Short-Term Mortality Lower With Type 2 MI Versus Type 1 MI

Patients with type 2 myocardial infarction (T2MI) without underlying coronary artery disease (CAD) have substantially lower event-related mortality compared with patients with T2MI without CAD, according to a study published Sept. 18 in the Journal of the American College of Cardiology.

In this secondary analysis of the APACE trial, Thomas Nestelberger, MD, et al., assessed the effect of the definition of T2MI on its incidence, treatment and event-related mortality among adults presenting with symptoms suggestive of MI from the time of presentation to 90-days follow-up.

Type 1 MI (T1MI) was defined as spontaneous MI related to ischemia due to a primary coronary event. T2MI-2007 was defined according to the second universal definition of MI published in 2007 as MI secondary to ischemia with known or newly diagnosed CAD. T2MI-2012 was defined using the third universal definition published in 2012 as MI secondary to ischemia but the presence of CAD was not required. Patients meeting the T2MI-2012 definition but not the T2MI-2007 definition were reclassified and analyzed separately (T2MI-2012-reclassified). T2MI-2012 included T2MI-2007 plus T2MI-2012-reclassified.

The results showed that of 4,015 patients eligible for analysis, 17 percent (n = 684) had T1MI, 2.8 percent (n = 112) had T2MI-2007 and 6 percent (n = 240) had T2MI-2012-reclassified. High-sensitivity cardiac troponin (hs-cTn) levels were highest in patients with T1MI and lowest in those with T2MI-2012-reclassified.

Ninety-day mortality was significantly lower in patients with T2MI-2012-reclassified (0 percent) vs. patients with T2MI-2007 (0 percent; log rank test, p = 0.03) and T1MI (3.7 percent; log rank test, p = 0.01).

This study showed that patients reclassified with cardiomyocyte injury due to supply-demand mismatch who do not have underlying CAD (T2MI-2012-reclassified) have substantially lower event-related mortality compared with patients with CAD (T2MI-2007). “Their classification as ‘MI’ may be misleading and should be reconsidered,” the study authors write.

In a related editorial, James L. Januzzi Jr., MD, FACC, et al., discuss several caveats with regard to the APACE study. “Though we agree in principle that T2MI without CAD likely has a more benign course, we do not support reconsideration of their diagnosis,” they write. “We propose investigating T2MI using a phenotype-specific approach…Only with a clear understanding of the spectrum of T2MI can we approach the development of treatment options.”  

Clinical Topics: Atherosclerotic Disease (CAD/PAD)

Keywords: United States, Coronary Artery Disease, Incidence, Myocytes, Cardiac, Follow-Up Studies, Myocardial Infarction, Ischemia, Phenotype, Troponin

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