It would be virtually impossible to remove all other factors to isolate the effect of long-term caffeine consumption on the human body. This becomes clear when there are about as many studies that show the positive effects of coffee as there are negative effects. Such a small percentage of the population eats quality food how can one test caffeine when diets are filled with artificial flavorings, colorings, preservatives, artificial sweeteners, GMO food sources, insecticides, heavy metals, high-fructose corn syrup, air pollution... it goes on and on. Add job and family stress levels and sedentary life styles and it's no wonder that heart disease, high blood pressure and the rest are such topics of consideration. They even come up with new names for diseases - instead of heart burn, we now get "acid reflux disease."
The point? Listen to what your body tells you. If you get heartburn, don't just take a pill. Look into your diet and eating habits. Drink more water. Eat smaller meals. If caffeine raises your blood pressure, don't drink it. But be careful about quoting medical studies to prove any dietary point. There are probably just as many that prove it wrong.
And what is "a healthy coffee"? If you are talking about anything other than decaf, we might have a problem here.