I heard on a segment by dr. sanjay gupta on cnn that some doctors think any oil, even olive oil, increase risk of cardiovascular disease. is it true?

Quite possibly: It is true that some doctors do think this, though they are a distinct minority, as most doctors consider olive oil to be heart-healthy. However, an examination of research gives support to the idea that, while healthier than most oils, olive oil, as well as other oils, increases risk of cardiovascular disease. See http://bit.ly/1lpJ3ak for a detailed review of the research on olive oil & health.

It's still a fat: Any type of oil is still a fat, high in calories which can ultimately contribute to overweight/obesity and thereby heart disease. Some oils have a better profile of fats, meaning saturated, polyunsaturated, monounsaturated and trans fats, but all contribute calories. Olive oil may just be the lesser of several evils.