Hypertension is a key risk factor for
cardiovascular disease. In this study, hypertension was defined as a top number
of 140 mmHg or higher, a bottom number of 90 or mmHg or the use of blood
pressure medication. In 2017, the Association updated its definition of
hypertension to be a top number of 130 mmHg or higher or a bottom number of 80
mmHg or higher.
High levels of lipoprotein(a), a type of “bad”
cholesterol, may be associated with an 18-20% higher risk of cardiovascular
disease among people who have hypertension, however, CVD risk was not higher
among those without hypertension, according to new research published in
Hypertension, an American Heart Association journal.
“High blood pressure is a known cardiovascular
disease risk factor, and lipoprotein(a) is a type of inherited ‘bad’
cholesterol that may also lead to cardiovascular disease,” said lead study
author Rishi Rikhi, M.D., M.S., a cardiovascular medicine fellow at Atrium
Health Wake Forest Baptist Medical Center in Winston-Salem, North Carolina. “We
found that among people with hypertension who have never experienced a stroke
or heart attack before, lipoprotein(a) seems to increase the risk of
cardiovascular disease and risk of a major cardiovascular event like heart
attack or stroke.”
Previous studies have indicated that when a
person has hypertension and lipid imbalance, or dyslipidemia, their
cardiovascular disease risk substantially increases. According to the study’s
authors, there is less information on how much of an affect lipoprotein(a) may
have on cardiovascular disease risk among people with hypertension.
Lipoproteins, which are made up of protein and
fat, carry cholesterol through the blood. The subtypes of lipoproteins include
low-density lipoprotein (LDL), high-density lipoprotein (HDL) and
lipoprotein(a), or Lp(a). Much like LDL cholesterol, lipoprotein(a) cholesterol
may deposit and build up in the walls of blood vessels, thus increasing a
person’s risk of a heart attack or stroke.
The research used health data from the Multi-Ethnic
Study of Atherosclerosis (MESA) study, an ongoing community-based study in the
U.S. of subclinical cardiovascular disease-meaning the disease is discovered
before there are clinical signs and symptoms. MESA is a research study
including nearly 7,000 adults that began in 2000 and is still following
participants in six locations across the U.S.: Baltimore; Chicago; New York;
Los Angeles County, California; Forsyth County, North Carolina; and St. Paul,
Minnesota. At the time of enrollment in the study, all participants were free
from cardiovascular disease.
The current study included 6,674 MESA
participants who had lipoprotein(a) levels and blood pressure assessed and for
whom there was documented cardiovascular disease event data throughout MESA’s
follow-up exams in approximately 2001, 2003, 2004, 2006, 2010, 2017 and in
telephone interviews every 9 to 12 months to gather interim data on new
diagnoses, procedures, hospitalization and deaths. The study’s participants
were from diverse racial and ethnic groups: 38.6% self-identified as white
adults; 27.5% self-identified as African American adults; 22.1% self-identified
as Hispanic adults; and 11.9% self-identified as Chinese American (n=791)
adults. Additionally, more than half of
the group was female (52.8%).
To evaluate the potential correlation between
hypertension and lipoprotein(a) on the development of cardiovascular disease,
the researchers first categorized the participants into groups based on their
lipoprotein(a) levels and blood pressure measures obtained once at baseline:
Group 1 (2,837 people): lipoprotein(a) levels
less than 50 mg/dL and no hypertension.
Group 2 (615 people): lipoprotein(a) levels
greater than or equal to 50mg/dL and no hypertension
Group 3 (2,502 people): lipoprotein(a) levels
less than 50mg/dL and hypertension
Group
4 (720 people): lipoprotein(a) levels ≥ 50mg/dL and hypertension
Participants were followed for an average of
approximately 14 years and cardiovascular events, including heart attack,
cardiac arrest, stroke or death from coronary artery disease, were tracked.
The study’s results include:
A total of 809 of the participants experienced
a cardiovascular disease event.
Lipoprotein(a) levels had an effect on
hypertension status that was statistically significant (meaning it was not due
to chance).
When compared to Group 1 (low lipoprotein(a)
levels and no hypertension), Group 2 (higher lipoprotein(a) levels and no
hypertension) did not have an increased risk for cardiovascular disease events.
Less than 10% of Group 1 (7.7%) and Group 2
(participants 8%) had cardiovascular disease events.
Participants in Groups 3 and 4, all of whom
had hypertension, demonstrated a statistically significant increase in risk for
cardiovascular disease events when compared to those in Group 1.
Approximately 16.2% of the people in Group 3
(lower lipoprotein(a) levels and hypertension) had cardiovascular disease
events, and 18.8% of the participants in Group 4 (higher lipoprotein(a) levels
and hypertension) experienced cardiovascular disease events.
“We found that the overwhelming amount of
cardiovascular risk in this diverse population appears to be due to
hypertension,” Rikhi said. “Additionally, individuals with hypertension had
even higher cardiovascular risk when lipoprotein(a) was elevated. The fact that
lipoprotein(a) appears to modify the relationship between hypertension and
cardiovascular disease is interesting, and suggests important interactions or
relationships for hypertension, lipoprotein(a) and cardiovascular disease, and
more research is needed.”
Everyone can improve their cardiovascular
health by following the American Heart Association’s Life’s Essential 8: eating
healthy food, being physically active, not smoking, getting enough sleep,
maintaining a healthy weight, and controlling cholesterol, blood sugar and
blood pressure levels. Cardiovascular disease claims more lives each year in
the U.S. than all forms of cancer and chronic lower respiratory disease
combined, according to the American Heart Association.
The study had limitations, including potential
selection bias from participants – potentially disproportionately from one of
the four subgroups – dropping out because the study was long-term.
Additionally, the study participants may have developed hypertension during the
follow-up period, which may have resulted in misclassification.
Reference:
Rishi Rikhi et al,Association of Lp(a) (Lipoprotein[a]) and hypertension
in primary prevention of cardiovascular disease: The MESA, Hypertension,
DOI:10.1161/HYPERTENSIONAHA.122.20189