Now a days heart disease has become very common across the world. Let's look at how a heart disease is predicted in the kundli (Horoscope).
Fourth house represents heart. If the lord of fourth house is in a dusthana (6th, 8th or 12th house), the moon and sun the lords of vitality, are devoid of strength and the fourth lord and the moon has evil aspects, the native suffers from heart disease. Aspect of Mars on 4th house, the sun, the moon and the 4th lord indicates heart attack.
Let's look at the horoscope of a native who died of heart attack in 1987. In the above horoscope, there are two malefics (Saturn being the lord of 8th house and Venus being the lord of 12th house, two dusthanas) in the fourth house, the house of heart. The malefics are making the house week. Jupiter, the lord of 7th house is aspecting the fourth house. The fourth house is surrounded by malefics in 3rd and 5th house (paapkartaari yog) making it even weaker.
Let's look at the fourth house lord Mercury. It is placed in 6th house, a dusthana, and aspected by two malefics; Mars, the karaka of blood pressure and Saturn which is already placed in 4th house. Sun and Moon both have evil aspects. The native died in the shani mahadasha in shani bhukti.