Third Heart Sound During Atrial Fibrillation? Confirming the Existence of Cardiac Vibrations During Deceleration Phase of Early Diastolic Filling While in Atrial Fibrillation

Introduction The third heart sound (S3), caused by rapid deceleration of the blood against a stiff ventricle during early diastolic filling, is an early and specific sign of heart failure and elevated filling pressure. Studies have shown S3 to be coincident with deceleration phase of E-wave and associated with a steeper E-wave. Atrial fibrillation (AF) is a common comorbidity in HF, however questions have arisen regarding the ability to reliably detect S3 during AF as typically it is difficult to auscultate an S3 during AF. Here we present a case of simultaneous implanted device measured heart sound (HS) and echo data while the patient was in AF. Methods MultiSENSE enrolled patients implanted with COGNIS CRT-D devices and followed for up to a year. At enrollment CRT-Ds were converted to enable collection of HS data using device based accelerometer. HS data was periodically collected as ensemble averaged (EA) waveforms of multiple neighboring beats that closely matched in RR interval. An optional echo was conducted if the patient was hospitalized for worsening HF. An independent core laboratory measured parameters from the echo images, including E-wave timing within the cardiac cycle (Q-E interval and E-wave deceleration time or EDT). EA waveforms over multiple days around the day of echo that matched the average heart rate (HR) around the echo exam to within 10 beats per min were identified and compared against E-wave timing. Results The patient, enrolled in November 2011 and reported to have a history of AF, was hospitalized for worsening HF on day 38 post enrollment. Device interrogation revealed ongoing AF burden of 24 hours since enrollment which transiently terminated on day 41 for several days before reverting to 24 hour AF burden. Patient underwent an echocardiogram starting at 9:22AM on day 39, which showed a Q-E interval of 562msec and EDT of 169msec. Figure shows one heart sound EA recorded at 10:49AM and clearly shows cardiac vibrations during the deceleration phase of the E-wave as deduced from Q-E interval and EDT (horizontal line). This observation is consistent across all EAs collected over 5 days around the day of the echo with matched HR. Conclusion Consistent with its known physiologic genesis, S3 measured using an implanted device occurred during the deceleration phase of early diastolic filling even when the patient was in AF. A device based objective measure may provide more consistent assessment of S3 than auscultation in the midst of an arrhythmic rumble of AF.