Heart attacks, heart failure, and strokes don’t come out of nowhere, a new study concludes. The first time they strike, patients, clinicians, and researchers might think there were no red flags.
But a prospective cohort study reports that more than 99% of people who experienced these illnesses had at least one of four risks for cardiovascular disease. They had “suboptimal” high blood pressure, cholesterol, or blood glucose, or they were current or former smokers. More than 93% of the more than 9.3 million people in two national cohorts followed for 20 years had more than one risk factor.
Among women under 60, often considered to be at lowest risk, more than 95% had at least one nonoptimal risk factor before heart failure or stroke.
This almost universal prevalence of warning signs is far higher than reported in other studies, the new paper asserted.
“Every practicing cardiologist has seen cases in which individuals without any known risk factors sustain an MI or develop significant coronary disease,” Neha Pagidipati of the Duke Clinical Research Institute wrote in a companion editorial, referring to myocardial infarction, or heart attack. “However, the prevalence of CVD without traditional risk factors may be significantly lower than previously described.”
The difference comes down to the definitions, Philip Greenland, a preventive cardiologist at Northwestern University Feinberg School of Medicine and a co-author of the study published Monday in the Journal of the American College of Cardiology, told STAT. There’s a crucial distinction between what the American Heart Association and other medical groups call “optimal” for good health and “clinical” for treatment — and what doctors treat.
Take blood pressure. AHA and others say the optimal level for ideal health is 120/80 mm or lower while the goal is 130/80 mm, meaning it’s the higher scores that usually trigger a discussion about diagnosis and possibly treatment. For blood cholesterol, the optimal total number is 200 mg/dL and clinical is 240; for fasting glucose optimal is 100 mg/dL and clinical is 126. For tobacco, optimal is past or current smoking but clinical is current tobacco use.
Doctors often use a higher clinical threshold before writing a prescription. For blood pressure, it’s 140/90.
“If you use that as your cut point, you’re missing a whole bunch of people in the population who have these levels that are nonoptimal, but not yet at the level that we’re using medication,” Greenland told STAT. “If you look carefully enough, heart attack, stroke, and heart failure are actually not occurring out of blue. People have these risk factors above optimal level and it’s very, very common to have at least two, or three, or four.”
In combination, Greenland said, even relatively modest exposures to nonoptimal blood pressure, cholesterol, blood sugar, and cigarette smoking predispose a person to cardiovascular risk.
“We need to be aware that even risk factor levels that don’t appear to be excessive are not optimal. And that’s a message, not only for doctors, but for patients as well,” Greenland said. “These very, very common nonoptimal levels can be treated. And if treated, should be capable of preventing heart attack, stroke, and heart failure.”
In the JACC study, the proportion of people with at least one clinically elevated risk factor — usually blood pressure — was large, 90% to 95%.
The WHO defines clinical hypertension in adults as systolic blood pressure at or above 140/90 while also saying blood pressure with a top number under 130 but over 120 mmHg isn’t classified as hypertension, but still raises health risks.
To understand risk, it also matters where the numbers come from, Greenland said. Researchers relying on medical charts to document a diagnosis may miss a lot of people. People participating in the cohorts studied for the JACC paper came from South Korea, where more than 9.3 million people had risk factors measured every year through the national health system. Nearly 7,000 people in the long-running U.S.-based Multi-Ethnic Study of Atherosclerosis also had their numbers recorded regularly.
Where does that leave patients and doctors?
Karen Joynt-Maddox, a general cardiologist at Washington University in St. Louis who co-directs the Health Services and Health Policy Research Center there, pointed to a health care system in the U.S. that invests far more in treatment than prevention.
“We have much that we could be doing. It’s just that the system is not in place to work like that,” she told STAT. She was not involved in the study. “And so you have exactly what this paper showed, which is people who are showing up with a really terrible thing, the worst day of their life, that some number of those could have been prevented.”
There’s also the nature of high blood pressure.
“No one wants to have a heart attack or a stroke,” she said. “High blood pressure is so intangible in some ways, until it’s not.”