Distance in meters walked in 6 minutes, longer distances indicate greater functional capacity. Missing 6MWT values due to non-COVID-19 death or inability to walk due to ATTR disease progression were imputed using the worst 10th percentile change observed in the DB period. Missing 6-MWT values due to other reasons are multiply imputed to create 100 complete datasets. The change from baseline is averaged across the 100 complete datasets.

Full Analysis Set: All randomized participants who received any amount of study drug. Participants were analyzed according to the treatment to which they were randomized.

The KCCQ is a 23-item self-administered questionnaire quantifying 6 domains (symptoms, physical function, quality of life, social limitation, self-efficacy, and symptom stability) and 2 summary scores (clinical and overall summary [OS]). Scores are transformed to a range of 0-100, in which higher scores reflect better health status.

Full Analysis Set: All randomized participants who received any amount of study drug. Participants were analyzed according to the treatment to which they were randomized. 'Overall number of participants analyzed' indicates the number of participants with data available for outcome measure analysis at the specified timepoint.

The composite endpoint was analyzed using the stratified win ratio method, stratified by baseline tafamidis use. This method combines all-cause mortality, frequency of CV events (CV hospitalizations and HF visits) and change from baseline in 6-MWT in a hierarchical fashion. This method makes within-stratum pairwise comparisons for all patisiran-placebo participant pairs in a sequential manner (first mortality, then CV events, then 6-MWT), with later steps evaluated only in the case of a tie on the prior step. Within each stratum, the win ratio is the total number of 'winners' divided by the total number of 'losers' in the active group. A win ratio >1 represents a favorable outcome for patisiran.

Participants from the Full Analysis Set (all randomized participants who received any amount of study drug (either placebo or patisiran), grouped based on their use of tafamidis at Baseline as pre-specified in the study protocol.

The hazard rate of all-cause mortality and all-cause hospitalizations and urgent HF visits will be compared between treatment groups using an Andersen-Gill model. A hazard ratio <1 represents a favorable outcome for patisiran.

Participants from the Full Analysis Set [all randomized participants who received any amount of study drug (placebo or patisiran)] and were not receiving tafamidis at Baseline were included in the data analysis for the outcome measure as pre-specified in the study protocol.

The hazard rate of all-cause mortality and all-cause hospitalizations and urgent HF visits was compared between treatment groups using a modified Andersen-Gill model. A hazard ratio <1 represents a favorable outcome for patisiran.

All the participants from the Full Analysis Set [all randomized participants who received any amount of study drug (either placebo or patisiran)] were included in the data analysis for the outcome measure as pre-specified in the study protocol.