A multitude of diseases fall under the umbrella of cardiovascular disease (CVD), but most hospital admissions occur for three conditions: cardiac heart failure, myocardial infarction (heart attack), and angina pectoris (ischemic chest pain). CVD is often associated with other comorbidities that places the individual at increased risk of severe complications associated with COVID-19.
Impact of COVID-19 on the cardiovascular system. Source: European Heart Journal
Previous coronavirus- and influenza-type respiratory virus infection pandemics, which include the Middle East respiratory syndrome (MERS), SARS, and H1N1 influenza, have shown that extrapulmonary manifestations in the form of acute and chronic cardiovascular complications typically follow in the aftermath of these disease infections.
While there is still much to be learned about the relation between COVID-19 and CVD, early data shows a striking trend. According to China’s CDC, the overall case fatality rate of men with COVID-19 was 2.8% and for women, 1.7%. However, for patients with both COVID-19 and CVD, there was a much higher case fatality rate of 10.5%. In contrast, patients with no comorbidities show a case fatality rate of 0.9%.
These striking statistics clearly highlight the need to maintain good cardiovascular health as one of the ways to increase the survival rate of patients with both CVD and COVID-19.
Market size of cardiovascular disease diagnostic kits:
The global market for diagnostic kits for CVD is expected to experience significant growth. This is due to the long-term effects of COVID-19 as extrapulmonary manifestations in the form of acute and chronic cardiovascular complications seen in a substantial percentage of the population. Before the COVID-19 pandemic hit the world, the cardiac biomarker diagnostic kits global market was valued at $2.1 billion in 2018 and was expected to grow at a CAGR of 5.3% from 2019 to 2027.
With more than 500,000 new cases of angina pectoris being registered every year in the United States, it was driving the market growth in this region. The total direct medical expenditure in relation to cardiovascular diseases was estimated to exceed $700 billion by 2035, according to a 2016 American Heart Association study. But the full impact of COVID-19 on this market will only be apparent after some semblance of stability is achieved in the world.
Current diagnostic methods:
In order to make a conclusive diagnosis, physicians often have to rely on imaging or more invasive procedures such as cardiac catheterization. For a patient presenting with chest pain in the emergency room, a quick test to diagnose the type of damage sustained by the heart is crucial in helping the physician determine the right therapy and prevent further damage to the heart. It is here that cardiac biomarker tests play a huge role in early diagnosis and preventing further complications after the initial myocardial injury suffered by the patient. A few of these cardiac biomarker diagnostic test kits are discussed below:
- Troponin test kits – This test is the most sensitive and specific to detect heart muscle damage. Troponin is a protein complex released during the breakdown of the heart muscle during a myocardial infarction. It starts being released 2-4 hours after the injury, and the peak is reached after 12 hours and can persist for 7 days. Elevated troponin levels indicate a recent or continuing heart attack.
- CK-MB test kits – As creatine kinase is an enzyme that is located in a number of tissues in the body, it is relatively specific only when there is no accompanying skeletal muscle damage present. Creatine kinase myocardial band (CK-MB) is expressed in the heart muscle, with the peak being achieved in 10-24 hours of myocardial infarction. Since it is only present for a short duration of 2-3 days, it cannot be used for late diagnosis.
- Myoglobin test kits – Myoglobin is an oxygen-carrying pigment in muscle tissues. As it can be present in the blood or urine after any kind of muscle damage, it is not specific enough to detect heart attacks. But the advantage of this test is that it is the most rapidly responsive test currently available. Since myoglobin reaches peak levels in as low as 2 hours and normalizes similarly rapidly, it may be used as a screening test for ongoing heart attacks.
Recent advances in early diagnostics of cardiovascular disease:
AI-based algorithms and digital tools will have a huge role in providing support and follow-up to patients with CVD, thereby reducing their risk of repeat hospitalization. A few examples include and are highlighted below.
Apple Heart Study
Apple conducted a joint study called the Apple Heart Study to test the Apple irregular pulse notification algorithm to detect atrial fibrillation, which can multiply the risk of stroke fourfold.
In this siteless study, the photoplethysmography (PPG) sensor on an Apple watch was used to monitor atrial fibrillation or atrial flutter in 419,297 participants over 117 days. An app that was installed on the phone for the study would send out notifications of an irregular pulse as soon as it was detected and initiate a telemedicine visit. Participants were also mailed an electrocardiography (ECG) patch that was to be worn for 7 days. The readings from both sources were studied and compared.
Of all the participants who reported atrial fibrillation, only 13% were notified by the Apple watch. In terms of sensitivity, only 56% of the notifications correlated with the ECG readings simultaneously. Moreover, 66% of participants received notifications when they were confirmed to have no irregular pulse on the ECG readings, which suggests low specificity.
