Heart attack deaths have plummeted in recent years — but other types of cardiovascular disease still pose a major threat.

A new study by the American Heart Association (AHA) found that overall heart disease-related death rates have declined by 66%, and heart attack deaths have dropped by almost 90%.

While heart attacks are no longer the most fatal form of heart disease, there have been increases in other types — heart failure, arrhythmias (irregular heartbeats) and hypertensive heart disease (long-term high blood pressure).

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The findings were published in the peer-reviewed Journal of the American Heart Association.

In the study, researchers analyzed more than 50 years of data from the U.S. Centers for Disease Control and Prevention (CDC), focusing on heart disease deaths among adults aged 25 and older.

In 1970, heart attacks — also known as ischemic heart disease — represented more than half (54%) of all heart disease deaths, the study found.

As of 2022, only 29% of heart disease deaths were caused by heart attacks.

Other types of heart disease deaths — such as heart failure, hypertensive heart disease and arrhythmia — have risen during that timeframe, however.

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In 2022, these other types were responsible for 47% of heart disease deaths, up from just 9% in 1970, the study found.

"This distribution shift in the types of heart disease people were dying from the most was very interesting to us," said the study’s first author, Sara King, M.D., a second-year internal medicine resident in the department of medicine at Stanford School of Medicine in Stanford, California, in the release. 

"This evolution over the past 50 years reflects incredible successes in the way heart attacks and other types of ischemic heart disease are managed," she went on.

"However, the substantial increase in deaths from other types of heart conditions, including heart failure and arrhythmias, poses emerging challenges the medical community must address."

Arrhythmias, or irregular heartbeats, happen when electrical impulses to the heart are too fast, slow or erratic, according to the AHA. One common example of an arrhythmia is atrial fibrillation (AFib), which begins in the upper chambers of the heart.

Heart failure is defined as a "chronic condition where the heart is unable to pump enough blood to meet the body's needs for blood and oxygen."

Hypertensive heart disease describes damage to the heart caused by long-term, unaddressed high blood pressure, the AHA stated.

Sadiya S. Khan, MD, a cardiologist and associate professor at Northwestern University in Chicago, was not involved in the study but commented on the "important analysis."

"Fortunately, this study suggests important progress in a preventable cause of death — heart attacks," she told Fox News Digital.

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"Unfortunately, it suggests that there is a smoldering crisis of other types of heart disease deaths that may be in part related to heart attacks, but speak to the growing burden of obesity that results in more heart failure and arrhythmia-related deaths."

"The increase in other types of heart disease leading to death has offset the wins from deaths from heart attacks declining."

The researchers presented several possible reasons for the decrease in heart attack deaths, primarily advancements in treatment for sudden and acute cardiac events.

"From the establishment and increased use of bystander CPR and automated external defibrillators (AEDs) to treat cardiac arrest outside the hospital setting, to the creation of systems of care that promote early recognition of and quick procedural and medical intervention to treat heart attacks, there have been great strides made in helping people survive initial acute cardiac events that were once considered a death sentence," King said in the release.

The researchers also touted several other medical advancements, including coronary artery bypass grafting, cardiac imaging and many new heart disease medications.

Healthy lifestyle modifications, such as quitting smoking, exercising regularly and managing cholesterol and blood pressure, have also contributed to the reduced heart attack deaths, the AHA report stated.

Khan added, "It is important to note that this doesn’t mean the heart attack may still not have been the driver, if someone with a heart attack developed heart failure and that is now called a heart failure death."

Despite the improvements, the researchers cautioned that several other heart disease risk factors — including obesity, type 2 diabetes, hypertension and physical inactivity — are still fueling cases.

Obesity in particular has risen from 15% to 40% during the study timeframe, and type 2 diabetes affects nearly half of U.S. adults, according to the report.

Increased life expectancy is another factor — as people are living longer, a larger aging population is more likely to experience various types of heart disease.

