A 67-year-old man walks into a gym and … cut! Everyone knows what happens next. It’s a familiar screenplay trope. But here’s how it played out for me.

It’s a Friday evening in March. I have spent the day working at home, interrupted only by lunch with my friend John. I haven’t been to the gym for a while, as my shoulder is knackered. But I’m missing the buzz of exercise. So, I head to the gym – the same one I have been going to regularly for nearly 30 years.

Result. My shoulder can cope with the movement on the cross-trainer, so I do a brisk 40 minutes on it. Not an epic session, but good enough for my first time back. I sit down to recover and get my breath back. Then it happens. The first thing I notice is a weird, out‑of‑body sensation, almost as if I am simultaneously there and not there. Not altogether unpleasant. Maybe I have overdone it a bit, after all.

Then I feel a tightness through my chest. A pressure. Fuck. What’s happening? I can’t be having a heart attack, can I? There’s no pain in my left arm. So maybe not.

Then the tightness moves to my left arm. Am I just imagining this? Did I make this happen? Can I make it stop? Get a grip, John. Just breathe.

After about five minutes, the pain is no more than a persistent ache. That’s got to be a good sign, surely? I walk downstairs and say goodbye to the woman on reception. “Have a good weekend,” she says. Unlikely. I make my way to the car and drive home, still unable to process what exactly has happened. Can such a major trauma be this banal?

After a quick shower, I lay down on the bed for a couple of hours and wait for my wife to get home. Am I making a fuss about nothing? Either way, I’m scared. “What do you think?” I ask Jill when she gets home. “We’ve got to go to A&E,” she says. “Just in case.”

Friday night is not the best time of the week to choose for your heart attack. There is a 15-minute queue at St George’s hospital A&E, south London, to the triage desk. The nurse takes my details and feeds my symptoms into the system. We take the last two chairs in the waiting room. It feels apocalyptic. Most people are locked in their private world of pain. Some have head wounds. Some are groaning incessantly. A homeless man wanders up and down asking for a bag of crisps. There is at least a five‑hour wait to see a doctor.

After about 20 minutes, my name is called. I do a blood test to determine my levels of troponin – a protein released into the bloodstream during a heart attack – and have an electrocardiogram (ECG) – which records my heart’s activity – before being sent back to the waiting room.

I lose track of time. At some stage, I’m recalled to the nurse’s station and do a second blood test and ECG. I’m moved to my own bay in the nerve centre of A&E. I’m not sure what is going on, but it doesn’t look promising. I’m hooked up to a heart monitor, which seems to cut out every few minutes, turning the gentle beep into an insistent alarm. Apparently, this is normal, but it’s not good for my nerves.

Eventually, a doctor comes to see me. She can’t tell me exactly what is going on; my test results are unclear. But she thinks it’s most likely that I had a heart attack. She is going to keep me in for more tests. I spend the rest of the night staring anxiously at the doctor’s station, wondering what is going to happen next. I appear to be in limbo. An emergency, but not that much of an emergency.

Hours later, a nurse moves me to an A&E overspill ward, Majors B. I spend Saturday here, with Jill by my side for most of it. Now, there are other patients to observe. A young woman with chronic asthma. An elderly woman with a wonderful sense of humour. An elderly man not keen to pee in a bottle. I don’t blame him. Meanwhile, I’m confined to bed with a lot of wires stuck to my chest. Moving around is not recommended.

A doctor comes to see me late in the afternoon. My troponin levels have gone up. There is no doubt that I had a heart attack. I feel numb. My mind is racing. I had guessed that this was the likely diagnosis, but I had been hoping it might be something trivial. Now for the kicker: my heart attack was mild. But a mild heart attack does not necessarily mean mild damage to the heart.

Is this how I die?

***

I had the same thought almost 25 years ago, when my father died after not regaining consciousness from heart bypass surgery. I wondered if it might be genetic. Back then, this was an abstract thought. We all have to die sometime – and the three most likely causes are heart disease, cancer and dementia. All I had done was narrow this down.

Now, though, it feels like more of a pressing reality. My mortality is staring down at me. I don’t feel ready to die. I want more time with Jill. I want to see my kids do yet more amazing things. I want to write more sketches, finish books, see Spurs win something again. Hell, I couldn’t be outlived by my dog, could I?

It’s a lot to take in. Family and friends are amazing. If love alone could heal, I would have been discharged already. Three local GPs who have learned what has happened get in touch. They are wonderful and full of reassurance. If you are going to have a heart attack, they say, you have chosen the right one to have. I have also chosen the right place to have it: two miles from St George’s, a centre of excellence for cardiac medicine. Thank God I don’t live in the middle of nowhere.

Late at night, a bed on a ward becomes free. Not a cardio ward, unfortunately, but the best they can come up with. A porter wheels me on to the acute assessment unit. Bay E. Or eBay. I try to get some sleep, but doze fitfully. Too wired. Too tense. Some time around 6am, the nurses come round with the meds. Really? Could you not have waited another couple of hours? I have only just got to sleep.