As atrial fibrillation tends to be paroxysmal and infrequent, this also causes ECG readings to be read as normal during healthcare visits, giving patients a false sense of security. This also highlights the many improvements that consumer devices like the Apple watch need to make to be comparable to medical devices before being deployed for use by patients.
Fitbit Sense
Fitbit has recently received approval by the US Food and Drug Administration (FDA) and the Conformité Européenne (CE) designation in the European Union for its electrocardiogram (ECG) app, which can be used to study heart rhythms to assess for atrial fibrillation. This app, which will be available starting in October 2020, is used with the Fitbit Sense smartwatch. It demonstrated a sensitivity of 98.7% in detecting atrial fibrillation and 100% accuracy in identifying clinical trial study participants with a normal sinus rhythm, also demonstrating its specificity.
But the caveat here is that this is currently a spot-check technology. To check for atrial fibrillation, the user must place their fingers on the corners of the watch on the steel bezel (where the sensors are located) and sit still for 30 seconds to a minute. The results will appear and the next steps suggested accordingly on the watch display.
For long-term heart rate monitoring, Fitbit is currently conducting a photoplethysmography (PPG)-sensor based heart study to validate its PurePulse technology, which detects fluctuations in blood flow and pulse rate in the blood vessels in the wrist using a PPG sensor. This is meant to be a pathway to monitor asymptomatic atrial fibrillation events, similar to Apple’s study above, while the ECG-based functionality can be used as a spot-check test by users who wish to screen themselves for atrial fibrillation.
A smart device such as a watch that can silently and continuously monitor patients, and send out push notifications, nudging patients to seek timely medical intervention, will be a huge help to patients at high risk of CVD. Although the Apple study had multiple inconsistencies due to relying on the participants to follow study protocols, and with Fitbit attempting to solve this problem as well, it shouldn’t take long for concrete technological solutions in telemedicine targeting cardiac health to emerge.
Adhesive wireless smart patches
There are several wirelesses and or adhesive smart patch devices for continuous monitoring of cardiac arrhythmia. One such device is the Zio Patch by iRhythm Technologies, a single-lead ECG patch monitor. It is waterproof, has no external leads or wires, and can be self-applied by the patient, thus minimizing any interference in daily activities. It is to be worn continuously for 14 days, after which it is mailed to a facility for the analysis of data, with the report being shared with the ordering physician.
The Zio Patch. Source: iRhythm Technologies
Insertable cardiac monitors
For longer periods of monitoring, doctors can recommend insertable cardiac monitors such as those manufactured by Medtronic. These can provide data for up to 3 years. Once implanted just under the skin, these monitors can communicate to the patient’s smartphone or the home communicator for the device and transmit data automatically to the physician. Detection of an event triggers a notification and an actionable alert.
Insertable Cardiac Monitors – Source: Medtronic
CardioMEMS HF System – Abbott
The previous options for cardiac monitors primarily measure the ECG, which is only capable of detecting a worsening heart condition when the individuals at high risk of heart failure are quite close to having an event. As a solution to this, Abbott’s CardioMEMS HF System offers a wireless sensor the size of a paper clip, which is directly implanted in the individual’s pulmonary artery via a catheterization procedure to measure arterial pressure.
This permanent implant has done away with the problem of batteries and long-term data collection by making use of radio frequency (RF) transmission technology. This technology enables detection of an impending heart failure event almost 30 days before requiring hospitalization, when the individual is hemodynamically stable, as compared to the 10 to 20 days before hospitalization when markers for presymptomatic congestion, such as intrathoracic impedance changes, appear.
In contrast to markers such as weight and blood pressure, which present much closer to the heart failure event and thus force healthcare practitioners to be merely reactive, measurements of arterial pressure made directly using the CardioMEMS HF System allow for better preparation prior to treating patients. The long-term data is also used to help patients proactively make appropriate changes to their healthcare routine simply by changing their medications, often without the need for an appointment, thus preventing hospitalizations.
Conclusions and future outlook:
Respiratory disease–based pneumonia can lead to serious cardiovascular complications, requiring regular follow-ups for the following decade. Even after recovery, 25 SARS victims did not regain normal function even after 12 years. However, in the case of H7N9-infected patients, cardiac function regained normalcy by the 1-year follow-up mark. These results indicate that there is a severe need for long-term studies to be done on the cardiovascular impact of COVID-19 to prepare for similar outbreaks in the future.
In an early report outlining clinical conditions of 138 patients hospitalized in Wuhan due to pneumonia associated with COVID-19, 7.2% developed an acute cardiac injury, while 16.7% experienced arrhythmia. With 41 million infected worldwide and 8.5 million cases in the United States alone (and counting), it is clear that there will be a massive influx of CVD patients as a result of COVID-19. Medical device companies must ramp up production to be able to supply enough devices to safely and remotely monitor these large numbers of new patients. The resulting data would greatly help the medical community in long-term studies for designing better treatment and disease management plans.
