Omega 3s have been shown to have a protective effect on the heart. The Vegetarian Society has a nice article about Omega 3 benefits:
"All three omega 3 fats have been shown to offer numerous physiological benefits, notably their anti-inflamatory properties and their ability to offer cardioprotective effects especially in people with pre-existing cardiovascular problems".
Most vegetarian and vegan diets are low in Omega 3. There are many vegetarian sources of Omega 3: walnuts, flax seeds, flax seed oil, canola oil, walnut oil, soybeans/soy products, wheat germ, and leafy greens. You don't have to take that fish oil tablet! You can also take a microalgea supplement for Omega 3.
An easy way to get flaxseeds into your diet is to put 3-4 tablespoons of whole flax seeds into a coffee grinder and add them to muffins. Flax Seeds must be ground or they will pass through the body undigested and provide no nutritional value. Wheat germ makes a great muffin topping to add even more Omega 3.