"We’ve won major battles against heart attacks; however, the war against heart disease isn’t over," King said. "We now need to tackle heart failure and other chronic conditions that affect people as they age."

"The next frontier in heart health must focus on preventing heart attacks, and also on helping people age with healthier hearts and avoiding chronic heart conditions later in life."

The AHA calculates heart health based on an individual’s score for what it calls "Life’s Essential 8."

Those who score high in those eight areas are, on average, six years younger biologically than their actual age. 

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The eight lifestyle behaviors for optimal heart health are listed below.

The researchers pointed out several limitations of their study, including that they did not analyze data by age, sex, race, ethnicity, region or urbanization.

There could also be potential inconsistencies and "miscoding" of data over the years, they noted.

It’s also possible that the "true burden" of heart attacks is "underestimated" in the findings, according to the researchers.

"Certain conditions including heart failure, cardiomyopathy and arrhythmias — and, in particular, ventricular arrhythmias and cardiac arrest — may be overly simplistic," they wrote. "Many of these cases likely have underlying causes that cannot be precisely differentiated using current or past ICD (International Classification of Diseases) codes."

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Khan pointed out that despite the decrease in direct heart attack deaths, heart disease overall is still the leading cause of mortality in the U.S., accounting for more than 900,000 deaths in 2022.

Senate Republicans pushed back against a leaked report that President Donald Trump’s strikes on Iran did not obliterate the Islamic Republic’s nuclear program, but still wanted more information on the full extent of the damage done to the key facilities.

A widely reported "low confidence" assessment from the Defense Intelligence Agency (DIA) suggested that the weekend strikes, dubbed Operation Midnight Hammer, did not completely destroy Iran's nuclear capabilities.

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Trump has remained firm that the sites were "totally obliterated," and the White House has strongly pushed back against the report. And both the Israeli and Iranian governments agree that the sites were badly damaged.

Members of the Senate Foreign Relations Committee and Senate Armed Services Committee told Fox News Digital that they were confident in the president’s assessment and pushed back against the DIA’s findings.

"First of all, one of the things I'd consider is the DIA said that Ukraine would be wiped out in three days," Sen. Kevin Cramer, R-N.D., told Fox News Digital. "And second, whatever the damage to Fordow is, the damage to the [nuclear] capabilities of Iran are devastating."

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Cramer said that the effectiveness of the bombing, which was carried out by several B-2 bombers armed with bunker-busting bombs, could not be "overstated," and warned that lingering questions surrounding the effectiveness of the operation were just "fodder for political discussion."

"I think the mission was accomplished," he said.

Senate Armed Services Committee Chair Roger Wicker, R-Miss., had not yet read the report, but called the DIA’s finding and subsequent news reports "bogus." Wicker’s sentiment came just after Senate Republicans met behind closed doors with Israeli Ambassador Yechiel Leiter.

"We just spoke to the Israeli ambassador to the United States just a few moments ago, and his assessment is that their capability has been destroyed for years," Wicker said.

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Still, just how damaged the nuclear facilities are, particularly the Fordow Fuel Enrichment Plant buried deep under layers of rock, is a question lawmakers want answered and believe would only come from a true boots-on-the-ground assessment.

Senators are set to receive a briefing Thursday afternoon from Trump officials on the strikes, and expect to learn more about the true extent of the damage.

Sen. Mike Rounds, R-S.D., told Fox News Digital that he’d seen all the evidence and there was not "an inconsistency" between the president’s assertions and the materials he had seen.

He said that the briefing would allow lawmakers "a chance from multiple sources to glean what's actually down deep underneath," but noted that until more clear information was available, absolute confirmation of the total damage wrought by the bombs was not complete.

Whether another strike should be authorized should further intelligence show that the program was not fully destroyed, Rounds said, "another strike depends on what the other options would be."

"I don't think you ever take anything off the table for the president, but there might be other ways of handling it as well, because we've really opened that place up now," he said.