For decades, heart attacks were seen as a disease of the elderly, an unfortunate outcome of decades of smoking, poor diet, and sedentary lifestyles. But a disturbing trend is rewriting this narrative. Increasingly, young men and women in their 20s, 30s, and early 40s are being struck by heart attacks, many of whom appear to live “healthy” lives, regular at the gym, active on social media with their fitness updates, and outwardly in their prime.