It’s Sunday and there isn’t much going on. I take stock of my surroundings. On the other side of the bay is an elderly man with dementia. Another elderly man, with his charming niece, is having his chest drained. The care and the love that everyone, from the nurses to the doctors and the porters, shows them is moving. The NHS may be creaking at the seams and appear to be on the verge of chaos, but its heart still beats. As does mine. I watch Spurs on my iPad. Most unusually, they win 4-0, as if they are determined, for once, not to put me through it. Thanks for that.

Another near sleepless night. The noise and the fear and the hunger pains. The food is inedible. Luckily, Jill is able to bring me sandwiches. Early on Monday morning, a senior nurse from the cardio ward comes to assess me. Her eyes look strained. Years of having to break not particularly good news to patients, I suspect, unable to provide the reassurance people crave. I couldn’t do her job. She makes some notes, listens to my anxieties and spells out a likely course of action.

The first step is an angiogram, to check the blood supply to my heart. If the surgeon can fix it from there, they will, via angioplasty (using a balloon or a stent to open a narrowed or blocked artery). And if they can’t? Let’s not go there. One day at a time. OK. I’m trying.

“Could you sign the consent form?” asks the nurse. “I have to tell you it comes with a very small risk of death.” Could I just for once do something that might not kill me? I sign anyway, as you do. “It won’t be today,” she says. “It could be Tuesday. But Wednesday is most likely. We’re going to have to fit you in somehow.”

This could be a mantra for my hospital stay. I am too much for the system when I walk through the door, but somehow the hospital has found room to accommodate me.

Waiting for two days to find out what is going on with my heart isn’t my idea of fun. Too much time to think. Then, at about 3.30 on Monday afternoon, there is a call from the cardio unit. I’m to be taken up for my angiogram immediately. I feel a rising sense of panic. Why me? Why now? Have I been upgraded to a proper emergency?

Is this when I die?

***

There is a long wait for the lifts. Two of the four are out of service. The first lift to arrive is full, but everyone gets out when they see I’m being wheeled by a porter. A simple act of kindness. I feel so vulnerable, yet seen.

The first-floor cardiac catheter labs are like another world. No noise. No people. Just a sense of calm. “Why me? Why now?” I ask. A nurse smiles. “We had a spare slot.” Amazing. They could use the downtime to have a break. But no. They decide instead to make another person’s life better.

The operating theatre is like a hi-tech movie set. A cannula is put in my left wrist and sedation is added. I can feel my arm relaxing, but only to the end of my elbow. Are you sure you’ve given me enough? Local anaesthetic is administered to my right hand. For three seconds, it feels as if it’s on fire. Then nothing.

The procedure begins. A wire is fed in to an artery in my wrist. It’s going to do a Tour de John before ending up in my heart. Whoever dreamed this up, that you could use the body’s own arterial system as a rat run? I feel humbled.

Is this where I die?

***

I try not to let these thoughts intrude. But they do. Of course they do. Why would they not? But I don’t feel too anxious about it. These are nice, caring people and there are worse places to die. Must be the sedation talking.

After about 45 minutes, the surgeon stops nattering to his team – he is teaching a student how to do the procedure – and talks to me. “You’ve got a naturally thin vein,” he says. Thanks, Dad. “And one of your arteries is blocked. But I can fix it.” The relief is intense. I’m not going to die. Not now. Not yet.

“With a stent?” I ask.

“Better than that,” he says. “I’m going to give you the VIP treatment. A stent costs the hospital £150. I’m giving you a drug that costs £1,100 and is more effective.”

After another 45 minutes, the surgeon declares that he is happy. The blood flow to the artery is back to 100% from its previous 40%. As I’m wheeled up to the day case unit, where a bed has been scrounged for me, I take a final look around – at the theatre, but mainly at the surgical team who have just saved my life. I won’t forget them.

Just one more day in hospital, to have the echocardiogram – to determine heart function – that I was meant to have earlier in my stay. The radiologist says my heart is “fine, not excellent”. Can I return it to excellence? “Yes.” That is my homework. No need to give up booze, drugs or cigarettes; I did that decades ago. I need to eat better and exercise more moderately. Starting now.

I have been home from hospital a week now. Every day, I feel a little stronger, physically and emotionally. When I was in hospital, I was in coping mode: surviving from minute to minute, trying not to be overwhelmed. Now, I have to deal with the feelings. Learn to trust my heart again, that it’s going to be OK, that not every twinge is fatal. This will take time.

It’s been one hell of a shock. On the day of my heart attack, I wrote in the Saturday diary that I was a lucky man. I feel that even more so now, restored to health by the love of not just family and friends, but strangers, too. How easily the outcome could have been different. The NHS can be frustrating – try getting your shoulder fixed – but when the chips were down, it was there for me.

St George’s is magnificent in its chaos. But it shouldn’t have to be in chaos. There is no point celebrating its successes if we don’t value it enough to give it the resources it needs. And then the staff. Over four days, I must have been in close contact with at least 50 members of staff. All but five or so were black, Asian or from other European countries. The NHS would fall apart without immigration. Something for Rishi Sunak to bear in mind if he ever happens to get chest pains on his Peloton.

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Depraved New World by John Crace (Guardian Faber Publishing, £16.99). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.