Role Reversal: Type 2 MIs in HIV as Common as Type 1 MIs

Patrice Wendling

January 04, 2017

SEATTLE, WA — In a large cohort of US patients with HIV, half of all MIs were type 2 MIs (T2MIs), a rate far exceeding that observed in the general population[1].

"The data in the general population is limited, but there are no data that suggest it is even close to this high," lead investigator and infectious disease specialist Dr Heidi M Crane (University of Washington, Seattle) commented to heartwire from Medscape.

Prior studies have shown that up to 26% but usually about 10% of all MIs are T2MIs depending on the population. Unlike type 1 MIs (T1MIs) that result from atherosclerotic plaque rupture, type 2 events are secondary to ischemia due to causes including arrhythmias, coronary artery spasm, anemia, and hypotension that either increase oxygen demand or decrease supply.

In the HIV cohort, however, almost half of T2MIs were caused by sepsis or bacteremia (34.7%) or vasospasm induced by use of cocaine or other illicit drugs (13.5%).

For those treating HIV patients, the findings may not be that surprising.

"It was already clear that we are seeing MIs in our patients that don't look like those in the general population," but "it hadn't been measured; no one had the data or ability to parse it this way to understand how common this is," she said.

The findings were published online today in the JAMA Cardiology.

Crane and her team used the Centers for AIDS Research Network of Integrated Clinical Systems Cohort database to identify 571 patients with HIV (75% male; median age 49 years) who had an incident MI between January 1, 1996 and March 1, 2014 and were receiving care at eight clinical sites across the US.

In all, 370 events were classified as definite and 201 as probable, of which 283 (49.6%) events were T1MI and 288 (50.4%) were T2MI as adjudicated by two expert physicians using physician notes, ECGs, imaging studies, cardiac biomarker values, and laboratory tests. An additional 79 patients not meeting the criteria for an MI but who underwent coronary intervention for severe atherosclerosis were included in the T1MI analysis.

Patients with a T2MI were significantly more likely than those with a T1MI or coronary intervention to be younger than 40 years (16.3% vs 8.8%), female (28.1% vs 19.1%), African American (70.1% vs 43.1%), and not receiving antiretroviral therapy (ART) (46.5% vs 25.1%).

Patients with a T2MI tended to be sicker in terms of their HIV (median current CD4 count 230 vs 383 cells/µL; HIV viral load 1808 vs 116 cells/mL) but had significantly lower lipid levels (mean total cholesterol 167 vs 190 mg/dL) and lower mean 10-year Framingham CHD risk scores (8% vs 10%).

"I think what this demonstrates is that traditional approaches such as instituting a statin are not going to have the same impact, if half of our events are due to type 2 MIs," Crane said.

Further research is needed to better understand the complex association between traditional and HIV-specific CVD risk factors and potential interactions with ART, but in the meantime, she said, clinicians can stress the importance of early ART initiation and risk-reduction strategies.

"This is one more piece of evidence for having a discussion with patients about cocaine and illicit drugs."

Crane said an easy critique of the study is that it did not address silent MIs and may have missed critically ill patients in whom cardiac biomarkers were not measured, "but that said, those sorts of errors would only increase the number of events in this population, and the fact that we are seeing such high rates already, that's not being driven by limitations in our data."

The investigators are currently examining outcomes data and "trying to understand why 1-year mortality is much higher in our type 2s than in our type 1s," despite being younger and having a more favorable lipid and CHD risk profiles, Crane said.

The research was supported by grants from the National Institutes of Health and American Heart Association. Crane reported no relevant financial relationships. Disclosures for the coauthors are listed in the paper.

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