Validation of a Novel Smartphone-based Photoplethysmographic Method for Ambulatory Heart Rhythm Monitoring in Connection to Treatment of Atrial Fibrillation With Direct Current Cardioversion

Atrial fibrillation is a heart rhythm disorder with increased risk of stroke, heart failure, dementia and death. The severity of symptoms in atrial fibrillation varies markedly, ranging from no symptoms to those with disabling symptoms. An ECG recording is currently mandatory for diagnosing atrial fibrillation.

The availability of long-term ECG and portable ECG registration for heart rhythm diagnostics within the healthcare sector is severely limited by waiting time both for ECG recording and for analysis and reporting. A method for heart rhythm diagnostics that is readily available is currently lacking in clinical practice, except for hospitalization, which is very costly and has low availability.

The lack of a method for diagnosis of heart rhythm disorders and atrial fibrillation that is readily available, cost-effective and simple to use is a problem for both the patients and for the healthcare system as a whole. The limited availability of patient-related diagnostics thus means that many patients, even those with symptoms, remain undiagnosed and thus untreated, which in turn means that the missing diagnosis gives an increased risk of stroke. If a standard smartphone could be used for reliable heart rhythm diagnostics, the availability could improve greatly.

Treatment with direct current cardioversion is a procedure in which the heart rhythm is normalized by an electrical shock through the chest. Patients with atrial fibrillation could in some cases be treated with cardioversion but the procedure is costly, has a high recurrence rate and includes an increased risk for thromboembolism and stroke. The benefit of the treatment is mainly symptomatic, with no proven long-term effects of mortality or morbidity.

In this study we will validate the use of a novel smartphone-based method for heart rhythm diagnostics when used by patients in their home environment after receiving treatment with direct current cardioversion. The novel method is using the smartphone camera as a sensor and records photoplethysmographic (PPG) measurements. We will also study the feasibility in using smartphone and mobile ECG recordings peri-cardioversion, to study the possible benefit of detecting pre-cardioversion spontaneous conversions to sinus rhythm and non-adherence to treatment with oral anticoagulants, both of which will lead to cancellation or detention of the cardioversion procedure. We will also detect the timing of post-cardioversion early recurrences into atrial fibrillation, as well as the heart rate and symptoms associated to recurrence, if any.