• Americans are dying from heart disease at a faster rate, stalling four decades of gains against the nation’s leading killer and driving up the U.S. mortality rate overall.

                                                                                                                                                                                The decline in heart-related deaths has been so precipitous, in fact, that until 2011 heart disease was poised to drop below cancer as the leading cause of death in the U.S., researchers say. But then the downward trajectory suddenly slowed at that point and remained slow until the heart disease death rate rose in 2015.                                                                                                                                                                                                                                           “It’s a definite milestone in the wrong direction, and the concern a lot of us have is that it reflects largely the approximately three-decade-long epidemic of obesity,” said Stephen Sidney, senior research scientist with the Kaiser Permanente Northern California division of research, who led a study published earlier this year that pinpointed the halt in progress against heart disease.                                                                                                                                                                                                                                                                                                                                The new findings offer just the latest sign that mortality rates are creeping up in the U.S., at least in some parts of the population, after decades of improvements in longevity—a startling reversal for a wealthy country blessed by advances in health care and standards of living. Last year, an analysis by two Princeton University economists identified rising death rates in white, middle-aged Americans, driven largely by increases in deaths from suicide, drug overdoses, alcohol abuse and chronic liver diseases.                                                                                                                                                                                                                                                                                                                            In the spring, the CDC reported that life expectancy fell for the white population in Now, the agency says the overall death rate rose 1.2% in 2015, to 733.1 per 100,000 people, the first significant increase in mortality overall in the U.S. since 1999. Increases occurred among white men and women as well as black men. Death rates rose for eight of the top 10 leading causes of death, the CDC noted, including for chronic lower respiratory diseases, unintentional injuries—which includes drug overdoses—Alzheimer’s disease, diabetes, kidney disease and suicide.The death rate declined only for cancer. Heart disease and cancer accounted for about 45% of U.S. deaths in 2015.                                                                                                                                                                                                                                     While it is difficult to know yet whether the mortality increase in 2015 is the beginning of a longer upward trend, “it’s something that we should pay attention to,” said Elizabeth Arias of the CDC’s National Center for Health Statistics, and an author of the report.                                                                                                                                                                                                                                                                                                                                       More people are dying at younger ages, she and other researchers noted. “Old age mortality has not changed that much, but there’s been pronounced increases in mortality in the middle ages,” Dr. Arias said.                                                                                                                                                                                                                         Researchers say the obesity epidemic, which took off in the 1980s, is probably mostly to blame for the higher death rate from heart disease, because it has driven increases in rates of hypertension, diabetes and other heart-related problems. “We’re reaping what we’ve sown,” said Donald Lloyd-Jones, head of preventive medicine at Northwestern University’s Feinberg School of Medicine. “It’s a clear causal chain.                                                                                                                                                                                                                                                             ”More public-health measures—such as policies to reduce smoking and help people lose weight—will be needed to make inroads, he said.                                                                                                                                                                                                                                                                                                                                           Rates of obesity have risen substantially over the past several decades. According to the latest data from the CDC, 38.2% of adults between ages 20-74 and 20.6% of teens ages 12-19 are obese, compared with 14.5% of adults and 6.1% of teens of those ages in the early 1970s.                                                                                                                                                                                                                                                                                 Raymond Gibbons, a cardiologist at Mayo Clinic, said the findings call for continued support for the Million Hearts Initiative, an ongoing five-year effort led by the CDC and the Centers for Medicare and Medicaid Services to prevent 1 million heart attacks and strokes in the U.S.  The initiative has set ambitious goals for improving compliance with various prevention strategies including controlling blood pressure and cholesterol.                                                                                                                                                                                                                                                                   About 34 million Americans don’t have their high blood pressure under control, including 11 million who don’t know they have it, according to CDC Director Tom Frieden. Patients with undiagnosed hypertension need to be identified, treatment should be simplified, and more can be done to help patients monitor their own blood pressure at home, he said.                                                                                                                                                                                         Another CDC and CMS project known as the Diabetes Prevention Program is based on a study that showed that modest weight loss with a healthy diet and regular exercise prevented more than half of high-risk patients from developing diabetes.                                                                                                                                                                                                                                                                                                                                                   “They didn’t lose a lot of weight but they were exercising and that made a huge difference in the rate of diabetes,” Dr. Gibbons said. “The program needs to be used on a much wider basis.”                                                                                                                                                                                                                                                               He also said cardiac rehabilitation designed for patients who have already suffered a heart attack or other serious event has been shown to improve survival and is another strategy that could be used more effectively to reduce heart-related deaths.                                                                                                                                                                                                                                                                                                                                                  Write to Betsy McKay at betsy.mckay@wsj.com and Ron Winslow at ron.winslow@wsj.com prevented more than half of high-risk patients from developing diabetes.