David Masson, 59, had been feeling unwell during a fishing trip last month but was convinced all he needed was a bite to eat. But when he arrived at his Penicuik home, his condition worsened and he began complaining about a “tightness” in his chest and arm. Son Jonathan, 16, instantly recognised the symptoms and worked hard to convince his dad he was gravely ill before raising the alarm. A nurse later told the family Mr Masson had faced a 20-minute race against time to survive and that his quick-thinking son had probably saved his life. Mr Masson said: “I’d walked about half a mile to the River Esk and although I had some cramp in my arm and a little tightening in my chest, I thought it was just indigestion. I started to head home thinking that once I had something to eat I would be OK to come back out fishing. “Jonathan was sitting in the living room watching TV when I got in and asked what was wrong. I told him my symptoms and he said, ‘Dad, I think you’re having a heart attack’. “I told him, ‘Don’t be silly’ and thought he was being a little melodramatic but he said, ‘I’m going to call my mum’ and grabbed my phone off me to ring her and the paramedics. He’s 6ft-something so I didn’t argue.” Paramedics rushed to the scene and after checking over the ailing father of three they revealed he was suffering a cardiac arrest. Mr Masson said: “Without Jonathan I would have died, without a shadow of a doubt. When I say he’s my hero I mean it.” Jonathan, who had fortunately completed a training course by the British Heart Foundation (BHF), said: “It was very scary. I asked him what was wrong and he said he had a pain in his arm and tightening in his chest. I clicked what it was but didn’t want to alarm him. “So I grabbed his phone to raise the alarm.” The youngster, who is to be awarded a certificate of achievement by the BHF, added: “It’s great that he’s proud of me and that I did the charity’s Heartstart programme because if I didn’t it may have turned out very differently.” His dad revealed that a nurse told him he had 22 minutes to get medical treatment or he would have died. “Jonathan recognised the symptoms in the nick of time,” he said. “I took a bit of convincing but that’s what I’m like.” Claire O’Neill, Heartstart programme lead for the BHF, said: “Every six minutes someone dies of a heart attack in the UK but Jonathan’s quick thinking made sure his dad definitely wasn’t one of them. “Jonathan’s dad is a lucky man and his family is rightly very proud of him – as are we.”