If you're being checked for a clogged heart artery, doctors might use two different tests: a stress MRI and a special X-ray called an angiogram. Sometimes, these tests disagree. The MRI might show a problem, but the angiogram looks normal. This can be confusing for both patients and doctors. This study looked at 354 people with suspected clogged arteries to understand why this happens. They found that people whose tests disagreed in this way—abnormal MRI but normal angiogram—had a thicker heart muscle than people whose tests both agreed everything was normal. The study also found a hint that these people might have more resistance in their tiniest blood vessels. The researchers conclude that a thicker heart muscle can potentially confuse the results. It might make the pressure reading from the angiogram look falsely normal, even when there is a problem. This means that for some people with a thicker heart muscle, a normal angiogram result might not tell the whole story.
Why do heart tests sometimes disagree? A thicker heart muscle might be the surprising reason.
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What this means for you:
A thicker heart muscle can make one heart test look normal when another suggests a problem. What this means for you:
A thicker heart muscle can make one heart test look normal when another suggests a problem. View Original Abstract ↓
AIMS: This study aimed to determine the impact of left ventricular mass (LVM) on discordant stress cardiac magnetic resonance (CMR) imaging and invasive coronary angiography (ICA) in patients with suspected coronary artery disease (CAD) at coronary computed tomography angiography (CCTA).
METHODS AND RESULTS: In this substudy of the Dan-NICAD 2 trial (NCT03481712), 354 patients with suspected obstructive CAD on CCTA were examined with both rest and stress CMR and ICA for invasive physiological measurements. An abnormal stress CMR was defined as ≥2 contiguous segments with a stress perfusion defect, late gadolinium enhancement, or wall motion abnormality. CMR-derived LVM was sex-adjusted by conversion from grams to per cent. Haemodynamically obstructive CAD at ICA was defined as visual diameter stenosis >90% or FFR ≤0.80. LVM was higher in patients with an abnormal stress CMR compared to those with a normal CMR (median difference = 8.0%, P < 0.001). Patients with or without haemodynamically obstructive CAD had similar LVM (median difference = 2%, P = 0.222). Within four binary groups based on normal/abnormal stress CMR and ICA, both median LVM and index of microvascular resistance were higher in patients with discordant abnormal stress CMR and normal ICA than in patients with concordant normal stress CMR and ICA (124% vs. 111%, P = 0.001, and 29 vs. 19, P = 0.072, respectively).
CONCLUSION: In patients with suspected obstructive CAD, increased LVM can potentially confound concordance between stress CMR and ICA. This is due to increased microvascular resistance, which decreases the pressure gradient across an epicardial stenosis, resulting in a false high FFR and thus, normal ICA.