There’s a patient I think about often. Mid-fifties, fit, no family history of cardiac problems. He’d been snoring for years, his wife complained constantly, but his GP kept telling him to lose weight (he was already lean) and cut back on alcohol (he barely drank). Then he had a heart attack.

His cardiologist, to her credit, ordered a sleep study. Severe obstructive sleep apnea — an AHI of 62. That’s 62 times per hour his airway was collapsing, his oxygen dropping, his heart struggling.

This story isn’t unusual. It’s actually disturbingly common.

The Cardiovascular Cost of Untreated OSA

Every time your airway collapses during sleep, your body mounts a stress response. Your sympathetic nervous system fires, blood pressure spikes, oxygen saturation plummets, and inflammatory markers flood your bloodstream. Do that 30, 40, 60 times an hour, every night, for years — and you’re essentially bathing your cardiovascular system in stress hormones.

The American Heart Association has been explicit about this link for over a decade. Untreated moderate-to-severe OSA roughly doubles the risk of stroke and significantly increases the risk of atrial fibrillation, heart failure, and coronary artery disease.

A landmark study published in the Lancet Respiratory Medicine followed over 10,000 patients and found that those with severe OSA who refused or couldn’t tolerate CPAP had a cardiovascular event rate nearly three times higher than those who used treatment consistently.

Why GPs Miss It

I don’t want to blame general practitioners. They’re overwhelmed, underfunded, and dealing with 15-minute consultations. But there are structural reasons sleep apnea gets overlooked in cardiac risk assessments:

It’s not on the standard checklist. When your GP calculates cardiovascular risk, they’ll consider cholesterol, blood pressure, smoking status, diabetes, and family history. Sleep-disordered breathing isn’t part of most risk calculators, even though the evidence says it should be.

The “typical” patient stereotype is wrong. Many doctors still picture sleep apnea as an overweight, middle-aged man who snores. But OSA affects women (especially post-menopause), thin people, and younger adults more often than most clinicians realise. If you don’t fit the stereotype, you don’t get the referral.

Symptoms overlap. Fatigue, morning headaches, difficulty concentrating — these symptoms could be depression, thyroid dysfunction, iron deficiency, or a dozen other things. Sleep apnea often sits at the bottom of the differential diagnosis list.

The Mechanisms That Matter

The damage isn’t just from low oxygen, though that’s bad enough. There are several distinct pathways through which OSA harms the heart:

Intermittent hypoxia. Repeated drops in blood oxygen trigger oxidative stress and endothelial dysfunction. Your blood vessels lose their ability to dilate properly, accelerating atherosclerosis.

Intrathoracic pressure swings. When you try to breathe against a closed airway, the pressure changes in your chest cavity can physically stress the heart walls. Over time, this contributes to left ventricular hypertrophy and atrial enlargement — both precursors to heart failure and arrhythmia.

Sympathetic overdrive. Your “fight or flight” system doesn’t get to rest. Chronic sympathetic activation raises baseline blood pressure and heart rate, even during waking hours. This is why many OSA patients have resistant hypertension — their blood pressure won’t respond to medication because the underlying cause hasn’t been addressed.

Systemic inflammation. C-reactive protein, TNF-alpha, interleukin-6 — these inflammatory markers are consistently elevated in untreated OSA patients. Chronic inflammation is a driver of plaque formation and instability in coronary arteries.

What Should Happen Instead

If you’ve had a cardiac event, or you’re being treated for hypertension, atrial fibrillation, or heart failure, you should be screened for sleep apnea. Full stop. The European Society of Cardiology includes this recommendation in their guidelines, though implementation varies wildly.

Screening doesn’t have to be complicated. A home sleep test can identify most cases of moderate-to-severe OSA. It’s a single night with a small device on your finger and a nasal cannula. Not fun, but not terrible either.

For patients already diagnosed with both conditions, treating the sleep apnea can make a measurable difference. CPAP therapy has been shown to reduce blood pressure by 3-5 mmHg on average — modest, but in the context of cardiovascular risk, clinically meaningful. More importantly, it reduces the nocturnal blood pressure surges that are particularly dangerous for cardiac patients.

The Frustrating Reality

Here’s what bothers me most: we have strong evidence, effective treatment, and relatively simple screening tools. Yet the average time from symptom onset to OSA diagnosis is still estimated at 5-7 years. During those years, hearts are taking damage that may not be reversible.

If you snore heavily, wake up gasping, have morning headaches, or feel exhausted despite sleeping eight hours — and especially if you also have high blood pressure or a cardiac history — push for a sleep study. Don’t wait for someone else to connect the dots.

Your heart can’t afford the delay.