A recent study by doctors at Toronto’s Hospital for Sick Children suggests that current screening guidelines for children from HCM families are inadequate and should instead recommend earlier screening exams. In the U.S., screening begins at age 12 pursuant to American College of Cardiology (ACC)/American Heart Association (AHA) guidelines. In Europe, screening begins at age 10 pursuant to the European Society of Cardiology (ESC) guidelines.
According to a limited study recently published in Nature, researchers were able to detect obstructive HCM (HOCM) using a noninvasive optical sensor contained in many commercial smartwatches.
How the Technology Works
These watches used photoplethysmography, a noninvasive optical method used to detect blood volume changes in the microvascular bed at the skin surface. The same technology is used in clinical pulse oximeters and is now widely incorporated in commercial smartwatches that have heart rate detection.
A recent study published in Circulation suggests that clinical testing of kids who are first degree family members of HCM patients (i.e. siblings and children of those who have already been diagnosed with HCM) could be improved by starting testing at a younger age. And, genetic testing should further improve diagnosis and treatment for this group.
A recent editorial published in Circulation: Genomic and Precision Medicine suggests that current HCM screening protocols may need adjustment to account for recent findings by a study by researchers in the Netherlands. The Dutch study, published in the same journal, found that of 620 relatives of HCM patients who underwent genetic testing, 43% were found to be genetically positive for HCM, while 30% were diagnosed with HCM at the initial screening. 16% more went on to develop HCM during 7 years of repeated cardiac evaluation.
On the other hand, the 57% of relatives found to be genotype-negative were released from clinical HCM follow-up.
The Australian authors of the editorial, Semsarian and Ingles, note that current screening protocols would have failed to identify the 6 children (15%) who were diagnosed under the age of 12, half of which had a particularly malignant family history.
Additionally, few teens were diagnosed with HCM, which stands in contrast to current opinion that HCM is most likely to develop during adolescence. Indeed, most newly diagnosed family members were older than the age of 36, with 44% being over the age of 50.
Lastly, Semsarian and Ingles note their concern with general utilization of the Dutch practice of releasing a gene negative family member from serial follow up since the impact of all genes which have a role in causing HCM is not yet known while new genes which may cause HCM are still being identified.
Semsarian and Ingles also note that the Dutch patient sample differs from more typical patient populations found in the U.S. and Australia where causes of HCM are more diverse and cannot be easily tied to a specific gene.
A recent Canadian study found that children with HCM who carry a single mutation in the MYH7 gene or who have multiple HCM-causative genetic mutations are at increased risk of major adverse cardiac events when compared to children who carry a single mutation in another gene.
Of the 98 gene positive children in this study, those with a MYH7 mutation or those with multiple mutations were more likely to need a myectomy or an ICD or to experience a sudden cardiac arrest or a heart transplant when compared to children with other HCM causative mutations.
The article also suggests that current screening protocols which recommend clinical and genetic screening for HCM beginning at age 12 may be insufficient.
Editor’s Note: This post originally appeared on the blog of Dr. Howard J. Luks. Dr. Luks wrote this blog entry in collaboration with HCM expert Dr. Srihari S. Naidu of New York’s Westchester Medical Center. You can find the original post here. You can find both Dr. Luks and Dr. Naidu on Twitter @hjluks and @SrihariNaiduMD.
Sudden cardiac death in young athletes continues with alarming frequency. The most common cause of sudden death in the young athlete is hypertrophic cardiomyopathy or HCM. Simply put, HCM means the heart muscle is bigger. Many of us believe that bigger muscle means stronger muscle. That is not always the case with the heart. The heart is a mechanical pump with a complex arrangement of chambers which store the blood. How that pump works is controlled by a very complex electrical system. Hypertrophic cardiomyopathy can interfere with one or both of these critical functions of the heart and lead to sudden cardiac death.
According to researchers at the University of Michigan, family members of HCM patients who have tested negative for genes associated with HCM and without a family history of HCM will usually be found to be free of HCM during routine family screening. And, in accordance a recent Australian study, relatives of these patients may be able to benefit from less rigorous screening protocols.
Patients with a known sarcomere mutation appear to have a different clinical profile, according to the researchers: they have more hypertrophy; they are younger when diagnosed; they have a higher risk for adverse events; and they are more likely to have a family history for the condition.
In contrast, when the initial diagnosis is made in a patient who is 50 or older with no known genetic mutations, a negative family history, and sigmoidal septal pattern hypertrophy, reduced family screenings may be appropriate and less burdensome. In addition, hypertension, large family size with no other affected family members, less severe hypertrophy, and lack of life-threatening complications related to HCM may provide additional comfort to families of newly diagnosed HCM patients.
The reduced protocol would consist of a single screening of adult family members, with the caveat that if and when any additional family additional member is found to have HCM, a more traditional screening protocol be instituted.
(Note that standard screening guidelines recommend screening of all first-degree family members of patients beginning with adolescence, repeated annually through the end of adolescent growth, and repeated every 3 – 5 years for life.)
Lisa Yu, founder of Children’s Cardiomyopathy Foundation, posted this article today on Huffington Post. This piece summarizes the efforts currently being made to screen Olympic athletes and elaborates on how better screening and response protocols might help to avoid tragedies.
A recent study followed 14 patients carrying one of two known genes associated with HCM (MYBPC3 and MYH7) over a 10+ year period . At the time of gene identification, none of the patients shown clinical evidence of hypertrophy. Over the time span of the study, 3 patients, who were then adults, had developed signs of HCM. Hence, the study suggests that periodic screenings are necessary for gene positive individuals throughout adulthood.
According to Cardiomyopathy U.K., the researchers undertook this project due to the lack of information and guidelines available to patients who are gene positive but have no outward signs of the disease.