SCAD in Men: Canadian Study Sheds Light on Rare Condition

Men account for one in 10 patients with spontaneous coronary artery dissection (SCAD), according to a recent report that takes a rare look at sex differences in a condition most often associated with women.

The analysis, from a large Canadian observational study, highlights a number of ways in which male and female SCAD patients diverge. Traditionally, SCAD was regarded as a pregnancy-related event, though in recent years understanding has begun to grow, with some studies suggesting SCAD is behind 25% of MIs in women younger than 50 as well as 1% to 4% of all ACS.

“It’s unusual for men to have SCAD,” said senior author Jacqueline Saw, MD (Vancouver General Hospital and University of British Columbia, Canada). “So it’s always been intriguing to me: why do certain men have SCAD? What are the causes?”

She had noticed in clinic that for many men coming in with SCAD, physical exertion, such as lifting very heavy weights, appeared to trigger their condition. She also saw an unusually high proportion of men with fibromuscular dysplasia (FMD), a known risk factor for SCAD. This “in and of itself, is really rare, because men aren’t supposed to have FMD,” Saw observed: nine out of 10 people with FMD are women.

Their new study, with a cohort of more than 1,100 patients, builds on a 2016 paper looking at 288 individuals with SCAD. It confirms both the earlier data and Saw’s clinical experience.

Led by Cameron McAlister, MBChB (Vancouver General Hospital and University of British Columbia), this latest study was published this month in JACC: Cardiovascular Interventions.

For cardiologists, the main takeaway pertains to diagnosis, Saw told TCTMD, noting: “A lot of clinicians don’t think of men having SCAD in the first place.”

But when male patients present to the cath lab with ACS and have “done intense exertion, you do have to think about SCAD as one potential cause,” she said, adding that men diagnosed with SCAD also need to be screened for FMD. Ideally, catheter-based screening of the renal and iliac arteries can occur in the cath lab, which Saw said would be more sensitive than later CT angiography at detecting FMD.

Fernando Alfonso, MD, PhD, and Teresa Bastante, MD (both from Hospital Universitario de La Princesa and Universidad Autónoma de Madrid, Spain), writing in an accompanying editorial, also highlight the uncertainty in this area. “Unfortunately, many knowledge gaps and unmet clinical needs persist in SCAD. Among them, it remains unclear why this disease mainly affects women. Similarly, the prevalence, characteristics, and clinical implications of SCAD in men remain unsettled,” they agree.

FMD and Physical Exertion

In the Canadian SCAD Study, 123 of 1,173 patients (10.5%) were men. Cardiovascular risk factors, such as diabetes, hypertension, and dyslipidemia, were similar between the sexes, as was body mass index.

Still, there were numerous statistically significant differences between the two groups. The male SCAD patients tended to be younger than their female counterparts (mean 49.4 vs 52.0 years). Men also less frequently had prior MI (0.8% vs 7.0%), FMD (27.8% vs 52.7% of the 915 patients screened), a history of depression (9.8% vs 20.2%), pulsatile tinnitus (8.1% vs 16.2%), and migraines (17.9% vs 35.8%).

A survey completed by 1,134 of the patients explored potential SCAD triggers. Men were less likely to report experiencing emotional stress (35.0% vs 59.3%) but more likely to cite physical exertion (58.1% vs 45.5%) and isometric activity (40.2% vs 24.0%), with an even larger gap for intense isometric exercises that involved lifting more than 50 lbs (25.6% vs 7.1%)—all significant differences. Men also were less likely than women to say they had high perceived stress (3.5% vs 11.0%; P = 0.025)

Angiographic parameters were similar for male and female study participants. However, there were anatomic differences: SCAD in men was more likely to occur in the circumflex artery (44.4% vs 30.9% in women) but less likely to be seen in the right coronary artery (11.8% vs 21.7% in women).

“In our series, men with SCAD were treated pretty similarly to women with SCAD, in the sense that the majority were treated conservatively, not undergoing PCI or bypass surgery,” Saw noted, and with that conservative treatment, most clinical outcomes were alike between the two groups. One exception to this similar care is statin use: 71.1% of men received it at discharge, compared with 61.3% of women (P = 0.037).

A lot of clinicians don’t think of men having SCAD in the first place. Jacqueline Saw

By a follow-up of 3 years, the male patients were less likely to present to the emergency department with chest pain (10.6% vs 24.8%; P < 0.001) and less apt to be hospitalized for the condition (0.8% vs 7.8%; P = 0.001). No differences were seen between men and women for recurrent MI (7.3% vs 10.4%), recurrent SCAD (4.1% vs 5.7%), or MACE (death, MI, stroke or TIA, heart failure hospitalization, and revascularization; 7.3% vs 12.7%). Kaplan-Meier analysis showed there was no sex difference in the time to first MACE.

The editorialists point to some good news, in that “once the diagnosis of SCAD was established, management, including most cardiovascular medications and PCI indication (and results) were similar between men and women, excluding a gender bias.” But they call attention to the “higher prescription of statins in men, despite a similar lipid profile” and the absence of a clear indication in SCAD patients without hyperlipidemia.

Like Saw, Alfonso and Bastante say that greater awareness is key. “In clinical practice, we should try to avoid a reversed gender bias” and suspect SCAD also in men when the clinical and angiographic scenarios are suggestive,” they advise. “When required, intracoronary imaging may be used to confirm diagnosis and rule out atherosclerosis in men.”

Saw said that next steps include genetic analyses of their overall cohort. For “men with SCAD, we need to get to the bottom line. Maybe it’s FMD, but maybe it’s something else,” she noted. Another question is whether men who have SCAD subsequent to physical exertion can safely return to intense isometric exercises.