Myocardial Infarction With Nonobstructed Coronary Arteries

Abstract

Word count: 4478words (including figures legends and references)Running title: Prognostic role of CMR and conventional risk factors in MINOCA Abstract: Objective: Assess the prognostic impact of Cardiovascular Magnetic Resonance (CMR) and conventional risk factors in patients with Myocardial infarction with non-obstructed coronaries (MINOCA). Background: MINOCA represents a diagnostic dilemma and the prognostic markers have not been clarified. Methods: 388 consecutive MINOCA patients undergoing CMR assessment were identified retrospectively from registry database and prospectively followed up for a primary clinical endpoint of all-cause mortality. 1.5T CMR was performed using a comprehensive protocol (cines, T2-weighted, and late gadolinium enhancement sequences). Patients were grouped into 4 categories based on their CMR findings: myocardial infarction (MI) (embolic/spontaneous recanalization), myocarditis, cardiomyopathy and normal CMR. Results: CMR(performed at a median of 37days from presentation) was able to identify the cause for the troponin rise in 74% of the patients (25% myocarditis, 25% MI and 25% cardiomyopathy), whilst a normal CMR was identified in 26%. Over a median follow-up of 1262days(3.5years), 5.7% patients died. Cardiomyopathy group had the worst prognosis (mortality 15%, log rank 19.9 p<0.001), MI had 4% mortality, and 2% in both myocarditis and normal CMR. In a multivariable cox regression model (including clinical and CMR parameters), CMR diagnosis of cardiomyopathy and ST-segment elevation on presentation ECG remained the only 2 significant predictors of mortality. Using presentation with ECG ST-elevation and CMR diagnosis of cardiomyopathy as risk markers, the mortality risk rates were 2%, 11% and 21% for presence of 0, 1 and 2 factor respectively(p<0.0001). Conclusion: In a large cohort of MINOCA, CMR(median 37days from presentation) identified a final diagnosis in 74% of patients. Cardiomyopathy had the highest mortality, followed by MI. The strongest predictors of mortality were a CMR diagnosis of cardiomyopathy and ST-elevation on presentation ECG.

Guidelines for the management of myocardial infarction/injury with non-obstructive coronary arteries (MINOCA): a position paper from the Dutch ACS working group

“…Recently, the prognostic role of cardiac magnetic resonance imaging (CMR) was assessed in MINOCA patients. It was found that a CMR diagnosis of cardiomyopathy was an independent predictor for mortality, whereas a diagnosis of MI, myocarditis or a normal CMR was not [19].…”

“…Thirteen studies have evaluated the diagnostic yield of CMR and were able to find a definitive diagnosis in 71% of the patients (19% MI, 33% myocarditis, 12% Takotsubo cardiomyopathy, 2% hypertrophic cardiomyopathy, 2% dilated cardiomy- opathy, 3% other), as illustrated in Fig. 1 [4,19,54,[59][60][61][62][63][64][65][66][67][68]. Based on these observations, we recommend routine examination with CMR within 4 weeks after hospital admission.…”

Diagnostic evaluation of chest pain

“…However, one should keep in mind that even in case obstructive CAD is found, it is not yet clear whether this should be treated with medication alone or in combination with coronary revascularization. 41 Some limitations of the current study should be considered. Firstly, this is a single centre observational study in an unselected population with acute chest pain and clinical decisions were made irrespective of our findings.…”

“…40 An editorial comment to that study suggested that for using different delta values, 5-67% of AMI may be missed. 41 This raises caution against the strict use of delta values to exclude AMI in patients with an otherwise high clinical probability of AMI. Moreover, dynamic changes are also not exclusive to AMI but rather indicative of acute myocardial injury.…”

“…Although in a substantial number of patients (29%) CMR does not provide a diagnosis, their prognosis is excellent. 40,41 A normal CMR study in MINOCA has been associated with: 1) Attenuated/small troponin release. 40 2) Diffuse injury rather than focal myocardial injury, which is more difficult to detect with conventional CMR sequences.…”